Enhanced bone formation by controlled growth factor delivery from chitosan-based biomaterials

For the purpose of obtaining high bone forming efficacy, development of chitosan was attempted as a tool useful as a scaffolding device. Porous chitosan matrices, chitosan-poly(L-lactide) (PLLA) composite matrices and chitosan coated on PLLA matrices were dealt with in this research. Porous chitosan matrix was fabricated by freeze-drying and cross-linking aqueous chitosan solution. Porous chitosan matrix combined with ceramics and constituents of extracellular matrices were prepared and examined for their bone regenerative potential. Composite porous matrix of chitosan-PLLA was prepared by mixing polylactide with chitosan and freeze-drying. All chitosan based devices demonstrated improved bone forming capacity by increasing mechanical stability and biocompatibility. Release of platelet-derived growth factor-BB (PDGF-BB) from these matrices exerted significant osteoinductive effect in addition to the high osteoconducting capacity of the porous chitosan matrices. The hydrophobic surface of PLLA matrices was modified by chitosan to enhance cell affinity and wettability. The chitosan coated PLLA matrix induced increased osteoblast attachment as compared with intact PLLA surface. Overall results in this study demonstrated the usefulness of chitosan as drug releasing scaffolds and as modification tools for currently used biomaterials to enhance tissue regeneration efficacy. These results may expand the feasibility of combinative strategy of controlled local drug delivery concept and tissue engineered bone formation in reconstructive therapy in the field of periodontics, orthopedics and plastic surgery.