Mesenchymal stem cells from trabecular meshwork become photoreceptor-like cells on amniotic membrane

Stem cell therapy is a promising approach for treatment of degenerative retinal disorders such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). In this study, human mesenchymal stem cells (MSCs) were isolated from the trabecular meshwork (TM), the major functional tissue of the anterior chamber angle in the eye, were characterized and differentiated into photoreceptor cells on amniotic membrane (AM). After isolation of trabecular meshwork and culture of the stromal segment of this tissue, fibroblast-like cells (CD105(+), CD90(+), CD44(+), CD166(+) cells) capable of differentiation toward mesenchymal and photoreceptor lineages were obtained. The isolated cells were seeded on amniotic membrane and were treated with induction medium. Immunocytochemistry and quantitative real time RT-PCR (qPCR) were used to detect expression of photoreceptor genes such as rhodopsin, recoverin, CRX, and peripherin; and the bipolar cell marker protein kinase C alpha (PKC-alpha). As a result, immunocytochemistry revealed that the differentiated TMMSCs expressed rhodopsin, CRX and PKC proteins. qPCR showed the expression of rhodopsin (rod like photoreceptor-specific marker), and CRX genes were significantly higher in TMMSCs differentiated on AM than those differentiated on tissue culture polystyrene (TCPS). In conclusion, our findings suggested that a combination of TMMSCs (as a new source) and basement membrane support from AM might be a suitable source of cells for subretinal transplantation in regenerative therapy for retinal disorders such as AMD and RP.