Heparin anchored to the surface of islet by avidin-biotin technique

BACKGROUND: Islet capillaries are damaged in the process of islet isolation, thereby affecting the nutrient supply of islets after transplantation. Heparin has a very important significance for the regeneration of blood vessels; meanwhile, heparin is commonly used in the clinical islet transplantation to inhibit thrombosis. But systemic heparin can increase the risk of bleeding. The avidin has two strong binding sites of biotin and heparin respectively. OBJECTIVE: To improve islet revascularization and decrease risk of bleeding resulting from heparin systemic application through anchoring the heparin on the surface of islet with avidin-biotin technique based on the characteristics of avidin. METHODS: Adult human pancreas were isolated and purified with Ricordi automation method, then the islets were incubated and cultured with 0, 0.5, 1, 1.5, 2 g/L biotin (including biotin-N-hydroxysuccinimide ester, N-hydroxy-succinimido-6-biotinyl amido hexanoate, biocytin hydrazine, biotin hydrazide and TFP-biotin), 1 g/L avidin, and 0.5, 1.0, 1.5 and 2.0 g/L heparin, the change of heparin was observed. RESULTS AND CONCLUSION: TFP-biotin had the best effect to mediate the islet surface heparinization, and there was no significant difference in the activity of islet before and after heparinization (P > 0.05); the heparinized and unheparinized heparin islets had the similar insulin release reaction (P > 0.05). Biotin-avidin technique is a safe and effective islet surface heparinization treatment method.