Human umbilical cord mesenchymal stromal cells derivatives in treating diabetic foot ulcers: a phase I/II safety and efficacy trial

Abstract

Diabetic foot ulcers (DFUs) are serious and prevalent complications of diabetes mellitus, affecting up to 34% of individuals and contributing substantially to morbidity, healthcare expenditures, and the risk of non-traumatic lower limb amputations. Despite the availability of standard treatment protocols, achieving complete and sustained healing remains a significant clinical challenge. This study investigates the safety and efficacy of allogeneic human umbilical cord mesenchymal stromal cell derivatives (hUC-MSCD), including conditioned media, extracellular vesicles, and exosomes, administered via perilesional injection in patients with chronic DFUs. In this single-center, phase I/II, open-label clinical trial (NCT06825884), ten adult patients (7 males, 3 females; mean age: 52.2 years) with type 2 diabetes mellitus and chronic DFUs classified as Texas Grade II–III (mean ulcer duration: 15 weeks), refractory to standard care, were enrolled. Participants received perilesional injections of allogeneic hUC-MSCD. Safety was evaluated through the monitoring of adverse events, and efficacy was assessed by the rate and duration of ulcer closure, as well as recurrence during follow-up. The intervention was well tolerated, with no significant adverse events observed. All patients achieved complete ulcer closure within a mean of 4.2 weeks (p < 0.00001). Importantly, no ulcer recurrence was documented during a 24-month follow-up period. These results provide strong preliminary evidence that allogeneic hUC-MSCD therapy is both safe and effective in promoting wound healing in refractory DFUs. Larger, randomized, double-blind, placebo-controlled trials are warranted to validate these findings and to further define the therapeutic potential of hUC-MSCD in this population.

Introduction

Diabetic foot ulcers (DFUs) are debilitating complications of diabetes mellitus, affecting up to 34% of patients and contributing substantially to morbidity, healthcare expenditures, and lower limb amputations [1]. Despite the use of standard therapeutic approaches, including wound debridement, infection control, offloading, and revascularization, many ulcers—particularly those that are chronic or ischemic—fail to achieve complete healing [2]. Consequently, novel therapeutic strategies are being explored, with mesenchymal stromal cell (MSC)-based interventions gaining considerable attention for their potential to enhance wound repair [3].

Human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) represent a particularly promising therapeutic option due to their robust immunomodulatory, pro-angiogenic, and regenerative capacities [4]. Compared to bone marrow- or adipose-derived MSCs, hUC-MSCs are more readily available, exhibit lower immunogenicity, and possess superior proliferative and differentiation potential [5]. Beyond direct cell therapy, derivatives of hUC-MSCs (hUC-MSCD)—including conditioned media, extracellular vesicles, and exosomes—have demonstrated the ability to stimulate tissue repair while circumventing challenges associated with cell-based transplantation, such as limited survival and engraftment [6].

Preclinical studies indicate that hUC-MSCD promote fibroblast migration, stimulate angiogenesis, and reduce inflammation in diabetic wounds [7]. Early clinical investigations further suggest that these derivatives accelerate wound closure, reduce recurrence, and improve overall foot function [8]. However, rigorous clinical trials evaluating their safety and efficacy remain scarce.

To date, no published human study has comprehensively evaluated the safety and efficacy of hUC-MSCD in DFUs. One phase I pilot study involving 14 patients with peripheral arterial disease and non-healing DFUs examined the topical and intravenous administration of hUC-MSCD, reporting a favorable safety profile and significant ulcer healing [9, 10]. These findings underscore the therapeutic potential of hUC-MSCD in refractory diabetic wounds.

The present phase I/II clinical trial aims to assess the safety and efficacy of perilesional allogeneic hUC-MSCD injections in patients with chronic DFUs. Primary outcomes included the rate and duration of ulcer closure, while secondary outcomes encompassed adverse event monitoring and functional assessments.

Patients and methods

This prospective, open-label, phase I/II clinical trial was conducted to evaluate the safety and efficacy of perilesional injections of allogeneic human umbilical cord mesenchymal stromal cell derivatives (hUC-MSCD) in patients with chronic diabetic foot ulcers (DFUs). The study protocol was reviewed and approved by the Institutional Review Board (IRB) of the Cell Therapy Center, University of Jordan. Written informed consent was obtained from all participants in accordance with the Declaration of Helsinki.

Patient selection

Eligibility criteria were adapted from previously published protocols by our group [11], with minor modifications, as shown in Table 1.

Table 1.

Inclusion and Exclusion Criteria

Inclusion Criteria

Exclusion Criteria

• Adults aged 30–70 years with type 2 diabetes mellitus and a DFU of at least 6 weeks’ duration. • Glycated hemoglobin (HbA1c) < 11%. • Index ulcer located on the plantar, medial, or lateral foot surface (including toes), with a wound area between 1 cm² and 60 cm². • Ulcers located beneath Charcot deformities required to demonstrate structural consolidation and absence of acute changes. • University of Texas stage A, Grade II or III ulcer classification [24,25]. • Post-debridement wounds free of necrotic debris, foreign bodies, or sinus tracts. • Ankle-Brachial Index (ABI) within acceptable range on non-invasive vascular testing. • No significant comorbid conditions on physical examination, including normal Semmes-Weinstein monofilament testing for neuropathy. • Laboratory tests within normal limits, including full blood count, liver and renal function, hepatitis screening, and standard biochemistry (excluding HbA1c). • Provision of signed, informed consent.

• Enrollment in another investigational device or drug trial within 30 days prior to screening. • Reduction of ulcer area by > 50% during the 7-day screening period. • Ulcers of non-diabetic etiology or failing to meet inclusion criteria. • Evidence of gangrene in the ulcer or elsewhere on the foot. • Receipt of radiation or chemotherapy within 3 months prior to randomization. • Administration of growth factor therapy within 7 days of randomization. • Screening platelet count < 100 × 10⁹/L or hemoglobin < 10 g/dL. • Current renal dialysis, known immunodeficiency, abnormal platelet activation disorder, active liver disease, malignancy, hematologic disorder, collagen vascular disease, rheumatic disease, or bleeding disorder. • History of peripheral vascular repair within 30 days prior to randomization. • Presence of physiological, developmental, physical, emotional, or social conditions that could compromise compliance with study requirements or wound healing. • History of alcohol or drug abuse within the year preceding enrollment.

Stem cell and hUC-MSCD Preparation and characterization

Human umbilical cord (Wharton’s Jelly) mesenchymal stromal cells (hUC-MSCs) were isolated from a single full-term umbilical cord obtained after elective caesarean section and expanded in a current Good Manufacturing Practice (cGMP)-compliant facility, as previously described by our group [12, 13]. Briefly, cords were processed using the explant method and cultured in Alpha-MEM (Gibco) supplemented with 4 mM L-glutamine, 1% penicillin-streptomycin, and 5% platelet lysate, under standard incubation conditions (37 °C, 5% CO₂). Conditioned media were collected at passage 4 upon achieving 80–90% confluence, centrifuged at 300 × g, filtered through 0.22 μm vacuum filtration units, aliquoted into sterile 10 mL tubes, and cryopreserved at − 80 °C for subsequent use.

Quality control (QC) testing was performed in accordance with EudraLex Volume 4 – Part IV: GMP for Advanced Therapeutic Medicinal Products (ATMPs) [14] and the International Council for Harmonisation (ICH) Q2(R2) guideline on validation of analytical procedures [15]. Flow cytometry (BD FACSLyrics, BD) with the BD Stemflow hMSC Analysis Kit was used to confirm MSC identity markers. Cell viability was assessed using dye exclusion assays on the Countess II automated cell counter. Conditioned media sterility was verified using the BactecAlert automated growth detection system (Biomeuriex), while mycoplasma contamination was excluded using the MycoSEQ real-time PCR detection kit (Thermo Fisher). Pyrogen absence was confirmed by the Limulus Amebocyte Lysate (LAL) assay (Endosafe, Charles River). Characteristic growth factors were quantified via enzyme-linked immunosorbent assay (ELISA); human TGF-β1 (R&D), human EGF (R&D) and human CXCL12/SDF-1α (R&D) were performed as per kit instructions. Acceptance criteria for MSCs and their derivatives are presented in Table (2) below.

Table 2.

Summary of Release Criteria and Biological Characterization of the Cell Therapy

Test	Specifications
Appearance	No particulate matter
Sterility: 1- Aerobic microbial count 2- Anaerobic microbial count 3- Fungal microbial count	1- < 1 CFU/ml 2- < 1 CFU/ml 3- < 1 CFU/ml
Endotoxin	< 150 IU/dose
Mycoplasma	Negative
Surface markers (Cells) 1- CD90, CD73, CD44 2- CD105 3- Negative cocktail (CD 45, CD34, CD14 or CD11b, CD79a or CD 19, HLA-DR)	1- ≥ 90% 2- ≥ 70% 3- < 10%
Morphology (Cells)	Plastic adherent, spindle shaped
Differentiation (Cells) 1- Osteogenic 2- Adipogenic 3- Chondrogenic	1- 50% of the field positive for Alizarin Red stain 2- 50% of the field positive for Oil Red stain 3- 50% of the field positive for Alacian blue stain
Growth Factors 1- Epidermal Growth Factor (EGF) 2- CXCL 12 (SDF-1) 3- TGFB-1	1- ≥ 50 pg/mL 2- ≥ 500 pg/mL 3- ≥ 1000 pg/mL

Clinical procedures and Follow-up

Patients received perilesional injections of hUC-MSCD along ulcer margins once weekly, for a maximum of 10 sessions. Each treatment consisted of 5 mL of hUC-MSCD, distributed in five 1 mL insulin syringes (Gauge 30). There was no need for local or general anesthetics during the injection procedures. Patients were monitored for adverse events using a standardized checklist. Laboratory investigations (complete blood count and biochemical profile) were repeated monthly for the first 6 months in accordance with the safety protocol; clinical assessments, wound measurements, photographic documentation, and surveillance for ulcer recurrence, hospitalization, amputation and other clinical endpoints continued for up to 24 months with visits at baseline, weekly until healing, then at weeks 9, and months 3, 6, 9, 12, 18 and 24. All assessments were performed by a vascular surgeon experienced in DFU management.

Ulcers were classified according to the University of Texas Grading System and the Wagner Ulcer Classification. At each visit, wound dimensions were measured and surface area calculated. Photographic documentation was obtained weekly until complete healing, and subsequently at 9 weeks, 6 months, 12 months, and 24 months. All assessments were performed by a vascular surgeon with expertise in DFU management.

Outcome measures

The primary safety outcome was the frequency and severity of adverse events. Patients were monitored for one hour post-injection, contacted by phone at 24 h and one week, and physically examined weekly. Laboratory investigations, including complete blood count and biochemical profile, were repeated monthly for six months in accordance with the safety protocol.

The primary efficacy outcomes were (a) complete ulcer healing within 10 weeks and (b) partial healing, defined as a reduction in ulcer surface area at 10 weeks. Treatment was classified as unsuccessful if neither outcome was achieved within the 10-week period. For patients achieving complete healing earlier, the time to closure was recorded. All patients continued to receive standard of care throughout the study period from week 1 through 6 months.

Statistical analysis

Statistical analyses were performed using Statistical Package for the Social Sciences (SPSS) version (25). Continuous variables were expressed as mean ± standard deviation (SD), and 95% confidence intervals (CI) were calculated where appropriate. Changes in ulcer surface area from baseline to week 5 were assessed using a paired t-test. Differences in healing time between Texas Grade AII and AIII ulcers were evaluated using the Mann–Whitney U test due to non-normal distribution. A p-value < 0.05 was considered statistically significant.

Results

Characterization of hUC-MSCs and derivatives

Human umbilical cord MSCs (hUC-MSCs) displayed the typical fibroblast-like (Fig. 1a), spindle-shaped morphology under inverted microscopy. Differentiation assays confirmed their trilineage potential, with ≥ 50% of cells in the field staining positively for Alizarin Red (osteogenic), Oil Red O (adipogenic), and Alcian Blue (chondrogenic) (Fig. 1b-d). Flow cytometry analysis (Fig. 1e) demonstrated high expression of MSC markers CD90 (≥ 90%), CD73 (≥ 90%), CD44 (≥ 90%), and CD105 (≥ 70%), with minimal expression (< 10%) of hematopoietic and immune markers (CD45, CD34, CD14/CD11b, CD79a/CD19, HLA-DR).

Fig. 1.

Characterization of human umbilical cord–derived mesenchymal stromal cells (hUC-MSCs). a Representative phase-contrast micrograph showing spindle-shaped fibroblast-like morphology of hUC-MSCs at passage 3 (scale bar = 50 μm). b Alizarin Red S staining demonstrating calcium deposition after osteogenic differentiation (scale bar = 50 μm). c Oil Red O staining showing intracellular lipid droplet accumulation after adipogenic differentiation (scale bar = 50 μm). d Alcian Blue staining confirming glycosaminoglycan production following chondrogenic differentiation (scale bar = 50 μm). e Flow cytometric immunophenotyping of hUC-MSCs showing high expression of positive MSC markers CD90 (98.80%), CD105 (97.54%), CD73 (98.76%), and CD44 (97.14%), with minimal expression of the hematopoietic lineage negative cocktail (0.20%)

Enzyme-linked immunosorbent assay (ELISA) (Table 3) confirmed the presence of key growth factors at therapeutically relevant concentrations: epidermal growth factor (EGF: 89.1 pg/mL), C-X-C motif chemokine ligand 12 (Stromal Derived Factor-1) CXCL12 (SDF-1: 1159.4 pg/mL), and Transforming Growth Factor Beta (TGFβ-1) (3151.3 pg/mL).

Table 3.

ELISA Results: Average Concentration ± Standard Deviation (S.D)

Marker	Average ± S.D
Epidermal Growth Factor (EGF)	89.08 ± 9.90
C-X-C motif chemokine ligand 12 (CXCL12)	1159.39 ± 317.14
Transforming Growth Factor Beta (TGF-β)	3151.32 ± 461.99

Patient demographics and baseline characteristics

A total of 10 patients (7 males, 3 females) with chronic DFUs were enrolled (Table 4). The mean age was 55.2 years (range: 40–75), with a mean diabetes duration of 13.3 years (range: 2–25). The mean HbA1c was 8.9% (range: 6.6–10.6), and mean ulcer duration was 10.5 months. The average baseline ulcer surface area was 5.58 cm² (range: 1.5–18.0). According to the University of Texas classification, 7 patients had Grade AII and 2 patients had Grade AIII ulcers. Wagner classification revealed 7 patients with grade 2 and 2 with grade 3 ulcers.

Table 4.

Baseline patient demographics and diabetic foot ulcer (DFU) characteristics

Parameter	Value
No. of Patients	10 Patients
Gender Distribution (M: Males, F: Females)	7 Males / 3 Females
Mean Age (years)	55.2 (40–75)
Mean Diabetes Duration (years)	13.3 (2–25)
Mean HbA1c (%)	8.90 (6.6–10.6)
Mean Wound Duration (months)	10.5 (2–24)
Mean Baseline Ulcer Surface Area (cm2)	5.58 (1.5–18.0)
Texas Grade	A2: 7 Patients A3: 2 Patients
Wegner Grade	2: 7 Patients 3: 2 Patients

Safety outcomes

Monthly hematology and chemistry panels revealed no significant abnormalities. No severe adverse events occurred during the treatment or follow-up period (Table 5). Short-term adverse events were mild and transient, including injection site pain (n = 7), erythema (n = 4), edema (n = 4), itching (n = 3), skin rash (n = 1), and mild fever (n = 1). All resolved spontaneously or with minimal intervention. No long-term complications such as cellulitis, abscess formation, osteomyelitis, gangrene, or sepsis were reported. Importantly, no thrombotic events, amputations, or wound recurrences were observed over a 24-month follow-up.

Table 5.

Incidence of Short- and Long-Term adverse events following hUC-MSCD therapy in DFU patients

Adverse events	Short term					Adverse events	Long term
	1 wk.	2 wks.	3 wks.	4 wks.	5 wks.		3 m	6 m	9 m	12 m	18 m	24 m
Injection site pain	7	6	4	3	0	Wound recurrence	0	0	0	0	0	0
Injection site edema	1	2	0	0	1	Thrombotic events	0	0	0	0	0	0
Injection site erythema	2	0	0	2	0	Abnormal wound healing	0	0	0	0	0	0
Itching	0	2	1	0	0	Tissue remodeling	0	0	0	0	0	0
Fever	0	0	1	0	0	Cellulitis	0	0	0	0	0	0
Skin rash	0	0	0	1	0	Osteomyelitis	0	0	0	0	0	0
Abscess	0	0	0	0	0	Abscess	0	0	0	0	0	0
Osteomyelitis	0	0	0	0	0	Sepsis	0	0	0	0	0	0
Sepsis	0	0	0	0	0	Gangrene	0	0	0	0	0	0
Gangrene	0	0	0	0	0	Amputation	0	0	0	0	0	0

Long-Term clinical outcomes

During the 24-month follow-up period, no cases of all-cause mortality, major or minor amputations, re-amputations, or ulcer recurrence were observed. Furthermore, no hospitalizations or re-hospitalizations related to diabetic foot complications occurred, and no patients developed new disabilities attributable to their index ulcer. Importantly, no cardiovascular events were reported in the study cohort throughout the observation period. These findings suggest a durable safety profile of hUC-MSCD therapy in this early-phase trial, although the limited sample size precludes definitive conclusions regarding long-term event rates.

Efficacy outcomes

All 10 patients achieved complete ulcer healing (Table 6). Mean time to healing was 20.1 days for Texas Grade AII ulcers and 35.0 days for Grade AIII ulcers. By week 5, the mean wound surface area had reduced from 5.58 ± 5.3 cm² at baseline to 0.00 ± 0.0 cm² (p < 0.00001).

Table 6.

Clinical outcomes of hUC-MSCD therapy: healing Duration, injection Frequency, and ulcer closure rates

Patient code	Gender	Days needed for full healing	Number of injections for full healing	Healing percentage after hUC-MSCD treatment
EV-01	M	21	4	100%
EV-02	M	14	3	100%
EV-03	M	21	4	100%
EV-04	M	28	5	100%
EV-05	F	14	3	100%
EV-06	F	21	4	100%
EV-07	M	21	4	100%
EV-08	M	21	4	100%
EV-09	M	35	6	100%
EV-10	F	35	6	100%

No partial or minimal healing was recorded, and no ulcer recurrence was observed during the 24-month follow-up period (Fig. 2). The mean ulcer surface area decreased to 0.00 cm² (SD ± 0.0) by day 35 in all patients. The reduction in ulcer size from baseline to day 35 was statistically highly significant (p < 0.00001).

Fig. 2.

Mean of wound surface area along treatment period up to 24 months

Figure 3 shows representative photographs illustrating the wound healing progression in selected patients over time.

Fig. 3.

Representative photographs of wound healing progression over 24 months

Discussion

Diabetic foot ulcers (DFUs) are a major complication of DM, affecting up to 34% of diabetic patients. They contribute significantly to morbidity, healthcare costs, and lower limb amputations [1]. Current treatment often fails to achieve complete healing, particularly in chronic and ischemic ulcers [2]. Human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) are a promising therapeutic option due to their potent immunomodulatory, pro-angiogenic, and regenerative properties [4].

Central to the regenerative efficacy of hUC-MSCD is their secretion of key growth factors. Epidermal Growth Factor (EGF), a potent mitogen and a mainstay in wound healing, stimulates keratinocyte proliferation and migration—essential drivers of re-epithelialization—and also activates fibroblast proliferation and migration, facilitating granulation tissue formation and extracellular matrix remodeling [16]. Physiologically, serum levels of EGF in healthy individuals hover around ~ 30 pg/mL, and may range from 30 to 60 pg/mL in diabetics, although endogenous wound fluid concentrations are significantly lower, likely due to local depletion and enzymatic degradation. Restoring local EGF via hUC-MSCD-mediated secretion could potentiate epithelial closure and matrix deposition.

CXCL12 (SDF-1), another critical component in the hUC-MSCD secretome, plays a pivotal role in angiogenesis, recruitment of stem/progenitor cells, and immune modulation. CXCL12 signaling is essential for neovascularization and cellular recruitment during wound repair. Although systemic/homeostatic levels of CXCL12 have been recorded in the range of ~ 100–200 pg/mL, local levels in chronic wound environments are substantially lower, limiting effective healing [17]. Enhancing CXCL12 availability through hUC-MSCD may therefore rejuvenate vascular responses and cell trafficking to the wound.

Transforming Growth Factor-β1 (TGF-β1) is a multifunctional cytokine integral to all phases of wound healing—modulating inflammation, recruiting immune cells (especially macrophages), activating fibroblasts, synthesizing ECM and collagen, inducing angiogenesis (via VEGF), and regulating keratinocyte behavior and integrin expression for re-epithelialization. In DFUs, wound fluid TGF-β1 levels around 115 pg/mL have been associated with healing outcomes; levels above this threshold may predict closure within 12 weeks. Conversely, non-healing ulcers often show deficient or dysregulated TGF-β1 activity [18]. By supplying balanced TGF-β1 via hUC-MSCD, you may help re-establish the essential inflammatory-proliferative equilibrium needed for healing [19].

The term human umbilical cord mesenchymal stromal cell derivatives (hUC-MSCD) refers to bioactive components obtained from human umbilical cord mesenchymal stromal cells (UC-MSCs). These derivatives include exosomes, extracellular vesicles (EVs), and conditioned media, and they retain the therapeutic properties of UC-MSCs—most notably, immunomodulation and tissue regeneration—while being explored as cell-free therapies for a range of medical conditions [20].

Recent studies indicate that hUC-MSC derivatives such as conditioned medium, EVs, and exosomes may offer distinct advantages over direct use of UC-MSCs in therapeutic applications [20]. A key benefit is their reduced risk of tumorigenicity and immune rejection compared with other stromal cell types. UC-MSCs themselves exhibit low immunogenicity, making their derivatives particularly appealing for allogeneic transplantation [21]. Importantly, these derivatives preserve the regenerative capabilities of their parent cells while minimizing the ethical concerns associated with direct stem cell therapies.

Another significant advantage of hUC-MSCD lies in their paracrine activity, secreting bioactive molecules such as growth factors, cytokines, and EVs that promote tissue repair and modulate immune responses. These results validated the paracrine regenerative potential of the prepared hUC-MSCD. Studies have shown that hUC-MSC-derived exosomes display anti-inflammatory, pro-angiogenic, and anti-fibrotic properties, making them promising candidates for conditions including myocardial infarction, osteoarthritis, and neurodegenerative diseases [21]. Additionally, hUC-MSC-derived conditioned media have been shown to accelerate wound healing and reduce tissue damage by promoting cell migration and proliferation [22, 23]. These characteristics make hUC-MSCD a more accessible, scalable approach to regenerative medicine, avoiding the logistical and safety challenges associated with direct UC-MSC use—such as the need for extensive in-vitro expansion and concerns about long-term engraftment.

To date, only one clinical study has investigated allogeneic hUC-MSCs in diabetic foot ulcers (DFUs) in humans [9]. This trial examined both topical and intravenous administration of hUC-MSCs in DFU patients with peripheral arterial disease (PAD). Fourteen patients received treatment, which was found to be safe and effective, achieving >95% ulcer closure in all cases within 1.5 months [9]. Remarkably, no amputations or ulcer recurrences were reported after three years of follow-up.

In another study, stromal vascular fraction (SVF) derived from adipose-origin MSCs was tested in a phase I clinical trial involving 63 patients with type II diabetes and chronic non-healing DFUs [22]. Autologous adipose-derived SVF was delivered via local injections and was reported to be safe and effective: at 12 months, 50 patients achieved complete healing and four patients achieved ≥ 85% healing. Six patients died during follow-up and three underwent amputation.

Our study offers the unique advantage of not using MSCs from any source. Instead, we utilized the unfractionated conditioned media derived fromhUC-MSCs, the complete secretome, encompassing soluble growth factors, cytokines, and naturally released extracellular vesicles (including exosomes). In this phase I/II study, we characterized sterility, endotoxin absence, and the presence of key soluble mediators (EGF, CXCL12/SDF-1, and TGF-β1) at therapeutic concentrations, confirming biological activity of the preparation. We acknowledge that we did not separately isolate or analyze the extracellular vesicle and exosome fractions in this trial. Future preclinical and clinical studies will focus on detailed characterization of these subcomponents to further delineate their individual contributions to wound healing.

This product demonstrated excellent safety, with only mild short-term adverse events, and remarkable efficacy in accelerating DFU healing. The absence of ulcer recurrence during two years of follow-up further underscores its therapeutic promise. Moreover, the preparation can be stored as a ready-to-use product, without requiring additional cell culture or expansion prior to administration.

Although no mortality, amputations, re-hospitalizations, or cardiovascular events were observed during the 24-month follow-up, the small sample size limits the strength of conclusions regarding long-term outcomes, which should be rigorously evaluated in larger, controlled trials. While these results are encouraging, the small sample size limits the generalizability of our findings. Future work should focus on larger, placebo-controlled clinical trials to confirm efficacy, optimize dosing strategies, and further validate hUC-MSCD as a potential off-the-shelf biologic therapy for DFUs.

Conclusions

This phase I/II trial demonstrates that perilesional administration of human umbilical cord–derived mesenchymal stromal cell derivatives (hUC-MSCD) is safe and well tolerated in patients with chronic, non-healing diabetic foot ulcers. All patients achieved complete wound closure within weeks, with no recurrence, amputations, or long-term adverse events observed during 24 months of follow-up. While these findings provide encouraging early evidence of efficacy, larger randomized controlled studies are needed to confirm therapeutic benefit, assess long-term outcomes, and explore integration with standard and advanced wound care strategies.

Author contributions

HJ supervised production and laboratory work, followed up clinical work, wrote the original manuscript. RA and HA performed patient recruitment and clinical procedures. DS, EA and NA performed laboratory experiments and prepared figures. AA revised the manuscript, provided overall supervision and clinical procedures. All authors reviewed and approved the manuscript.

Data availability

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request. De-identified clinical data supporting the findings of this study can be shared with qualified investigators upon approval by IRB of the Cell Therapy Center, University of Jordan.

Declarations

Ethics approval and consent to participate

This study was conducted in accordance with the Declaration of Helsinki. The project entitled “The use of extracellular vesicles extracted from allogenic mesenchymal cells of the umbilical cord for the management of chronic diabetic foot ulcers” was reviewed and approved by the Institutional Review Board (IRB) of the Cell Therapy Center, University of Jordan (Approval No. IRB-CTC/1-2021/01b; approved 1 February 2021). Written informed consent was obtained from the mother for donation and use of umbilical cord tissue, and from all participating patients (or their legally authorized representatives) for trial enrollment and use of their clinical data and samples.

Competing interests

The authors declare no competing interests.