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Ben Mead, Donald J Zack, Zubair Ahmed, Stanislav I Tomarev; Neuroprotection of retinal ganglion cells by BMSC-derived exosomes. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5174. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously demonstrated that exosomes derived from human bone marrow mesenchymal stem cells (BMSC) provide retinal ganglion cell (RGC) neuroprotection in short-term rat models of optic nerve crush and glaucoma. Our current study has 3 aims: 1), test the long-term effect of exosome treatment in a DBA/2J glaucoma mouse model; 2), test the neuroprotective efficacy of exosomes on human RGC derived from iPSC; and 3), assess whether the neuroprotective efficacy of exosomes can be improved by priming BMSC prior to isolation.
Exosomes were isolated from human BMSC and fibroblasts and characterized by NanoSight and Western blot. DBA/2J mice were used as a chronic model of glaucoma and exosomes were intravitreally injected at a concentration of 3x109 monthly. Intraocular pressure (IOP; monthly) and positive scotopic threshold response (pSTR; quarterly) recordings were taken whilst RBPMS+ RGC were counted in retinal wholemounts and paraphenylenediamine+ (PPD) axons were counted in optic nerve sections. RNAseq was used to quantify miRNA present in BMSC- and fibroblast-derived exosomes as well as purified RGC with or without exosome treatment. Neuroprotective efficacy of exosomes was also tested on cultured human RGC derived from iPSC, with or without priming/activation via TNFα.
DBA/2J mice exhibited elevated IOP, RGC dysfunction and loss, and axonal degeneration. BMSC but not fibroblast exosomes promoted significant preservation of RGC function for up to 6 months, as measured by pSTR amplitudes. BMSC exosome-treated mice had 3.7-fold greater numbers of RBPMS+ RGC in comparison to untreated/fibroblast exosome-treated mice. BMSC but not fibroblast exosomes reduced axonal degeneration as evaluated by PPD+ axonal staining. The number of optic nerves graded as mild, moderate or severe was 12%, 22%, 66%, respectively in untreated mice and 33%, 37%, 40%, respectively in BMSC exosome-treated mice. BMSC exosomes provided significant neuroprotection of human RGC in vitro after injury induced with colchicine. The effects of priming are still under investigation with preliminary data suggesting the neuroprotective efficacy of exosomes can be improved through treatment with TNFα prior to exosome isolation.
We demonstrate for the first time that BMSC-derived exosomes offer significant therapeutic benefits in a 12-month model of glaucoma as well as an in vitro model of human RGC loss.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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