Antibacterial Fluorinated Diamond-Like Carbon Coating Promotes Osteogenesis—Comparison with Titanium Alloy

Fluorinated diamond-like carbon (F-DLC) coating is biologically safe, provides superior antibacterial properties, and shows promise in preventing postoperative peri-implant infections. However, potential negative effects of this coating on in vivo bone formation and resorption have not been studied. The authors investigated the effects of F-DLC coatings on bone union in beagle dogs. Seventy-two solid columns of titanium alloy were prepared with equally spaced slits. Half of these columns were coated with F-DLC (Group F), and the others were left uncoated as controls (Group C). Columns were implanted in the femurs of beagle dogs, and in vivo bone formation and resorption were assessed 4, 8, and 12 weeks after implantation. In comparison to Group C, Group F showed significantly greater bone volume and trabecular thickness at Week 8 (p < 0.05) and Week 12 (p < 0.005) and significantly lower bone resorption activity, measured by the ratio of osteoclasts to bone surface and of eroded surface to bone surface, at Week 12 (p < 0.05). The F-DLC coating encouraged bone formation in vivo more effectively than uncoated titanium alloy, suggesting that F-DLC will prove to be a useful coating material for antibacterial intraosseous implants.

Umbilical Cord Mesenchymal Stem Cell-Derived Nanovesicles Potentiate the Bone-Formation Efficacy of Bone Morphogenetic Protein 2

Recombinant human bone morphogenetic protein 2 (rhBMP-2) is one of the most potent osteogenic factors used to treat bone loss. However, at higher doses, rhBMP-2 does not necessarily increase bone formation but rather increases the incidence of adverse side effects. Here, we investigated whether umbilical cord mesenchymal stem cell (UCMSC)-derived nanovesicles (NVs) further increase the in vivo bone formation at high doses of rhBMP-2. In the presence of UCMSC-derived NVs, proliferation, migration, and tube formation of human umbilical vein endothelial cells were stimulated in vitro. Furthermore, migration and osteogenesis of human bone marrow-derived mesenchymal stem cells were stimulated. To examine the efficacy of UCMSC-derived NVs on in vivo bone formation, collagen sponges soaked with rhBMP-2 and UCMSC-derived NVs were used in athymic nude mice with calvarial defects. At a high rhBMP-2 dosage (500 ng/mL), UCMSC-derived NVs significantly promoted bone formation in calvarial defects; however, the UCMSC-derived NVs alone did not induce in vivo bone formation. Our results indicate that UCMSC-derived NVs can potentiate the bone formation efficacy of rhBMP-2 at a high dosage.