Effects of rhBMP-2 on Bone Formation Capacity of Rat Dental Stem/Progenitor Cells from Dental Follicle and Alveolar Bone Marrow.

Dental stem/progenitor cells are a promising cell sources for alveolar bone (AB) regeneration because of their same embryonic origin and superior osteogenic potential. However, their molecular processes during osteogenic differentiation remain unclear. The objective of this study was to identify the responsiveness of dental follicle cells (DFCs) and AB marrow-derived mesenchymal stem cells (ABM-MSCs) to recombinant human bone morphogenetic protein-2 (rhBMP-2). These cells expressed vimentin and MSC markers and did not express cytokeratin and hematopoietic stem cell markers and showed multilineage differentiation potential under specific culture conditions. DFCs exhibited higher proliferation and colony-forming unit-fibroblast efficiency than ABM-MSCs; rhBMP-2 induced DFCs to differentiate toward a cementoblast/osteoblast phenotype and ABM-MSCs to differentiate only toward a osteoblast phenotype; and rhBMP-2-induced DFCs exhibited higher osteogenic differentiation potential than ABM-MSCs. These cells adhered, grew, and produced extracellular matrix on nanohydroxyapatite/collagen/poly(l-lactide) (nHAC/PLA). During a 14-day culture on nHAC/PLA, the extracellular alkaline phosphatase (ALP) activity of DFCs decreased gradually and that of ABM-MSCs increased gradually; rhBMP-2 enhanced their extracellular ALP activity, intracellular osteocalcin (OCN), and osteopontin (OPN) protein expression; and DFCs exhibited higher extracellular ALP activity and intracellular OCN protein expression than ABM-MSCs. When implanted subcutaneously in severe combined immunodeficient mice for 3 months, DFCs+nHAC/PLA+rhBMP-2 obtained higher percentage of bone formation area, OCN, and cementum attachment protein expression and lower OPN expression than ABM-MSCs+nHAC/PLA+rhBMP-2. These results showed that DFCs possessed superior proliferation and osteogenic differentiation potential in vitro, and formed higher quantity and quality bones in vivo. It suggested that DFCs might exhibit a more sensitive responsiveness to rhBMP-2, so that DFCs enter a relatively mature stage of osteogenic differentiation earlier than ABM-MSCs after rhBMP-2 induction. The findings imply that these dental stem/progenitor cells are alternative sources for AB engineering in regenerative medicine, and developing dental tissue may provide better source for stem/progenitor cells.

Combined Use of Recombinant Human BMP-7 and Osteogenic Media May Have No Ideal Synergistic Effect on Leporine Bone Regeneration of Human Umbilical Cord Mesenchymal Stem Cells Seeded on Nanohydroxyapatite/Collagen/Poly (l-Lactide).

Human umbilical cord mesenchymal stem cells (hUC-MSCs) are a promising alternative source of mesenchymal stem cells (MSCs) that are enormously attractive for clinical use. This study was designed to investigate the effect of recombinant human bone morphogenetic protein-7 (rhBMP-7) and/or osteogenic media (OMD) on bone regeneration of hUC-MSCs seeded on nanohydroxyapatite/collagen/poly(l-lactide) (nHAC/PLA) in a rabbit model. The characteristics of stem cells were analyzed by plastic adherence, cell phenotype, and multilineage differentiation potential. Cell proliferation was examined using cell counting kit-8 assay. Osteogenic differentiation was evaluated by quantitative Ca2+ concentration, PO43- concentration, alkaline phosphatase (ALP) activity, osteocalcin (OCN) secretion, and mineralized matrix formation. Bone regeneration was investigated in jaw bone defect repair in rabbit by microcomputed tomography, fluorescent labeling, and hematoxylin and eosin staining. Except for initial stress response, OMD and OMD + rhBMP-7 inhibited the proliferation of hUC-MSCs seeded on nHAC/PLA; rhBMP-7 inhibited cell proliferation in the nonlogarithmic phase and attenuated the inhibitory effect of OMD on cell proliferation. The inhibitory effects of OMD, rhBMP-7, and OMD + rhBMP-7 on cell proliferation were ranked as OMD > OMD + rhBMP-7 > rhBMP-7. OMD, rhBMP-7, and OMD + rhBMP-7 promoted Ca2+ concentration, PO43- concentration, ALP activity, OCN secretion, and mineralized matrix formation of hUC-MSCs seeded on nHAC/PLA. The promoting effects of OMD, rhBMP-7, and OMD+rhBMP-7 on Ca2+ concentration, PO43- concentration, ALP activity, OCN secretion, and mineralized matrix formation were ranked as rhBMP-7 > OMD > OMD + rhBMP-7, OMD > OMD + rhBMP-7 > rhBMP-7, OMD > rhBMP-7 > OMD + rhBMP-7, rhBMP-7 > OMD + rhBMP-7 > OMD, and OMD > rhBMP-7 > OMD + rhBMP-7, respectively. In rabbit jaw bone defect repair, OMD, rhBMP-7, and OMD + rhBMP-7 enhanced bone regeneration of hUC-MSCs seeded on nHAC/PLA, but the largest bone mineral apposition rate and bone formation were presented in cultures with rhBMP-7. These findings suggested that the combined use of rhBMP-7 and OMD may have no ideal synergistic effect on bone regeneration of hUC-MSCs seeded on nHAC/PLA in rabbit jaw bone defect.

Tantalum-incorporated hydroxyapatite coating on titanium implants: its mechanical and in vitro osteogenic properties.

OBJECTIVE: The fabrication of bioactive coatings on metallic implants to enhance osseointegration has become a topic of general interest in orthopedics and dentistry. Hydroxyapatite (HA) coating has been shown to induce bone formation and promote bone-implant integration. Unfortunately, poor mechanical performance has hindered this from becoming a favorable coating material. The majority of present studies have focused in incorporating different elements into HA coatings to improve mechanical properties. In recent years, tantalum (Ta) has received increasing attention due to its excellent biocompatibility and corrosion resistance. The aim of on the present study was to investigate the fabrication and biological performance of Ta-incorporated HA coatings. METHODS: Ta-incorporated HA coatings were fabricated using the plasma spray technique on a titanium substrate, and the surface characteristics and mechanical properties were examined. In addition, the effects of Ta-incorporated HA coatings on the biological behavior of mesenchymal stem cells (BMSCs) were investigated. RESULTS: Ta-incorporated HA coatings with microporous structure had higher roughness and wettability. In addition, the bonding strength of Ta/HA coatings with the substrate was substantially superior to HA coatings. Furthermore, Ta-incorporated HA coatings not only facilitated initial cell adhesion and faster proliferation, but also promoted the osteogenic differentiation of BMSCs. CONCLUSION: These results indicate that the incorporation of Ta could improve mechanical performance and increase the osteogenic activity of HA coatings. The Ta-incorporated HA coating fabricated by plasma spraying is expected to be a promising bio-coating material for metallic implants.

Treatment of Saos-2 osteosarcoma cells with diallyl trisulfide is associated with an increase in calreticulin expression.

Diallyl trisulfide (DATS) is a natural organic sulfur compound that may be isolated from garlic and has strong anticancer activity. DATS has been demonstrated to upregulate the expression of calreticulin (CRT) in various types of human cancers, which is associated with the prognosis of cancer and its response to therapy. However, whether DATS has the same effect on human osteosarcoma cells is not known. Therefore, in the present study, Saos-2 human osteosarcoma cells were cultured with different concentrations of DATS (0, 25, 50 and 100 µmol/l) for 24 h, or with 50 µmol/l DATS for different time periods (0, 12, 24 and 36 h). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting and immunofluorescent staining were used to detect CRT mRNA and protein in the Saos-2 cells. Exposure to DATS changed the morphology and inhibited the growth of the Saos-2 cells, and its effects appeared to be concentration- and exposure time-dependent. The optimum concentration and exposure time of DATS were 50 µmol/l and 24 h, respectively. The levels of CRT mRNA and protein in the Saos-2 cells were significantly upregulated following exposure to DATS. The upregulation of CRT expression by DATS may be a mechanism underlying the ability of DATS to inhibit the growth of human osteosarcoma Saos-2 cells.

Pathological changes in the maxillary sinus mucosae of patients with recurrent odontogenic maxillary sinusitis.

OBJECTIVE: To study the structural and functional changes of maxillary sinus mucosae of patients with odontogenic maxillary sinusitis, and to improve the therapeutic effects. METHODS: Ten mucosal biopsy samples collected during the surgeries of patients with recurrent odontogenic maxillary sinusitis were selected as Group A. Another ten mucosal biopsy sample were collected during retention cyst-removing surgeries and referred to as Group B. The mucosae were put in 10% neutral formalin solution for 1 day and prepared into 5-7 µm thick paraffin sections which were subjected to hematoxylin-eosin staining. The reactions included: (1) Reaction with T-lymphocyte (CD-3); (2) reaction with T-helper cell (CD-4); (3) reaction with T-suppressing cell (CD-8); (4) reaction with B-lymphocyte (CD-20). Polymeric horseradish peroxidase visualized detection system was used. The contents of CD3, CD4, CD8 and CD20 in the stained cells of the maxillary sinus mucosal layer were calculated. The responses of receptors to muramidase were classified as mild, moderate and strong. All data were analyzed by Statistica 6.0 package for Windows based on Mann-Whitney non-parametric standards. RESULTS: The epithelial tissues in the maxillary sinus mucosa of Group B were covered with multiple rows of cilia. The epithelial cells of Group A suffered from degeneration, shrinkage and desquamation. Different cells were distributed in the autologous mucosal layer, of which macrophages, fibroblasts, lymphocytes and neutrophils were dominant. The average contents of macrophages and lymphocytes accounted for 42.8%. Lymphocyte subset analysis showed that the number of CD3 cells exceeded that of CD20 ones and there were more CD4+ cells than CD8+ ones. T-helper and T-suppressing cells were distributed remarkably differently. CD8+ cells were mainly located inside and under the epithelium, while CD4+ cells were scattered in the autologous matrix. CONCLUSION: For patients with recurrent odontogenic maxillary sinusitis, the maxillary sinus mucosa mainly suffered from regeneration of epithelial tissues and inhibition of cell proliferation, which were accompanied by damages to the protective and shielding effects of the mucociliary transport system. Macrophages and lymphocytes dominated in the infiltration of autologous mucosal layer, and the coexisting copious fibroblasts indicated the onset of inflammation.