Retinal vascular endothelial cells and pericytes. Differential growth characteristics in vitro.

Long-term cultures of retinal capillary endothelial cells (RCEC) and of pericytes were grown from collagenase-treated calf retinal vessels. By the use of mechanical separation and differential growth response in various media, pure cell lines were derived from cloned capillary cells as well as from multiple vessel fragments. RCEC and pericytes appeared different under phase contrast microscopy. In addition, RCEC produced factor VIII antigen and angiotensin-converting enzyme, and pericytes did not. RCEC preferred to grow in tumor-conditioned medium, whereas pericytes preferred a standard tissue culture medium supplemented with calf serum. Extracellular matrix, together with tubular structures, developed in postconfluent RCEC but not in pericytes. This study demonstrates that it is possible to grow long-term, pure cultures of RCEC and of pericytes that possess distinctive morphology, growth, and synthetic capabilities in vitro.