COLLAGEN AND COLLAGEN-DERIVED PRODUCTS FREE OF ANY INFECTIOUS AGENT, IMPLANTS COMPRISING THE SAME AND METHODS OF MAKING THEREOF

摘要

The use of collagen as a biomedical implant raises safety issues towards viruses and prions. The physicochemical changes and the in vitro and in vivo biocompatibility of collagen treated with heat, and by formic acid (FA), trifluoroacetic acid (TFA), tetrafluoroethanol (TFE) and hexafluoroisopropanol (HFIP) were investigated. FA and TFA resulted in extensive depurination of nucleic acids while HFIP and TFE did so to a lesser degree. The molecules of FA, and most importantly of TFA, remained within collagen. Although these two acids induced modification in the secondary structure of collagen, resistance to collagenase was not affected and, in vitro, cell growth was not impaired. Severe dehydrothermal treatment, for example 110 ~C for 1-3 days under high vacuum, also succeeded in removing completely nucleic acids. Since this treatment also leads to slight cross-linking, it could be advantageously used to eliminate prion and to stabilize gelatin products. Finally, prolonged treatment with TFA provides a transparent collagen, which transparency is further enhanced by adding glycosaminoglycans or proteoglycans, particularly hyaluronic acid. All the above treatments could offer a safe and biocompatible collagen-derived material for diverse biomedical uses, by providing a virus or prion-free product.