| Popis: |
Bone marrow stromal cells (MSCs) are regulated by the chemical and physical features of a biomaterial surface. When grown on titanium (Ti) and Ti alloy surfaces like titanium-aluminum-vanadium (Ti6Al4V) with specific topographies that mimic the micro, meso, and nanoscale features of an osteoclast resorption pit, they undergo a rapid change in cell shape to assume a columnar morphology typical of a secretory osteoblast. These cells exhibit markers associated with an osteoblast phenotype, including osteocalcin and osteopontin and they secrete factors associated with osteogenesis, including bone morphogenetic protein 2 (BMP2), vascular endothelial growth factor (VEGF), and neurotrophic semaphorins. The pathway involves a shift in integrin expression from α5β1 to α2β1 and signaling via Wnt5a rather than Wnt3a. Conditioned media from these cultures can stimulate vasculogenesis by human endothelial cells as well as osteoblastic differentiation of MSCs not grown on the biomimetic substrate, suggesting that the surface could promote osteogenesis in vivo through similar mechanisms. In vivo studies using a variety of animal models confirm that implants with biomimetic surfaces result in improved osseointegration compared to Ti implants with smooth surfaces, as do meta-analyses comparing clinical performance of implant surface topographies. |
