Hyaluronic Acid Based Drug Delivery System for the Treatment of Type 2 Diabetes

Abstract

Despite clinical exploitation of exendin 4 for the treatment of type 2 diabetes, the significantly short half-life requiring twice a day injection has limited the wide applications. In this work, a novel protocol for the synthesis of long acting hyaluronate (HA) ？ exendin 4 conjugate was successfully developed using Michael addition chemistry between vinyl sulfone modified HA (HA-VS) and thiolated exendin 4. The exendin 4 content could be controlled in the range of 5~30 molecules per single HA chain with a bioconjugation efficiency higher than 90%. The conjugation of exendin 4 with HA resulted in about 20 times improved in vitro serum stability maintaining the hypoglycemic and gluco regulatory bioactivities of exendin 4. HA ？ exendin 4 conjugates showed excellent glucose-lowering capabilities in type 2 db/db mice demonstrating protracted hypoglycemic effect up to 3 days after a single subcutaneous injection. Furthermore, insulin immunohistochemical analysis of islets in db/db mice confirmed the improved insulinotropic activity of HA ？ exendin 4 conjugates. The novel HA ？ exendin 4 conjugates will be investigated further as a twice a week injection dosage form for clinical applications.