Freshly isolated RPE cells, dedifferentiated RPE cells cultured for 14 days in the presence of 100 ng/ml of PDGF, or spontaneously dedifferentiated RPE cells cultured for 14 days were plated onto collagen gels (10⁵ cells per well) and incubated in DMEM-5 for 24 hours to allow the cells to adhere to collagen gels. Then, collagen gels were detached from the culture plate and floated in the medium. After another 24 hours, collagen gels were photographed and their areas were measured using NIH Image software. Data for the areas are expressed as integrated pixels of three independent experiments. Contraction of collagen gels (mean (SE), n=3) is expressed as the percentage of (whole pixels of the well − pixels of the gel)/whole pixels of the well.

↵p <0.01, with PDGF versus without PDGF in dedifferentiated cells.