Blood vessel fibronectin increases in conjunction with endothelial cell proliferation and capillary ingrowth during wound healing

The regulation of angiogenesis and alterations in the structure of blood vessels taking part in wound healing are poorly understood. In studies of guinea pig 4-mm skin wound, left uncovered for 1-28 days, biopsied and processed for 1-micrometer section and immunofluorescence, we found that fibronectin in blood vessel walls markedly increased in conjunction with endothelial cell proliferation and capillary ingrowth. Both the endothelial cell proliferation and the increased vessel wall fibronectin were restricted to a 0.5-mm area along the margin of the wound and occurred 3-7 days after injury. Fibronectin was easily demonstrated in capillaries of the peripheral granulation tissue but was difficult to demonstrate in central areas of the granulation tissue secondary to a brightly fluorescent reticular background staining probably attributable to fibroblast-related fibronectin. The fibronectin in blood vessel walls rapidly diminished as endothelial cell proliferation and capillary ingrowth ceased. These data suggest that fibronectin may provide a provisional substratum for endothelial cell mitosis and movement.