1. Introduction: The Upstream Etiology of the Exosome Quality Crisis

Extracellular vesicles (EVs) secreted by mesenchymal stem/stromal cells (MSCs)—specifically exosomes—have emerged as prime candidates for cell-free regenerative therapies due to their low immunogenicity, potent paracrine activity, and ability to traverse biological barriers such as the blood–brain barrier (Kou et al., 2022; Kalluri & LeBleu, 2020). Relative to intact cell therapies, MSC-EVs offer distinct operational advantages in long-term storage, transport, and standardised manufacturing (Pegtel & Gould, 2019).

Despite rapid industrial scale-up, a central quality paradox has surfaced: therapeutic potency varies considerably across research laboratories, donor lots, and manufacturing runs, impeding regulatory approval and clinical translation. As highlighted in a policy review by Na et al. (2026) in the Journal of Extracellular Vesicles, China ranks second globally in EV clinical trial registrations, with over 95% utilising naturally derived stem cells (MSCs accounting for ~60%). Nevertheless, tailored regulatory frameworks governing EV-based therapeutics remain underdeveloped.

This quality crisis stems not primarily from downstream purification limitations, but from an overlooked upstream reality: exosomes constitute direct molecular snapshots of their parent cells' physiological state. If MSCs undergo replicative senescence, metabolic dysregulation, genetic drift, or unmonitored microenvironmental stress, their secreted exosomes faithfully mirror these functional impairment profiles. Consequently, biomanufacturing paradigms must pivot from quantifying EV production volume to ensuring that starting MSC quality guarantees exosome Critical Quality Attributes (CQAs).

Aligned with China's National Health Commission Guidelines for the Filing of Clinical Research on Novel Cell Component and Derivative Therapies (2025, "Filing Guidelines") and the ISEV MISEV2023 standards (Welsh et al., 2024), this review systematically examines the multi-parametric impacts of MSC state on exosome CQAs and critically evaluates quality control capabilities across major bioprocessing platforms to inform CMC development.

2. Theoretical Framework: Bidirectional Mapping Between MSC Quality Attributes and Exosome CQAs

Understanding the relationship between MSC quality and exosome quality first requires establishing a clear logical chain: MSC quality attributes → exosome critical quality attributes (CQAs) → clinical therapeutic efficacy. This chain is not a simple linear mapping, but a highly nonlinear, systemic output relationship. The tissue source specificity of MSCs, donor age and metabolic health status, senescence accumulation during in vitro passaging, physicochemical parameters of the culture microenvironment, and the mechanical stresses imposed by bioreactors collectively determine the exosomal proteome, miRNA cargo, lipid composition, and even vesicle subtype distribution.

Na et al. (2026) explicitly state in their policy review that the quality assessment criteria for stem cells intended for EV production differ fundamentally from those for MSCs used solely for cell therapy: the former require additional evaluation of average EV secretion levels, cross-passage EV yield stability, and batch-to-batch consistency of EV functional cargo. This viewpoint carries significant CMC guidance—it implies that an MSC line certified by the traditional International Society for Cell Therapy (ISCT) criteria could entirely fail to meet the quality standards required for EV production.

The Filing Guidelines similarly emphasise the linkage between process research and quality research, requiring systematic characterisation of the relationships between starting cell characteristics, culture process parameters, and product critical quality attributes. This aligns closely with the ICH Q8 (Pharmaceutical Development) principle of "Quality by Design" (QbD): only by thoroughly understanding the impact of upstream MSC quality on downstream EV product CQAs can truly effective process control strategies be established.

3. Tissue Origin as a Determinant of Lineage-Specific EV Tropism

MSCs are not a homogeneous cell type but exhibit significant biological heterogeneity depending on their tissue origin. Bone marrow (BM-MSC), adipose (AD-MSC), umbilical cord/Wharton's jelly (UC/WJ-MSC), placenta, and dental pulp-derived MSCs differ substantially in their proteomic composition, miRNA profiles, and functional propensities. Importantly, this variability is directly transmitted to their secreted exosomes. Literature reports indicate that the proteomic overlap among exosomes from different MSC sources is only approximately 60%, meaning that "MSC exosomes" as a collective term is scientifically overly broad (Almeria, 2022).

From an industrial development perspective, UC-MSCs have emerged as a preferred substrate due to non-invasive collection, young donor age, low senescence background, and suitability for scalable Good Manufacturing Practice (GMP) cell banking. Clinical audit data indicate that UC-MSCs account for 44% of registered EV trials in China, co-leading with BM-MSCs (Na et al., 2026). Conversely, AD-MSC-EVs exhibit enhanced pro-angiogenic and wound-healing signatures suited for localised tissue repair.

Matching tissue origin to clinical indications is crucial for process selection:
●Osteochondral Defect & Bone Repair: Aligns with osteogenic signalling enriched in BM-MSC-EVs.
●Systemic Inflammation & Immune Modulation: Aligns with immunomodulatory cargo in UC-MSC-EVs.
●Ischaemic & Vascular Regeneration: Aligns with angiogenic factors enriched in AD-MSC-EVs.

Regardless of origin, establishing fully characterised Master Cell Banks (MCB) and Working Cell Banks (WCB) remains essential to ensure batch-to-batch EV consistency (Na et al., 2026, Tables 1 & 2).

4. Multi-Parametric Drivers of MSC Quality Degradation and EV Cargo Remodelling

The quality deterioration of MSC exosomes is by no means limited to a single factor of "excessive passage number", but is instead co-determined by systemic dysregulation across multiple upstream quality dimensions. Understanding this multidimensional mechanism is the theoretical foundation for establishing a scientific process control system.

4.1 Cell Passage Number and Replicative Senescence: A Quantifiable Baseline for Functional Decline

Serial in vitro passaging induces DNA damage accumulation, telomere shortening, mitochondrial dysfunction, and activation of the senescence-associated secretory phenotype (SASP). This transition drives a fundamental shift in exosomal non-coding RNA profiles:

●Early-Passage (P2–P4) MSC Exosomes: Rich in pro-regenerative miRNAs, including miR-126 (VEGF/PI3K-eNOS angiogenic axis), miR-210 (HIF-1α axis), and miR-199b-3p (survival signalling).
●Late-Passage (P8+) MSC Exosomes: Downregulation of regenerative miRNAs alongside upregulation of inflammatory/fibrotic miRNAs, such as miR-21 (TGF-β/SMAD axis), miR-155 (NF-κB activation), miR-34a (p53-SIRT1 senescence cascade), and dysregulated miR-146a (Phinney & Pittenger, 2017).

Based on the above mechanisms, an analytical framework with CMC application value can be established—the "Regenerative Index/Senescence Index ratio": the combined levels of miR-126, miR-210, miR-199b-3p, miR-145-5p, and miR-335-5p represent regenerative capacity, while miR-34a, miR-21, and miR-155 represent SASP/inflammatory burden. Continuous monitoring of this ratio can serve as a functional predictive indicator for exosome batch quality. It is particularly important to emphasise that high-passage MSCs may still satisfy the ISCT-defined surface marker criteria (CD73+/CD90+/CD105+) yet produce exosomes with significantly diminished efficacy. This phenomenon is considered one of the most critical blind spots in current commercial development.

4.2 Donor Quality and Metabolic Status: The Innate Background of Exosome Function

The physiological status of the donor individual exerts a profound "imprinting" effect on MSC quality. MSCs from elderly donors generally exhibit reduced proliferative capacity, mitochondrial dysfunction, elevated reactive oxygen species (ROS) levels, and epigenetic drift, with their exosomes showing significantly impaired pro-angiogenic and immunomodulatory functions. In pathological states, MSCs from diabetic donors produce exosomes with markedly reduced pro-angiogenic miRNA cargo, while those from obese donors may generate EVs with pro-inflammatory tendencies (Cell & Bioscience, 2022).

At the metabolic level, MSCs fluctuate between two principal energetic regimes:

1.Glycolysis-Dominant State (Stem-like / Hypoxic Adaptation): Promotes secretion of EVs rich in regenerative miRNAs (miR-210, miR-126) with enhanced tissue repair capacity.
2.Oxidative Phosphorylation (OXPHOS)-Dominant State (Senescent / Stressed): Skews EV cargo toward SASP factors (miR-34a, miR-155), reducing therapeutic efficacy and inducing pro-fibrotic responses

Precise control of dissolved oxygen thus serves as an active metabolic switch to maintain regenerative EV profiles rather than a mere survival variable.

4.3 Exosome Quality Risks from Hypoxic Necrotic Cores: A Seriously Underestimated GMP Hazard

In high-density MSC culture systems (particularly fixed-bed bioreactors), cells in the inner layers of the carrier may experience severe hypoxia or even necrosis due to restricted nutrient and dissolved oxygen diffusion, forming so-called "necrotic cores." This phenomenon has profound and seriously underestimated negative effects on exosome product quality.

MSCs under necrotic or apoptotic stress massively release apoptotic bodies—a class of EV subtype with diameters of 500–5000 nm whose contents are distinctly different from those of therapeutic exosomes: fragmented nuclear DNA, damaged organelles, histones, and highly immunogenic signalling molecules. Once apoptotic bodies enter the harvest fluid, if not adequately separated, they will directly contaminate the product batch, causing the following quality issues: 

●Strong pro-inflammatory signalling, contradicting the intended anti-inflammatory therapeutic effects of MSC-derived exosomes.
●Significantly increased immunogenicity risk, with the potential to trigger unintended adaptive immune responses.
●Greater downstream safety assessment complexity due to contamination with intracellular nucleic acids and other apoptotic components (van Niel et al., 2022).
More critically, exosomes with reduced functionality secreted by cells in the necrotic core, and therapeutic exosomes from normal cells, are difficult to distinguish using routine particle number detection (NTA) or size distribution analysis. This means that even if the final product passes basic physicochemical characterisation, its biological activity may have been significantly compromised due to uncontrolled upstream cellular states. Na et al. (2026) also specifically note in their quality assessment framework that EV subtype purity is a key consideration for evaluating product homogeneity; relying solely on particle counting without functional potency assays cannot adequately reflect the safety and efficacy of EV products.

4.4 Regulation of Exosome Quality by Physical Stimuli: The Hidden Impact of Bioreactor Parameters

Wu et al. (2024), in a systematic review published in Cell Proliferation, comprehensively collated the intervention effects of physical regulatory modalities on MSC exosome quality, providing an important scientific basis for bioreactor process parameter design.

Fluid shear stress is the most representative physical parameter in bioreactors. Moderate laminar shear stress can upregulate the enrichment of pro-regenerative miRNAs in exosomes through activation of the integrin-YAP/TAZ mechanosensing pathway; however, excessively high turbulent shear stress (e.g., due to improper impeller design) can induce MSCs to shift toward a mechanical stress state, skewing the EV subtype distribution toward microvesicles, diluting the proportion of therapeutic exosomes, and potentially compromising vesicle membrane integrity (Wu et al., 2024).

Substrate stiffness is another non-negligible physical parameter. MSCs perceive mechanical signals from the substrate through integrin-focal adhesion complexes, directly influencing cytoskeletal organisation and thereby regulating endosomal multivesicular body (MVB) maturation and ESCRT-mediated exosome biogenesis pathways. Softer biomimetic substrates (approaching the 1–10 kPa range of native soft tissues) help maintain the stem cell phenotype of MSCs, whereas stiffer substrates may accelerate osteogenic differentiation and alter the functional cargo composition of exosomes (Wu et al., 2024).

Furthermore, hypoxia preconditioning, as a widely studied functional enhancement strategy, can systematically upregulate the expression of pro-angiogenic miRNAs (miR-210, miR-126, miR-26a) in exosomes via activation of the HIF-1α pathway, showing significant efficacy enhancement in ischaemic injury, myocardial protection, and other indications (Zhuo, 2024). However, it is worth noting that a 2026 systematic review cautioned that in tumour-associated environments, hypoxia-preconditioned MSC exosomes may carry potential risks of promoting tumour angiogenesis and inhibiting apoptosis (Seddighi, 2026), indicating that indication-specific safety assessments are indispensable in functional enhancement strategies.

4.5 The "Quality Contagion" Effect of the SASP Secretome

EVs secreted by senescent MSCs, carrying SASP-associated miRNAs (such as miR-34a, miR-21, and miR-155), can induce secondary senescence in recipient cells—the so-called "bystander effect" (Ahmadi, 2021). In vitro experiments have observed in various target cells, including renal tubular cells and cardiomyocytes, that exosomes carrying SASP-related cargo can induce upregulation of fibrotic markers (TGF-β, α-SMA) and inhibit the proliferative capacity of recipient cells (Devulder, 2025; Mensa, 2020; Zhong, 2025). This finding carries serious GMP implications: if a production batch contains a certain proportion of senescent MSCs, their secreted SASP-EVs will contaminate the entire batch in a manner undetectable by routine particle quality control, posing a potential safety hazard. This further supports the necessity of incorporating "senescence burden" as a process control parameter.

5. Systematic Comparison of Culture Processes: Quality Visibility as the Core Dimension of Process Selection

Based on the foregoing analysis of the multidimensional determinants of MSC quality, the evaluation logic for process platforms should undergo a fundamental shift: one cannot simply use yield as the sole criterion for superiority; rather, a core question must be placed at the forefront—can the platform sense and actively control the quality state of MSCs in real time, thereby ensuring batch-to-batch consistency of exosome CQAs?

The following sections provide a systematic comparison of mainstream platforms across multiple dimensions (Table 1), with particular focus on the structural quality advantages of the degradable microcarrier 3D suspension culture system relative to other platforms.

Table 1: Multidimensional Quality Assessment Comparison Matrix for Mainstream MSC-EV Production Platforms 

5.1 Structural Quality Deficiencies of Fixed-Bed Bioreactors

The core problem with fixed-bed bioreactors lies in their "quality black-box" character. The closed three-dimensional space formed by non-degradable solid packing means that inner-layer cells are chronically exposed to systemic microenvironmental dysregulation, including oxygen gradients (high oxygen in outer layers/hypoxia to necrosis in inner layers), restricted nutrient diffusion, and accumulation of metabolic waste. Because cells at different spatial positions cannot be directly observed morphologically, tested for viability, or analysed metabolically, the quality state of MSCs throughout the culture system is entirely inaccessible to real-time sensing.

From the perspective of exosome quality control, this structural deficiency means that apoptotic bodies and functionally impaired EV subtypes from cells in necrotic regions will enter the harvest fluid together with therapeutic exosomes from normal cells, making them difficult to distinguish and exclude effectively at the harvest stage. Furthermore, non-degradable carriers require repeated enzymatic digestion during passaging; the trypsin treatment causes cell surface marker damage and metabolic stress, further perturbing the exosome secretion profile (Haraszti et al., 2018).

5.2 Limitations of Hollow-Fibre Systems

Hollow-fibre bioreactors achieve high-density culture by encapsulating cells within the fibre lumens, yielding high EV production, but share similar "quality invisibility" issues with fixed-bed systems: the microenvironment within the high-density cell layers is difficult to precisely control; EV products co-accumulate with cellular metabolic waste (including potential apoptotic debris) in the fibre interstitial space, increasing the burden on downstream purification due to harvest fluid compositional complexity; additionally, the scale-up logic of hollow-fibre systems is constrained by fibre surface area, making truly linear scale-up challenging.

5.3 Degradable 3D Microcarriers: A Systemic Advantage Balancing Yield, Quality Controllability, and GMP Suitability

Lenzini et al. (2025), in a cross-platform comparative study presented at the American Society of Gene and Cell Therapy (ASGCT) Annual Meeting and published in Cytotherapy, systematically analysed and compared the quality attributes of MSC-EVs across different tissue sources and production platforms, providing important analytical evidence for process platform selection. The study revealed that production platform choice significantly affects EV size distribution, surface marker expression stability, and batch-to-batch consistency, with particular emphasis that the enzyme-free harvest method using degradable microcarriers showed distinct advantages in maintaining the integrity of EV functional cargo.

The quality control advantages of the degradable microcarrier suspension culture system can be understood from the following four dimensions:

●Elimination of Necrotic Gradients: Microcarriers are uniformly suspended as small particles in the bioreactor, with cells growing on the microcarrier surfaces. Nutrients and dissolved oxygen can be uniformly supplied through agitation, fundamentally avoiding the oxygen gradients and necrotic zone formation inherent in fixed-bed systems.
●Real-Time Quality Monitoring: Because the culture system is a suspension, samples can be taken at any time point for morphological observation, cell viability assays (e.g., AO/PI method), phenotypic analysis (flow cytometry), and metabolic parameter monitoring (e.g., glucose consumption, lactate production), thereby maintaining continuous visibility into MSC quality status.
●Enzyme-Free Dissociation: Degradable microcarriers can be gradually degraded through gentle hydrolysis at the harvest stage, eliminating the need for repeated trypsin digestion of MSCs. Digestion itself induces membrane damage and activates stress signalling pathways, causing transient alterations in EV secretion profiles; the use of degradable carriers allows cells to maintain a more physiological state during harvest, helping preserve the integrity of EV functional cargo (Haraszti et al., 2018).
●Defined Hydrodynamic Control: In 3D suspension culture systems, critical physical parameters such as agitation speed and dissolved oxygen set points can be precisely set and recorded, enabling shear stress to remain within the beneficial window of moderate mechanical stimulation (activating YAP/TAZ to promote EV secretion) while achieving batch-to-batch reproducibility, thereby providing process assurance for the stability of exosome responses to physical stimuli (Wu et al., 2024).

Industrial manufacturing solutions have increasingly incorporated these quality-by-design principles to improve the scalability, controllability, and regulatory compliance of MSC-EV production. One example is CytoNiche's 3D FloTrix™ cell culture platform, which utilises degradable three-dimensional porous microcarriers (3D TableTrix™ and 3D RecomTrix™) to provide a biomimetic microenvironment for MSC expansion while supporting scalable suspension bioreactor culture. By combining degradable microcarrier technology with a chemically defined harvest medium, the platform is designed to minimise culture medium-derived contaminants during the critical EV collection stage and facilitate consistent upstream cell quality control and downstream EV product characterisation. Such design features are aligned with the quality considerations proposed by Na et al. (2026) and the Guidelines for Clinical Research Filing of Cell Components and Derivatives Therapy, which emphasise comprehensive control of both upstream manufacturing processes and downstream critical quality attributes.

6. Refined Design of Harvest Processes: Two-Stage Media Strategy and Scientific Considerations for Sequential Harvesting

Once a high-quality upstream MSC culture platform is established, harvest-stage process design becomes the critical link in translating MSC quality into controllable exosome product quality.

6.1 Two-Stage Media Strategy: An Engineering Balance Between Efficiency and Purity

The media requirements for the expansion phase and the harvest phase differ fundamentally; a "one-medium-throughout" strategy is unacceptable in exosome production. A validated and rational strategy is: use medium containing platelet lysate (PL) during the cell expansion phase, leveraging its abundant growth factors and adhesion molecules to support efficient and cost-effective MSC proliferation; upon switching to the harvest phase, replace the medium with an EV-depleted/xeno-free, defined medium free from exogenous EV/nanoparticle interference.

The scientific rationale for this switch is that serum- or platelet-lysate-containing media inherently carry substantial amounts of donor-derived EVs. If not removed, these exogenous EVs will directly enter the conditioned medium and become proteomic impurities in the EV product that cannot be distinguished from MSC-derived EVs. Na et al. (2026) explicitly note in their exosome quality assessment framework that medium-derived exogenous proteins and nucleic acid components are important potential contaminants affecting EV product purity and safety, and should be ruled out through appropriate analytical testing to confirm the presence or absence of such contamination.

6.2 Feasibility and Quality Management Considerations for Sequential Harvesting Strategies

The sequential harvesting strategy—collecting supernatants in multiple rounds from the same batch of MSCs—has theoretical appeal for significantly increasing yield per batch. However, its feasibility depends on the ability to maintain MSC quality state stability across multiple harvest rounds, thereby preserving EV functional CQA batch-to-batch consistency.

From the available evidence, the following aspects require particular evaluation: 

●Secretion Kinetics Monitoring: Secretion rates and cell viability must be tracked across harvesting cycles to define the optimal production window.
●Cargo Stability: High-resolution RNA-seq and proteomic profiling should confirm that miRNA and protein profiles remain consistent across early and late collections.
●Senescence Tracking: Prolonged culture in starvation or collection media can accelerate SASP; regular testing (e.g. SA-β-gal staining, p16/p21 expression) is required to verify cell health (Welsh et al., 2024).

7. Incorporating MSC Quality into the Process Control Parameter System: From Regulatory Requirements to Process Practice

Synthesising the evidence discussed above, the systematic integration of MSC quality attributes into process control strategies has become increasingly important for ensuring the consistency and functionality of MSC-derived extracellular vesicle (MSC-EV) products. This concept is reflected in the Guidelines for Clinical Research Filing of Cell Components and Derivatives Therapy, which state that critical process parameters (CPPs) should be established based on their relationship with product critical quality attributes (CQAs). It is also consistent with the Quality by Design (QbD) principles outlined in ICH Q8(R2) and ICH Q10, which emphasise scientific process understanding as the foundation for quality assurance.

Within this framework, cell identity and viability constitute the primary level of process control. Cell viability should be maintained at high levels (typically ≥90%), while the stability of the characteristic MSC immunophenotype (CD73^+, CD90^+, and CD105^+) should be routinely verified throughout culture expansion. Passage number and passage history should likewise be tightly controlled, as extended in vitro expansion is closely associated with cellular senescence and declining biological function.

Cellular senescence represents a second critical dimension of process monitoring because of its direct influence on EV composition and therapeutic function. Functional assessment of senescence-associated β-galactosidase (SA-β-gal) activity, together with molecular markers such as p16 and p21, provides complementary indicators of senescence burden. In addition, monitoring EV secretion rate, expressed as particle number produced per cell per unit time, may provide a practical indicator of cellular secretory function and manufacturing consistency.

At the product level, EV functional CQAs should extend beyond conventional physicochemical characterisation. In addition to particle size distribution and concentration, the relative expression of regenerative-associated microRNAs (e.g., miR-126 and miR-210) compared with senescence-associated microRNAs (e.g., miR-34a and miR-21) may serve as indicators of batch functionality. Likewise, potency assays evaluating indication-relevant biological activities, such as macrophage M2 polarisation or pro-angiogenic capacity, provide a more direct assessment of therapeutic potential. As emphasised by Na et al. (2026), potency assays should function as mechanism-based surrogate measures of biological activity rather than relying solely on physical parameters as indicators of product quality.

The quality control framework proposed by Na et al. (2026) further extends these principles to the establishment of hierarchical cell banking systems. From the primary cell bank (PCB) through the master cell bank (MCB) and working cell bank (WCB), each stage should undergo comprehensive evaluation of genomic stability, biological function, and EV secretion characteristics before release. Such a tiered quality management strategy enhances traceability while supporting the consistency and predictability of MSC quality throughout the manufacturing process.

8. Conclusion: From "Being Able to Produce Exosomes" to "Being Able to Control Exosome Quality"

Exosomes are direct functional indicators of the physiological state of their parent cells. As highlighted across biological, mechanical, and clinical studies, compromised MSCs cannot reliably yield potent EV therapeutics.

Evaluating current culture technologies reveals distinct differences in process visibility and environmental control. Fixed-bed and hollow-fibre platforms present operational challenges regarding internal gradients and cell monitoring. In contrast, 3D suspension systems utilising degradable microcarriers enable real-time sampling, uniform environmental conditions, and stress-free harvest, providing a scalable path for GMP-compliant manufacturing.

As EV-based therapies advance through clinical trials, regulatory bodies are increasing emphasis on upstream process characterisation and product consistency. Establishing quantifiable links between MSC state attributes and exosome CQAs will be essential for overcoming manufacturing bottlenecks and advancing cell-free therapeutics toward clinical commercialisation.

CytoNiche has long been committed to providing underlying technology platform support for MSC and exosome industrialisation, with sustained accumulation of core capabilities in 3D culture technology, scale-up expansion processes, and GMP-compatible manufacturing systems, having successfully supported the IND acceptance of China's first exosome-based new drug. With the continued iteration of the 3D FloTrix™ product and technology portfolio, CytoNiche hopes to join hands with more developers dedicated to advancing the serious medical application of exosomes, making "high-quality MSCs" the foundational infrastructure of exosome manufacturing, and collectively driving this field from scientific exploration towards high-standard engineered production.

References

Ahmadi, M., & Rezaie, J. (2021). Ageing and mesenchymal stem cells derived exosomes: Molecular insight and challenges. Cell Biochemistry and Function, 39(1), 60–66.

Almeria, C., Kreß, S., Weber, V., Egger, D., & Kasper, C. (2022). Heterogeneity of mesenchymal stem cell-derived extracellular vesicles is highly impacted by the tissue/cell source and culture conditions. Cell & Bioscience, 12(1), 51.

Devulder, J. V., Baker, J. R., Fenwick, P. S., Odqvist, L., Donnelly, L. E., & Barnes, P. J. (2025). Chronic obstructive pulmonary disease airway epithelial cell-derived extracellular vesicles spread cellular senescence via microRNA-34a. American Journal of Respiratory Cell and Molecular Biology, 73(2), 210–220.

Gonzalez-King, H., García, N. A., Ontoria-Oviedo, I., Ciria, M., Montero, J. A., & Sepúlveda, P. (2017). Hypoxia inducible factor-1α potentiates Jagged1-mediated angiogenesis by mesenchymal stem cell-derived exosomes. Stem Cells, 35(7), 1747–1759. https://doi.org/10.1002/stem.2618

Haraszti, R. A., Miller, R., Stoppato, M., Sansone, P., Coles, A. H., Alterman, J. F., Echeverria, D., Hassler, M. R., Szemraj, J., Nikan, M., O'Brien, J., Kaplan, A., Falentin-Daudré, C., Artzi, N., Gait, M. J., Aronin, N., & Bhargava, A. (2018). Exosomes produced from 3D cultures of MSCs by tangential flow filtration show higher yield and improved activity. Molecular Therapy, 26(12), 2838–2847. https://doi.org/10.1016/j.ymthe.2018.09.015

Kalluri, R., & LeBleu, V. S. (2020). The biology, function, and biomedical applications of exosomes. Science, 367(6478), eaau6977. https://doi.org/10.1126/science.aau6977

Kou, M., Huang, L., Yang, J., Shao, Z., Zhang, S., Luo, Q., Xi, X., & Yang, J. (2022). Mesenchymal stem cell-derived extracellular vesicles for immunomodulation and regeneration: A next generation therapeutic tool? Cell Death & Disease, 13(7), 580. https://doi.org/10.1038/s41419-022-05034-x

Lenzini, S., Cramer, M., Zakhem, E., & Rowley, J. A. (2025). Analytical comparison of MSC-EV quality attributes across tissue sources and production platforms. Cytotherapy, 27(5), S85. https://doi.org/10.1016/j.jcyt.2025.03.146

Mensà, E., Guescini, M., Giuliani, A., Bacalini, M. G., Ramini, D., Corleone, G., ... & Olivieri, F. (2020). Small extracellular vesicles deliver miR-21 and miR-217 as pro-senescence effectors to endothelial cells. Journal of Extracellular Vesicles, 9(1), 1725285.

Na, T., Zhang, K., Zhao, L., Yao, X., Xu, C., Zhang, Y., Wang, L., Xu, M., Zhang, H., & Meng, S. (2026). Quality evaluation considerations for stem cell-derived extracellular vesicles-based therapeutic products in China. Journal of Extracellular Vesicles, 15(5), e70297. https://doi.org/10.1002/jev2.70297

Nguyen, V. V. T., Welsh, J. A., Tertel, T., Steinhage, A., Llorente, A., Llorente, A., & Giebel, B. (2024). Inter-laboratory multiplex bead-based surface protein profiling of MSC-derived EV preparations identifies MSC-EV surface marker signatures. Journal of Extracellular Vesicles, 13(1), e12463. https://doi.org/10.1002/jev2.12463

Pegtel, D. M., & Gould, S. J. (2019). Exosomes. Annual Review of Biochemistry, 88, 487–514. https://doi.org/10.1146/annurev-biochem-013118-111902

Phinney, D. G., & Pittenger, M. F. (2017). Concise review: MSC-derived exosomes for cell-free therapy. Stem Cells, 35(4), 851–858. https://doi.org/10.1002/stem.2575

Rodrigues, C. A., Fernandes, T. G., Diogo, M. M., da Silva, C. L., & Cabral, J. M. S. (2011). Stem cell cultivation in bioreactors. Biotechnology Advances, 29(6), 815–829. https://doi.org/10.1016/j.biotechadv.2011.06.009

Seddighi, N., Talebi, M., Shamsasenjan, K., Raeisi, M., & Movassaghpour, A. (2026). Pro-tumorigenic effects and therapeutic implications of mesenchymal stem cell-derived exosomes under hypoxic conditions: A systematic review. Discover Oncology.

van Niel, G., Carter, D. R. F., Clayton, A., Lambert, D. W., Raposo, G., & Vader, P. (2022). Challenges and directions in studying cell-cell communication by extracellular vesicles. Nature Reviews Molecular Cell Biology, 23(5), 369–382. https://doi.org/10.1038/s41580-021-00460-3

Welsh, J. A., Goberdhan, D. C. I., O'Driscoll, L., Buzas, E. I., Blenkiron, C., Bhattacharyya, S. N., Cheng, H., Colombo, M., Devitt, A., Fahmy, T. M., Fatima, F., Hendrix, A., Hill, A. F., Lenassi, M., Lim, S. K., Mahivainkar, A. S., Mohanty, S., Möller, A., Ng, C. Y., ... Witwer, K. W. (2024). Minimal information for studies of extracellular vesicles (MISEV2023): Communication from the ISEV and ISEV President. Journal of Extracellular Vesicles, 13(2), e12404. https://doi.org/10.1002/jev2.12404

Wu, D., Zhao, X., Xie, J., Yuan, R., Li, Y., Yang, Q., & Zhu, N. (2024). Physical modulation of mesenchymal stem cell exosomes: A new perspective for regenerative medicine. Cell Proliferation, 57(8), e13630. https://doi.org/10.1111/cpr.13630

Zhong, Q., Zeng, J., Li, Y., Zhang, H., Lin, T., & Song, T. (2025). Senescent renal tubular cells derived extracellular vesicles transported miR-20a and miR-21 induced macrophage-to-myofibroblast transition in renal fibrosis after ischemia reperfusion injury. International Journal of Biological Sciences, 21(3), 940.

Zhuo, H., Chen, Y., & Zhao, G. (2024). Advances in application of hypoxia-preconditioned mesenchymal stem cell-derived exosomes. Frontiers in Cell and Developmental Biology, 12, 1446050.

National Health Commission of the People's Republic of China. (2025). Guidelines for Clinical Research Filing of Novel Cell Component and Derivative Therapies (First Edition). National Center for Medical Science and Technology Development, National Health Commission.