Study On Compatibility Of Silk Membrane As A Dural Substitute

OBJECTIVE: Blood compatibility and tissue compatibility were investigated. Porous silk membrane, SD-1 silk membrane, epoxide silk membrane and bovine pericardium were repaired in rabbits. The results among the four materials were compared and the possibility of silk membrane as a dural substitute was probed.METHODS: 1. Blood compatibility test: Recalcification test, hemolysis test and platelet adhesive test were conducted for compact silk membrane, polyporous silk membrane, bovine pericardium and collagen sponge. 2. Test of tissue compatibility: After New Zealand rabbits were anesthetized, craniotomy was created in the bilateral temporoparietal bone. A elliptical piece of dura mater, measuring 1.0 X 0.8cm, was removed with the aid of a surgical microscope. The dural defect was then repaired with either polyporous silk membrane, SD-1 silk membrane, epoxide silk membrane or bovine pericardium. Neurological performance was observed. At 15,30,90 days, three rabbits were put to death respectively in each groups. The dural repair site with surrounding skull dura and brain was removed en bloc and placed in 10% formalin. The specimens were processed for paraffin embedding, and sagittally sectioned. Sections were stained with hematoxylin/eosin and Masson trichrome stain for histological evaluation.RESULTS: 1. Recalcification time of compact silk membrane was longer than that of other three materials. The homolysis rate of compact silk membrane and polyporous silk membrane was a little higher than that of bovine pericardium and collagen sponge. But the homolysis rate of all materials was less than 5%. Platelet adhesive test shows that the surface of compact silk membrane had less platelet than that of other three materials. The platelets on surface of all four materials show no obvious malformation. 2. Wound healing was achieved in all cases without any wound infection. The behavior of all rabbits remained completely normal, without symptoms of meningitis and tic. 3. Early period after surgery in all cases, only mildinflammatory reaction was observed. In late period, lymphocytic cells were observed in the three silk membranes, and thin neomembrane was formed between the silk membrane and brain. However, in the control material, bovine pericardium, there were less inflammatory cells. The appearance of the underlying cerebral cortex was normal in all cases.CONCLUSIONS: l.The research showed that the silk membrane has a good blood compatibility, and the compact silk membrane has some anticoagulant effect. 2.Three silk membranes show good tissue compatibility. But the level of inflammatory reaction in silk membrane is higher than that in bovine pericardium. 3. If the technique of making silk membrane is improved, the silk membrane is hopeful for a dural substitute.