Abstract
Purpose
To assess the safety and feasibility of intravitreal injection of autologous CD34+ bone marrow stem cells (BMSCs) in eyes with vision loss from central retinal vein occlusion (CRVO).
Design
Phase I/II single-center, prospective, randomized, sham-controlled, double-masked study.
Participants
Participants with CRVO of 6 to 42 months duration, best-corrected visual acuity (VA) of 20/40 to 20/400, and no concurrent retinopathy or optic neuropathy contributing to vision loss in the study eye. The exclusion criteria include any concurrent systemic condition that would alter bone marrow components.
Methods
Participants were randomized to immediate cell injection followed by sham injection at month 6 or immediate sham injection followed by cell injection at month 6. Cell injection consisted of a bone marrow aspiration and intravitreal injection of autologous CD34+ BMSCs. CD34+ BMSCs were isolated from the mononuclear cell fraction of bone marrow using Miltenyi CliniMACS system under current good manufacturing practices. Isolated cells were released for intravitreal injection if they passed the release criteria for quantity, sterility, and viability accepted by the US Food and Drug Administration. Sham injection consisted of a sham bone marrow aspiration and intravitreal injection without entering bone or eye. Eye examination, microperimetry, fundus photography, fluorescein angiography, electroretinography, OCT, and OCT angiography were performed at baseline and during study follow-up of 12 months.
Main Outcome Measures
Adverse events (AEs) associated with study treatment, number of CD34+ BMSCs injected intravitreally.
Results
Sixteen participants (16 eyes) were randomized to 1 of 2 study groups. All received intravitreal injection of autologous CD34+ BMSCs (mean 4.3 million cells) and completed the study follow-up. Rubeosis with vitreous hemorrhage occurred in 1 study eye, <1 month after sham injection and 7 months after cell injection, attributed to normal progression of CRVO. There were no other serious ocular AEs. The most common AE related to the study cell injection was new floaters (15/16, 93%). Other ocular AEs were similarly noted after sham injection. No eye had persistent VA loss of ≥15 letters after cell injection.
Conclusions
Intravitreal injection of autologous CD34+ BMSCs appears well-tolerated and feasible in eyes with vision loss from CRVO.
Financial Disclosure(s)
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
Keywords: Autologous stem cells, Bone marrow stem cells, CD34+ cells, Intravitreal cell injection, Retinal vein occlusion
Retinal vein occlusion (RVO), including central RVO (CRVO), is the most common retinal vascular disorder after diabetic retinopathy. Approximately 16 million persons are afflicted with RVO worldwide.1,2 The incidence of RVO increases with age and is estimated to be 1% to 2% in 10 to 15 years among the population >40 years of age.2
Vision loss associated with RVO occurs due to retinal ischemia and secondary macular edema, a complication of the retinal ischemia.3,4 Secondary macular edema can develop and contribute to vision loss in some eyes. Currently, macular edema can be treated with intravitreal drug or laser therapy, but there is no treatment for vision loss associated with retinal ischemia, which may lead to retinal degeneration and dysfunction.5,6 In fact, RVO is one of the leading causes of unilateral blindness in the elderly population.
Our group has explored the potential use of intravitreal injection of human CD34+ bone marrow stem cells (BMSCs) as potential treatment for vision loss from retinal ischemia or degeneration.7, 8, 9, 10, 11 Human CD34+ stem cells are found in highest concentration in bone marrow. These CD34+ cells are natural repair cells that mobilize into the systemic circulation in response to tissue ischemia, home to ischemic tissue, and promote repair via paracrine mechanisms.12 Because some of these CD34+ cells are endothelial progenitor cells, CD34+ cells also may engraft into the damaged vascular endothelium.13 Clinical trials have explored local intravenous infusion of autologous CD34+ cells as therapy for ischemic conditions, such as cardiomyopathy, and have demonstrated safety and efficacy.14,15 By harvesting cells from bone marrow and directly injecting the cells in the vitreous, we aim to maximize the repair potential of these cells on the retina.
Intravitreal injection of human CD34+ cells was first explored by Caballero et al13 using rodent models of retinal vasculopathy. They showed that injected CD34+ cells rapidly homed into the damaged retinal vasculature, similar to that observed after intravenous infusion. More recently, our group demonstrated that intravitreal injection of human CD34+ BMSCs results in preservation of the retinal vasculature in a murine model of diabetic retinopathy with systemic immunosuppression to avoid rejection of human cells.11 We also demonstrated long-term ocular and systemic safety of intravitreal injection of human CD34+ BMSCs using a nonobese diabetic-severe combined immunodefficiency murine model of retinal ischemia-reperfusion injury.16
Based on these promising preclinical studies, we obtained an investigational new drug (IND) clearance from the US Food and Drug Administration (FDA) to start clinical trials exploring intravitreal injection of autologous CD34+ BMSCs in eyes with retinopathy. Our pilot phase I study showed safety and feasibility among 6 participants with vision loss from various retinal disorders, including atrophic nonexudative age-related macular degeneration, retinitis pigmentosa, hereditary macular dystrophy, and CRVO.8 Among the pilot study participants, the participant with vision loss from CRVO had the largest improvement in visual acuity (VA) after cell injection. In order to study further the safety, feasibility, and potential efficacy of this cell therapy in eyes with vision loss from CRVO, this larger phase I/II, randomized, sham-controlled, double-masked study, called the TRUST Study (Treatment of Retinal vein occlusion Using STem cells) was conducted. In this TRUST Report #1, we summarize the primary outcome measures of the study, namely feasibility and safety of this novel cell therapy. Subsequent TRUST Reports are planned to summarize functional and imaging analysis of the study eyes and further characterize the isolated CD34+ cells and the isolation process.
Methods
This is a phase I/II, prospective, randomized, double-masked, sham-controlled study that enrolled patients seen at the University of California, Davis (UC Davis) Eye Center between October 2019 and October 2022. The study was conducted under an IND clearance (IND #17023; cross-referenced IND #13307) from the FDA and followed a protocol that was approved by the UC Davis Office of Human Research (local institutional review board) and UC Davis Stem Cell Oversight Committee.
The Emmes Company was the Data Coordinating Center (DCC) for the study. A Data Safety and Monitoring Committee selected by the study sponsor (National Eye Institute), the UC Davis Office of Human Research, the UC Davis Stem Cell Oversight Committee, and the FDA provided oversight for the duration of the study. The study enrollment began after the study was registered on www.clinicaltrials.gov (NCT03981549). The study protocol is available in www.clinicaltrials.gov. The study was conducted in adherence to the Declaration of Helsinki, the National Institute of Health guidelines for clinical research, and the guidelines outlined by the International Society of Stem Cell Research. All participants signed an informed consent form at study enrollment.
The study enrolled all patients seen at the study center with CRVO who met the study inclusion and exclusion criteria, agreed to participate in the study, and signed the informed consent form. The enrollment period was extended during the course of the study due to the coronavirus disease 2019 (COVID-19) pandemic and associated travel restrictions that went into effect to varying degrees during the enrollment period. The final study inclusion and exclusion criteria are summarized in Supplemental Table 1a, available at www.ophthalmologyscience.org. If both eyes met study eye inclusion and exclusion criteria, the eye with the worse ETDRS best-corrected VA (BCVA) at the screening visit was selected as the study eye. If both eyes had equal BCVA, the eye with more stable fixation on microperimetry was selected as the study eye. During the course of the study, several changes to the study protocol were made as summarized in Supplemental Table 1b. The upper limit of the enrollment BCVA criteria of the study eye was changed from 20/60+ to 20/40+ and the duration of CRVO prior to study enrollment was extended from 36 months to 42 months to increase study enrollment and minimize study screen failure. The study follow-up duration was shortened from 24 months to 12 months to increase enrollment and ensure study completion within the funding period. The diagnosis of CRVO was confirmed by the study principal investigator (S.S.P.) before study enrollment based on past ocular history, clinical examination, fundus photography, fluorescein angiography, and macular OCT.
The study schedule is summarized in Table 1. After obtaining informed consent, a copy of which is included as Supplemental Material, each participant had a comprehensive eye examination with ETDRS BCVA, fundus photography, fundus autofluorescence, fluorescein angiography, macular OCT, OCT angiography (OCTA), microperimetry, and electroretinography (ERG), both full-field and multifocal ERG. For women of childbearing age, a urine pregnancy test was performed at baseline and at month 6; all participants of childbearing age were required to abstain from intercourse or practice effective contraception for the duration of the study. In addition, each participant completed a National Eye Institute Visual Function Questionnaire and hematology consult. Vital signs and a blood sample for a complete blood count were obtained. Each participant was also given the option to consent to high-resolution OCT and OCTA imaging using a research grade, ultrahigh-resolution OCT/OCTA instrument custom-made by the UC Davis Advanced Retinal Imaging Lab if the study eye had stable fixation on microperimetry and clear media on OCTA, that is, signal strength >6 on 3 mm macular scan.
Table 1.
Study Visit Schedule
| Visit | Screening Period |
Study Period 1 |
Study Period 2 |
Study Exit¶ | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Screening or Baseline 1 | Study Treatment 1 | Day 1 | Week 1 | Month 1 | Month 3 | Month 6 or Baseline 2# | Study Treatment 2# | Day 1 | Week 1 | Month 1 | Month 3 | Month 6 | ||
| Target month | + | - | - | - | 1 | 3 | 6 | - | - | - | 7 | 9 | 12 | ¶ |
| Target day | - | 0 | 1 | 7 | 28 | 91 | 181 | 182 | 183 | 190 | 210 | 273 | 364 | ¶ |
| Window | + | - | - | ±2 d | ±7 d | ±14 d | ±30 d | ±30 d | - | ±2 d | ±7 d | ±14 d | ±30 d | ¶ |
| Medical history/ROS | X | X | X | X | X | X | X | X | X | X | X | X | X | |
| Ophthalmic history | X | X | X | X | X | X | X | X | X | X | X | X | X | |
| Assessment of concomitant medications | X | X | X | X | X | X | X | X | X | X | X | X | X | X |
| Informed consent | X | |||||||||||||
| Vital signs | X | X∗ | X | X | X | X∗ | X | X | ||||||
| CBC | X | X | X | X | ||||||||||
| Urine pregnancy test† | X | X | ||||||||||||
| ETDRS VA | X | X∗∗ | X∗∗ | X∗∗ | X | X | X | X∗∗ | X∗∗ | X∗∗ | X | X | X | |
| Microperimetry | X | X | X | X | X | X | X | |||||||
| Eye examination and IOP | X | X†† | X | X | X | X | X | X†† | X | X | X | X | X | |
| Fundus photography | X | X | X | X | X | |||||||||
| FA | X | X | X | X | X | |||||||||
| OCT/OCTA | X | X | X | X | X | X | X | |||||||
| AF | X | X | X | X | X | |||||||||
| ERG‡ | X | X | X | X | X | X | X | |||||||
| NEI VFQ | X | X | X | |||||||||||
| Advanced retinal imaging§ | X | X | X | |||||||||||
| Hematology consult | X | X | ||||||||||||
| Cellular or sham therapy‖ | X | X | ||||||||||||
| Adverse events | X | X | X | X | X | X | X | X | X | X | X | X | X | X |
| Postprocedure satisfaction survey | X | X | ||||||||||||
| Study satisfaction survey | X | X | ||||||||||||
AF = fundus autofluorescence; CBC = complete blood count; ERG = electroretinography; FA = fluorescein angiography; IOP = intraocular pressure; NEI VFQ = National Eye Institute Visual Function Questionnaire; OCTA = OCT angiography; ROS = review of systems; VA = visual acuity.
Shaded cells represent visits which are conducted by unmasked staff.
Vital signs at study treatment 1 and study treatment 2 will be performed just before and after bone marrow or sham aspiration.
For women of childbearing potential, urine pregnancy testing should be done within 2 weeks prior to sham or cellular therapy.
Includes full field and multifocal ERG.
Optional ultrahigh resolution OCT and OCTA imaging offered to participants with stable fixation on microperimetry and OCTA signal strength >6.
For immediate cell therapy or deferred sham therapy group, study treatment at day 0 consists of bone marrow aspiration followed by intravitreal injection of CD34+ cells, and study treatment at 6 months consists of sham bone marrow aspiration followed by sham injection. For immediate sham therapy or deferred cell therapy group, treatment at day 0 consists of sham bone marrow aspiration followed by sham injection, and study treatment at 6 months consists of bone marrow aspiration followed by intravitreal injection of CD34+ cells.
The exit visit is comprised of review and close-out of adverse events and concomitant medication records and completion of the study satisfaction survey.
The baseline 2 and study treatment 2 visit must be separated by ≥1 day but <30 days.
Using refraction previously obtained at Baseline visit.
Study Treatment 1 and Study Treatment 2 eye examinations will be done before and after cell or sham injection.
Each enrolled study participant who completed the baseline diagnostic testing and met the study inclusion and exclusion criteria was randomized 1:1 to 1 of 2 treatment groups by the DCC, using a web-based permuted block design with random block sizes of 2 and 4 (with equal weight) (See Fig 1). The immediate cellular/deferred sham group (referred to as “immediate cell”) received study cell injection in the study eye on day 0 and received sham study injection in the study eye 6 months later. The immediate sham/deferred cellular group (referred to as “immediate sham”) received sham study injection in the study eye on day 0 and received the study cell injection in the study eye 6 months later. Treatment period 1 refers to the period starting on the day of the first study treatment (cell or sham) (day 0) up to but not including the day of second injection. Treatment period 2 refers to the period starting on the day of the second study treatment (cell or sham) through study completion.
Figure 1.
Study schema. A summary of screening process for selecting study participants, randomization for study treatment, and schedule of study follow-up. ∗ Some baseline evaluations may be done postrandomization but prior to day 0.
Study participants were masked to which group they were assigned. The study was designed for masking to be maintained for the duration of the study. The masked study personnel included the study principal investigator (S.S.P.), examining study ophthalmologist (S.S.P.), masked study coordinators, VA examiner, and imaging and diagnostic test technicians. The unmasked study personnel included the study hematologists (M.A. and R.H.) and hematology nurse practitioners, treating ophthalmologists (A.M. and K.M.), unmasked study coordinators, current good manufacturing practices (cGMPs) laboratory personnel isolating CD34+ cells, and the members of the Advanced Retinal Imaging Lab team (when applicable). The study randomization was administered centrally by the DCC, whose staff were unmasked to treatment assignment. The unmasked Study Coordinator was responsible for performing the randomization within the electronic data capture system. Upon randomization, the unmasked Study Coordinator disseminated the treatment assignment in a confidential manner to the unmasked study personnel so that they may prepare for the appropriate procedures to be conducted on the day of treatment. The masked study visits were conducted by masked study personnel and included all visits after randomization except the 2 study treatment visits and the follow-up visits within 14 days of study treatment. The unmasked visits, which included the 2 study treatments and any follow-up visits within 14 days after study treatment including the planned visits 1 day and 1 week after study treatment, were conducted by unmasked members of the study team. Caution was taken during interactions involving both masked and unmasked study staff to ensure masking stayed intact.
Study Treatments
Study cell treatment was a 1-day procedure consisting of bone marrow aspiration by the study hematologist under local anesthesia as an outpatient, isolation of the CD34+ BMSCs performed in the cGMP laboratory at the UC Davis Institute for Regenerative Cures, and intravitreal injection of isolated CD34+ BMSC in the study eye by the study retinal specialist as outlined previously.8 The study participant was premedicated with oral medications to minimize anxiety and pain 1 hour before bone marrow aspiration. About 50 to 100 mL of bone marrow was aspirated from the iliac crest by the study hematologist under local anesthesia and promptly transported at 4 °C to the UC Davis cGMP laboratory for CD34+ cell isolation. Mononuclear cells were enriched from the bone marrow aspirate using a Ficoll density gradient. This was followed by positive selection of CD34+ cells from the mononuclear cell fraction using the Miltenyi CliniMACS system. The isolated cells were washed with sterile balanced salt solution and tested for immediate release by applying a stat gram stain and stat endotoxin assay. The isolated CD34+ cells were released for intravitreal injection if they passed the release criteria accepted by the FDA and Data Safety and Monitoring Committee, that is, number of cells available for intravitreal injection between 800 000 and 10 million, an absence of visible microorganisms on Gram stain, a stat endotoxin assay confirmed as acceptable endotoxin result (<0.5 EU/ml), and the viability of the isolated cells >70% by trypan blue staining. A 14-day sterility test was set up at the same time, and a positive culture action plan was in place, in case the 14-day sterility assay showed growth at any point in culture. The released, final cell product was suspended in 0.1 ml of sterile saline for eye injection and transported at 4 °C to the eye clinic in a tuberculin syringe. Intravitreal injection of the isolated CD34+ BMSCs was performed in the study eye under local anesthesia using a 30-gauge needle and within 2 hours of cell release.
For sham therapy, the participant underwent a sham bone marrow aspiration performed by the study hematologist where the skin was broken but not the bone. The participant also underwent a sham intravitreal injection where the eye was not penetrated by the treating study ophthalmologist.
After study treatment, slit lamp biomicroscopy and indirect fundoscopy were performed. Vital signs were obtained and the participant was closely observed in the supine position for ≥30 min before ambulating. Topical antibiotic was administered 4 times daily for a week in the study eye. No systemic or topical corticosteroids were used in any of the study eyes because the only cells injected were autologous cells.
Characterization of the Cells in the Final Product
A fraction of the final cell product was saved for further analysis after release of the cells for intravitreal injection. The postrelease analysis of the final cell product included flow cytometry to determine percent CD34+ cells, percent CD3+ cells, and percent viability based on 7-amino-actinomycin D testing. Additional flow cytometric panel analysis was performed to further characterize the cellular composition of the final cell product. The analysis included percent of CD34+ cells with VEGF receptor-2 (VEGFR-2), namely VEGFR-2(+)/CD34(+), as well as percent of CD133(+) cells, percent of CD31(+) cells, percent CD45(+) cells, and percent VEGFR-2(+) cells. Additional analysis included percent hematopoietic stem cells, that is, CD133(+)/CD45(+)/CD34(+) versus percent angiogenic cells, that is, endothelial progenitor cells that are CD31(+)/VEGFR-2(+)/CD45(–)/CD34(+).
Study Follow-Up
As shown in Table 1, each participant was seen 1 day, 1 week, 1 month, 3 months, and 6 months after each study treatment. At each study follow-up, an update of review of systems, medical and ophthalmic history, and concomitant medications was obtained and a comprehensive eye examination, including ETDRS BCVA was performed. At 1 day and 1 week follow-up visits, the bone marrow or sham aspiration site was inspected for erythema or tenderness. At 1 week after study treatment, blood work for a complete blood count was repeated. Follow-up diagnostic testing was conducted during masked visits 1 to 6 months after study treatment. Testing included OCT, OCTA, ERG (multifocal and full-field), and microperimetry at 1, 3, and 6 months after study treatment; fundus photography, fundus autofluoresence, and fluorescein angiography at 3 and 6 months after study treatment; and National Eye Institute Visual Function Questionnaire at 6 months after study treatment. Ultrahigh resolution OCT and OCTA imaging, when applicable, was conducted 1 month after study treatment. A study feedback survey was administered at 1 week after each study treatment and at study exit to determine the degree of satisfaction regarding study participation and participants’ impressions on timing of receipt of stem cell injection versus sham injection despite masking.
For the duration of the study, all adverse events (AEs) were reviewed promptly by either an unmasked investigator (for AEs reported within 2 weeks of study treatment) or the masked study principal investigator (for all others) for seriousness, severity, and possible association to study procedure or study cell injection and followed until resolution or up to 30 days from study termination. All AEs were also reviewed by the DCC Medical Monitors (R.L. and R.K.). Any serious AE (SAE) that was unexpected and related to study treatment was promptly reported to the Data Safety and Monitoring Committee, the FDA, the UC Davis Office of Research, and the UC Davis Stem Cell Oversight Committee.
The primary study objective was to assess the safety and feasibility of the stem cell therapy, as determined by the following outcome measures: the incidence and severity of ocular and systemic AEs reported after the first treatment (primary safety outcome) and throughout study duration (secondary safety outcome), and the mean and range number of CD34+ cells isolated from the bone marrow aspirate and the number injected into the eye (feasibility outcome). The secondary objective was to determine the effect of stem cell therapy on retinal function and morphology as measured by changes in the following tests after study treatment compared with baseline: BCVA, microperimetry, OCT, OCTA, fundus photography, fundus autofluorescence, fluorescein angiography, multifocal and full-field ERG, and National Eye Institute Visual Function Questionnaire. Exploratory outcome measures included characterization of percent hematopoietic versus endothelial stem cell subcomponents and percent CD34+ cells with VEGFR-2 in the final cell product. Additional exploratory analysis included the number of study participants who were able to correctly identify the timing of the sham versus cell injection during the study and any retinal or retinal vascular changes noted on ultrahigh-resolution OCT and OCTA images at 1 month after study treatment when compared with baseline, when applicable. This manuscript focuses on reporting the safety and feasibility data. A separate manuscript will summarize the results of other study outcome measures.
The pause criteria for study enrollment included the occurrence of any of the following events: development of any new intraocular tumor in the study eye during the course of the study; any eye with severe intraocular inflammation or endophthalmitis associated with >3 lines of drop in BCVA and positive 14 day culture despite passing release criteria or ≥2 eyes with severe intraocular inflammation or endophthalmitis with >3 lines of drop in BCVA and negative 14-day culture; drop in BCVA of >3 lines not attributable to normal progression of CRVO in ≥2 participants during the study follow-up; new retinal vascular occlusion not attributable to normal progression of CRVO in ≥2 participants during the study follow-up; new ocular neovascularization during the study follow-up noted in ≥2 participants and not attributed to normal progression of CRVO; sustained elevation of intraocular pressure (IOP) >30 mmHg not controlled with medication or paracentesis and directly attributed to study therapy, and any AE resulting in enucleation or loss of eye directly attributed to the study therapy.
Statistical Considerations
No formal sample size calculations were performed for this small phase I/II study with the primary objective of assessing the safety and feasibility of the stem cell therapy. A sample size of 20 participants was chosen as the estimated maximum number of study participants that could be enrolled in this single-center study within the study enrollment period given available resources and staffing.
A t test was used to compare the duration of vision loss from CRVO between groups. Descriptive statistics were used for safety and feasibility outcomes. The primary outcomes included solicited and unsolicited ocular and systemic AEs during treatment period 1 and feasibility of the bone marrow aspiration. Descriptive statistics were also provided for the secondary safety outcome which encompasses the AE experience throughout study duration. Summaries of the solicited and unsolicited AEs were broken down by the treatment received and treatment period in which the AE occurred.
The mean change in BCVA, microperimetry, and ERG from time of cellular treatment for all participants at 1, 3, and 6 months after the cellular injection was administered was calculated in both treatment arms, and at 12 months for the participants in the immediate cell group. Comparisons were made between the 2 arms to identify any differences in the effect of cellular therapy. If no statistically significant differences were identified, the treatment arms were combined, and a within-patient paired t test was performed to detect change over time, with 95% confidence intervals (CIs) provided. Box plots were used to display the results graphically.
Frequencies and changes from baseline of >25% were used to report on events observed on fundus photography, fluorescein angiography, OCT, and OCTA. In addition, descriptive statistics are provided for data collected on 2 surveys: (1) the postprocedure satisfaction survey collected at 1 week after both sham and cellular treatments and (2) the study satisfaction survey collected at study exit.
All participants who were randomized were included in the analyses and analyzed in the arm to which they were randomized (intent-to-treat analysis). Analyses were conducted in SAS version 9.4.
Results
As noted earlier, the original study protocol aimed to enroll and randomize 20 participants. However, enrollment was slow due to the strict study inclusion and exclusion criteria which were modified during the course of the study to increase enrollment (Supplemental Tables 1a and 1b). In addition, the enrollment period, originally planned for 24 months, was extended to 50 months during the course of the study due to the COVID-19 pandemic and associated travel restrictions that went into effect to varying degrees during the enrollment period. With these modifications, the study enrolled 24 and randomized 16 participants, rather than the original goal of 20.
Among the 24 enrollees, 8 failed screening and 16 were randomized to 1 of the 2 study treatment groups, 7 to immediate cell/deferred sham injection and 9 to immediate sham/deferred cell injection (Fig 2). Reasons for screen failure after enrollment included withdrawal of consent by the participant (n = 2), participant not completing screening within the visit window (n = 2), participant not meeting the eligibility criteria based on vaccination within 8 weeks of anticipated study treatment (n = 1), ETDRS BCVA during screening period not being within enrollment criteria (n = 2), and previous eye treatment within 6 months of enrollment (n = 1). Three participants who failed initial screening were later rescreened and randomized if they met the study criteria.
Figure 2.
CONSORT diagram. A summary showing how enrolled study participants were selected for study randomization and followed-up during the study.1 Three of the 8 participants were initially ineligible at screening but were later reconsented, rescreened, and randomized. Note, these participants are counted twice in the number consented. BCVA = best-corrected visual acuity; CONSORT = Consolidated Standards of Reporting Trials.
The baseline characteristics of the 16 randomized participants are summarized in Table 2. The mean age was 64.9 ± 12.47 years (range 40 to 78) with 5 of the 16 (31%) being female. The majority of study participants (88%) were White. The mean duration of vision loss from CRVO was 19.6 ± 8.87 months (range 7.8 to 40.4) at study enrollment. The mean duration of vision loss from CRVO was slightly longer for the immediate cell group when compared with the immediate sham group (24.7 ± 9.80 months versus 15.6 ± 5.90 months; P = 0.04). All study eyes had been treated with intravitreal anti-VEGF for secondary cystoid macular edema since diagnosis and 10 received it within 3 months prior to the time of enrollment. The mean interval between the last 2 anti-VEGF injections just prior to enrollment was 8.8 weeks and ranged from 5 to 12.7 weeks for these 10 participants. One (6.3%) eye had prior vitrectomy in the study eye 6 months prior to study enrollment. Three (18.8%) eyes had prior panretinal photocoagulation in the study eye, ranging from 6.0 to 32.9 months prior to study enrollment. Two (12.5%) of the study eyes were pseudophakic. None of the study participants had surgery or intraocular procedure in the study eye within 6 months of study enrollment, except for intravitreal anti-VEGF injections for CRVO-related secondary macular edema.
Table 2.
Baseline Demographics and Clinical Features of the 16 Randomized Study Participants and Study Eyes
| Characteristic | Immediate Cell/ Deferred Sham (N = 7) | Immediate Sham/ Deferred Cell (N = 9) | Total (N = 16) |
|---|---|---|---|
| Age (mean [SD]; range) | 67.9 (12.59); [41, 78] | 62.7 (12.62); [40, 77] | 64.9 (12.47); [40, 78] |
| Female (%) | 3 (42.9%) | 2 (22.2%) | 5 (31.3%) |
| Hispanic or Latino (%) | 0 (0%) | 1 (11.1%) | 1 (6.3%) |
| Race | |||
| Asian | 0 (0%) | 2 (22.2%) | 2 (12.5%) |
| White | 7 (100.0%) | 7 (77.8%) | 14 (87.5%) |
| Visual acuity (mean [SD]; Snellen equivalent) | 41.1 (20.99); 20/150 | 45.9 (15.52); 20/125 | 43.8 (17.62); 20/150+ |
| Duration of CRVO (months) | |||
| Mean (SD) | 24.7 (9.80) | 15.6 (5.90) | 19.6 (8.87) |
| Median [range] | 23.4 [11.4, 40.4] | 15.4 [7.8, 25.5] | 18.1 [7.8, 40.4] |
| Right study eye | 3 (42.9%) | 5 (55.6%) | 8 (50.0%) |
| Prior anti-VEGF therapy (%)∗ | 7 (100%) | 9 (100%) | 16 (100%) |
| Time between last injection and study enrollment (months) | |||
| Mean | 7.6 | 4.7 | 6.0 |
| Median [range] | 4.1 [0.7, 27.6] | 2.4 [0.5, 16.4] | 2.6 [0.5, 27.6] |
| Prior PRP laser∗ | 1 (14.3%) | 2 (22.2%) | 3 (18.8%) |
| Prior vitrectomy surgery∗ | 0 (0%) | 1 (11.1%) | 1 (6.3%) |
| Prior cataract extraction∗ | 1 (14.3%) | 1 (11.1%) | 2 (12.5%) |
| Concurrent glaucoma∗ | 0 (0%) | 1 (11.1%) | 1 (6.3%) |
| Uncomplicated diabetes mellitus | 0 (0%) | 1 (11.1%) | 1 (6.3%) |
| Hypertension | 4 (57.1%) | 8 (88.9%) | 12 (75.0%) |
| Hyperlipidemia | 4 (57.1%) | 7 (77.8%) | 11 (68.8%) |
| Anemia | 0 (0%) | 2 (22.2%) | 2 (12.5%) |
| Cerebral vascular accident | 0 (0%) | 2 (22.2%) | 2 (12.5%) |
| Coronary artery disease | 1 (14.3%) | 0 (0%) | 1 (6.3%) |
CRVO = central retinal vein occlusion; PRP = panretinal photocoagulation; SD = standard deviation.
In the study eye.
Among the 16 participants who were randomized, all 16 received study cell injection, either at baseline or at month 6, except 1. The only exception is a study participant who received study treatment #1 (sham injection) at baseline and could not return for study treatment #2 until almost 2 years later due to the COVID-19 pandemic and associated travel restrictions. All 16 participants tolerated the study treatments and completed the 6-month follow-up after each study treatment. Nine of the interim study follow-up visits were conducted by the local retinal specialist if the participant had travel restrictions. For these visits, a copy of the examination done locally was obtained and an update of review of systems, concomitant medications, and any AEs were obtained remotely.
Bone Marrow Aspiration
All study participants tolerated the bone marrow aspiration as well as the sham aspiration. The mean volume of bone marrow aspirate obtained per participant was 48.8 ml (range 39 ml to 73 ml). As shown in Supplemental Table 2, available at www.ophthalmologyscience.org, there was 1 participant who reported severe pain and severe tenderness during the aspiration procedure that resolved when the procedure completed. Other AEs associated with the bone marrow aspiration procedure included 2 participants reporting mild pain on the day of procedure and 1 each reporting mild pain on 1 day and 1 week after the procedure, and 4 participants with mild tenderness on the day of the procedure and 1 on the day after. Mild erythema was also noted in 1 participant after bone marrow aspiration. All but 1 AE associated with the bone marrow aspiration resolved within 4 days with 1 participant reporting mild tenderness on the day of treatment which took 15 days to resolve.
Adverse events reported on the day of the sham aspiration procedure included 1 participant who reported severe pain and tenderness (different participant from the one who noted severe pain with bone marrow aspiration), 2 who reported mild tenderness, and 1 who had mild bruising at the sham aspiration site. One participant reported mild pain 1 day postprocedure. All AEs associated with sham aspiration resolved within 4 days.
CD34+ BMSC Isolation and Intravitreal Injection
The bone marrow aspirate was promptly transported on ice to the cGMP laboratory for CD34+ isolation. Although all syringes used to collect bone marrow aspirate were heparinized prior to use, visible clotting of the bone marrow was noted in 3 of 16 aspirates (18.8%) by the time the aspirate was analyzed at the cGMP laboratory. However, the presence of clotting did not appear to adversely affect the percent yield of isolated CD34+ cells in the final product; the mean percent yield was 44.7% (range 25.9% to 62.2%) among the 3 participants with visible clotting versus a mean of 34.3% (range 3.5% to 72.8%) among the remaining 13 participants without clotting. All final isolated cell products passed the release criteria accepted by the FDA in terms of purity, sterility, viability, and quantity, except for 1 where the cell number released for intravitreal injection was 14.1 million, exceeding the upper limit of 10 million cells as outlined in the IND. This protocol deviation was reported promptly to the FDA and institutional review board once identified. No ocular or systemic AEs were associated with this deviation. None of the isolated cell products had positive 14-day culture after product release.
Table 3 summarizes the total number of CD34+ cells isolated from bone marrow and injected intravitreally among the 16 randomized study participants. The mean number of viable nucleated CD34+ cells isolated from CliniMACs was 5.7 million cells per participant (range 1.1 million to 16.1 million cells), with the mean number injected intravitreally being 4.3 million cells (range 0.9 million to 14.1 million). The mean percent viable nucleated cells in the final released product based on trypan blue staining was 96% (range 92.1% to 100%), with the mean percent of viable cells with irregular or abnormal shape being 1.4% (range 0% to 22.4%).
Table 3.
Characteristics of the CD34+ Cells Isolated from Bone Marrow and Injected Intravitreally in the Study Eye
| Participant No. | Prerelease Analysis |
Postrelease Analysis |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| Total CD34+ Cells Isolated from the CliniMACS (Millions) | No. of Viable CD34+ Cells Injected Intravitreally Based on CliniMACs (Millions) | % Viability of the Final Cell Product Based on Trypan Blue Staining | % Viable Nucleated Cells Based on Trypan Blue with Irregular or Abnormal Shape | Clotting Present?∗ | % Cell Viability (7-AAD) | % CD34+ Cells in Final Product Based on Flow Cytometry | No. of Viable CD34+ Cells Injected Intravitreally Based on Flow Cytometry (Millions) | % CD3+ Cells in Final Product by Flow Cytometry | |
| 001 | 7.77 | 5.7 | 98.3 | 0 | No | 94 | 88.5 | 5.04 | 0.04 |
| 002 | 6.75 | 5.25 | 99.4 | 0 | Yes | 86.94 | 77.42 | 4.06 | 0.16 |
| 005 | 5.55 | 4.3 | 100 | 0 | No | 94 | 87.9 | 3.78 | 0.31 |
| 006 | 4.99 | 3.33 | 95 | 0 | No | 93.2 | 88.1 | 2.93 | 0.1 |
| 007 | 4.39 | 2.89 | 93.6 | 22.4 | No | 88.8 | 77 | 2.22 | 0.2 |
| 008 | 4.05 | 2.8 | 97.3 | 0 | Yes | 95.2 | 87.3 | 2.44 | 0.12 |
| 010 | 1.79 | 1.16 | 97.7 | 0 | No | 92.5 | 80.9 | 0.93 | 0.4 |
| 011 | 1.14 | 0.94 | 92.7 | 0 | Yes | 89.5 | 73.5 | 0.69 | 0.7 |
| 013 | 5.7 | 4.2 | 97.4 | 0 | No | 94.33 | 81.4 | 3.42 | 0.15 |
| 014 | 7.43 | 5.43 | 93.8 | 0 | No | 76.78 | 54.61 | 2.96 | 0.19 |
| 015 | 4.43 | 2.92 | 98.3 | 0 | No | 96.65 | 90.97 | 2.66 | 0.31 |
| 017 | 7.2 | 5.2 | 94.24 | 0 | No | 98.7 | 95.4 | 4.96 | 0.4 |
| 018 | 16.05 | 14.05 | 94.7 | 0 | No | 98.2 | 99.5 | 13.98 | 0.4 |
| 020 | 2.21 | 1.1 | 96.7 | 0 | No | 98.5 | 94.7 | 1.04 | 0.5 |
| 023 | 9.53 | 7.53 | 95.1 | 0 | No | 97.2 | 90.9 | 6.85 | 0.3 |
| 024 | 1.74 | 1.47 | 92.06 | 0 | No | 95.3 | 42.6 | 0.62 | 0.5 |
| Mean (SD); [range] | 5.7 (3.68); [1.1, 16.1] | 4.3 (3.23); [0.9, 14.1] | 96.0 (2.43); [92.1, 100.0] | 1.4 (5.60); [0.0, 22.4] | - | 93.1 (5.56); [76.8, 98.7] | 81.9 (14.99); [42.6, 99.5] | 3.7 (3.25); [0.6, 14.0] | 0.3 (0.18); [0.0, 0.7] |
7-AAD = 7-amino-actinomycin D.
Clotting present indicates clotting was present in ≥1 of the syringes received.
The final product was further analyzed postrelease. Based on postrelease cell viability testing using 7-amino-actinomycin D, the mean percent cell viability in the final product was 93.1% (range 76.8% to 98.7%). The percent CD34+ cells in the final product as confirmed by postrelease flow cytometry ranged from 42.6% to 99.5% (mean 81.9%). The calculated mean number of CD34+ cells confirmed by flow cytometry and injected intravitreally was 3.7 million (range 0.62 million to 13.98 million). The mean percent CD3 cells in the final product based on postrelease flow cytometry was 0.3% (range 0.04% to 0.7%).
All eyes had at least counting fingers vision immediately after study injection. The meanIOP immediately after CD34+ cell injection was 31.2 mmHg which was higher than the mean IOP after sham injection (14.5 mmHg). No eye required paracentesis or additional IOP–lowering therapy after cell injection. Slit lamp biomicroscopy performed immediately after the cell injection revealed new visible cells without flare in the anterior vitreous in 9 of 16 eyes (56%). One eye (6.3%) had cells visible in the anterior chamber immediately after the injection. Visible vitreous or anterior chamber cells that were observed right after study injection were decreased to trace or no cells without intervention when examined 1 day after injection, except for 1 participant who had grade 1 cells in the vitreous 1 day after cell injection and trace cells 1 week after injection which resolved without intervention when examined 1 month later by a local retinal specialist.
Table 4 summarizes the ocular AEs noted in the study eye. In the 6-month period after the administration of the first treatment (treatment period 1), 68 ocular AEs were reported in the study eye, 40 after cell injection, and 28 after sham injection. Of the 40 reported ocular AEs after cell injection, 36 (90%) were considered mild in severity and 4 (10%) were moderate, 29 (72.5%) ocular AEs resolved, and 28 (70%) were considered related to study treatment. The 4 moderate AEs after cell injection included vision blurred, visual impairment, vitreous floaters, and dry eye. Of the 28 reported ocular AEs after sham treatment, 24 (85.7%) were mild, 4 (14.3%) were moderate, 23 (82.1%) resolved, and 16 (57.1%) were considered related to study sham injection. The moderate ocular AEs included cystoid macular edema, VA reduced, dermatochalasis, and chalazion. There were no ocular SAEs reported during this period.
Table 4.
Summary of Posttreatment Ocular Adverse Events in the Study Eye
| Treatment Period 1 |
Treatment Period 2 |
|||
|---|---|---|---|---|
| Cellular-Sham∗ (N = 7†) | Sham-Cellular∗ (N = 9†) | Cellular-Sham∗ (N = 7†) | Sham-Cellular∗ (N = 9†) | |
| Number of posttreatment AEs‡ | 40 | 28 | 25 | 40 |
| Severity of AE | ||||
| Grade 1-mild | 36 (90.0%) | 24 (85.7%) | 20 (80.0%) | 33 (82.5%) |
| Grade 2-moderate | 4 (10.0%) | 4 (14.3%) | 4 (16.0%) | 7 (17.5%) |
| Grade 3-severe | - | - | 1 (4.0%) | - |
| Number of serious AEs | - | - | 2 (8.0%) | - |
| Number of AEs resolved | 29 (72.5%) | 23 (82.1%) | 19 (76.0%) | 34 (85.0%) |
| Number of AEs related to study eye treatment§ | 28 (70.0%) | 16 (57.1%) | 17 (68.0%) | 32 (80.0%) |
| Number of pts with each AE related to study eye treatment (%) | ||||
| Eye irritation | 5 (71.4%) | 4 (44.4%) | 3 (42.9%) | 4 (44.4%) |
| No. of events/No. resolved (mean days to resolution) | 5/5 (2.2) | 4/4 (2.0) | 3/3 (2.7) | 4/4 (2.5) |
| Ocular hyperemia | 3 (42.9%) | 3 (33.3%) | 4 (57.1%) | 5 (55.5%) |
| No. of events/No. resolved (mean days to resolution) | 3/3 (2.7) | 3/3 (2.7) | 4/4 (40.0) | 5/5 (3.0) |
| Vitreous floaters | 6 (85.7%) | - | - | 9 (100%) |
| No. of events/No. resolved (mean days to resolution) | 8/7 (43.4) | - | - | 9/9 (3.4) |
| Foreign body sensation in eyes | 2 (28.6%) | 3 (33.3%) | 4 (57.1%) | 4 (44.4%) |
| No. of events/No. resolved (mean days to resolution) | 2/2 (3.0) | 3/3 (3.3) | 4/4 (1.8) | 5/5 (3.2) |
| Eye pain | 3 (42.9%) | 2 (22.2%) | 3 (42.9%) | 4 (44.4%) |
| No. of events/No. resolved (mean days to resolution) | 3/3 (2.7) | 2/2 (4.0) | 3/3 (2.3) | 4/4 (4.8) |
| Visual impairment | 2 (28.6%) | - | 1 (14.3%) | 2 (22.2%) |
| No. of events/No. resolved (mean days to resolution) | 2/2 (15.0) | - | 1/1 (3.0) | 2/2 (3.0) |
| Dry eye | - | 2 (22.2%) | - | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | - | 2/2 (2.0) | - | 1/1 (4.0) |
| Vision blurred | 1 (14.3%) | 1 (11.1%) | 1 (14.3%) | - |
| No. of events/No. resolved (mean days to resolution) | 1/1 (2.0) | 1/1 (2.0) | 1/1 (2.0) | - |
| Swelling of eyelid | 1 (14.3%) | - | 1 (14.3%) | - |
| No. of events/No. resolved (mean days to resolution) | 1/1 (4.0) | - | 1/1 (3.0) | - |
| Eye pruritus | 1 (14.3%) | - | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/1 (2.0) | - | - | - |
| Eye swelling | - | - | - | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | - | - | - | 1/1 (3.0) |
| Visual acuity reduced | - | - | - | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | - | - | - | 1/1 (7.0) |
| Photopsia | - | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | - | 1/0 (–) | - | - |
| Vitreous degeneration | 1 (14.3%) | - | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/0 (–) | - | - | - |
| Vitreous detachment | 1 (14.3%) | - | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/0 (–) | - | - | - |
| Number of AEs not related to study eye treatment | 12 (30.0%) | 12 (42.9%) | 8 (32.0%) | 8 (20.0%) |
| Number of pts with each AE not related to study eye treatment (%) | ||||
| Dry eye | 2 (28.6%) | 2 (22.2%) | - | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | 2/1 (59.0) | 2/1 (485.0) | - | 2/0 (–) |
| Vision blurred | 1 (14.3%) | - | 1 (14.3%) | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | 2/1 (27.0) | - | 1/0 (–) | 1/0 (–) |
| Visual impairment | 1 (14.3%) | - | 1 (14.3%) | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | 2/1 (27.0) | - | 1/0 (–) | 1/0 (–) |
| Eye irritation | - | 1 (11.1%) | - | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | - | 1/1 (31.0) | - | 2/2 (1.5) |
| Chalazion | - | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | - | 2/2 (37.0) | - | - |
| Eye pruritus | 1 (14.3%) | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/1 (2.0) | 1/1 (120.0) | - | - |
| Meibomian gland dysfunction | 1 (14.3%) | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/0 (–) | 1/0 (–) | - | - |
| Vitreous hemorrhage | - | - | 2 (28.6%) | - |
| No. of events/No. resolved (mean days to resolution) | - | - | 2/1 (215.0)‖ | - |
| Altered visual depth perception | 1 (14.3%) | - | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/0 (–) | - | - | - |
| Cataract | - | - | - | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | - | - | - | 1/0 (–) |
| Cataract cortical | - | - | 1 (14.3%) | - |
| No. of events/No. resolved (mean days to resolution) | - | - | 1/0 (–) | - |
| Cystoid macular edema | - | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | - | 1/0 (–) | - | - |
| Dermatochalasis | - | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | - | 1/1 (41.0) | - | - |
| Eye pain | 1 (14.3%) | - | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/0 (–) | - | - | - |
| Foreign body sensation in eyes | - | - | - | 1 (11.1%) |
| No. of events/No. resolved (mean days to resolution) | - | - | - | 1/0 (–) |
| Iris neovascularisation | - | - | 1 (14.3%) | - |
| No. of events/No. resolved (mean days to resolution) | - | - | 1/1 (161.0) | - |
| Lacrimation increased | - | - | 1 (14.3%) | - |
| No. of events/No. resolved (mean days to resolution) | - | - | 1/0 (–) | - |
| Ocular hyperemia | - | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | - | 1/1 (7.0) | - | - |
| Periorbital irritation | - | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | - | 1/1 (17.0) | - | - |
| Presbyopia | 1 (14.3%) | - | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/0 (–) | - | - | - |
| Retinal neovascularisation | - | - | 1 (14.3%) | - |
| No. of events/No. resolved (mean days to resolution) | - | - | 1/0 (–) | - |
| Visual acuity reduced | - | 1 (11.1%) | - | - |
| No. of events/No. resolved (mean days to resolution) | - | 1/0 (–) | - | - |
| Vitreous floaters | 1 (14.3%) | - | - | - |
| No. of events/No. resolved (mean days to resolution) | 1/0 (–) | - | - | - |
AE = adverse event; pts = participants.
Cellular-sham refers to participants who received the cellular injection on day 0 and the sham injection at 6 months. Sham-cellular refers to participants who received the sham injection on day 0 and cellular injection at 6 months.
N represents number of participants who received treatment in the specified arm in the specified treatment period.
Includes all AEs reported during unmasked and masked study visits.
Adverse events that were considered by the investigator to be possibly related to study treatment where study treatment includes both intravitreal injection of stem cells after bone marrow aspiration and sham injection in the eye after sham aspiration. Masked investigators are asked to evaluate whether the AE may be related to the study treatment during the masked study visits. Since they do not have knowledge of which treatment the participant received, it is possible that an AE of a participant who received the sham treatment could be categorized as related to treatment.
One participant experienced a grade 2 vitreous hemorrhage 16 months after cell injection and 10 months after sham injection, which had not resolved at date of last follow-up. This participant was followed for >12 months as the protocol had not yet been modified to shorten the length of follow-up.
For treatment period 2, there were a total of 25 ocular AEs after the delayed sham injection and 40 ocular AEs after the delayed cell injection. After the deferred sham injection, 20 AEs (80.0%) were mild, 4 (16.0%) were moderate, and 1 (4.0%) was severe. A total of 19 AEs (76%) resolved. There was 1 participant with 2 ocular SAEs in the study eye concurrently, neovascularization of the iris and vitreous hemorrhage. These SAEs were noted 26 and 22 days, respectively, after delayed sham injection and 7 months after immediate cell injection. This study eye had no prior vitrectomy or panretinal laser photocoagulation and had remained off intravitreal anti-VEGF starting 4 months prior to study enrollment until vitreous hemorrhage occurred. This study eye received 5.4 million CD34+ cells during treatment period 1. These SAEs were attributed to the natural course of CRVO and treated with standard of care, that is, intravitreal anti-VEGF and panretinal laser photocoagulation. Of note, a second study participant was noted with new vitreous hemorrhage in the study eye at 16 months after cell injection. This second study eye also had no prior vitrectomy or panretinal laser photocoagulation and had remained off intravitreal anti-VEGF starting 7.5 months prior to study enrollment and until vitreous hemorrhage occurred. This study eye received 5.7 million CD34+ cells during treatment period 1. This AE was captured in the study data before study follow-up was shortened to 12 months. This AE is included in Table 4 and was attributed to normal progression of CRVO and treated with standard of care. After the deferred cellular therapy, 33 ocular AEs (82.5%) were mild, 7 (17.5%) were moderate, none were severe, and 32 (80%) were related to study treatment. The moderate ocular AEs included 3 reports of vitreous floaters, 2 reports of dry eye, 1 report of visual impairment, and 1 VA reduced. There were no ocular SAEs after the deferred cell injection. A total of 34 AEs (85.0%) resolved.
The most common ocular AEs related to study treatment included eye irritation, ocular hyperemia, vitreous floaters, foreign body sensation, and eye pain. Each of these AEs, except for vitreous floaters, were reported after both cell and sham injection.
Supplemental Table 3, available at www.ophthalmologyscience.org, summarizes the systemic AEs noted by treatment period. In treatment period 1, 41 systemic AEs were reported, 19 after cellular treatment and 22 after sham. Of the 19 reported systemic AEs after cellular treatment, 9 (47.4%) were considered mild in severity and 10 (52.6%) were considered moderate. Of the 22 reported systemic AEs after sham treatment, 5 (22.7%) were mild, 15 (68.2%) were moderate, and 2 (9.1%) were considered severe. The 2 severe systemic AEs included appendicitis and worsening anemia. The incidence of appendicitis was also considered an SAE. None of the systemic AEs, in either arm, were considered related to study treatment.
In treatment period 2, 24 systemic AEs were reported, 10 after deferred sham treatment and 14 after deferred cellular treatment. Of the 10 reported systemic AEs after deferred sham treatment, 3 (30.0%) were considered mild and 7 (70.0%) were considered moderate. Of the 14 systemic AEs reported after deferred cellular treatment, 2 (14.3%) were considered mild and 12 (85.7%) were considered moderate. No systemic SAEs were reported and none of the systemic AEs were considered related to study treatment in either arm.
New floaters were reported by 15 of 16 participants in the study eye (94%) after the cell administration on the day of study treatment or 1 day after the CD34+ cell injection (versus 0 of 16 participants noted after sham injection). In addition, delayed onset of new floaters was reported in 3 of the 15 participants 15, 86, and 93 days after cell injection. All but 1 of the new floaters resolved during study follow-up. The 1 unresolved floater had a delayed onset, occurring 93 days after cell injection in an eye with pre-existing posterior vitreous detachment on eye examination. There was no associated retinal tear or detachment during the study follow-up.
There were no SAEs related to intravitreal CD34+ cell injection, sham injection, or bone marrow aspiration in any of the study participants during the study follow-up. There was 1 nonocular SAE in a participant who needed surgery for appendicitis after sham injection. There was no hyphema or endophthalmitis that developed in any of the study eyes after cell injection. The pause criteria for enrollment were not met at any point during the study.
BCVA
As shown in Figure 3A, the mean change in BCVA among the 16 study participants after cell injection ranged from +2.3 letters at 1 month to +0.9 months after 6 months (all 95% CIs contain 0). Among the 6 of 7 study participants in the immediate cell injection group for which BCVA data were available at 12 months after cell injection, a mean change of +5.8 letters from time of enrollment (95% CI: 1.94, 9.73; P = 0.01) was observed. In contrast, the mean BCVA changed by –0.4 letters at 3 months and +2.1 letters at 6 months postsham injection in the immediate sham or deferred cell injection group (Fig 3B).
Figure 3.
Change in BCVA letter score after cell injection during study follow-up. (A) The mean ± SD change in BCVA from baseline during study follow-up visits after cell injection. Red bar represents all study eyes after cell injection. Blue bar represents the 6 study eyes that completed 12-month study follow-up after cell injection at study baseline (immediate cell injection or deferred sham injection group). (B) The mean ± SD change in BCVA from baseline during study follow-up after immediate cell injection (blue bar), immediate sham injection (green bar), and deferred cell injection (red bar). Top and bottom of box represent upper and lower quartile, respectively. Upper and lower whiskers represent greatest and smallest value, respectively, excluding outliers. Outliers are any values >1.5 times upper and lower quartiles. BCVA = best-corrected visual acuity; pts = participants; SD = standard deviation.
No eye had a decrease of BCVA of ≥15 letters from baseline after immediate or deferred cell injection except for 1 eye noted with a 16-letter vision decline 1 day after cell injection that resolved by 1 week. During the initial 6 months after sham injection, this same eye also had a 15-letter decrease in BCVA at month 3 after initial sham injection that resolved at month 6. A second study eye in this group had persistent decrease in BCVA of ≥15 letters during the initial 6 month follow-up period after sham injection.
Best-corrected VA improvement of ≥10 letters was observed in some eyes after cell injection and sham injection. Best-corrected VA improvement of ≥10 letters was observed in 2 participants after immediate cell injection, one who had a 12-letter improvement at 1 month postcell injection and one with a 10-letter increase at 7 months postcell injection. Best-corrected VA improvement of ≥10 letters was also observed in 2 participants after deferred cell injection, one who had a 10- and 11-letter improvement at 3 and 6 months post cell injection, respectively, and one who had a 14-letter improvement 1 month postcell injection. There were also 3 participants in the immediate sham injection group for whom BCVA improvement of ≥10 letters was observed after the sham injection, one who had an 11-letter increase at 6 months postsham injection, one who had an 11 to 16 letter increase at 1 week and at 1, 3, and 6 months postsham injection, and one who had a 10-letter increase on 1 day, 1 week, and 1 month postsham injection.
Microperimetry
No significant change was noted at 1 month, 3 months, or 6 months after cell injection for percent reduced sensitivity or average threshold (all 95% CIs contain zero) when compared with baseline. Supplemental Figures 1a and 1b, available at www.ophthalmologyscience.org, summarize the mean changes 1, 3, and 6 months after immediate cell injection and deferred cell injection for average threshold and percent reduced sensitivity, respectively. At 12 months postcellular injection, average threshold decreased by a mean of 2.0 decibels for the 6 of 7 study participants in the immediate cell group that completed this test (95% CI: –3.40, –0.54; P = 0.02) when compared with baseline.
ERG
For multifocal ERG, there was no significant change in number of abnormal amplitude hexagon, mean amplitude standard deviation, number of abnormal latency hexagon, and mean latency standard deviation after cellular injection at all test study time points (1, 3, and 6 months) and at 12 months for the immediate cell group when compared with baseline.
Similarly, for full-field ERG, there was no significant change in photopic or scotopic response after cellular injection at all tested study time points (1, 3, and 6 months) and at 12 months for the immediate cell group when compared with baseline.
Imaging
Fundus photography, fluorescein angiography, OCT, and OCTA of the study eye at baseline were compared with follow-up images after cell injection for both study groups. There were some minor fluctuations in imaging from visit to visit. Thus, changes from baseline of >25% which persisted in >2 consecutive study visits were considered noteworthy for the safety analysis.
On fundus photography, no noteworthy change was noted during study follow-up. Mild retinal fibrosis or possible retinal neovascularization was noted in fundus photographs of some study eyes, but no eye had new epiretinal membrane (ERM) formation, persistent neovascularization of the retina or disc, or persistent retinal fibrosis during study follow-up. The retina remained attached throughout study follow-up for all study eyes. The vitreous remained clear except for the one eye that developed vitreous hemorrhage 7 months after cell injection.
Similarly, fluorescein angiography showed no neovascularization or persistent worsening of retinal ischemia of >25% from baseline during study follow-up except for the one eye that had possible neovascularization of the disc 6 and 12 months after cell injection, with an increase in peripheral retinal ischemia of >25% from baseline also noted at 6 and 12 months after cell injection. This is the same eye that developed vitreous hemorrhage and iris neovascularization 7 months after cell injection and 1 month after sham injection. This same eye had >25% increase in area of leakage from baseline at 3 and 6 months after cell injection, which improved after intravitreal anti-VEGF was used to treat neovascularization of the iris and vitreous hemorrhage. None of the other study eyes had persistent increase of area of leakage of >25% from baseline.
OCT of the macula showed residual macular edema at baseline for 5 of 16 study eyes. The macular volume remained stable or improved during study follow-up. Nine of 16 study eyes had disruption or loss of photoreceptor inner segment or outer segment junction in the central 1-mm zone at baseline; no study eye had persistent worsening of photoreceptor inner segment or outer segment junction disruption during study follow-up. Mild ERM was detected on macular OCT at baseline in 8 of 16 eyes which remained stable during study follow-up. One eye was noted with a new mild ERM on OCT at 3 and 6 months after cell injection, but the ERM was not noted in subsequent follow-up OCT. No other study eye had new ERM detected on 2 consecutive follow-up OCT images. On OCTA, there was no persistent worsening of retinal vascular flow after cell injection during study follow-up.
Study Surveys
In order to determine if masking of study participants was maintained during the study given the design of the study, including the use of sham bone marrow aspiration and sham intravitreal injection, a survey was conducted 1 week postprocedure to determine whether the study participants could correctly identify the treatment they received at day 0 and month 6. Across both treatment groups, 1 week after the first treatment, 8 of 16 (50%) participants indicated they were “extremely certain” or “very certain” about what aspiration procedure they had received (43% of those who had received the cellular treatment and 56% of those who had sham) and 7 of 16 (44%) reported the same about what eye injection they had received (43% of those who had received the cellular treatment and 44% of those who received sham treatment). In contrast, 1 week after the second treatment, 12 of 16 (75%) participants reported being “extremely certain” or “very certain” about both the aspiration procedure and eye injection they had received (57% in those who received sham and 89% in those who received cell injection).
Among study participants randomized to immediate cell injection, 4 of the 7 (57%) study participants correctly identified the bone marrow aspiration after the first treatment on day 0 and 3 of 7 (43%) participants correctly identified the sham aspiration after the second study treatment at month 6. Similarly, for intravitreal injection, 3 of the 7 (43%) study participants correctly identified the treatment received as the cell injection after the first treatment on day 0 and only 1 (14%) participant correctly identified the sham injection after the second study treatment at month 6.
Among study participants randomized to immediate sham injection, all correctly identified the timing of the bone marrow aspiration and intravitreal cell injection, both of which were done at month 6. However, only 5 of the 9 study participants (56%) correctly identified both the sham aspiration and intravitreal injection done on day 0.
The study satisfaction survey conducted at study exit revealed that 12 of the 16 participants were satisfied or very satisfied with the overall experience in the study and would be willing to participate in the study again. Two participants were very dissatisfied with the overall study experience, one due to uncomfortable study procedures and the other due to disappointment regarding lack of visual improvement, but both stated they would probably or definitely participate again if offered the option. Two participants felt neutral about the overall experience in the study, but both also stated they would be definitely willing to participate again if given the option.
Discussion
This phase I/II prospective, randomized, sham-controlled, double-masked single-center study assessed the safety and feasibility of intravitreal injection of autologous CD34+ BMSCs in eyes with persistent vision loss from CRVO. Although the study enrollment was impaired and delayed by the unexpected COVID-19 pandemic and associated travel restrictions, we were able to enroll 24 participants, randomize 16 study participants, and follow each randomized participant for the 12 months study follow-up. Our study results demonstrate that intravitreal injection of autologous CD34+ BMSCs is feasible and well-tolerated in eyes with vision loss from CRVO. We were able to consistently isolate autologous CD34+ BMSCs of high viability and sterility using the Miltenyi CliniMACs system under cGMP conditions.
All 16 randomized study participants tolerated the bone marrow aspiration procedure under local anesthesia. As shown in Supplemental Table 2, the AEs associated with bone marrow aspiration were similar to those observed after sham aspiration. All AEs resolved within a few days of study treatment. Only 1 participant reported severe pain and tenderness during the bone marrow aspiration procedure which resolved after the procedure. Similarly, a different participant noted severe pain with sham aspiration that resolved after the procedure.
In each study participant, we were able to isolate CD34+ BMSCs using the Miltenyi CliniMACs under cGMP conditions with the FDA-accepted release criteria for sterility, viability and quantity being met. As a result, all study participants received intravitreal injection of autologous CD34+ BMSCs either at baseline or at month 6, the timing of which was dependent on the group to which they were randomized (Table 3). The only exception was a study participant who was randomized to the deferred cell injection group and received the cells 2 years after randomization because he could not return to complete the study due to COVID-19 travel restrictions.
The calculated mean number of CD34+ cells injected intravitreally, based on flow cytometry after release, was 3.7 million cells per eye (range 0.62 to 13.98 million cells). A wide range of isolated CD34+ BMSCs for intravitreal injection has been observed in our prior phase I studies,8,17 but the range was wider in the current study, partly because 1 participant was injected with a higher number of CD34+ BMSCs than intended in the study protocol. This deviation occurred because the study manual of procedures did not specify steps to be taken in the rare event that >10 million CD34+ cells were available for intravitreal injection. This will be corrected for future study manuals. The upper limit of 10 million CD34+ cells for intravitreal injection was specified in the IND based on the number of CD34+ BMSCs injected intravitreally for our long-term preclinical safety study.16 We have no preclinical data regarding safety of intravitreal injection of >10 million CD34+ cells, but our current study finding inadvertently provides some additional safety information regarding injecting >10 million CD34+ cells in human eyes.
It is not clear at the present time all the factors that might be contributing to the variable yield of isolated CD34+ cells using our current isolation protocol. We did observe partial clotting of the bone marrow aspirate in a few samples during our study, but the percent yield of CD34+ cells from these clotted bone marrow aspirates was not lower than that from nonclotted aspirates. Prior studies have shown that the number of CD34+ cells in the blood and bone marrow may vary depending on the age and general health of the individual.7 In order to minimize this factor, our study enrolled relatively healthy study participants. Nonetheless, our participants’ age ranged from 40 to 78 years (Table 2), reflecting the expected age demographics of patients with CRVO.1,2
All study participants tolerated the intravitreal injection of autologous CD34+ BMSCs for the study duration with no ocular SAEs associated with the study cell injection. This includes the one study participant who received autologous CD34+ BMSCs that was above the 10 million upper limit.
The only AE found to be unique after cell injection when compared with sham injection was new onset of floaters, which was observed in almost all participants immediately after cell injection. This is not unexpected because the intravitreal injection procedure might introduce microscopic air bubbles into the vitreous cavity or move the vitreous fluid, resulting in new floaters. In addition, injected cells migrating in the vitreous gel soon after injection also may be perceived as new floaters. In fact, cells were seen in the anterior vitreous in about half of the study participants immediately after cell injection. These anterior vitreous cells resolved completely without intervention, usually within days and are unlikely to represent cells from inflammation. It is unclear at the current time why cells were not seen in the anterior vitreous on slit lamp biomicroscopy in all study eyes after cell injection. Perhaps injected cells migrate posteriorly to the ischemic retina more quickly in some eyes than others. Preclinical studies show that retinal homing of CD34+ cells to the ischemic retina occurs within 2 days of intravitreal cell injection.13 A few study eyes also had cells visible in the anterior chamber without flare right after cell injection. A similar finding also was observed in a participant of the prior phase I study exploring this autologous cell therapy for retinitis pigmentosa.17 In this latter participant, IOP was elevated to 30 mmHg concurrently. However, the anterior chamber cells resolved within hours without intervention and IOP normalized within hours after administering a single drop of glaucoma medication and remained normal for the study duration without further intervention.
Despite new floaters, there were no cases of new retinal break or detachment after intravitreal CD34+ cell injection. Vitreous hemorrhage was noted in 2 study eyes, one at 26 days after sham injection and 7 months after cell injection concurrent with new neovascularization of the iris and another noted at 16 months after cell injection with presumed retinal neovascularization. Because iris or retinal neovascularization and associated vitreous hemorrhage are known complications of CRVO and associated retinal ischemia,3,4 these ocular AEs were attributed to normal progression of CRVO. These eyes were treated with standard of care treatment, that is, intravitreal anti-VEGF drug and panretinal photocoagulation, with good response and no other adverse effects. Neither of these eyes had vitrectomy or panretinal photocoagulation prior to study enrollment. In both eyes, intravitreal anti-VEGF therapy had been discontinued prior to study enrollment. Whether these 2 ocular AEs represent potential long-term AEs associated with intravitreal CD34+ BMSCs cannot be completely ruled out at the current time. CD34+ cells have been shown to promote angiogenesis and revascularization of ischemic tissue.7,12 Nonetheless, no pathologic ocular neovascularization has been observed in preclinical or clinical studies associated with CD34+ cell injection to date.7, 8, 9, 10, 11
Other ocular AEs, such as eye redness or irritation or blurry vision, were observed soon after either sham or cell injection and likely associated with the use of topical betadine and local anesthetic in preparation of the eye for study treatments. These AEs are commonly reported by patients after intravitreal injection in clinical practice. As expected, these ocular AEs resolved within a couple of days in our study.
There were no cases of endophthalmitis or intraocular inflammation in any of our study participants during the study follow-up. Postrelease sterility testing for all final isolated cell products passed with “no growth” during the 14-day culture. Cells were seen in the anterior vitreous or anterior chamber via slit lamp biomicroscopy immediately after intravitreal CD34+ cell injection in a majority of study eyes. However, there was no associated flare, eye pain, or eye infection. Most, if not all, cells resolved without intervention when examined 1 day later. Thus, it is unlikely that these cells seen in the vitreous and anterior chamber in the study eye immediately after cell injection represented intraocular inflammation.
There were no cases of visually significant abnormal intraocular proliferation of cells noted after intravitreal CD34+ cell injection in our study on serial retinal imaging, including fundus photography, fluorescein angiography, OCT, and OCTA. Specifically, there was no new persistent ERM, retinal neovascularization, retinal fibrosis, or retinal detachment except in the one study eye that developed iris neovascularization and vitreous hemorrhage during study follow-up, where increase in retinal ischemia and leakage and possible neovascularization of the disc was noted on fluorescein angiography 1 month before onset of vitreous hemorrhage. There was no worsening of ERM in study eyes with ERM noted on baseline OCT. There was 1 study eye noted with a mild new ERM on OCT at 3 and 6 months after cell injection, but the ERM was not observed in subsequent follow-up OCT. This point is noteworthy because abnormal intraocular cell proliferation was observed in some clinical trials after intravitreal injection of cultured mesenchymal stem cells.7 Abnormal intraocular cell proliferation with severe vision loss was observed also after intravitreal injection of autologous cells among participants of unregulated fee-for-service clinical trials for macular degeneration.7,18, 19, 20, 21 In fact, there is a case report of ERM being surgically removed from an eye that participated in one of these unregulated fee-for-service trials.22 The removed ERM stained positively with CD34 on immunohistochemistry, leading to the presumption that the ERM formation was due to intraocular proliferation of injected cells that were CD34+. However, CD34 is not a cell surface marker unique to BMSCs and is also found in vascular endothelial cells and actively dividing tissue.14
CD34+ BMSCs are not actively dividing cells. In fact, these CD34+ cells do not readily expand in culture.7 Thus, there is minimal risk of abnormal proliferation of these cells after intravitreal injections. In our study, these CD34+ BMSCs were isolated from bone marrow and promptly injected into the vitreous. There was no manipulation or expansion of the cells.
Finally, our study showed no significant adverse effects on visual function after CD34+ cell injection based on BCVA and ERG. Best-corrected VA varied somewhat during the study follow-up after either sham or cell injection, but no study eye had a persistent decrease of BCVA of ≥15 letters from baseline after immediate or deferred cell injection. Similarly, there was no significant decrease in retinal function on ERG or multifocal ERG during the study follow-up after cell injection when compared with baseline. Microperimetry also showed no significant change from baseline at 6 months follow-up after cell or sham injection. However, among the subset of 6 of the 7 participants seen at 12 months after immediate cell injection, a mean decrease in average sensitivity of 2.7% was noted on microperimetry with a concurrent improvement in mean BCVA. This finding is not well explained and its significance, if any, is unclear given the small sample size and potential variability in BCVA and microperimetry from visit to visit which is compared to a single baseline measurement in our study design.
As part of study feasibility analysis, we also evaluated whether masking of study participants was maintained during the study because each study participant received both the cell injection and sham injection. We surveyed each study participant 1 week after each study treatment and at study exit. Only half or less of the participants correctly identified the timing of the cell injection and sham injection after the first study treatment, indicating that masking was maintained for this period. However, in the deferred cell injection group, most of the study participants were able to identify the timing of the cell injection and bone marrow aspiration at month 6. This is not surprising because these participants likely noted the difference between the cell injection and the initial sham injection. This potential unmasking of the deferred cell injection group after month 6 will need to be considered in designing any future clinical trials exploring this cell therapy.
The survey also assessed participants’ satisfaction regarding study participation given the frequency of study follow-ups, diagnostic tests, and study treatments. Most were satisfied with the study overall. A couple of the study participants were not satisfied with study participation either because of pain associated with bone marrow aspiration or lack of perceived improvement in visual function after study participation. Nonetheless, all study participants completed the study follow-up and stated in the survey that they would be willing to participate in the study again if given the option.
The study had several limitations. First, the study is relatively small for a phase I/II study. As a single-center study, the sample size was limited by available resources and staff in the center. In addition, travel restrictions due to COVID-19 and the strict study enrollment criteria slowed enrollment. The goal sample size of 20 participants was not achieved despite multiple modifications to enrollment criteria and extension of the enrollment period. Nonetheless, we enrolled 24 participants and randomized 16 participants. As such, it is the largest study to date evaluating safety and feasibility of intravitreal injection of autologous CD34+ BMSCs. In our current study, a complete list of systemic and ocular AEs, both solicited and volunteered by the participants, were collected after cell injection and sham injection according to study protocol. The randomized, sham-controlled, double-masked design of our study allowed us to identify AEs that may be unique after cell injection. This was not possible in our 2 prior smaller phase I studies.8,17 Our current study is not powered to evaluate for efficacy. However, the randomized, sham-controlled study design also allows us to evaluate for efficacy signals in visual function and imaging. We are conducting this additional data analysis which will be summarized in a separate report.
A second study limitation is that not all study follow-up was conducted at the study center, mostly due to travel limitations from COVID-19. These participants were contacted remotely to obtain medical history updates and records of eye examination conducted by the local retinal specialists. In addition, the study coordinator interviewed the participant to obtain any solicited or unsolicited AEs, similar to the interview process conducted at study visits at the study center. Nonetheless, we have some missing data for some diagnostic tests that could only be performed at the study center. Although the local retinal specialists were not specifically trained on AE reporting for the study, they were all experienced retinal specialists who were aware of the patient’s participation in our study.
Another potential study limitation is the longer mean duration of vision loss from CRVO in the immediate cell group when compared with the immediate sham group. Longer duration of vision loss from CRVO may potentially result in less visual recovery after cell injection. In our study, this was not observed. The immediate cell group did not have less visual recovery after cell injection when compared with the immediate sham/deferred cell group (Fig 3B).
Last, the study masking was maintained for the study duration but survey results indicate that the participants who received deferred cell injection might have been unmasked thereafter. Most of the participants in this immediate sham or deferred cell injection study group appear to have noticed the difference between sham and cell injection. Surprisingly, it does not appear to be the case for participants who received immediate cell injection followed by sham injection, although all study participants have had prior intravitreal injections of anti-VEGF drugs before study enrollment. Nonetheless, this potential unmasking does not appear to affect AE reporting by participants which were similar throughout the study.
In summary, this phase I/II study showed that intravitreal injection of autologous CD34+ BMSCs is feasible and well-tolerated in patients with vision loss from CRVO. High quality CD34+ BMSCs could be isolated from bone marrow aspirate under cGMP conditions in all study participants for intravitreal injection. The study further substantiates observations made in our 2 prior smaller phase I studies also showing safety and feasibility of this cell therapy.8,17 The sham-controlled design of our current larger study provides a complete list of AEs associated with both cell injection and sham injection, critical safety information that has not been previously reported and is a strength of this current study. Ocular AEs were noted after cell injection and sham injection, but they were all mild or moderate in severity and most resolved. Ocular SAEs were limited to 1 study eye with vitreous hemorrhage and iris neovascularization which occurred >6 months after cell injection and resolved after standard of care treatment for ischemic CRVO. These SAEs were attributed to normal expected progression of CRVO. The second study eye with vitreous hemorrhage, presumably from ocular neovascularization, was considered an AE, not SAE, based on severity of vision loss associated with the event.
The current study also provides invaluable insight to the study design that can be used in planning future larger clinical trials exploring this cell therapy for retinal disorders. The study treatment, that is, bone marrow aspiration and intravitreal cell injection, was well tolerated, with mostly mild to moderate AEs. Although some study participants noted varying levels of discomfort during the bone marrow aspiration, all participants were willing to participate in a similar clinical trial in the future if given the option. The participant surveys seem to indicate that masking can be maintained in a randomized study exploring this cell therapy using sham bone marrow aspiration and sham intravitreal injection as control, as long as cell injection is not administered after sham injection in the same participant. Our study findings provide invaluable insight that can be used in the design of larger future clinical trials, which will be needed to fully assess the safety and efficacy of this cell therapy in treating vision loss associated with various retinal disorders, including CRVO.
Acknowledgments
The authors thank the members of the UC Davis Eye Center Clinical Trials team and hematology nurse practitioners from the UC Davis Cancer Center for their contributions to data collection. In addition, we thank the members of the TRUST DSMC committee for their oversight and invaluable input for the study duration: Leslie G. Hyman (chair), Wills Eye Hospital, Thomas Jefferson University; Richard J. Chappell, University of Wisconsin-Madison; Michael B. Gorin, University of California, Los Angeles; Joshua M. Hare, University of Miami; Insoo D. Hyun, Museum of Science, Boston; David H. McKenna, Jr, University of Minnesota; Cynthia A. Toth, Duke University.
Manuscript no. XOPS-D-25-00077.
Footnotes
Abstract presented in part as a paper at the annual Association for Research in Vision and Ophthalmology (ARVO) meeting, May 5, 2025, Salt Lake City, UT; abstract to be presented as a paper at the annual Retina Society meeting, September 10, 2025, Chicago, IL.
Disclosure(s):
The Article Publishing Charge (APC) for this article was paid by National Eye Institute via grant to University of California Davis Eye Center.
All authors have completed and submitted the ICMJE disclosures form.
The authors have made the following disclosures:
S.S.P.: Grants – Roche or Novartis, Ophtea, EyePoint (contracted clinical research grant to employer [UC Davis] which has no overlap with the research summarized in this manuscript); Honoraria – Boston University, Department of Defense, National Eye Institute; Leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid – Macula Society Research Committee, Retina Society Research Committee.
M.A.: Speakers bureau – E. R. Squibb & Sons, L.L.C. (BMS), Kite Pharma, Inc. (Gilead), AbbVie Inc.
J.A.N.: Participation on a Data Safety Monitoring Board or Advisory Board – McKesson- CAR-T; Editor – Journal Stem Cells.
This study was supported by the following grants from NEI/NIH: UG1 EY026876 (S.S.P., A.M., M.A.) (S.S.P., UC Davis) and UGI EY028517 (J.M., D.S., J.S.K., R.K., R.L.) (J.M., Emmes Company). The study sponsor participated in oversight of study activities including participant safety monitoring and assisted in formulating recommendations to enhance the trial’s scientific integrity and timeliness including recommendations relating to the selection, recruitment, and retention of participants, their management, improving adherence to protocol-specified treatments, and procedures for data management and quality control.
HUMAN SUBJECTS: Human subjects were included in this study. The study was conducted under an Investigational New Drug (IND) clearance (IND #17023; cross-referenced IND #13307) from the US Food and Drug Administration and followed a protocol that was approved by the UC Davis Office of Human Research (local institutional review board) and UC Davis Stem Cell Oversight Committee. The study was conducted in adherence to the Declaration of Helsinki, National Institute of Health guidelines for clinical research and guidelines outlined by the International Society of Stem Cell Research. All participants signed an informed consent form at study enrollment.
No animal subjects were used in this study.
Author Contributions:
Conception and design: Park, McCormack
Analysis and interpretation: Park, McCormack, Salazar, King, Fury
Data collection: Park, Salvador, Bauer, Fury, Abedi, Moshiri, Macias, Moussa, Kondapaka, Lindblad, Hoeg, Nolta
Obtained funding: Park, McCormack
Overall responsibility: Park, McCormack, Salazar, King, Salvador, Bauer, Fury, Abedi, Moshiri, Macias, Moussa, Kondapaka, Lindblad, Hoeg, Nolta
Supplemental material available atwww.ophthalmologyscience.org.
Supplementary Data
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