Purpose: To investigate whether retinal glial cells (RGCs), which are believed to play an important role in the development and maintenance of microvessels, stimulate the proliferation of retinal bovine microvascular pericytes, an essential component of the vessels.
Methods: Conditioned medium (CM) was collected from a primary culture of RGC obtained from chick embryonic retina. The cell number was assayed after stimulation by RGC-CM. Also, by neutralizing antibody and reverse transcription polymerase chain reaction (RT-PCR), we tried to identify which factor of the RGCs contributes to the pericyte stimulation.
Results: Pericyte proliferation was stimulated by RGC-CM in a dose-dependent manner. Platelet-derived growth factor-BB (PDGF-BB), acidic fibroblast growth factor (aFGF), and basic fibroblast growth factor (bFGF) stimulated pericyte proliferation; however, PDGF-AA, transforming growth factor-beta2 (TGF-beta2), and vascular endothelial growth factor (VEGF) did not. The RGC-CM-dependent stimulative effect was blocked, in part, by the neutralizing antibodies for aFGF, bFGF, and PDGF. A mixture of these three antibodies completely blocked the stimulation. RT-PCR revealed that RNA for aFGF, bFGF, and TGF-beta2 were expressed in RGCs.
Conclusions: Pericyte growth is stimulated in vitro by RGC-CM through aFGF, bFGF, PDGF-BB, at least in part. This finding suggests that RGCs may modulate in vivo pericyte cell growth through these three growth factors.