Carnosine Biofunctionalized Hydroxyapatite Induces Copper-Driven Osteogenesis and Angiogenesis, Strengthening Its Bone Regenerative Capacities

Hydroxyapatite (Hap) is a prominent biomaterial used as an effective implant material in bone tissue engineering, but its use presents some points of weakness in bone regeneration efficiency. Different biofunctionalization strategies have been utilized to increase the regenerative Hap capacities. Carnosine (Car) or β-alanyl-l-histidine dipeptide has received much attention due to its beneficial effects in osteoarticular diseases and bone tissue healing. Hap functionalized in noncovalent mode with Car at a nominal Ca:Car molar ratio (10:1, 2:1, and 1:1) was synthesized. The Hap-Car composites were characterized by using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopies. The structural and morphological feature comparisons indicate a similarity between Hap-Car10:1 and Hap. The Hap-Car composites and Hap bind copper present at submicromolar concentration in the complete culture medium, determined by inductively coupled plasma-optical emission spectroscopy. Hap-Car composites enhance the biological properties of Hap in in vitro assays and promote the mineralization process and the expression of alkaline phosphatase, osteocalcin, vascular endothelial growth factor, brain derived neurotrophic factor, and bone morphogenetic protein-2 in hFOB1.19 cells. The protective and regenerative activities of the metal ion are also related to the intracellular chaperone copper chaperones for superoxide dismutase.