Effect of growth factors on expression of integrin subtypes in microvascular endothelial cells isolated from bovine retinas.

We isolated microvascular endothelial cells from bovine retinas (BREC) by a colony isolation method, and investigated the effects of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) on growth as well as integrin subtype expression of the cultured BREC. Either of the growth factors stimulated growth of the cultured BREC. In non-stimulated BREC, alpha v beta 3 integrin expression was predominant over the other integrin subtypes tested (alpha v beta 5, alpha 2 beta 1 and alpha 5 beta 1), but no enhancement of the alpha v beta 3 expression occurred by either growth factor stimulation. On the other hand, bFGF addition stimulated alpha v beta 5 and alpha 5 beta 1 expression while VEGF induced the alpha 2 beta 1 expression as well. These results suggest that external stimuli such as bFGF and VEGF alter integrin expression profiles of BREC and probably influence interactions of endothelial cells with extracellular matrix during angiogenesis which must be involved in pathogenesis of ischemic retinal disorders. In this respect, this BREC culture system could be useful to study the mechanism of neovascularization in these disorders.