High and low molecular weight forms of endothelial cell growth factor.

Endothelial cell growth factor (ECGF) is a neural-derived mitogen capable of stimulating the proliferation of quiescent populations of human umbilical vein endothelial cells (HUV-EC). ECGF has been isolated from bovine hypothalamus in two forms: a high molecular weight from (high Mr ECGF, greater than 70,000) and a low molecular weight form form (low Mr ECGF, 17,000 to 25,000). Isoelectric focusing of high Mr ECGF and low Mr ECGF revealed that both Mr forms possess similar anionic isoelectric points (pI 4 to 6). High Mr ECGF can be converted into low Mr ECGF by mild acidification of the high Mr ECGF complex. Low Mr ECGF prepared by the high Mr to low Mr transition procedure is biologically active at 100 ng/ml in the low density HUV-EC growth assay and is capable of stimulating DNA synthesis in Balb/c 3T3 cells at 10 ng/ml. The two Mr forms of ECGF are related since they (i) share similar biological activity, (ii) possess similar isoelectric points, and (iii) high Mr ECGF can be converted into low Mr ECGF by mild treatment with acetic acid. Furthermore, the high Mr and low Mr forms of ECGF are not related to the cationic bovine brain fibroblast growth factor.