Culture and Identification of Human Bone Marrow Mesenchymal Stem Cells From Alveolar Ridge Dental Implant Site:

Bone regeneration capacities of alveolar bone mesenchymal stem cells sheet in rabbit calvarial bone defect

Mesenchymal stem cells sheets have been verified as a promising non-scaffold strategy for bone regeneration. Alveolar bone marrow mesenchymal stem cells, derived from neural crest, have the character of easily obtained and strong multi-differential potential. However, the bone regenerative features of alveolar bone marrow mesenchymal stem cells sheets in the craniofacial region remain unclear. The purpose of the present study was to compare the osteogenic differentiation and bone defect repairment characteristics of bone marrow mesenchymal stem cells sheets derived from alveolar bone (alveolar bone marrow mesenchymal stem cells) and iliac bone (Lon-bone marrow mesenchymal stem cells) in vitro and in vivo. Histology character, osteogenic differentiation, and osteogenic gene expression of human alveolar bone marrow mesenchymal stem cells and Lon-bone marrow mesenchymal stem cells were compared in vitro. The cell sheets were implanted in rabbit calvarial defects to evaluate tissue regeneration characteristics. Integrated bioinformatics analysis was used to reveal the specific gene and pathways expression profile of alveolar bone marrow mesenchymal stem cells. Our results showed that alveolar bone marrow mesenchymal stem cells had higher osteogenic differentiation than Lon-bone marrow mesenchymal stem cells. Although no obvious differences were found in the histological structure, fibronectin and integrin β1 expression between them, alveolar-bone marrow mesenchymal stem cells sheet exhibited higher mineral deposition and expression levels of osteogenic marker genes. After being transplanted in the rabbit calvarial defects area, the results showed that greater bone volume and trabecular thickness regeneration were found in bone marrow mesenchymal stem cells sheet group compared to Lon-bone marrow mesenchymal stem cells group at both 4 weeks and 8 weeks. Finally, datasets of bone marrow mesenchymal stem cells versus Lon-bone marrow mesenchymal stem cells, and periodontal ligament mesenchymal stem cells (another neural crest derived mesenchymal stem cells) versus umbilical cord mesenchymal stem cells were analyzed. Total 71 differential genes were identified by overlap between the 2 datasets. Homeobox genes, such as LHX8, MKX, PAX9, MSX, and HOX, were identified as the most significantly changed and would be potential specific genes in neural crest mesenchymal stem cells. In conclusion, the Al-bone marrow mesenchymal stem cells sheet-based tissue regeneration appears to be a promising strategy for craniofacial defect repair in future clinical applications.

Titanium Surface Properties Influence the Biological Activity and FasL Expression of Craniofacial Stromal Cells

Mesenchymal stromal cells (MSCs) can be easily isolated form craniofacial bones during routine dentistry procedures. Due to their embryological origin from neural crest, they represent a suitable cell population to study cell-biomaterial interaction in the craniofacial field, including osteoinductive/osteointegrative processes. The biological and immunomodulatory properties of MSCs may be influenced by chemistry and topography of implant surfaces. We investigated if and how three different titanium surfaces, machined (MCH), sandblasted with resorbable blasting medium (RBM), and Ca⁺⁺-nanostructured (NCA), may affect biological activity, osseointegration, and immunomodulatory properties of craniofacial MSCs. Cell proliferation, morphology, osteogenic markers, and FasL were evaluated on MSCs isolated from the mandibular bone after seeding on these three different surfaces. No statistically significant differences in cell proliferation were observed whereas different morphologies and growth patterns were detected for each type of surface. No difference in the expression of osteogenic markers was revealed. Interestingly, FasL expression, involved in the immunomodulatory activity of stem cells, was influenced by surface properties. Particularly, immunofluorescence analysis indicated that FasL expression increased on MCH surface compared to the others confirming the suggested role of FasL in promoting osteogenic differentiation. Titanium surface treatments and topography might reflect different biological behaviours of craniofacial MSCs and influence their osseointegration/immunomodulation properties.