Müller glial cells promote stem cell features in retina progenitor cells.

SIMON V.; DE GENARO P.; GERMAN O. L.; DE LOS SANTOS B.; ROTSTEIN N.; POLITI L.

Rio de Janeiro

Congreso; 1st Meeting of the Institute of Glia: a South American Alliance; 2011

Institute of Glia: a South American Alliance. iGlia

Müller glial cells (MGC) play many critical roles in the retina. Recently, these cells have been proposed as stem cells, potentially capable of regenerating the retina including photoreceptor neurons (PHRs). This phenomenon has great relevance in the treatment of retinal neurodegenerative diseases, such as retinitis pigmentosa, in which PHR depletion leads to a progressive blindness. Although much progress has been accomplished in studying the role of MGC as stem cells, several important issues remain obscure. We here analyzed the mutual interactions between retinal progenitors and MGC and whether these glial cells might give rise to newly generated photoreceptors.We used retinal pure glial cultures and mixed neuron-glia cultures prepared from 2-day old rats. Mixed neuron-glia cultures were consecutively harvested and re-seeded until their fifth passage. In order to explore the ability of MGC to generate retinal progenitors, both pure glial cultures and neuron-glia cultures were separately labeled with a fluorescent probe (Cell Tracer) and were later re-seeded together. Stem and retinal progenitor cells were identified by 5-bromo-2-deoxyuridine  uptake, and by the expression of many stem, neuronal and PHR markers. The different cell types were quantified by microscopic analysis and flow cytometry.In mixed neuron-glia cultures about 5% of the cells were newly generated retinal progenitors. Interestingly, many of these progenitors expressed stem cell markers, and were preserved even after several re-seedings. Under suitable conditions, these retina progenitors began to express many molecular and functional photoreceptor markers, including opsin and light responses. On the contrary, new retina progenitors were virtually absent in pure glial cell cultures.Our results suggest that in addition to giving rise to new neurons, MGC cells might contribute to retina regeneration by preserving and/or generating a pool of proliferative progenitors with stem cell characteristics, which might later differentiate as PHRs.