Studies on copolymers of collagen and a synthetic polymer. First report--experimental study on biocompatibility of laminar copolymers of collagen and a synthetic polymer

Soft tissue reaction to collagen-immobilized porous polyethylene: subcutaneous implantation in rats for 20 wk

Collagen-immobilized porous polyethylene, in which the immobilization was through covalent bonding, and virgin porous polyethylene were implanted subcutaneously in rats from 1 to 20 wk. The results were the ingrowth of the connective tissue into collagen-immobilized porous polyethylene was rich and contained a low level of inflammatory cellular infiltration compared with that of virgin porous polyethylene. The material-tissue interface showed that the living body-originated collagen fibres were firmly anchored into the immobilized collagen layer. These results suggested that covalent immobilization of collagen on to the biomaterial surface is useful in promoting the ingrowth of soft tissue and the tissue adhesion.

In vivo biocompatibility of collagen-poly(hydroxyethyl methacrylate) hydrogels

Collagen-p(HEMA) hydrogels were subcutaneously implanted in rats for up to 6 month and the immediate short- and long-term tissue response to these implants was studied. Histopathological data indicated that the tissue reaction at the implant site progressed from an initial acute inflammatory response characterized by the presence of eosinophils and polymorphs to a chronic response marked by few macrophages, foreign body giant cells and fibroblasts. After one month a very thin fibrous capsule (approximately 11 microns thick) was observed around the implant. Even 6 month post-implantation, the capsule thickness was maintained at about 11-12 microns. No necrosis, calcification, tumorigenesis or infection was observed at the implant site up to 6 month. Fibrous capsule analysis showed that the collagen content and the capsule thickness were well within the threshold limits. The collagen-p(HEMA) hydrogels were found to be well-tolerated, non-toxic and highly biocompatible.

The in vitro and in vivo behavior of urokinase immobilized onto collagen-synthetic polymer composite material

With a view to developing biomaterials for semipermanent substitution, we have studied a composite material constituted with collagen and a synthetic polymer which possesses high tissue compatibility. This collagen-synthetic polymer composite was applied as a support for immobilization of enzymes for the purpose of providing a material surface with biological function. The enzymes, urokinase and trypsin, were successfully bound to the collagen membrane layer which had been activated by acyl azide formation of its carboxyl groups. The enzyme-bearing composite material showed excellent catalytic activity toward a protein substrate as well as a low-molecular-weight synthetic substrate. The immobilized urokinase was characterized enzymatically and compared with native urokinase. The apparent affinity of immobilized urokinase for the substrate was slightly decreased, but its intrinsic kinetic properties were not significantly affected. No decrease in its esterase activity was observed both on repeated use and on long-term storage, and its fibrinolytic activity was stable on heat or disinfection treatment. When this urokinase-bearing composite material was applied into rabbit blood vessels, its in vivo fibrinolytic activity was maintained. Thus, enzyme-collagen-synthetic polymer composites may find wide application for biomaterials and artificial organs as functional biomaterials.

Use of collagen-hydroxyethylmethacrylate hydrogels for cell growth

Collagen-hydroxyethylmethacrylate hydrogels were prepared by polymerizing monomeric hydroxyethylmethacrylate in the presence of various concentrations of soluble native collagen. The resulting transparent hydrogels were evaluated as substrata for growth of IMR-90 human embryonic lung fibroblasts. Without collagen no significant growth occurred, whereas a dose-response curve expressing maximal cell growth against collagen concentration could be constructed quite readily by the use of appropriate hydrogels. The method allows for quantification of the collagen contribution to cell growth and, in a more general sense, provides the foundation for a relatively easy procedure to probe mechanisms of cell adhesion and cell differentiation.