In Vitro Experimental Study on Chitosan as Carrier for Sustained Release of Recombinant Human Bone Morphogenetic Protein-2

The objective of this study was to assess the feasibility of using a chitosan scaffold as a carrier for controlled release of recombinant human bone morphogenetic protein-2 (rhBMP-2) and to evaluate the release kinetics of rhBMP-2 through in vitro release tests. The chitosan scaffolds for the rhBMP-2 sustained release system were made by an emulsion freeze-drying method, and were compared with the chitosan scaffolds without rhBMP-2 as the control group. The samples were observed with scanning electron microscopy. The samples were immersed into phosphate buffer solution (PBS). The rhBMP-2 released from the samples was dynamically measured by using high performance liquid chromatography at various incubation time points. The curve of cumulative rhBMP-2 release kinetics was analysed. Morphological results indicated that the scaffold was loose, multiporous and sponge-like. An initial burst in the release of the incorporated rhBMP-2 (33.2%) was observed during the first day; and this continued at a rapid rate during the 2nd to 7th days. A slower release was apparent during the 8th to 14th days; followed by further sustained release from the 15th to 30th days, which reached a total of 81.3% release of the incorporated rhBMP-2 by the 30th day. It can be concluded that the porous chitosan scaffold shows characteristics as a sustained delivery system for rhBMP-2 and may be used as a sustained release carrier for rhBMP-2. This scaffold has the potential for supply of rhBMP-2 for the continuous induction of bone formation in bone tissue engineering and is suitable for future clinical application.