Grace Hamadeh

Background: Autoimmune uveitis is a chronic immune-mediated inflammatory disease of the eye and a major cause of preventable vision loss in working-age populations. Recurrent intraocular inflammation leads to progressive retinal damage and irreversible visual impairment. Current therapies, including corticosteroids and systemic immunosuppressants, primarily suppress inflammation but fail to restore long-term immune balance and are associated with significant systemic toxicity. Recent studies suggest that the therapeutic effects of mesenchymal stem cells (MSCs) are largely mediated through extracellular vesicles (EVs), which contain immunomodulatory cytokines, proteins, and microRNAs capable of regulating inflammatory pathways.^1-3 Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) therefore represent a promising cell-free therapeutic platform for autoimmune ocular disease.

Objective: This narrative literature review evaluates strategies designed to enhance the therapeutic efficacy and translational potential of mesenchymal stem cell-derived extracellular vesicles in autoimmune uveitis through optimization of immunomodulatory function, engineered cargo, targeted delivery, and manufacturing approaches.

Search Methods: A literature search was conducted using the PubMed database for studies published between 2018 and 2024. Search terms included “autoimmune uveitis,” “mesenchymal stem cells,” “extracellular vesicles,” “exosomes,” “IL-10,” “ocular drug delivery,” and “experimental autoimmune uveitis.” Primary studies investigating MSC-EV immunomodulation, engineered extracellular vesicle therapeutics, ocular delivery strategies, manufacturing optimization, and translational barriers were reviewed.

Results: Mesenchymal stem cell-derived extracellular vesicles demonstrated significant immunomodulatory effects in experimental autoimmune uveitis models through suppression of pathogenic Th1 and Th17 responses and reduction of pro-inflammatory cytokines, including interferon-gamma and IL-17. EV treatment reduced retinal inflammation, preserved retinal architecture, and demonstrated therapeutic efficacy comparable to mesenchymal stem cell therapy.² Multiple optimization strategies further enhanced EV therapeutic potential. EVs derived from early-passage MSCs demonstrated greater immunosuppressive potency compared to late-passage MSCs, with enhanced suppression of inflammatory cytokines. Additionally, EVs generated under three-dimensional culture conditions exhibited increased anti-inflammatory cytokine expression, including IL-10 and TGF-beta, along with reprogrammed protein and microRNA cargo associated with enhanced immunoregulatory function. Engineering MSCs to overexpress IL-10 produced EVs with greater suppression of pathogenic Th1 and Th17 responses and improved disease outcomes in vivo.⁴ EVs also demonstrated targeted localization to inflamed retinal tissue and effective noninvasive topical ocular delivery, particularly following TAT-mediated surface modification.⁵ Despite these advances, substantial translational barriers remain, including variability in EV composition and therapeutic potency due to donor source, culture conditions, and manufacturing methods.⁶

Conclusion: Engineered mesenchymal stem cell-derived extracellular vesicles represent a promising multi-mechanistic therapeutic platform for autoimmune uveitis by combining targeted immunomodulation, customizable engineering strategies, and localized delivery within a cell-free system. Optimization of EV manufacturing conditions, cargo composition, and delivery approaches may enhance therapeutic consistency and clinical applicability. However, further studies are required to establish standardized production methods, define reliable potency biomarkers, and evaluate long-term safety and efficacy in clinical trials. Collectively, these findings support MSC-EVs as a scalable and translational platform for next-generation immunotherapy in autoimmune ocular disease.

Works Cited:

1. Lee RH, et al. Mesenchymal stem cell–derived extracellular vesicles as mediators of immunomodulation. Stem Cell Res Ther. 2018.
2. Lee RH, et al. Mesenchymal stem cells and their extracellular vesicles in autoimmune uveitis. Invest Ophthalmol Vis Sci. 2020.
3. Rossi DC, Ribi C, Guex-Crosier Y. Treatment of chronic non-infectious uveitis and scleritis. Swiss Med Wkly. 2019;149:w20005.
4. Li Y, Ren X, Zhang Z, Duan Y, Li H, Chen S, et al. Effect of small extracellular vesicles derived from IL-10-overexpressing mesenchymal stem cells on experimental autoimmune uveitis. Stem Cell Res Ther. 2022;13(1):100.
5. Yang H, Wu P, Wang T, Yu Y, Li J, Liu R, Ruan Q. Topical ophthalmic instillation of engineered hMSC-derived exosomes: a novel non-invasive therapeutic strategy for ocular posterior-segment disorder. Biochem Biophys Res Commun. 2024;723:150212.
6. Kaur G, Bae EH, Zhang Y, et al. Biopotency and surrogate assays to validate the immunomodulatory potency of extracellular vesicles derived from mesenchymal stem/stromal cells for the treatment of experimental autoimmune uveitis. J Extracell Vesicles. 2024;13(8):e12497.