Bioactive biomaterials: Potential for application in bone regenerative medicine

Abstract

Critical-sized bone defects can be repaired by using bone tissue engineering (BTE) procedures which rely on the combined use of cells, scaffolds and biologically active molecules. Based on their bioreactivity, biomaterials can be bioinert or bioactive. Bioinert biomaterials cause fibrous capsule formation upon implantation which favors the appearance of micromovements in the implant-tissue interface so the prosthesis fails. Bioactive biomaterials elicit a specific biological response thus avoiding fibrous layer formation and are able to interact with the biological environment. Bioactive biomaterials can be natural (bovine bone mineral matrix, hyaluronic acid, collagen, gelatin, fibrin, agarose, alginate, chitosan, silk) or synthetic (ceramics, metals, polymers, hydrogels and composites). Ceramics (bioactive glasses, glass-ceramics, calcium phosphates ceramics and cements) are most frequently used among these biomaterials due to similarity with the bone mineral phase. Another advantage from the use of ceramics is the presence of biologically active hydroxycarbonate apatite layer formed on the surface of these biomaterials, which represents the bonding interface with the tissues. Bioactive biomaterials have wide application as medical devices and in drug delivery systems. Since cells cannot survive without an adequate blood supply, future directions in bioactive biomaterials applications lies in the construction of bioactive and biodegradable 3D scaffolds that have osteogenic and angiogenic features. A possible alternative to improve osteogenic and angiogenic potential of the applied biomaterials is to incorporate bioactive biomolecules (e.g. growth factors) into the scaffold. One of the future perspectives in this area is the construction of smart biomaterials that respond to their environment in predetermined way regarding the protein release, thus allowing release initiated by microenvironmental conditions.