Chitosan-hyaluronic acid polyelectrolyte complex scaffold crosslinked with genipin for immobilization and controlled release of BMP-2

Polyelectrolyte complex (PEC) is formed when polymers with opposite charges are combined in solution. PECs are recently gaining attention as carriers for controlled release of drugs and proteins. Herein, bone morphogenetic protein-2 (BMP-2) was immobilized in a PEC of natural polymers, chitosan and hyaluronic acid. Charge-to-charge stoichiometry of the formed PEC was estimated based on turbidity of combined chitosan and hyaluronic acid solutions. Free amino groups in chitosan were crosslinked with different amounts of genipin. The degree of crosslinking, consequently its effects in vitro in terms of swelling, degradation and cytocompatibility were analyzed. Immobilization of three different amount of BMP-2 in chitosan-hyaluronic acid PEC scaffold resulted sustained release of the growth factor for more than 30 days. Immobilization efficacies varied from 61% to 76% depending on the amount of BMP-2. Finally effects in osteogenic differentiation of the PEC with BMP-2 to MC3T3-E1 cells were determined by reverse transcriptase PCR.