BACKGROUND:Thrombogenesis is the most common cause of failure in the implantation of tissue engineered small-caliber vesselgrafts.And immobilizing heparin onto the surfaces of vascular scaffoidgrafts is often applied to improve their blood compatibility and patency.OBJECTIVES:To investigate the small intestinal submucosa(SIS)surface after heparinizadon with hypothermic plasma technique,to ireprove the blood compatibility of SIS and to explore the possibility for the construction of small-caliber vascular grafts with modified SIS seaffolds in vivo.DESIGN:Single exponent study.SETTING:Department of Orthopaedics,the Six People's Hospital Affiliated to Shanghai Jiao Tong University;ShanghaiInstitute for Microsurgery of Extremities.MATERIALS:This study was performed in the Shahghai Institute for Microsurgery of Extremities from January to October 2006.The jejuna were taken from farm pigs.METHODS:The SIS surface of pigswere processed by argon plasma(20mL/min)technique at different time periods(0,2,4,6,8,10,12,and 14 s),which were then immediately immerged in heparin sodium solution for 24 hours.Dogs were divided into two groups.The SIS films were sewn into a 3-mm diameter tube and implanted into the defect of a canine femoral by anastomosis as a vascular graft.The observation lasted for 6 weeks.MAIN OUTCOME MEASURES:The surface morphologies of SIS were observed under scanning electron microscope(SEM).The antithrombogenicity of SIS films was tested by water contact angle,blood coagulation time and platelet adherence observation by SEM.The efficiency of the SIS graft was evaluated by the patency in the circulation of blood with colour doppler detection and histology.RESULTS:Heparinized SIS showed great different surface morphology comparing with untreated SIS.Untreated SIS surface looked like wrinkled film,but on heparinized SIS surface spread with uniform micro-dots,which looked like a layer of heparin adhesion.Water contact angle decreased with the increase of plasma irradiation time.Prothrombin time (PT),partial thromboplastin time(APTT),and thrombin time(TT)of the SIS films modified with heparin were prolonged.Platelets adhered much more on untreated SIS film than on heparinized SIS film.Vascular graft from SIS embolized in the lumina completely at day 3 after anastomosis.Heparinized SIS graft kept patency for six weeks,and the inner surface of graft was covered with full endothelial cells.CONCLUSION:Hydrophilicity and antithrombogenicity of heparinized SIS are increased obviously after hypothermia plasma treatment.