The Experimental Evaluation Of Biocompatibility Of The Genipin Biotype Artificial Esophagus

ObjectiveConventional esophageal surgery is of large trauma,and often results in reflux esophagitis, anastomotic stenosis and postoperative disorders. It is difficult for patients with poor cardiopulmonary function to endure conventional esophagectomy with reconstruction of esophagus,which is typically performed with sacrificing part of the digestive tract, and often results in postoperative digestive disorders and nutrient malabsorption.In-situ esophageal reconstruction and replacement with biotype artificial material could spare gastrointestinal function.It is important and practicable for surgical treatment of many esophageal diseases. The genipin biotype material of artificial esophagus has good physical and chemical properties,such as the biomechanics,denaturation temperature and a high ability to resistance against enzymatic degradation.besides,it needs have good biocompatibility. The biocompatibility of the biotype material of artificial esophagus made up of genipin cross-linked pig aorta was evaluated,which provided the basis for in-situ reconstruction of esophagus of large animals in the future in this article.Methodsaccording the evaluation criterion and requirement of medical apparatus and instruments which was made by the International Standard Organization(IS O1099-1:1992),The biocompatibility of the genipin biotype artificial esophagus was primarily evaluated using the acute and subacute toxicity tests, hemolysis test, cytotoxicity test, and muscle implantation test.Results(1) Acute toxicity testNo death was found in all the mice within the 3 days,and no toxicosis sympt- om or ill efect was found within the 72 hours.There was no difference between the material group and the control group.(2) Subacute toxicity testWithin 2 weeks after intraperitoneal injection, the general state of health of Kunming mice were in good condition. all the mice did not die during the test. No degeneration or necrosis was seen with heart,liver and kidney of the mice.There was no difference in weight, red blood cell count and white blood cell before and after injection between the material group and the control group.(3) Cytotoxicity testMTT method showed that The relative cell proliferation rate of the experim- ental material was more than 90% .Toxicity grading of the experimental material was O-level or 1-level. The experimental material could meet the accepted crite- ria for the cytotoxicity test. (4) Hemolytic testOptical density of the negative control group was 0.0202, optical density of the positive control group was 0.8607.The hemolysis rate of the experimental material was 0.559%, less than 5%. the experimental material could meet the accepted criteria for the hemolytic test.(5) Muscle implantation testNo experimental animal died during the experiment, and the wound healed well. No significant congestion,degeneration or necrosis occurred in the muscle around the material.1 week after implantation,a mild inflammatory reaction with a small amount of lymphocytic infiltration was observed around the experimental material in rabbit's muscle, and there was fibroblast proliferation and formation of new small blood vessels around the experimental material in rabbit's muscle. There was fibroblast proliferation and multinucleated giant celll around the control material in rabbit's muscle.The degree of inflammatory cell response wasâ…¡grade, the degree of fibrous capsule formation was IV grade in both two experimental materials of different pH values and control materials. 4 weeks after implantation, there was more lymphocyte and eosinophils in two experimental materials of different pH values, but no neutrophil and macrophage was seen. Fibroblast reduced. Compare with 1w the fibrous capsule become more thin in 4 w, fibrous capsular space formation was seen. There was more multinucleated giant celll around the control material in rabbit's muscle,What's more,little lymphocyte was seen. The degree of inflammatory cell response wasâ…¡grade, the degree of fibrous capsule formation wasâ…¢grade in both two experimental materials of different pH values and control materials. 12 weeks after implantation , fibrous tissue encasement was seen around the two experimental materials of different pH values. The thickness of the fibrous capsule wall did not continue increase ,and the fibrous capsule became thinner after 12w. Lymphocyte and eosinophils reduced significantly in the two experimental materials of different pH values, and there was biochemical Center formation with lymphocyte. Multinucleated giant celll reduced significantly around the control material in rabbit's muscle. The degree of inflammatory cell response wasâ…¡grade, the degree of fibrous capsule formation was I grade in both the two experimental materials of different pH values and the control materials. There was slight inflammatory reaction on tissue-material surface. The experimental material had no significant irritation for rabbit's muscle.ConclusionOur findings showed that the genipin biotype material of artificial esophagus is not only non-toxic and non-induced hemolysis,but also has good biocompatibility and security. With the tests of physical and chemical properties,such as the biomechanics,denaturation temperature and an ability to resistance against enzymatic degradation, the genipin biotype material of artificial esophagus would be an applicable and prospective biomaterial for clinical application.