Bone Repair Material Made From Pig Bone By Enzymolgy

Bone defects are common diseases in orthopaedic surgeries. To repair these defects, bone replants,including autografts and allografts,are available in some cases. However, because of the limited donor areas and complications led by the operation for autografts and the danger of disease transmission by allografts ,the xenografts are taken into account today.Though largely supplied,fresh mammalian bones can not be used directly as material for repairs of bone defects because they cause severe immune response and they are probable of disease transmission. Oxidants are used by many researchers in their treating method to eliminate antigens in mammalian bones.It is commented that better methods to process mammalian bones are needed because of bad mechanical and bio-functional properties of mammalian bones processed with oxidants.Enzymes are selected to process mammalian bones in our experiments.Bones of mammals are mainly composed of collagens and hydroxyapatite while enzymes selectively act on substrates. The hydrolysis of enzymes may be used to eliminate the fats and proteins other than collagen in that collagen usually remains intacted after treated by many enzymes. It is expected that antigens be eliminated and at the same time collagens and bone salts keep intacted in enzyme processing.Compact bones of pig femur are studied in our reseach.The processing of compact bones include preliminary disposal,defatting and enzyme processing.Fats in bones can be largely eliminated after 48 hours as evaluated by N% in defatted bones.The Enzyme processing appeared little harmful effect on bone collagen when appraised by the amount of hydroxyproline dissolved in the solution and the mechanical property of enzyme processed bones . The percentage of tryptophan in bones show that the optimum concentration of enzyme solution is 1% and the optimum pH of the solution is 8.0.To get more entire elimination of proteins other than collagens,longer than 18 hours is needed in 1% ,pH8.0 processing solution. X-ray diffraction spectrums of unprocessed bone ,defatted bone and enzyme processed bone show that crystals of hydroxyapatite change little after processing. Infrared absorption spectrums show that fats in bones can be eliminated by defatting and enzyme treating.To find out how tense of immune response caused by enzyme processed bone,a man-made non-union model,as the defects by 1.5cm of segmental radius bone,wascreated in 4 rabbits. Evaluation by Enzyme-linked-immuno-absorbency exhibited processed femur compact bones cause little immune response 2 weeks after replanted into radius bone defects. X-ray radiographys for rabbits of 2 months after operation also showed that enzyme processed bones are biocompatible material for bone repairs.