In vivo release of bovine serum albumin from an injectable small intestinal submucosa gel

We aimed to develop a delivery system capable of maintaining a sustained release of protein drugs at specific sites using potentially biocompatible biomaterials. Here, we used bovine serum albumin (BSA) as a test protein to explore the potential utility of an injectable small intestine submucosa (SIS) as a depot for protein drugs. The prepared SIS powder was dispersed in PBS. The SIS suspension easily entrapped BSA in pharmaceutical formulations at room temperature. When this was suspension subcutaneously injected into rats, it gelled, forming an interconnecting three-dimensional network SIS structure to allow BSA to penetrate through it. The amount of BSA-FITC released from the SIS gel was determined in rat plasma and monitored by real-time in vivo molecular imaging. The data indicated the sustained release of BSA-FITC for 30 days in vivo. In addition, SIS gel provoked little inflammatory response. Collectively, our results show that the SIS gel described here could serve as a minimally invasive therapeutics depot with numerous benefits compared to other injectable biomaterials. (c) 2011 Elsevier B.V. All rights reserved.