Exosome-mediated differentiation of adipose-derived mesenchymal stem cells to trabecular meshwork cells
Vannatta, Richard Taylor
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Glaucoma is the second leading cause of blindness and affects over 70 million people worldwide. Intraocular pressure (IOP), a well-established risk factor for primary open angle glaucoma, the most common form of glaucoma, is primarily regulated by aqueous humor outflow through drainage tissues, specifically the trabecular meshwork (TM). In primary open angle glaucoma, TM cellularity is significantly decreased in comparison to age-matched healthy eyes, presumably limiting the TM’s ability to regulate IOP. It is hypothesized that regenerating TM cellularity in a glaucomatous eye would lead to proper IOP and aqueous outflow regulation, preventing further vision loss associated with glaucoma. Towards this, we investigated the use of TM cell-derived exosomes, small secreted particles 40nm-1μm in diameter, to induce differentiation in adipose-derived mesenchymal stem cells (MSC) toward a TM lineage. Using established TM characterization and exosome isolation methods, we co-cultured TM-derived exosomes and MSCs, along with control TM and MSC cells, for two weeks and observed changes relative to untreated MSCs and TM cells. While experimental groups were not significantly different from untreated MSC cells, trends relating exosome concentration and TM phenotype were observed. Importantly, untreated TM cells were found to be significantly different from past research in three out of four characterization assays, indicating phenotypic loss during cell culture without exosome treatment. These results highlight the importance of culture conditions necessary to attain and maintain the TM phenotype. Further, trends from this study support the idea that exosomes play a role in TM differentiation and inform efforts to develop glaucomatous, stem cell-based regenerative therapeutics.