Effects of a purified low molecular weight tumour angiogenesis factor on cell morphology of bovine brain capillary endothelial cells growing on a native collagen substratum.

A tumour angiogenesis factor (TAF) (molecular weight = 300 daltons) purified from rat Walker sarcoma was tested for its effects on the interaction of bovine capillary endothelial cells (BCEC) with a native collagen substratum in vitro. BCEC growing on collagen appeared less flattened than they were on plastic. Within five minutes of TAF addition a shape change was induced from fusiform to polygonal (p less than 0.05) and the number of spherical cells increased (p less than 0.05), implying a general cell retraction from the collagen substratum. TAF added to BCEC in suspension increased the number of cells with surface microvilli at the expense of blebbed cells (p less than 0.0001). The effect was immediate and transient. When the other parameters of cell spreading on to collagen were analysed, no difference was observed between TAF-treated cells and controls. The significance of TAF induced morphological changes are discussed with reference to the effects of polypeptide or steroid growth factors on their target cells.