THE STABILIZATION OF FIBRILLAR COLLAGEN MATRICES WITH 3,4-DIHYDROXYPHENYLALANINE

Pepsin-treated type I collagen fibrils were reconstituted by warming to 37-degrees-C in the presence of DOPA at a concentration of 1 x 10(-3)M. Following a 1-1.5-h lag period the "gels" became progressively stabilized as indicated by an inability to disperse these at 0-degrees-C. Following 24 h of incubation at 37-degrees-C, the DOPA-collagen gels were insoluble in dilute acetic acid even under denaturing conditions. The effect on both gel stability and solubility was concentration-dependent and was maximum at 1 x 10(-3)M. Gel solubility changes were significant, with the greatest change occurring between concentrations of 3.1 x 10(-5)M and 1.65 x 10(-5)M. DOPA exposure did not alter the fibrillar banding pattern seen at the electron microscopic level. Collagen felts prepared by lyophilization of DOPA-collagen gels demonstrated an increase in shrinkage temperature which after 24 h exceeded that of rat tail tendon. Preformed collagen felts incubated for 24 h in the presence of 1 mM DOPA also had a greatly increased shrinkage temperature. Pepsin-treated collagen control felts were consistently unstable at 37-degrees-C. The tensile properties of DOPA-collagen felts were altered with respect to control felts in a time dependent manner. The wet tensile strength increased to four times that of control after 3 days of incubation at 37-degrees-C. Matrix extensibility initially increased to 1.5 times that of control felts after 4 days of incubation at 37-degrees-C, but decreased to below control values following 6 additional days of incubation. These properties suggest that DOPA may be useful as a stabilizing agent of collagen biomedical prostheses.