Effectiveness of regenerative medicine for skin lightening and rejuvenation: a systematic review of extracellular vesicles and conditioned media

Abstract

Aims and objectives

This study aims to evaluate and summarize the efficacy and safety of extracellular vesicles (EVs) and conditioned media (CM) as emerging therapeutic approaches in regenerative medicine for skin rejuvenation and lightening.

Methods

A systematic search was conducted up to September 19, 2024, using the PubMed, Scopus, and Web of Science databases. Keywords included "conditioned media," "secretome," "extracellular vesicles," “exosome,” "rejuvenation," "lightening," and others. Studies were screened based on predefined inclusion criteria, followed by data extraction. Key extracted data included study design, population characteristics (mean age and range), intervention duration, comparisons, outcomes with statistical results, and adverse effects. The statistical methods applied in individual studies were documented to assess the validity of reported improvements.

Results

This review included 19 studies with a total of 624 patients evaluating the efficacy and safety of EVs and CMs for skin lightening and rejuvenation. Among these, 21% investigated the effects of EVs, while 78% focused on CMs. The most commonly assessed skin parameters included wrinkles, pigmentation, spots, elasticity, and hydration. Various application methods were used, including topical administration, microneedling, and fractional laser therapy. Reported improvements included a 27.07% increase in skin elasticity (p < 0.05), over 10% reduction in wrinkles (p < 0.05), and more than 20% enhancement in hydration (p < 0.05). No serious adverse effects were reported, with only transient minor reactions such as erythema observed.

Conclusion

EVs and CMs appear to be safe and potentially effective for skin rejuvenation and lightening. However, further high-quality studies are required to confirm long-term safety, investigate variations in efficacy based on cell sources, and optimize application techniques for clinical use.

What is already known about this topic?

• Skin aging, hyperpigmentation, and wrinkles significantly impact quality of life, prompting a heightened demand for effective rejuvenation and lightening therapies. Traditional treatment methods often have limitations, necessitating the exploration of novel, less invasive therapeutic options.

• Extracellular Vesicles or Exosomes are small extracellular vesicles, typically 30–150 nm in diameter, that are released from various types of cells into the extracellular environment. They originate from the inward budding of the endosomal membrane and are involved in intercellular communication, carrying proteins, lipids, and nucleic acids that can influence the behavior of recipient cells.

• Conditioned medium refers to the nutrient-rich fluid collected from cell cultures after cells have been grown in it for a period. This medium contains a mixture of secreted proteins, growth factors, and other signaling molecules released by the cells, reflecting their metabolic activity and physiological state.

What does this study add?

• A total of 19 articles were included in the review on the efficacy and safety of extracellular vesicles (EVs) and conditioned media (CM) after screening an initial set of 893 articles, with 4 focusing on EVs and 15 on CMs.

• The application of Lactobacillus plantarum-derived extracellular vesicles (lpEV5) resulted in a 27.07% increase in skin elasticity and a 21.40% increase in skin hydration after four weeks of treatment.

• Adipose tissue-derived mesenchymal stem cell exosomes led to a significant decrease in melanin levels, from 187.78 to 169.33, representing a reduction of approximately 9.81% after 8 weeks (p < 0.01). Even greater reductions were observed in participants under 50 years of age.

• Intradermal injection of cell-free blood cell conditioned media demonstrated a 58.9% improvement in overall aesthetic appearance as assessed by physicians, along with a 76.8% self-reported improvement from participants.

• The human umbilical cord-derived mesenchymal stem cell conditioned media resulted in a significant decrease in the melanin index, from 24.25 ± 15.55 to 12.36 ± 16.38 (p = 0.00), indicating substantial efficacy in skin lightening when combined with microneedling.

• In a study comparing microneedling with AMSC-CM to fractional CO₂ laser with AMSC-CM, significant results were as follows: microneedling with CM reduced UV spots by 2.50 (p = 0.01) and improved skin tone by 1.00 (p = 0.04), while the CO₂ laser reduced UV spots by 1.00 and showed no change in skin tone (0.00).

Introduction

Skin aging, hyperpigmentation, and wrinkles are significant factors affecting individuals' quality of life. Skin aging is a multifactorial process involving intrinsic factors such as genetics and hormonal changes, as well as extrinsic factors like environmental stressors, including UV radiation and pollution [1]. These factors alter intracellular and extracellular compositions, impacting skin elasticity, texture, thickness, and tone, ultimately leading to the formation of fine lines, wrinkles, and uneven pigmentation. Consequently, the demand for effective rejuvenation and lightening therapies has surged, prompting researchers and clinicians to explore innovative treatment modalities [2].

Traditional approaches to skin rejuvenation and hyperpigmentation management, such as cosmetic topical agents, chemical agents, and laser treatments, often have limitations regarding efficacy, patient satisfaction, compliance, and side effects. For example, topical agents may require prolonged use to achieve noticeable results, while chemical peels and laser treatments can be invasive and associated with downtime. There is a clear need for novel, less invasive, and more effective therapies that can provide consistent and remarkable outcomes [3, 4].

Among the innovative treatment options, extracellular vesicles (EVs) and conditioned media (CM) have gained attention for their regenerative and therapeutic properties. Recent advancements in regenerative dermatology have increasingly emphasized the potential of EVs and CMs as next-generation biologics, offering a paradigm shift in aesthetic and therapeutic dermatology [5]. Unlike conventional treatments that primarily target superficial symptoms, EVs and CMs exert their effects at the cellular level, fostering deeper tissue regeneration and enhanced physiological recovery. These properties distinguish them as highly promising agents in the evolving landscape of non-invasive skin therapies. EVs are lipid-membrane-enclosed structures found in most cells that transfer active biological substances and play a crucial role in cellular communication and physiological processes, including inflammation [5, 6]. EVs are primarily classified into exosomes (30–200 nm), which are released from multivesicular endosomes, and microvesicles (100–1000 nm), which form through budding from the plasma membrane. These vesicles regulate physiological processes, including immune responses and inflammation [5, 6].

EVs and CMs hold promise for skin rejuvenation because they can modulate key biological pathways critical for skin repair and regeneration. Exosomes, for instance, contain bioactive molecules such as microRNAs, proteins, and lipids that influence gene expression and cellular behavior. These bioactive components can stimulate fibroblast activation, collagen synthesis, and tissue remodeling, which are fundamental for improving skin elasticity and reducing wrinkles [7, 8]. Furthermore, exosomes can suppress inflammation by regulating cytokine production, which is a key factor in the aging process and the formation of hyperpigmentation [9]. Similarly, CM, rich in growth factors and cytokines, can activate the Wnt/β-catenin signaling pathway to promote dermal fibroblast proliferation and collagen deposition, enhancing skin elasticity and texture [10]. Additionally, the vascular endothelial growth factor (VEGF) present in CM contributes to increased angiogenesis, improving skin hydration and overall skin tone [11]. These biological effects position EVs and CMs as powerful tools for regenerative dermatology.

Research has shown that exosomes can enhance tissue repair, promote collagen synthesis, and modulate inflammatory responses, making them particularly appealing for dermatological applications. Their ability to facilitate cellular signaling and regeneration positions exosomes as potential game-changers in the field of skin rejuvenation [7, 8]. Emerging studies suggest that exosome-based therapies may surpass traditional mesenchymal stem cell (MSC) treatments in terms of bioavailability, stability, and targeted effects, addressing limitations previously encountered with direct stem cell applications [9].

Similarly, CM—the liquid byproduct of cultured cells—contains a diverse array of soluble factors, including growth factors, cytokines, and extracellular matrix components. Utilizing CM in skincare offers a less invasive alternative to direct cell-based therapies, allowing for the delivery of bioactive molecules that significantly influence skin physiology [9, 10]. Clinical studies suggest that CM can enhance skin hydration, improve elasticity, and promote a more even skin tone, thereby addressing both rejuvenation and lightening concerns [11, 12]. Notably, recent research highlights advancements in the optimization of CM formulations, including cell-source specificity, cryopreservation techniques, and combinatorial applications with adjunctive dermatological treatments [12]. These innovations broaden the clinical applicability of CM in aesthetic medicine, reinforcing its therapeutic potential.

Tissue engineering techniques can aid in repairing or regenerating damaged teeth by promoting cell proliferation and differentiation in endodontic regeneration. For optimal integration with native tissue, scaffolds should mimic the properties of the cellular matrix. Bioprinting, a novel technique, utilizes bioinks—combinations of live cells, biomaterials, and biomolecules—to create 3D structures that replicate the topology and mechanical/biological properties of human tissues or organs [13–15].

Despite the promising potential of exosomes and CM, there is a need for comprehensive evaluations of their efficacy in clinical settings [16, 17]. While previous reviews have explored the mechanistic and preclinical aspects of EVs and CMs, a dedicated synthesis of clinical data focusing on in vivo human outcomes remains limited. This systematic review aims to bridge this gap by providing a critical analysis of the latest clinical studies investigating the effects of exosomes and CM on skin rejuvenation and lightening. By focusing on clinical variables such as skin texture, elasticity, pigmentation changes, and patient-reported outcomes, we will synthesize the existing evidence regarding the therapeutic effects of these interventions.

In this systematic review, we investigate the clinical performance, effective routes of administration, safety, and limitations of these therapeutic methods. However, the underlying mechanisms by which exosomes and CM exert their effects on skin cells and tissues, as well as cellular and animal studies, are outside the scope of this review. By consolidating findings from diverse clinical trials and emerging trends, this review not only provides a comprehensive perspective but also highlights crucial gaps that must be addressed in future research, paving the way for more standardized and effective regenerative dermatology treatments.

Method and materials

We conducted a systematic review to investigate the efficacy and safety of EVs and/or CM in clinical settings. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [18].

Search strategy

A systematic search was conducted on PubMed, Scopus, and Web of Science up to September 19, 2024, using a predefined combination of Medical Subject Headings (MeSH) terms and keywords relevant to EVs, CM, and skin rejuvenation. The full search query was as follows:

(“conditioned medium" OR "conditioned media" OR "stem cell conditioned medium" OR "stem cells conditioned medium" OR "stem cell-conditioned medium" OR "stem cell-conditioned media" OR "mesenchymal stem cell-conditioned medium" OR "mesenchymal stem cell-conditioned media" OR "cultured medium" OR "growth medium" OR "basal medium" OR "supplemented medium" OR "nutrient medium" OR "mesenchymal stem cell exosomes" OR "mesenchymal stem cell-derived exosomes" OR "secretome" OR "exosome" OR "extracellular vesicles" OR "EV") AND ("rejuvenation" OR "lightening" OR "skin lightening" OR "skin brightening" OR "wrinkle" OR "skin wrinkling" OR "wrinkling" OR "infraorbital dark circles" OR "infraorbital puffiness" OR "skin rejuvenation").

Search results were limited to peer-reviewed original research articles published in English. No restrictions were placed on the year of publication to ensure comprehensive coverage of existing literature.

Study selection and data extraction

We included original in vivo human studies investigating the efficacy or safety of EVs or CM that reported clinical outcomes related to skin rejuvenation or lightening.

Inclusion criteria

Studies were included if they met the following criteria:

• Population: Human subjects undergoing EV or CM treatment for skin rejuvenation, lightening, or related dermatological applications.

• Intervention: Use of EVs or CM as a primary or adjunctive treatment.

• Comparator: Studies with or without a control group were included.

• Outcomes: Clinical measures assessing skin texture, elasticity, pigmentation changes, hydration, wrinkle reduction, or other dermatological improvements.

• Study Design: Clinical trials, cohort studies, and case series with quantitative clinical assessments.

Exclusion criteria

The following exclusion criteria were applied:

• Non-original articles (e.g., reviews, editorials, and conference abstracts).

• Non-English publications to ensure accessibility and consistency in data extraction.

• Animal or in vitro studies as they do not provide direct clinical outcomes in humans.

• Studies lacking clinical outcomes, including those focusing solely on mechanistic insights or biomolecular analyses without measurable patient-related results.

Study selection process

Study selection was performed in two phases:

• Title and Abstract Screening: One reviewer (S.S.) initially screened titles and abstracts to exclude irrelevant studies.

• Full-Text Screening: The remaining articles underwent full-text review. Any discrepancies during this process were resolved through discussion with a second reviewer (A.J.), and if necessary, a third independent reviewer (A.G.) was consulted. The study selection process is illustrated in Fig. 1.

Fig. 1.

PRISMA chart of search result screening steps

Data extraction

Data were extracted using a standardized template, ensuring consistency across studies. Extracted variables included:

• Study design (e.g., randomized controlled trial, cohort study, case series).

• Population characteristics (mean age, range, gender distribution).

• Intervention details (type of EVs or CM, dosage, administration method, duration of treatment).

• Comparison groups (if applicable).

• Clinical outcomes (quantitative results on skin rejuvenation and lightening).

• Adverse effects (if reported).

Two reviewers (S.S. and A.J.) independently performed data extraction. Any conflicts were resolved by an independent third reviewer (A.G.) to ensure accuracy and consistency in the extracted information.

Risk of bias assessment

The risk of bias in each included study was assessed using the Cochrane Risk of Bias 2.0 (RoB 2) tool, which evaluates five key areas: bias from the randomization process (D1), deviations from intended interventions (D2), missing outcome data (D3), outcome measurement (D4), and selection of reported results (D5). Each domain was classified as having a "low risk," "some concerns," or "high risk" of bias. Assessments were conducted independently by the primary investigators [A.J.] and [S.S.], with any disagreements resolved through discussion with a third reviewer [A.G.]. The overall risk of bias for each study was determined based on the ratings of these individual domains (Fig. 2).

Fig. 2.

Risk of Bias Assessment: the risk of bias across five domains for various studies, indicating low (green), some concerns (yellow), and high risk (red)

Results

Search results

From an initial search of 893 articles, a total of 19 articles were ultimately included in our review. The screening process is illustrated in the PRISMA chart (Fig. 1), and the extracted data from these articles are presented in Table 1.

Table 1.

Search strategies for databases

PubMed	("conditioned medium" OR "conditioned media" OR "stem cell conditioned medium" OR "stem cells conditioned medium" OR "stem cell-conditioned medium" OR "stem cell-conditioned media" OR "mesenchymal stem cell-conditioned medium" OR "mesenchymal stem cell-conditioned media" OR "Cultured medium" OR "Growth medium" OR "Basal medium" OR "Supplemented medium" OR "Nutrient medium" OR "mesenchymal stem cell conditioned medium" OR "mesenchymal stem cell conditioned media" OR "secretome" OR "Exosome" OR "extracellular vesicles" OR "EV" OR "mesenchymal stem cell exosomes" OR "Mesenchymal stem cell-derived exosomes" OR "Mesenchymal‐stem‐cell‐derived exosomes") AND ("rejuvenation" OR "lightening" OR "skin-lightening" OR "skin brightening" OR "wrinkle" OR "skin wrinkling" OR "wrinkling" OR "infraorbital dark circles" OR "infraorbital puffiness" OR "skin rejuvenation")
Scopus	(TITLE-ABS-KEY("conditioned medium" OR "conditioned media" OR "stem cell conditioned medium" OR "stem cells conditioned medium" OR "stem cell-conditioned medium" OR "stem cell-conditioned media" OR "mesenchymal stem cell-conditioned medium" OR "mesenchymal stem cell-conditioned media" OR "Cultured medium" OR "Growth medium" OR "Basal medium" OR "Supplemented medium" OR "Nutrient medium" OR "mesenchymal stem cell conditioned medium" OR "mesenchymal stem cell conditioned media" OR "secretome" OR "Exosome" OR "extracellular vesicles" OR "EV" OR "mesenchymal stem cell exosomes" OR "Mesenchymal stem cell-derived exosomes" OR "Mesenchymal‐stem‐cell‐derived exosomes") AND TITLE-ABS-KEY("rejuvenation" OR "lightening" OR "skin-lightening" OR "skin brightening" OR "wrinkle" OR "skin wrinkling" OR "wrinkling" OR "infraorbital dark circles" OR "infraorbital puffiness" OR "skin rejuvenation"))
Web of Science	TS = ("conditioned medium" OR "conditioned media" OR "stem cell conditioned medium" OR "stem cells conditioned medium" OR "stem cell-conditioned medium" OR "stem cell-conditioned media" OR "mesenchymal stem cell-conditioned medium" OR "mesenchymal stem cell-conditioned media" OR "Cultured medium" OR "Growth medium" OR "Basal medium" OR "Supplemented medium" OR "Nutrient medium" OR "mesenchymal stem cell conditioned medium" OR "mesenchymal stem cell conditioned media" OR "secretome" OR "Exosome" OR "extracellular vesicles" OR "EV" OR "mesenchymal stem cell exosomes" OR "Mesenchymal stem cell-derived exosomes" OR "Mesenchymal‐stem‐cell‐derived exosomes") AND TS = ("rejuvenation" OR "lightening" OR "skin-lightening" OR "skin brightening" OR "wrinkle" OR "skin wrinkling" OR "wrinkling" OR "infraorbital dark circles" OR "infraorbital puffiness" OR "skin rejuvenation")

Characteristics of eligible studies

The 893 articles were sourced from PubMed (208, 23%), Scopus (389, 43%), and Web of Science (296, 33%). After removing duplicates, 393 articles were eliminated. In the first step of screening, two reviewers (S.H. and A.J.) assessed the remaining articles based on their titles and abstracts. Eighty-two articles were excluded due to inappropriate study types, including reviews, editorials, conference proceedings, and retractions. Additionally, 71 articles were excluded as they focused on animal studies that did not meet our inclusion criteria, and a further 328 articles were excluded for having irrelevant titles and/or abstracts. Ultimately, 19 articles were included for review. Among these, 4 articles (21%) focused on EVs and 15 articles (79%) on CMs.

The gender distribution of participants was as follows: 526 females, 21 males, and 77 with undefined gender. Specifically, for the studies involving EVs, there were 88 females and 8 males, while the CM studies included 438 females, 13 males, and 77 individuals with undefined gender. Among the studies that reported the mean age of participants (12 of the 19 articles), the mean age was 49.08 years.

EVs

In the studies reviewed, one reported exclusively on the lightening effects of their intervention, while another focused solely on rejuvenation parameters. The remaining two studies (50%) investigated both rejuvenation and lightening outcomes. The route of administration was topical in all studies except one, which utilized microneedling [19]. All articles demonstrated significant effects on both lightening and rejuvenation outcomes, particularly concerning hydration, moisturizing, pigmentation, and elasticity. Detailed findings are described below.

Rejuvenation outcomes of EVs

Skin elasticity was measured using a Cutometer® (MPA 580, Courage + Khazaka, Germany), which evaluates the ability of the skin to return to its original shape after stretching by measuring R2 (gross elasticity) and R7 (biological elasticity). One study conducted a 4-week clinical trial comparing the effects of twice-daily topical application of Lactobacillus plantarum-derived EVs (lpEV5) with a placebo group. The results indicated a 27.07% increase in skin elasticity (p < 0.05) and a 21.40% increase in skin hydration (p < 0.05). Additionally, skin density, assessed through high-frequency ultrasound imaging (DermaScan C, Cortex Technology, Denmark), increased by 24.11% (p < 0.05) compared to the placebo group, alongside significant reductions in pigmentation. No adverse effects were reported [5].

Another study used a prospective, randomized, split-face design comparing microneedling with human adipose tissue stem cell-derived exosomes (HACS) to microneedling with normal saline over 12 weeks. Skin elasticity, measured through Cutometer® parameters, increased by 11.3% in the HACS group, compared to a 3.3% decrease in the control group (p = 0.002). Skin hydration, determined using a Corneometer® CM 825 (Courage + Khazaka, Germany), improved by 6.5% in the HACS group versus 4.5% in the control group (p = 0.037), and the melanin index, measured using a Mexameter® MX 18 (Courage + Khazaka, Germany), decreased by 9.9% in the HACS group compared to 1.0% in the control group (p = 0.044). Only mild transient erythema, edema, and petechiae were reported as adverse effects [19].

Additionally, one study conducted a 4-week trial evaluating the effects of twice-daily topical application of milk-derived exosomes (MK-Exo). Skin moisture content, measured using a Corneometer®, increased by 5.6% by week 4 (p < 0.05), with significant improvements observed in the 36–45 age group (p < 0.05). Skin elasticity, analyzed using Cutometer® R2 values, improved by 6.33% (p < 0.05), with a 10.74% increase in the 36–45 age group (p < 0.01). The wrinkle area, assessed via VISIA® Complexion Analysis (Canfield Scientific, USA), decreased by 9.59% (p < 0.001), and the number of wrinkles was reduced by 4.99% (p = 0.001) [20].

Lightening outcomes of EVs

Skin pigmentation was assessed using the Mexameter® technique, which quantifies melanin levels through spectrophotometry. One study evaluated the effects of twice-daily topical ASC-exosomes compared to a placebo over 8 weeks. This study showed a significant reduction in melanin levels, decreasing from 187.78 to 169.33 (p < 0.01). Participants under 50 years of age exhibited even greater reductions in melanin [21].

A different study using microneedling with human adipose tissue stem cell-derived exosomes (HACS) resulted in a significant reduction in the melanin index (p = 0.044) over 12 weeks [5].

In a different study, microneedling with human adipose tissue stem cell-derived exosomes (HACS) resulted in a significant reduction in the melanin index (p = 0.044) over 12 weeks [19].

Finally, while one study did not specify a quantitative pigmentation score, it reported dramatic qualitative improvements in skin brightness following the use of topical milk-derived exosomes (MK-Exo) over 4 weeks [20].

Overall, the studies indicated promising effects of various types of EVs on skin pigmentation, with ASC-exosomes demonstrating particularly potent performance. Additional details from each study are summarized in Tables 2 and 3.

Table 2.

Extracted data from included articles

N	year	DOI	Study Design	Population (mean, range)	Intervention (duration)	Comparison	Outcome (p value)	Adverse effects
1	Kerscher et al. 2022 [22]	10.2147/CCID.S357810	Prospective, one-armed, multicenter interventional therapeutic study	95 F1 (50.2)	Secretome—Intradermal injection of BCS2 (48 weeks)	–	Skin Firmness: From 0.4 mm to 0.37 with ES3 0.35 (< 0.0024) Skin Tiring: From 0.45 mm to 0.41 with ES 0.43 (< 0.0005) FACE-QTM satisfaction with appearance: From 42.56 to 51.99 with ES 0.65 (< 0.0001) FACE-QTM satisfaction with skin: From 39.64 to 53.99 with ES 0.85 (< 0.0001) Psychological function From 59.75 to 66.43 with ES 0.38 (< 0.0003) Social function: From 57.54 to 62.90 with ES 0.34 (< 0.0013) Aging Appraisal score: From 52.94 to 65.23 with ES 0.73 (< 0.0001) Patient Perceived Age: + 1.68 years younger GAIS (physician assessment): 58.9% improvement (< 0.0001) GAIS (patient self-assessment): 76.8% improvement (< 0.0001)	From 380 times injection:  Hematoma: 17 times (16 mild, 1 moderate)  Redness: 5(mild)  Pain: 4(mild)  Swelling: 5(mild), 1(moderate)  Urticaria: 3(Mild), 1(moderate)
2	Jo CS et al. 2022 [5]	10.3390/cimb44020036	Clinical Trials	16 women (50 s)	EV4- Topical lpEV5 treatment (4 weeks)	Placebo	Indentation Index (A.U.) − 15.89% Skin elasticity + 27.07% Water content + 21.40%—with skin density + 24.11% than placebo Pigmentation Reduction Significant decrease – with skin density improvement + 8.7%	N/A6
3	Liang X et al. 2022 [23]	10.3389/fmed.2022.837332	Randomized Controlled Split-Face Study	30 (41, 35–60) With skin aging	Human umbilical cord-derived mesenchymal stem cells conditioned media (hUC-MSCs-CM) via microneedling (MN) (10 weeks)	Saline via MN	Subjective Evaluations  Self-Evaluation (Satisfaction):  MN + hUC-MSCs-CM side: More satisfied versus Control side: Less satisfied (p < 0.05)  Clinical Assessment (Brightness & Texture):  MN + hUC-MSCs-CM side: Greater improvement in brightness and texture versus Control side: Less improvement (< 0.05) Objective Assessments Skin Physiological Parameters  Hydration:  MN + hUC-MSCs-CM side: No significant change (2.18 ± 5.80) (0.06)  MN Alone side: No significant change (2.07 ± 6.78) (0.12)  TEWL (Trans-Epidermal Water Loss):  MN + hUC-MSCs-CM side: No significant change (1.96 ± 5.15) (0.05)  MN Alone side: No significant change (1.10 ± 3.79) (0.13)  Skin Pigmentation  Melanin Index (Brightness):  MN + hUC-MSCs-CM side: Decrease (24.25 ± 15.55) versus MN Alone side: Decrease (12.36 ± 16.38) (0.00)  Ultraviolet Spots:  MN + hUC-MSCs-CM side: Decrease from 24.39 ± 7.11 to 14.47 ± 5.38 versus MN Alone side: Decrease from 23.08 ± 7.58 to 17.72 ± 6.18 (< 0.05)  Brown Spots:  MN + hUC-MSCs-CM side: Decrease from 40.21 ± 5.14 to 34.18 ± 6.32 versus MN Alone side: Decrease from 39.71 ± 5.82 to 37.75 ± 5.63 (0.00)  Erythema Index (EI):  MN + hUC-MSCs-CM side: No significant difference (336.69 ± 63.08 to 336.85 ± 60.06) (0.90)  MN Alone side: No significant difference (336.68 ± 60.80 to 337.29 ± 57.05) (0.87)  Red Spots:  MN + hUC-MSCs-CM side: Decrease from 29.30 ± 5.58 to 28.20 ± 4.92 (0.17)  MN Alone side: Decrease from 29.17 ± 5.93 to 28.08 ± 5.38 (0.12)  Skin Rejuvenation  Wrinkles:  MN + hUC-MSCs-CM side: Significant decrease from 12.15 ± 10.26 to 5.06 ± 3.44 versus MN Alone side: Decrease from 10.73 ± 10.63 to 7.46 ± 6.07 (0.00)  Pores:  MN + hUC-MSCs-CM side: Significant decrease from 23.55 ± 10.52 to 14.05 ± 6.11 versus MN Alone side: Decrease from 24.40 ± 10.77 to 18.59 ± 7.70 (0.00)  Elasticity:  MN + hUC-MSCs-CM side: Significant increase from 0.56 ± 0.07 to 0.69 ± 0.05 versus MN Alone side: Increase from 0.57 ± 0.06 to 0.65 ± 0.07 (0.00)	No severe side effect In hUC-MSCs-CM group: two dry skin and one erythema In MN alone group: Three dry skin and two erythema
4	Kerscher M et al. 2021 [24]	10.36849/JDD.2021.5018	Prospective, single-armed, mono-center study	21F (–) with age-related reduced facial skin elasticity	Sub-dermal micropuncture injections of cell-free Blood Cell Secretome (BCS) (24 weeks)	–	In 24-week, evaluation:  Skin firmness: increased significantly (p < 0.001)  Skin tiring: reduced significantly (< 0.001) Skin hydration and aesthetic: improved significantly	No AE
5	Bhat S et al. 2022 [25]	10.1111/jocd.14145	Mono centric, open-label, single-arm, clinical trial	20F (-, 18–66) With under-eye dark circle	Stromal cell-derived conditioned medium (MSC-CM) and antioxidants (12 weeks)	No control group	Clinical Efficacy Parameters:  Improvement in Under-eye Dark Circles: Significant reduction (p: N/A)  Eye Puffiness: Improved in 70% of subjects (p: N/A)  Periorbital Fine Lines: Improved in 26.7% (p: N/A)  Crow's Feet: Improved in 62.5% (p: N/A)  Even Skin Tone: Improved in 68.8% (p: N/A)  Radiance: Improved in 73.3% (p: N/A)  Skin Smoothness and Texture: Improved in 25% (p: N/A)  Skin Brightness/Whitening: Improved in 62.5% (p: N/A)  Skin Tightening: Improved in 18.2% (p: N/A)  Refreshing/Soothing Effect: Improved in 29.5% (p: N/A)  Self-Assessment of Improvement:  60% felt moderate to large improvement 35% felt small worthwhile improvement and 5% felt slight improvement	No AE
6	Hoss E et al. 2020 [26]	10.36849/JDD.2020.5246	Prospective, randomized controlled, double-blind trial	20- (–) with moderate to severe photodamage	Red deer umbilical cord-derived stem cell conditioned media (USCCM) cream and serum, applied pre- and post-procedure (- weeks)	Vehicle cream and serum (placebo)	USCCM is efficacious using before and after facial laser resurfacing Full-text of the study was not available	No serious AE
7	El-Domyati M et al. 2020 [27]	10.1111/jocd.13594	Split-face, comparative study	10(3M7, 7F) (49.9, 41–60) With skin aging	Needling with amniotic fluid mesenchymal stem cell derived conditioned media (AF-MSC-CM) (12 weeks)	Needling alone	Patient Improvement:  Control side:  Mild: 30%, Moderate: 70%, Statistical Significance: p = 0.026  AF-MSC-CM:  Moderate: 20%, Good: 70%, Very Good: 10%, Statistical Significance: p = 0.019  Comparison Between Sides: p = 0.003  Mean Percentage of Improvement  AF-MSC-CM: 60.6 ± 9.77  Control side: 33.2 ± 8.95  P < 0.001 Specific Improvements  Crow’s Feet Wrinkles: Almost all patients showed improvement, especially on the AF-MSC-CM  Forehead Wrinkles: Improvement observed in 50% of patients  Skin Texture: Improvement observed in 70% of patients Patient Satisfaction  Completely Satisfied: 6 patients (60%)  Somewhat Satisfied: 2 patients (20%)  Unsatisfied: 2 patients (20%) Histologic Evaluation  Collagen Fibers (Mason Trichrome Stain):  Before Treatment: Disorganized collagen bundles with increased intercellular spaces  After Treatment: Increased and more organized collagen bundles; decreased interfibrillary spaces (more significant on the AF-MSC-CM)  Elastic Fibers (Orcein Stain):  Before Treatment: Dense elastotic material near the epidermis  After Treatment: Decrease in elastotic material; appearance of fine, well-arranged elastic fibers (more pronounced on the AF-MSC-CM treated side) Histometric Evaluation  Epidermal Thickness  Control Side:  From 47.55 ± 5.52 µm to 62.18 ± 5.69 µm (< 0.001)  DR + AF-MSC-CM:  From 48.19 ± 4.36 µm to 64.08 ± 4.30 µm (< 0.001)  Comparison Between Both Sides: P = 0.41	No long-term AE8 Transient Erythema and slight edema
8	Prakoeswa CRS et al. 2019 [28]	10.1080/09546634.2018.1530438	Analytic, experimental research	48F with photoaging (50.3)	Amniotic Membrane Stem Cell-conditioned medium (AMSC-CM) + microneedling (8 weeks)	Normal saline + microneedling	Pore: Better than control group with p = 0.003* versus 0.774 in control group Wrinkle: Better than control group with p = 0.011* versus 0.801 Spot (polarized): Better than control group with p = 0.041* versus 0.606 Spot (UV): Better than control group with p = 0.032* versus 0.465 Skin Tone: No significant improvement. 0.208 versus 0.432	Minimal transient side effects in both groups
9	Zhou BR et al. 2016 [11]	10.3109/14764172.2015.1114638	Single center, prospective, pilot study	12F, 10M (36.4, 24–50) 9 skin rejuvenation, 13 acne scar group	Fractional carbon dioxide laser resurfacing (FxCR) on all participants in 3 sessions. Adipose-derived stem cell conditioned medium (ADSC-CM) to the treatment site of one randomly selected side of the face (12 weeks)	FxCR with placebo (DMEM)	Subjective Satisfaction Scale:  Skin Rejuvenation Group:  Satisfaction scores in both sides increased after each session  In 8 and 12 weeks, the satisfaction scores for the ADSC-CM side were 2.36 ± 0.42 and 2.56 ± 0.65, significantly higher than the DMEM side  Acne Scar Group:  Satisfaction scores also increased after each treatment  In 12 weeks, the score on the ADSC-CM side was 2.35 ± 0.69, significantly higher than the DMEM side (2.08 ± 0.76) Objective Clinical Assessment:  Skin Rejuvenation Group:  In 8 and 12 weeks, the clinical assessment score on the ADSC-CM side was 2.56 ± 0.52 and 2.78 ± 0.45, significantly higher than the DMEM side (1.89 ± 0.60 and 2.00 ± 0.71)  Acne Scar Group:  ECCA score: significantly lower after treatment  In 12 weeks, the ECCA score on the ADSC-CM side was 32.69 ± 18.10, significantly lower than the DMEM side (26.15 ± 19.16) Biophysical Analysis:  Erythema Index (EI):  Both groups had peak EI values one week after the first treatment, but the differences between the two sides were not statistically significant  Melanin Index (MI):  The ADSC-CM side had a significantly lower MI, particularly one week after the first treatment and in 12 weeks  Elasticity (R2): Skin Rejuvenation Group: Elasticity increased from 0.7325 ± 0.079 to 0.8809 ± 0.032 in the ADSC-CM side, significantly higher than the DMEM side (0.7607 ± 0.072 to 0.8083 ± 0.039) Acne Scar Group: Elasticity also increased on both sides, with the ADSC-CM side showing significantly higher values in 8 and 12 weeks  Transepidermal Water Loss (TEWL):  increased initially but then decreased to baseline  In the ADSC-CM side, TEWL was significantly lower than the DMEM side in 8 and 12 weeks  Hydration:  significantly increased in the ADSC-CM side in both groups  In the skin rejuvenation group, increased from 52.42 ± 11.00 to 64.03 ± 8.17, while in the acne scar group, it increased from 36.05 ± 10.54 to 54.82 ± 6.39 Skin Surface Roughness: increased significantly on both sides, with more pronounced changes on the ADSC-CM side Comparison of Adverse Reactions: Edema: ADSC-CM edema score of 1.51 ± 0.68 in the skin rejuvenation group and 1.77 ± 0.44 in the acne scar group versus DMEM 1.98 ± 0.77 and 1.46 ± 0.52, respectively  Crust Duration:  ADSC-CM significantly shorter crust duration in the skin rejuvenation group (7.45 ± 1.28 days) versus DMEM side (10.23 ± 1.58 days)  In the acne scar group, the ADSC-CM side 9.38 ± 1.12 days versus 7.61 ± 1.44 days for the DMEM side Histologic Analysis: significantly increased dermal collagen and elastin density on the ADSC-CM side compared to the DMEM side  Collagen Density (Masson-Trichrome staining):  ADSC-CM higher collagen density (49.98 ± 0.62%) versus DMEM side (36.09 ± 0.61%)  Elastin Density (Gomori’s aldehyde fuchsin staining):  ADSC-CM significantly higher elastin density (37.61 ± 0.79) versus DMEM side (26.13 ± 0.35)	No serious AE and no withdrawal
10	Lee HJ et al. 2014 [3]	10.5021/ad.2014.26.5.584	Randomized, Controlled, Blinded Split-Face Study	25F (51.6, 41–64) with aging skin	Microneedling with human embryonic stem cells (hESC-EPC) conditioned medium (CM) (12 weeks)	Microneedling with Saline (placebo)	Clinical Assessments:  Satisfaction Scores:  Participants' satisfaction scores significantly higher for hESC-EPC CM (3.25 ± 1.26) compared to microneedling alone (2.72 ± 1.45) (p < 0.05) Pigmentation Improvement:  Objective Clinical Improvement:  The mean grade for clinical improvement in pigmentation, based on photographs, was significantly higher for microneedling plus hESC-EPC CM (1.54 ± 0.57) compared to microneedling alone (1.32 ± 0.62) (p < 0.05)  Mexameter Scores:  The mean pigmentation index (MI) decreased significantly for hESC-EPC CM group from 138 ± 14.2 at baseline to 113 ± 12.1 12 weeks (p < 0.05), whereas the reduction in the microneedling alone group was not significant (143 ± 11.1 to 136 ± 12.8, p = 0.052) Wrinkle Improvement:  Objective Clinical Improvement:  The mean grade for clinical improvement in wrinkles, based on photographs, was significantly higher for microneedling plus hESC-EPC CM (1.92 ± 0.42) compared to microneedling alone (1.49 ± 0.48) (p < 0.05)  Visiometer Measurements: The R2 value decreased significantly in hESC-EPC CM group (0.58 ± 0.1 to 0.46 ± 0.09, p < 0.05), while the change in the microneedling alone group was not significant The R3 value (indicating wrinkle roughness) significantly decreased in hESC-EPC CM group (0.4 ± 0.1 to 0.31 ± 0.06, p < 0.05), with no significant change in the microneedling alone group Erythema Improvement:  The erythema index (EI):  significantly decreased in hESC-EPC CM group from 271 ± 24.2 at baseline to 243 ± 21.1 in 12 weeks (p < 0.05). The reduction in the microneedling alone group was not significant	No serious AE Mild pain and temporary erythema were tolerable for all participants, and one participant experienced mild desquamation, which resolved within a week
11	Indramaya M Y et al. 2023 [29]	10.4103/ijd.ijd_839_20	experimental analytic, controlled, matching research	60F With photoaged skin	topical combination of amniotic membrane stem cell-conditioned medium (AMSC-CM) and vitamin C, administered via fractional CO2 laser (14 weeks)	topical combination of amniotic membrane stem cell-conditioned medium (AMSC-CM) and vitamin C, administered via Microneedling	Microneedling + AMSC-CM + VC in 8 weeks;  Wrinkles: 0.983, UV spots: 0.848, polarized spots: 0.876, skin tones: 0.963, pores: 0.848 Fractional CO2 + AMSC-CM + VC in 8 weeks;  Wrinkles: 0.152, UV spots: 0.255, polarized spots: 0.027*, skin tones: 0.812, pores: 0.440 Comparing Microneedling + AMSC-CM + VC versus Fractional CO2 + AMSC-CM + VC in 8 weeks:  Wrinkles: 0.00* (MN: 6.18 and FCO2: 3.71), UV spots: 0.21 (MN: 4.17 and FCO2: 6.23), polarized spots: 0.12 (MN: 4.21 and FCO2: 5.27), skin tones: 0.00* (MN: 8.34 and FCO2: 3.78), pores: 0.01* (MN: 4.13 and FCO2: 4.29)	N/A
12	Ahn et al. 2023 [30]	10.5021/ad.21.287	Randomized, single-blinded, prospective, split-face comparison study	27 patients (20–80y/o) with sensitive skin	UCB-MSC-CM on one side of the face after non-ablative fractional laser treatment (10 weeks)	normal saline on the other side of the face	Five-point global assessment scale: No significant difference in subjective satisfaction as well as global assessment scale in the last visit Transepidermal water loss (TEWL): 3.23 ± 1.53 in treated group comparing 1.97 ± 1.46 in untreated group (< 0.0001) in 10 week Erythema index (EI): 5.96 ± 4.44 in treated group comparing 2.27 ± 3.99 in untreated group (< 0.0001) in 10 week Sensitive Scale-10: From 10.3 score in baseline to 31.7 in 10 weeks	No adverse effect
13	Park et al. 2023 [19]	10.1111/jocd.15872	Prospective, randomized, split-face study	28 (20F, 8M) (54, 43–66) With skin aging	Microneedling with human adipose tissue stem cell-derived exosomes (HACS) (12 weeks)	Microneedling with normal saline	GAIS Score at Week 12:  HACS: 46% scored 3, 14% scored 4, 14% scored 5 versus Control: 46% scored 3, 7% scored 4, 7% scored 5 (p: 0.005) Skin Wrinkles Mean Reduction:  HACS: Ra: 12.4% Rt: 14.4% Rz: 13.4% versus Control: Ra: 6.6% Rt: 6.8% Rz: 7.1% (p: Ra: 0.031, Rt: 0.008, Rz: 0.007) Skin Elasticity Increase:  HACS: 11.3% increase versus Control: 3.3% decrease (p: 0.002) Skin Hydration Increase:  HACS: 6.5% increase versus Control: 4.5% increase (p: 0.037) Melanin Index Change:  HACS: 9.9% decrease versus Control: 1.0% decrease (p: 0.044) Histopathologic Evaluation:  HACS: Greater density of collagen and elastic fibers versus Control: Less pronounced changes (N/A)	No serious AE Transient mild erythema, edema and petechia
14	Lu et al. 2024 [20]	10.1111/jocd.16112	Preclinical experiment and clinical trial	31F (-, 26–45)	Topical milk-derived exosomes (MK-Exo) (4 weeks)	–	Skin Moisture Content:  Increase on week 4: 5.6% (< 0.05)  Age Group Differences:  Aged 36–45 years: Significant increase in moisture content. (< 0.05)  Aged 26–35 years: Increase did not achieve statistical significance. (> 0.05) Skin Brightness:  Observation on week 4: Dramatic improvement noted Participant Satisfaction:  Satisfaction Rate: More than 90% reported satisfaction with the moisturizing effects of MK-Exo  Facial Skin Gloss:  Observation on week4: Enhancement noted (details in photographs, not quantified) Skin Elasticity:  F3/F4 Value Increase: 6.33% (< 0.05)  Age Group (36–45 years): 10.74% increment noted. (< 0.01)  R2 Value Increase: 7.24% (< 0.01) Wrinkle Assessment:  Wrinkle Area Reduction: − 9.59% (< 0.001)  Quantity of Wrinkles Reduction: − 4.99% (0.001)	No sensitization or irritation
15	Yusharyahya et al. 2023 [4]	10.2147/CCID.S401839	Single-blind, randomized, split-face clinical trial	30F (47.97, 35–59) With cutaneous senescence	Microneedling of Adipose-Derived Mesenchymal Stem Cells (ADMSC) Secretome (6 weeks)	Fractional CO2 laser (FL) of ADMSC Secretome	Dermoscopic Appearance (DPAS): Microneedling (MN) Group:  Week 0: 9.00 (4.00)  Week 6: 8.00 (2.25)  (< 0.01) Fractional CO2 Laser (FL) Group:  Week 0: 10.00 (4.00)  Week 6: 7.50 (3.00)  (< 0.01) Wrinkles (Janus-III): Microneedling (MN) Group:  Week 0: 3.50 (9.25)  Week 6: − 2.50 (7.00)  (< 0.001) Fractional CO2 Laser (FL) Group:  Week 0: 2.5 (8.00)  Week 6: − 1.00 (9.00)  (< 0.001) Sebum (Janus-III): Microneedling (MN) Group:  Week 0: − 31.50 (182.75)  Week 6: − 64.00 (12.50)  (< 0.001) Fractional CO2 Laser (FL) Group:  Week 0: − 35.00 (134.50)  Week 6: − 62.50 (13.75) (< 0.001) Porphyrin (Janus-III): Microneedling (MN) Group:  Week 0: − 1.80 ± 16.30  Week 6: − 18.70 ± 16.04  (< 0.001) Fractional CO2 Laser (FL) Group:  Week 0: 0.00 (25.50)  Week 6: − 23.50 (17.25)  (< 0.001) Pain Experience: Pain: 100% in FL and 50% during MN Burning sensation: 73.3% in FL versus 13.3% in MN group Satisfaction: 80% in MN and 93.3% in FL group were extremely pleased Comfortable level: 80% none to mild pain in MN and moderate-to-severe in FL group Preference: 66.7% chose FL as the preferable	Reddish skin in all participants which relived before 24 h except in 2 subjects
16	Sari et al. 2021 [31]	–	analytical method experiment	60F (49.65, 40–65) With photoaging skin	Microneedling plus Amniotic Membrane Stem Cell Conditioned Media (AMSC-CM) (12 weeks)	CO2 laser plus AMSC-CM	Skin Analyzer (Janus) Results:  Wrinkle (Median improvement): Microneedling Group: − 1.00 versus Fractional CO2 Group: 1.00 (p = 0.05)  Pore:  − 2.00 versus 3.00 (0.00)  UV Spot:  − 2.5 versus 1.00 (0.01)  Skin Tone:  − 1.00 versus 0.00 (0.04)  Polarized delta spot (Mean):  − 1.07 versus 5.13 (0.00)	No serious AE
17	Setyaningrum et al. 2021 [32]		Analytical experimental study	30F (50.53, 42–63) With photo aged skin	Combination therapy of AMSC-CM and vitamin C after CO2 fractional laser (8 weeks)	–	Wrinkles:  Significant improvement in 4 weeks:  From 9.7 ± 4.51 (Baseline) to 6.3 ± 3.11  P value: .000 (highly significant)  Significant improvement in 8 weeks:  To 7.33 ± 3.99  P value: .012 (significant) Pores:  Significant improvement in 4 weeks:  From 53.4 ± 5.88 to 50.63 ± 4.89  P value: .004  No significant improvement in 8 weeks:  To 51.13 ± 4.98  P value: .061 Spots:  Significant improvement in 4 weeks:  From 31.4 ± 6.32 to 29.57 ± 6.63  P value: .000 (highly significant)  No significant improvement 8 weeks:  To 31.3 ± 7.79  P value: .466 Skin Tone:  No significant improvements between any evaluations:  Evaluation first 4 weeks: P = .109  Evaluation second 4 weeks: P = .794  Evaluation 8 weeks: P = .180	N/A
18	Wang et al. 2018 [33]	10.1080/14764172.2017.1400171	Double-blind, split-face, randomized control study	30F (51.3, 40 to 63)	Micro needling of protein extracts from the medium of adipose-derived stem cells (ADSCs) (12 weeks)	ultrapure water on the control side	Melanin Index: A significant decrease after 12 weeks (< 0.01) Skin Color (ITA): Significant improvement compared with control group (< 0.01) Skin Radiance (Gloss Value): Significant improvement after 12 weeks (< 0.001) Skin Surface Topography: Roughness (SEr), smoothness (SEsm), scaliness (SEsc), and wrinkles (SEw) has significantly decrease with p value < 0.001 (0.05 in control group), 0.01 (vs 0.01), 0.001 (vs 0.01), and 0.001 (vs 0.001) respectively Skin Elasticity (R2 Value): Significant improvement both forehead (< 0.01) and crow’s feet (< 0.01) Periorbital Skin Relief: wrinkle parameters (Ra, Rq, Rz, and Rmax) The mean differences at week 12 were as follows: Ra (Arithmetic Roughness average) = − 3.08 ± 2.61, Rq (Quadratic Roughness average) = − 3.83 ± 3.15, Rz (Roughness) = − 11.48 ± 10.01, Rmax (Maximal roughness) = − 21.66 ± 21.90 Self-Evaluation Questionnaire: Significant improve in overall satisfaction (< 0.001)	No AE
19	Cho et al. 2020 [21]	10.3390/cosmetics7040090	Prospective, split-face, randomized, placebo-controlled study	21F (39 to 55) With hyperpigmentation	exosomes derived from human adipose tissue-derived mesenchymal stem/stromal cells (ASC-exosomes) (8 weeks)	Placebo	Melanin levels (Mexameter): Significant reduction with mean from 187.78 to 169.33 (p < 0.01) after 8 weeks More significant reduction in aged < 50	No AE

¹Female, ²Cell-free Blood Cell Secretome, ³Effect Size, ⁴Extracellular Vesicles, ⁵Lactobacillus plantarum Extracellular Vesicles, ⁶Not Available, ⁷Male, ⁸Adverse Effect

Table 3.

Comparative Analysis of EVs and CM in Skin Treatment

Parameter	Extracellular vesicles (EVs)	Conditioned media (CM)
Number of studies	4 (21%)	15 (79%)
Main applications	Skin rejuvenation, pigmentation reduction	Wrinkle reduction, skin hydration, elasticity improvement
Routes of administration	Topical, microneedling	Intradermal injection, topical, microneedling
Effect on skin elasticity	+ 27.07% (p < 0.05)	+ Significant improvement (p < 0.001)
Effect on wrinkles	10–14% reduction (p < 0.05)	Greater reduction observed (p < 0.001)
Effect on hydration	+ 21.40% (p < 0.05)	Increased hydra ion (varies by study, p < 0.05)
Pigmentation reduction	Melanin index decreased by ~ 9.81% (p < 0.01)	Variable reduction, dependent on CM type (p < 0.05)
Adverse effects	None to mild erythema	Mild redness, occasional hematomas

All statistical analyses were performed using SPSS software (version 25.0, IBM Corp., USA). Paired t-tests and ANOVA were used to compare within-group and between-group differences. A p value < 0.05 was considered statistically significant. The reliability of skin elasticity and hydration measurements was ensured by averaging three consecutive readings per site.

CM

Fifteen studies (79%) were included in this review. All of these studies incorporated rejuvenation parameters, and eight of them reported effects on skin lightening.

The studies assessing CM effects used standardized dermatological tools for evaluation. Skin elasticity was measured using a Cutometer® (MPA 580, Courage + Khazaka, Germany), assessing R2 (gross elasticity) and R7 (biological elasticity). Skin hydration was determined using a Corneometer® CM 825 (Courage + Khazaka, Germany). High-frequency ultrasound imaging (DermaScan C, Cortex Technology, Denmark) was used to assess skin density. Patient-reported outcomes were also included, such as the FACE-QTM questionnaire for satisfaction and the Global Aesthetic Improvement Scale (GAIS) for perceived improvement.

Rejuvenation outcomes of CM

A study conducted a prospective, one-armed, multicenter interventional trial involving 95 female participants to evaluate the effects of intradermal injection of cell-free blood cell secretome (BCS) over 48 weeks. The results demonstrated a significant increase in skin firmness, with measurements decreasing from 0.4 to 0.37 mm (p < 0.0024), and skin tiring improving from 0.45 to 0.41 mm (p < 0.0005). Participants reported enhanced satisfaction with their appearance, as indicated by a rise in FACE-QTM scores from 42.56 to 51.99 (p < 0.0001), and satisfaction with skin improved from 39.64 to 53.99 (p < 0.0001). Psychological function scores increased from 59.75 to 66.43 (p < 0.0003), while social function improved from 57.54 to 62.90 (p < 0.0013). Notably, participants perceived themselves to be approximately 1.68 years younger, and the Global Aesthetic Improvement Scale (GAIS) showed a 58.9% improvement by physician assessment and a 76.8% improvement by patient self-assessment (both p < 0.0001). Although 380 injections were administered, mild adverse effects were reported, including 17 occurrences of hematomas, 5 instances of redness, 4 episodes of pain, 6 instances of swelling, and 4 cases of urticaria [22].

Another study conducted a randomized controlled split-face trial over 10 weeks to evaluate the efficacy of human umbilical cord-derived mesenchymal stem cell CM (hUC-MSCs-CM) combined with microneedling (MN) versus MN alone in individuals with skin aging. The findings revealed significant improvements in subjective satisfaction, with participants reporting greater satisfaction on the hUC-MSCs-CM treated side compared to the control (p < 0.05). Objective assessments indicated notable enhancements in skin brightness and texture on the hUC-MSCs-CM side (p < 0.05), alongside significant decreases in wrinkles (from 12.15 ± 10.26 to 5.06 ± 3.44, p < 0.00), pore size (from 23.55 ± 10.52 to 14.05 ± 6.11, p < 0.00), and elasticity (from 0.56 ± 0.07 to 0.69 ± 0.05, p = 0.00). However, there was no significant difference in hydration (p = 0.06), transepidermal water loss (p = 0.05), or erythema index (p = 0.90). Minor side effects, including dry skin and erythema, were reported in both groups, but no severe adverse effects occurred [23].

In another study, a 24-week prospective, single-armed, monocenter trial was conducted to investigate the effects of sub-dermal micropuncture injections of cell-free blood cell secretome (BCS) in 21 women with age-related reduced facial skin elasticity. The results demonstrated a significant increase in skin firmness (p < 0.001) and a substantial reduction in skin tiring (p < 0.001). Additionally, marked improvements in skin hydration and overall aesthetics were observed, with no adverse effects reported throughout the study [24].

Another clinical trial evaluated the effects of stromal cell-derived CM (MSC-CM) applied topically twice daily, along with antioxidants, on under-eye dark circles over a 12-week period in 20 female participants aged 18 to 66. Significant improvements were noted in various clinical efficacy parameters, including a reduction in under-eye dark circles, and improvements in eye puffiness (70% of subjects), periorbital fine lines (26.7%), crow’s feet (62.5%), skin tone (68.8%), radiance (73.3%), skin smoothness and texture (25%), skin brightness (62.5%), skin tightening (18.2%), and a refreshing/soothing effect (29.5%). Additionally, 60% of participants reported moderate to large improvements, 35% reported small but worthwhile improvements, and 5% noted slight improvements, with no adverse effects observed [25].

A prospective, randomized, controlled, double-blind trial involving 20 participants with moderate to severe photodamage compared the efficacy of red deer umbilical cord-derived stem cell CM (USCCM) cream and serum applied both pre- and post-facial laser resurfacing to a placebo group using vehicle cream and serum. The findings indicated that USCCM was effective in improving outcomes following facial laser resurfacing. No serious adverse effects were reported, although the full text of the study is not available for further details [26].

Another study conducted a 12-week split-face comparative trial to assess the effects of microneedling combined with amniotic fluid mesenchymal stem cell-derived CM (AF-MSC-CM) versus microneedling alone in patients with skin aging. The AF-MSC-CM treated side showed a significantly higher mean percentage of improvement (60.6 ± 9.77) compared to the control side (33.2 ± 8.95, p < 0.001). Patient improvement was more prominent in the AF-MSC-CM group, with 70% showing good and 10% showing very good results compared to the control side (p = 0.003). Specific improvements included reductions in crow’s feet and forehead wrinkles, along with enhanced skin texture. Histologic evaluation revealed increased and more organized collagen bundles and better-arranged elastic fibers, especially on the AF-MSC-CM treated side. Histometric evaluations showed a significant improvement in epidermal thickness (p < 0.001), but no significant difference between the two sides (p = 0.41). No long-term adverse effects were reported, with only transient erythema and slight edema observed [27].

In an 8-week experimental study, the effects of amniotic membrane stem cell-CM (AMSC-CM) combined with microneedling were evaluated on 48 patients (24 males and 24 females, mean age 50.3) with photoaging. Significant improvements in various skin parameters were observed compared to the control group receiving normal saline. Pore size showed marked improvement with p = 0.003 versus 0.774 in the control group. Wrinkle reduction was also significant, with p = 0.011 versus 0.801 in the control group. Minimal transient side effects were observed in both groups [28].

Another pilot study conducted over 12 weeks compared the effects of adipose-derived stem cell CM (ADSC-CM) on skin rejuvenation and acne scars with those of a placebo (Dulbecco's Modified Eagle Medium, DMEM). Participants received fractional carbon dioxide laser resurfacing (FxCR) on both sides of the face, with ADSC-CM applied to one side. Significant improvements were noted in subjective satisfaction (2.56 ± 0.65 in the rejuvenation group and 2.35 ± 0.69 in the acne scar group) and clinical assessments (2.78 ± 0.45 in the rejuvenation group and 32.69 ± 18.10 in ECCA scores for the acne scar group), as well as skin elasticity on the ADSC-CM-treated side. The ADSC-CM side also demonstrated increased hydration (from 52.42 ± 11.00 to 64.03 ± 8.17 in the rejuvenation group and from 36.05 ± 10.54 to 54.82 ± 6.39 in the acne scar group), reduced transepidermal water loss (TEWL, p < 0.05), and higher collagen (Masson-Trichrome staining: 49.98 ± 0.62% vs. 36.09 ± 0.61% on the control side) and elastin (Gomori’s aldehyde fuchsin staining: 37.61 ± 0.79 vs. 26.13 ± 0.35 on the control side) density. No serious adverse effects were reported [11].

Next, a 12-week randomized controlled blinded split-face trial evaluated the effects of microneedling with human embryonic stem cell-derived endothelial progenitor cells CM (hESC-EPC CM) compared to microneedling with saline (placebo) in 25 female participants with aging skin. The hESC-EPC CM group exhibited significantly higher satisfaction scores (3.25 ± 1.26) compared to the placebo group (2.72 ± 1.45, p < 0.05). Improvements in wrinkles were also significantly better in the hESC-EPC CM group, with objective clinical improvement (1.92 ± 0.42 compared to 1.49 ± 0.48 in the control group, p < 0.05) and greater wrinkle reduction observed with both R2 (0.58 ± 0.1 to 0.46 ± 0.09, p < 0.05 for the intervention group, no significant change in control group) and R3 (0.4 ± 0.1 to 0.31 ± 0.06, p < 0.05 for the intervention group, no significant change in control group). The erythema index significantly decreased in the hESC-EPC CM group (271 ± 24.2 to 243 ± 21.1, p < 0.05), while no significant changes were observed in the placebo group. Mild pain and temporary erythema were reported, with one case of mild desquamation that resolved within a week. No serious adverse events were observed [3].

Another study conducted an 8-week experimental controlled matching trial compared the efficacy of topical administration of a combination of amniotic membrane stem cell-CM and vitamin C with microneedling against fractional CO₂ laser treatment in 60 female participants. The microneedling group showed p values of 0.983 for wrinkles and 0.848 for pores. In contrast, the fractional CO₂ laser group revealed p values of 0.152 for wrinkles and 0.440 for pores. The scores for facial skin improvement between microneedling and fractional CO₂ laser were 6.18 versus 3.71 for wrinkles (p < 0.001) and 4.13 versus 4.29 for pores (p < 0.01) at 8 weeks. No adverse effects of treatment were reported [29].

In a 10-week randomized, single-blinded, prospective split-face comparison study of 27 patients aged 20 to 80 with sensitive skin, one side of the face received UCB-MSC-CM after non-ablative fractional laser treatment, while normal saline was used on the other side. Results showed no significant differences in subjective satisfaction or global assessment scale scores at the final visit. However, the treated group exhibited a significant increase in transepidermal water loss (TEWL) at 3.23 ± 1.53 compared to 1.97 ± 1.46 in the untreated group (p < 0.0001). Additionally, the erythema index (EI) was notably higher in the treated group at 5.96 ± 4.44 versus 2.27 ± 3.99 in the untreated group (p < 0.0001). The Sensitive Scale-10 score improved from 10.3 at baseline to 31.7 at 10 weeks, with no adverse effects reported [30].

Another study conducted a 6-week single-blind, randomized, split-face clinical trial to evaluate the effects of microneedling (MN) versus fractional CO₂ laser (FL) treatments using adipose-derived mesenchymal stem cell (ADMSC) secretome on skin rejuvenation in 30 female participants (mean age 47.97) with cutaneous senescence. Results indicated significant improvements in dermoscopic appearance (DPAS), with the MN group showing a reduction from 9.00 to 8.00 (p < 0.01) and the FL group from 10.00 to 7.50 (p < 0.01). Both treatments significantly reduced wrinkles and sebum levels, with the MN group showing a decrease in wrinkles from 3.50 to − 2.50 (p < 0.001) and the FL group from 2.50 to − 1.00 (p < 0.001). Sebum levels decreased significantly in both groups (MN from − 31.50 to − 64.00 and FL from − 35.00 to − 62.50, p < 0.001). Porphyrin levels also showed notable reductions, with the MN group decreasing from − 1.80 to − 18.70 (p < 0.001) and the FL group from 0.00 to − 23.50 (p < 0.001). Despite these findings, 93.3% of participants in the FL group and 80% in the MN group reported being extremely pleased, with 66.7% preferring the FL treatment. Side effects were minimal, with all participants experiencing mild redness that resolved within 24 h [4].

Lastly, a 12-week analytical method experiment compared the effects of microneedling combined with amniotic membrane stem cell CM (AMSC-CM) versus fractional CO₂ laser plus AMSC-CM in individuals with photoaging skin. Sixty females participated in the study, with an average age of 49.65. Results, assessed using a skin analyzer (Janus), showed that the microneedling group demonstrated significant improvements in wrinkle reduction (− 1.00 for microneedling vs. 1.00 for fractional CO₂, p = 0.05) and pore size (− 2.00 vs. 3.00, p = 0.00) compared to the CO₂ laser group. Both treatments were effective, but microneedling with AMSC-CM yielded significantly better outcomes, especially in pore size. No serious adverse effects were reported [31].

An 8-week analytical experimental study evaluated the effects of a combination therapy using adipose-derived mesenchymal stem cell-CM (AMSC-CM) and vitamin C following CO₂ fractional laser therapy on photo-aged skin in 30 female participants (age range: 42–63 years, mean: 50.53). The study revealed a significant reduction in wrinkles after 4 weeks, with scores improving from 9.7 ± 4.51 at baseline to 6.3 ± 3.11 (p = 0.000), and further improvement to 7.33 ± 3.99 after 8 weeks (p = 0.012). There was significant improvement in pore size at 4 weeks (53.4 ± 5.88 to 50.63 ± 4.89, p = 0.004), but no significant change after 8 weeks (p = 0.061). No adverse effects were reported [32].

Lastly, a double-blind, split-face, randomized controlled trial evaluated the effects of microneedling with CM derived from adipose-derived stem cells (ADSC-CM) versus a placebo (ultrapure water) on skin parameters in 30 female participants aged 40 to 63 years (mean age 51.3). The study spanned 12 weeks. The results showed significant improvements in skin radiance, measured by gloss value (p < 0.001). Skin surface topography analysis revealed significant decreases in roughness, smoothness, scaliness, and wrinkles, with p values of < 0.001 (vs. 0.05 in the control group), 0.01 (vs. 0.01), < 0.001 (vs. 0.01), and < 0.001 (vs. 0.001), respectively. Additionally, skin elasticity, measured as R2 values, improved significantly around the forehead and crow’s feet (p < 0.01). Wrinkle parameters, including Ra, Rq, Rz, and Rmax, showed substantial reductions by week 12. Self-evaluation questionnaires indicated significant improvement in overall satisfaction (p < 0.001), with no adverse effects reported [33].

Lightening outcomes of CM

Skin pigmentation was measured using the Mexameter® technique (Courage + Khazaka, Germany).

A study examining the effects of human umbilical cord-derived mesenchymal stem cell CM (hUC-MSC-CM) combined with microneedling (MN) versus MN alone in individuals with skin aging demonstrated a significant decrease in the melanin index (24.25 ± 15.55 vs. 12.36 ± 16.38, p = 0.00), ultraviolet spots (from 24.39 ± 7.11 to 14.47 ± 5.38, p < 0.05), brown spots (from 40.21 ± 5.14 to 34.18 ± 6.32, p = 0.00), and red spots (from 29.30 ± 5.58 to 28.20 ± 4.92, p = 0.17) with hUC-MSC-CM treatment [23].

Another study evaluated the effects of amniotic membrane stem cell-CM (AMSC-CM) in conjunction with microneedling. Polarized light analysis revealed better outcomes with a p value of 0.041 compared to 0.606, while UV light analysis showed similar improvements with a p value of 0.032 compared to 0.465. However, there was no significant improvement in skin tone, with p = 0.208 compared to 0.432 in the control group [28].

In a separate study, the effects of adipose-derived stem cell CM (ADSC-CM) on skin rejuvenation and acne scars were assessed using a placebo (DMEM) in combination with fractional carbon dioxide laser resurfacing (FxCR) on both sides of the face. Significant improvements in the melanin index were observed on the ADSC-CM-treated side in both groups (p < 0.05) [11].

Another study involving microneedling with human embryonic stem cell-derived endothelial progenitor cell CM (hESC-EPC CM) compared to microneedling with saline (placebo) showed more pronounced clinical improvements in pigmentation in the hESC-EPC CM group, with a mean grade of 1.54 ± 0.57 versus 1.32 ± 0.62 in the placebo group (p < 0.05). Additionally, mexameter scores indicated a significant reduction in pigmentation (p < 0.05) [3].

A further study compared the efficacy of topical administration of a combination of amniotic membrane stem cell-CM and vitamin C accompanying microneedling with fractional CO₂ laser treatment. In the microneedling (MN) group, the results were as follows: UV spots 0.848, polarized spots 0.876, and skin tone 0.963. In contrast, the fractional CO₂ laser group showed UV spots at 0.255, polarized spots at 0.027*, and skin tone at 0.812. The comparison between the MN group and the fractional CO₂ group indicated values of 8.34 versus 3.78 for skin tone (p = 0.00*), 4.17 versus 6.23 for UV spots (p = 0.21), and 4.21 versus 5.27 for polarized spots (p = 0.12) at 8 weeks [29].

Another study compared the effects of microneedling combined with AMSC-CM versus fractional CO₂ laser plus AMSC-CM. Using a Skin Analyzer (Janus), the microneedling group demonstrated significant improvement in UV spots (− 2.50 vs. 1.00, p = 0.01), skin tone (− 1.00 vs. 0.00, p = 0.04), and polarized delta spots (− 1.07 vs. 5.13, p = 0.00) compared to the CO₂ laser group. While both treatments were effective, microneedling with AMSC-CM yielded significantly better outcomes, particularly in UV and polarized spots [31].

In another investigation, the effects of a combination therapy using adipose-derived mesenchymal stem cell-CM (AMSC-CM) and vitamin C after CO₂ fractional laser therapy revealed significant spot reduction at 4 weeks (31.4 ± 6.32 to 29.57 ± 6.63, p = 0.000), though no further improvement was observed by 8 weeks (p = 0.466). Skin tone showed no significant changes throughout the study (p values > 0.1) [32].

Additionally, a study investigating the effects of microneedling with CM derived from adipose-derived stem cells (ADSCs) versus a placebo (ultrapure water) showed a significant reduction in the melanin index (p < 0.01), along with notable improvements in skin color (ITA) compared to the control (p < 0.01) [33].

All statistical analyses were conducted using SPSS software (version 25.0, IBM Corp., USA). Paired t-tests and ANOVA were used for within-group and between-group comparisons, with a p value < 0.05 considered statistically significant. Measurements for skin elasticity, hydration, and pigmentation were taken at three different anatomical sites per participant and averaged over three consecutive readings to enhance reliability.

No serious adverse events were reported in either group. The most common adverse effect was transient mild erythema, which resolved within 24 h, particularly in studies involving microneedling. Transient mild edema was reported in a few studies as well.

Risk of bias assessment

We assessed the risk of bias in the included clinical trials using the RoB 2 tool, evaluating 19 studies across five key domains.

• Randomization process (D1): 7 studies (36.8%) had low risk, 10 studies (52.6%) had some concerns, and 2 studies (10.6%) were rated as high risk.

• Deviations from intended interventions (D2): 5 studies (26.3%) had low risk, 13 studies (68.4%) had some concerns, and 1 study (5.3%) was classified as high risk.

• Missing outcome data (D3): All 19 studies (100%) were rated as low risk.

• Measurement of outcomes (D4): 7 studies (36.8%) had low risk, while 12 studies (63.2%) had some concerns, with none classified as high risk.

• Selection of the reported result (D5): 5 studies (26.3%) had low risk, 13 studies (68.4%) had some concerns, and 1 study (5.3%) was rated as high risk.

Overall assessment: 5 studies (26.3%) were categorized as low risk, 11 studies (57.9%) had some concerns, and 3 studies (15.8%) were classified as high risk (Fig. 2).

Discussion

This systematic review analyzed the clinical applications of EVs and CM in skin rejuvenation and lightening, revealing their promising therapeutic potential and safety. The growing demand for effective, non-invasive skincare treatments has highlighted EVs and CMs as emerging alternatives to conventional methods such as topical agents, chemical peels, and laser treatments, which are often associated with prolonged use, side effects, and patient dissatisfaction [34, 35].

The review indicated that EVs, particularly exosomes, have significant effects on key skin parameters, including elasticity, hydration, and pigmentation [20]. EVs appear to facilitate these outcomes by enhancing cellular signaling and regeneration, delivering bioactive molecules like growth factors and cytokines to targeted skin areas [36]. For example, Jo et al. (2022) demonstrated that Lactobacillus plantarum-derived EVs (lpEV5) significantly improved skin elasticity and hydration over a four-week period with no adverse effects [5]. Similarly, Park et al. (2023) showed that human adipose tissue-derived stem cell exosomes delivered via microneedling resulted in notable improvements in skin hydration, elasticity, and reduced wrinkle depth [19]. Based on these findings and prior research, EVs not only support tissue repair and collagen synthesis but may also regulate inflammatory responses that can accelerate skin aging [37].

EVs also demonstrated promising outcomes in skin lightening, with studies reporting significant reductions in pigmentation indices, such as melanin levels. Jo et al. (2022) observed reduced pigmentation with lpEV5, and Park et al. (2023) recorded improvements in melanin indices with human adipose-derived exosomes via microneedling [5, 19]. The skin lightening effects of EVs may be attributed to their ability to regulate melanogenesis. Some studies suggest that EVs derived from mesenchymal stem cells can modulate tyrosinase activity, reducing melanin synthesis and promoting an even skin tone [34, 36].

Although these studies suggest that EVs could provide an effective solution for pigmentation concerns, further investigations are needed to determine optimal dosages and routes of administration for achieving consistent outcomes across various skin types [21]. Given the potential variability in EV composition depending on their source, future research should focus on characterizing specific cell-derived EVs and their safety profiles to mitigate risks associated with pro-inflammatory or tumorigenic exosomes.

Furthermore, age may influence the clinical outcomes of EV and CM treatments. A few studies included in our review reported more pronounced improvements in pigmentation and elasticity among younger participants. For instance, participants under 50 years showed greater melanin reduction following exosome therapy, and subjects aged 36–45 demonstrated enhanced elasticity and hydration responses. Although these findings suggest a possible age-related variation in treatment efficacy, the current evidence remains limited. Further studies are warranted to investigate age as a potential moderator of treatment outcomes [4, 11, 27, 31].

CM offers another promising, less invasive approach to skin treatment by delivering a wide spectrum of growth factors, cytokines, and extracellular matrix components derived from cultured cells. CM applications demonstrated significant efficacy in improving skin hydration, elasticity, and tone. Studies included in this review reported that CM could produce visible results within a few weeks, comparable to traditional topical agents but with fewer side effects [10]. These findings underscore the therapeutic versatility of CM, as it provides bioactive molecules that facilitate skin regeneration and hydration without the invasiveness of direct cell-based therapies [30]. CM from stem cells, particularly mesenchymal stem cells (MSC-CM), is rich in bioactive factors such as vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF), which may enhance wound healing, collagen formation, and hydration [10].

As with EVs, the origin of CM is a critical determinant of its safety and efficacy. CM derived from mesenchymal stem cells (MSC-CM) is often considered optimal due to its regenerative potential, whereas CM from uncharacterized or tumor-derived cells could present safety concerns [38]. Future studies should focus on establishing standardized protocols for CM preparation to ensure consistency and reproducibility across clinical applications.

The method of obtaining CM and its functions are closely tied to the type of cells used, the culture conditions, and the bioactive molecules present in the media. CM derived from stem cells (MSCs, ADSCs) or fibroblasts tends to have regenerative properties such as collagen stimulation, skin healing, and hydration, while CM from keratinocytes may focus on epidermal renewal. The culture conditions, including the medium, density, and environmental factors, all influence the composition of CM and its effectiveness for specific skin concerns like rejuvenation, lightening, or anti-aging. These functions make CM a promising alternative to traditional skincare treatments, but standardization and rigorous testing of CM are essential to ensure its safety and efficacy [3, 4, 9]. Additionally, CM combined with procedures such as laser resurfacing or microneedling may show enhanced results due to the increased absorption and cellular response triggered by these procedures [39].

Similar to EVs, CM has shown effectiveness in addressing hyperpigmentation. Research suggests that CM formulations, particularly those derived from mesenchymal stem cells, may reduce pigmentation and enhance skin brightness through mechanisms such as inhibiting melanin synthesis and promoting epidermal renewal [6]. However, there have been relatively few studies directly comparing the effects of CM and EVs on pigmentation reduction, indicating a need for future comparative trials to evaluate which approach may be more effective for specific skin concerns [19].

Microneedling and laser therapy may enhance the efficacy of EVs by creating microchannels in the skin, facilitating deeper penetration and increasing the bioavailability of bioactive molecules. These minimally invasive techniques may also stimulate wound healing responses, which synergize with EV-derived regenerative factors [40].

Despite the potential of EVs and CM in skin rejuvenation and pigmentation reduction, this review highlights some limitations. The studies reviewed varied widely in methodology, including differences in administration routes (e.g., topical application vs. microneedling) and dosages, which may contribute to inconsistencies in outcomes. For instance, while most studies applied EVs and CM topically, Park et al. (2023) employed microneedling, suggesting that delivery methods may play a critical role in enhancing bioavailability and therapeutic effects [19]. Additionally, the diversity in cell sources and preparation methods for EVs and CM raises questions regarding standardization and reproducibility, as different extraction and purification processes may impact the efficacy and safety profiles of these products [3].

Furthermore, the source of EVs and CM remains a key issue in ensuring safe and effective application. Standardizing the selection of cell sources and optimizing extraction techniques are necessary steps toward minimizing potential risks [41].

The therapeutic effects of EVs and CM are primarily attributed to their ability to modulate cellular processes such as collagen synthesis, extracellular matrix remodeling, and pigmentation regulation. EVs, particularly exosomes, facilitate intercellular communication by transferring bioactive molecules, including growth factors, microRNAs (miRNAs), and cytokines, to recipient skin cells. These molecules activate key signaling pathways, such as TGF-β, PI3K/Akt, and MAPK, promoting fibroblast proliferation, collagen deposition, and oxidative stress inhibition, all of which are essential for skin rejuvenation. Similarly, CM contains a rich milieu of bioactive compounds that influence melanogenesis by modulating tyrosinase activity and melanin synthesis [42]. Studies have shown that specific growth factors in CM, such as hepatocyte growth factor (HGF) and transforming growth factor-beta (TGF-β), play a critical role in skin brightening by downregulating melanin production and enhancing epidermal renewal [6, 19, 38] (Fig. 3).

Fig. 3.

Graphical abstract illustrating how EVs and CM promote skin rejuvenation and pigmentation regulation

In a systematic review and meta-analysis on the role of stem cell-derived CM in the treatment of alopecia by Chien et al., the results indicate that stem cell-derived CM can effectively increase hair density and thickness in individuals with alopecia, with no significant difference between application methods (topical application, microneedling, or injection) [41]. Additionally, a systematic review on the role of CM in the treatment of hypertrophic scars by Jafarzadeh et al. highlighted its effectiveness in improving hypertrophic scars [10]. Furthermore, systematic reviews conducted by Gupta et al. and Jafarzadeh et al. have demonstrated the beneficial role of exosomes in the treatment and significant improvement of alopecia [6, 43].

Moreover, many studies had relatively small sample sizes and short follow-up periods, limiting the generalizability of the results. The long-term effects and safety profiles of EVs and CM, particularly regarding repeated use, remain unclear and warrant further investigation. Future studies should prioritize exploring the optimal frequency of application, dosage, and administration routes for both EVs and CM, as well as potential side effects associated with extended use.

The findings of this review underscore the potential of EVs and CM as innovative, non-invasive therapies for skin rejuvenation and pigmentation management. By targeting cellular mechanisms involved in skin regeneration and pigmentation, these treatments offer a valuable alternative to traditional therapies with fewer side effects and faster onset of results [35]. However, as EVs and CM are still emerging technologies, further large-scale, long-term studies are needed to establish comprehensive clinical guidelines for their use. Comparative studies examining different cell sources, formulations, and application methods could also help identify the most effective and practical approaches for various patient populations.

Future research should also emphasize comparative studies examining different cell sources, formulations, and application methods to identify the safest and most effective approaches for various patient populations. By ensuring rigorous safety assessments and standardized preparation methods, EV- and CM-based therapies could become a reliable mainstay in dermatological treatments.

Limitations and future directions

Despite the potential of EVs and CM in skin rejuvenation and pigmentation reduction, this review highlights several limitations. A major limitation is the variability in study design, including differences in participant demographics, intervention protocols, and measurement techniques. Many studies included in this review employed small sample sizes and short follow-up periods, which limit the generalizability of findings. Moreover, differences in EV and CM sources, purification techniques, and application methods introduce inconsistencies in reported outcomes.

Another key challenge is the lack of standardization in EV and CM formulations. The composition of these biologics varies depending on cell type, culture conditions, and processing methods, making it difficult to compare results across studies. Establishing standardized manufacturing and quality control protocols is essential for translating these therapies into clinical practice.

Bias is another potential concern, as many studies lacked blinding and placebo controls, which may have influenced subjective outcome assessments. Future research should prioritize well-designed, randomized controlled trials with larger sample sizes, longer follow-up periods, and objective measurement tools. The effectiveness of EVs and CM in skin rejuvenation and lightening may vary depending on several factors, such as the source and concentration of EVs, delivery method (e.g., microneedling or topical application), frequency of administration, and combination with other agents.

Some studies in this review indicated that younger age groups (e.g., under 50 years) showed more pronounced improvements in pigmentation and elasticity following EV or CM treatment. However, the influence of age was not consistently reported across all studies and warrants further investigation in future trials.

Future investigations should also explore the long-term safety of repeated EV and CM applications. While no serious adverse effects were reported in the included studies, the potential for immune reactions, allergenic responses, or unintended tissue remodeling remains unknown. Longitudinal studies assessing the durability of treatment effects and potential late-onset adverse reactions are critical for ensuring the safe and effective use of EV and CM-based therapies.

By addressing these limitations and focusing on long-term studies, optimized formulations, and comparative effectiveness trials, EV and CM therapies have the potential to become standardized, widely accepted treatments for skin rejuvenation and pigmentation management.

Conclusion

In conclusion, the use of EVs and CM through topical application or microneedling is both safe and effective for skin lightening and rejuvenation. However, further studies comparing different types of CMs and EVs, as well as various routes of administration, are needed to optimize clinical utility, address existing limitations, and ensure long-term safety. In short-term trials, both EVs and CMs have demonstrated significant efficacy and safety. Nonetheless, there is a lack of studies comparing CMs and EVs, exploring different sources of agents, and examining the various routes of application, particularly in relation to long-term safety. Additionally, the reproducibility of the processes for standardization, purification, and preparation of these biological agents raises questions that need to be addressed.

Abbreviations

EV

Extracellular vesicle

CM

Conditioned media

lpEV

Lactobacillus plantarum-derived extracellular vesicle

UV

Ultraviolet

Author contributions

Contributions to the current study includes AJ and AG and SH and EB in study idea and design and in the literature review, and drafting and revising the manuscript critically for importance intellectual content. AJ and MR in drafting the revised manuscript and literature review, and analysis and interpretation of revised version and drafting the manuscript. SH in the proposal preparation and statistics and analysis and drafting the revised manuscript. AG and AJ in the study supervision, data gathering and literature review. All authors have read and approved the final version to be published and agreed to be accountable for all aspects of the work. All authors agreed on the order in which their names are listed in the revised manuscript.

Funding

This study did not receive any funding in any form.

Availability of data and materials

The data that support the findings of this study are available from the corresponding author, [A.G], upon reasonable request. also all additional files are included in the manuscript.

Declarations

Ethics approval and consent to participate

All collected data were kept confidential and analyzed without specific names attached. The study adhered to Helsinki ethical principles. The project was registered at Iran University of Medical Sciences with registration No. IR.IUMS.SD8619232476231H1, bearing the scientific title "Effectiveness of Regenerative Medicine for Skin Lightening and Rejuvenation: A Systematic Review of Extracellular Vesicles and Conditioned Media" It was approved by the Research Council under the ethics code number IR.IUMS.FMD.REC.1403.911.

Consent for publication

The authors obtained consent to publish. The current manuscript contains no individual person’s data. Therefore, consent to publish is not applicable.

Competing interests

All the authors declare that there is no conflict of interest for this project.