Retinal pigment epithelial cell differentiation in vitro

Cultured chick pigment epithelial (PE) cells from stages 29 to 31 chick embryos grown innormal Eagle's minimum essential medium (MEM) exhibit marked colonial organization and differentiation. Individual cells appear epithelial and heavily pigmented. In contrast, cells grown in Ham's modified F-12 medium appear fibrocytic with colonial disorganization and little visible pigmentation. Biochemically, cells grown in F-12 medium lack receptors for both A H-retinol and s H-retinoic acid, although cells grown in MEM exhibit specific 3 H-retinol binding. Pathways of glucose utilization differ significantly in cells grown in the two media, with considerably lower overall respiratory activity and lower pentose phosphate pathway activity seen with the F-12 medium. Thus different nutritional states can markedly affect PE cell characteristics in culture and possibly in vivo as well.