Physiological and cell biological properties in vitro of collagen isolated from calf limed splits

Experiments on self-assembly, susceptibility to collagenase degradation and activity for cell adhesion were carried out to determine the differences between collagen isolated from calf limed splits with acetic acid, alkali or pepsin treatment and commercial type I collagen produced from fresh bovine skins with acetic acid. Self-assembly was observed in all collagen solutions; however, fibril formation of acetic acid-treated collagen and pepsin-treated collagen was observed at neutral pH, as was that of commercial type I collagen whereas, alkali-treated collagen lost its ability of assembly at neutral pH but was able to form fibrils under acidic conditions. Scanning electron microscopy showed that the assembled fibrils from acetic acid-treated collagen had a major fibrous and minor membranous structure similar to that of commercial type I collagen but that reconstructed fibrils from pepsin-treated collagen were more rectilinear and evenly dispersed than were those of other collagens. Analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed that matrix metalloproteinase (MMP-1) cleaved collagen isolated from limed splits at a similar locus to that of commercial type I collagen. Keratinocytes cultured on collagen showed increased rates of attachment and proliferation. Moreover, pepsin-treated collagen had more significant effects on cell attachment and proliferation than commercial acetic acid-extracted type I collagen.