Preparation of recombinant human bone morphogenetic protein-2 loaded dextran-based microspheres and their characteristics

Abstract

Aim: To prepare new pharmaceutical forms with sustained delivery properties of recombinant human bone morphogenetic protein-2 (rhBMP 2) for tissue engineering and guided tissue regeneration (GTR) use. Methods: rhBMP 2-loaded dextran-based hydrogel microspheres (rhBMP 2-MPs), which aimed to keep rhBMP 2 bioactivity and to achieve long-term sustained release of rhBMP 2, were prepared by double-phase emulsified condensation polymerization. The physical, chemical performances and biological characteristics of those microspheres were studied both in vitro and in vivo. Results: The microspheres' average diameter was 30.33±4.32 μm with 75.4% ranging from 20 μm to 40 μm and the drug loading and encapsulation efficiency were 7.82% and 82.25%, respectively. The rhBMP 2-releasing profiles in vitro showed that rhBMP 2 release could be maintained more than 10 d. The rhBMP 2-MPs, with good swelling and biodegradation behavior, could be kept for 6 months at below 4 °C without significant characteristic change or bioactivity loss. Cytology studies showed that rhBMP 2-MPs could promote the proliferation of periodontal ligament cells (PDLCs) approximately 10 d, while the bioactivity of concentrated rhBMP 2 solution could keep no more than 3 d. Scanning electron microscope showed that rhBMP 2-MPs could be enchased into the porous structure of calcium phosphate ceremic (CPC) and the eugonic growth of PDLCs in CPC/rhBMP 2-MPs scaffolds. Animal experiments indicated that using CPC/rhBMP 2-MPs scaffolds could gain more periodontal tissue regeneration than using rhBMP 2 compound firsthand with CPC (CPC/rhBMP 2). Conclusion: By encapsulating rhBMP 2 into dextran-based microspheres, a small quantity of rhBMP 2 could achieve equivalent effects to the concentrated rhBMP 2 solution and at the same time, could prolong rhBMP 2 retention both in vitro and in vivo. ©2005 CPS and SIMM.