Abstract
Purpose::
For regenerative medicine of retina, characterization of retinal stem cells is essential issue to be clarified. Many works suggested that multipotent retinal stem cells to locate in ciliary margin of mammalian retina, however, their nature had not been revealed. To identify surface antigens expressed in retinal stem cells, we screened the expression of a panel of CD (Cluster of Differentiation) antigens in ciliary margin of adult mouse retina. Furthermore, we examined proliferation and differentiation abilities of subsets of cells in this region using in vitro culture system.
Methods::
Antibodies against more than 70 CD antigens were screened for their expression in the adult ciliary margin by a flow cytometry. Antigens showing positive signals were further examined for their expression pattern in developing and mature retina by immunohistochemistry. Cells expressing these antigens were examined for their proliferation and differentiation abilities by in vitro culture system such as reaggregation and monolayer cultures.
Results::
Several CD antigens expressed in the ciliary margin of adult retina by FACS analysis were identified. Immunohistochemical analysis revealed that the antigens expressed specifically either in non-pigmented ciliary epithelium, pigmented ciliary epithelium or RPE. Some antigens expressed with overlapping pattern in an early stage, but their expressions are become segregated along with development. Sub-population of ciliary marginal cells labeled by certain CD antigen in the non-pigmented cells proliferated in an early stage, but this ability was lost at around E15-E16. By contrast, other sub-population in the pigmented cells in adult retina maintained proliferation ability during development.
Conclusions::
Transition of distinct populations in ciliary margin of mouse retina were defined by examining expression of different CD antigens. Commitment to the non-pigmented cells was suggested to occur in an early stage of development. Although pigmented cells maintained proliferation ability until maturation, non-pigmented cells of mouse retina lost it, suggesting a difference from previous observations in avian retina.