An in Vitro Comparison of Two Different Subpopulations of Retinal Progenitor Cells for Self-Renewal and Multipotentiality

Retinal progenitor cells (RPCs) show enormous potential for the treatment of retinal degenerative diseases. It is well known that in vitro cultures of RPCs comprise suspension spheres and adherent cells, but the differences between the two cell populations are not fully understood. In this study, cultured RPCs were sorted into suspension and adherent cells. Analyses of cell morphology, cell growth and retinal progenitor-related expression markers were performed using quantitative polymerase chain reaction (qPCR) and immunocytochemistry to identify the proliferative and multipotent capacity of the cells in vitro. The data showed that both the suspension and adherent cells were maintained in an undifferentiated state, although the former exhibited a greater proliferative potential than the latter. Immunocytochemistry analysis indicated that the two subsets of RPCs were able to differentiate into different retinal cells in the presence of fetal bovine serum (FBS); the adherent cells were more likely to differentiate toward the β3-tubulin-, AP2α- and Map2-positive neuronal lineage, while the suspension cells were more effective at differentiating into rod photoreceptors, which was consistent with the qPCR results. These findings suggest that adherent RPCs may be a potential candidate for retinal interneuron or ganglion cell substitution therapies, whereas suspension RPCs may be preferred for photoreceptor cell replacement.