Characteristics of progenitor cells derived from adult ciliary body in mouse, rat, and human eyes.

PURPOSE To isolate and characterize progenitor cells derived from adult mammalian ciliary body. METHODS The authors isolated progenitor cells from the ciliary body of adult mice, rats, and human cadaver eyes and determined quantitative growth characteristics of groups of progenitor cells called neurosphere (NS) cells, including individual cell diameter, NS diameter, percentage of NS-forming cells, and cell number per eye in mouse, rat, and human eyes. The immunolabeling and ultrastructure of NS cells were investigated by confocal and transmission electron microscopy. RESULTS Average diameters of individual cells and neurospheres after 1 week in culture were similar in mice, rats, and humans (cell diameters: 22 +/- 1.1, 21 +/- 0.3, 25 +/- 0.4 mum; NS diameters: 139 +/- 22, 137 +/- 9, 141 +/- 11 mum, respectively). Mean numbers of cells per NS were estimated to be 1183 in mice, 5360 in rats, and 685 in humans. Molecules that were identified by immunolabeling in NS cells included nestin, Chx-10, vimentin, GFAP, and Pax-6. Thy-1 was expressed in some NS cells. Ultrastructurally, NS cells displayed abundant rough endoplasmic reticulum and many cellular processes but no characteristics of mature retinal neurons or glia. CONCLUSIONS Progenitor cells from adult mammalian ciliary body have significant, but limited, proliferation potential and express markers characteristic of other progenitor cells and seen during early retinal development. The ciliary body could be a source of cells for transplantation in experimental rodent eyes and for autotransplantation in human eyes.