In vivo bone formation by human alveolar-bone-derived mesenchymal stem cells obtained during implant osteotomy using biphasic calcium phosphate ceramics or bovine bone as carriers

Abstract

Objectives: The aim of this study was to evaluate HA(hydroxyapatite) coated with different ratios of TCP as a carrier for hABMSCs obtained during implant osteotomy in comparison to slowly-resorbing biomaterial, bovine bone, as a negative control, using in vitro and in vivo experiments. Materials and methods: Human ABMSCs (hABMSCs) harvested during implant osteotomy were transplanted using HA/TCP or , bovine bone as carriers in a murine ectopic transplantation model (n=12). Pore size and cell affinity were evaluated in vitro. The area of newly formed bone was analyzed histometrically, the number of osteocytes was counted, and immunohistochemical staining was conducted against several markers of osteogenesis, including alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX-2), osteocalcin (OCN), and osteopontin (OPN). Osteoclast formation was evaluated by tartrate-resistant acid phosphatase staining. Results: MBCP mean pore size diameter was 369.77μm. MBCP plus was 234.13μm and bovine bone was 238.76μm. The carrier materials had similar pore sizes. The cell affinity assay resulted in a high proportion of cell adhesion (>90%) in all experimental groups. New bone and osteocyte formation were greater in the hABMSC-loaded HA/TCP groups than in the hABMSC-loaded bovine bone group. Positive immunostaining for ALP, RUNX-2, OCN, and OPN was observed with HA/TCP, but only limited expression of osteogenic markers with Bio-Oss. Conversely, there was a minimal osteoclast presence with Bio-Oss, but a significant presence of osteoclasts with both HA/TCP carriers. Conclusion: Use of HA/TCP ceramics as a cell carrier for hABMSCs resulted in a significantly greater degree of bone formation in the ectopic transplantation model with than bovine bone. Both types of scaffolds, HA/TCP and bovine bone, showed high stem cell-carrying potential, but the in vivo healing patterns of their complexes with hABMSC could be affected by the microenvironment on the surfaces of the scaffolds.