The proposed research is designed to study the cell biology of human chorioretinal pigment epithelium (CRPE) in tissue culture in order to understand the molecular basis of inherited retinal disease. The project will attempt to determine the optimum in vitro growth conditions of human CRPE cells, to describe the fundamental proliferative kinetics of these cells, and to define criteria that identify CRPE cells in vitro as differentiated. The capacity of these cells to perform certain biochemical operations thought to be more uniquely characteristic of the CRPE cells will be studied. The proliferative properties will be determined by means of tritiated thymidine autoradiography. The state of differentiation will be examined by light and electron microscopy and through biochemical studies. The biochemistry will focus on the ability of these cells to metabolize and store vitamin A and will involve measuring total cellular vitamin A content, identifying the cytosol binding protein for retinol, and determining the activity of the enzyme retinyl palmitate hydrolase. A search for other unique proteins or protein patterns that might characterize these cells will be made by two-dimensional protein electrophoresis. It is planned to extend these studies to the examination of CRPE cells from human donors with specific retinal degenerations and to attempt to develop the methodology so as to be able to culture other cellular elements of the human retina.