Collagen production by cultured retinal capillary pericytes

The cells that proliferate from microvessels isolated from calf retinas and placed in tissue culture have been found to derive from the intramural pericytes. When these cells were cultured in medium supplemented with ascorbate and pulsed for 24 hr with [14C]proline, about 2% of the [14C]proline in the nondialyzable protein secreted into the culture medium by these cells was hydroxylated, and about 10% of the incorporated [4C]proline was solubilized by purified collagenase. Agarose gel chromatography of the postculture media showed that unreduced [14C]collagen polypeptides were recovered in large-molecular-weight aggregates (greater than 300,000 daltons) which were largely converted to chains of approximately 95,000 molecular weight and some dimers and trimers of MW approximately 180,000 and 270,000 when the medium was subjected to reduction and alkylation prior to chromatography. The findings indicate that cultured retinal pericytes elaborate collagen and suggest the production of type III collagen. Retinal microvessel cells in culture may facilitate study of abnormalities in retinal pericyte function and collagen synthesis that occur in retinal vascular diseases.