The bone regeneration efficiency of bone marrow mesenchymal stem cells (BMSCs) and dental pulp mesenchymal stem cells (DPSCs) combined with xenografts in the craniofacial region remains unclear. Accordingly, this study commenced by comparing the cell morphology, cell proliferation, trilineage differentiation, mineral synthesis, and osteogenic gene expression of BMSCs and DPSCs in vitro. Four experimental groups (empty control, Bio-Oss only, Bio-Oss+BMSCs, and Bio-Oss+DPSCs) were then designed and implanted in rabbit calvarial defects. The BMSCs and DPSCs showed a similar morphology, proliferative ability, surface marker profile, and trilineage-differentiation potential in vitro. However, the BMSCs exhibited a higher mineral deposition and expression levels of osteogenic marker genes, including alkaline phosphatase (ALP), runt related transcription factor 2 (RUNX2), and osteocalcin (OCN). In the in vivo studies, the bone volume density in both MSC groups was significantly greater than that in the empty control or Bio-Oss only group. Moreover, the new bone formation and Collagen I / osteoprotegerin protein expressions of the scaffold+MSC groups were higher than those of the Bio-Oss only group. Finally, the Bio-Oss+BMSC and Bio-Oss+DPSC groups had a similar bone mineral density, new bone formation, and osteogenesis-related protein expression. Overall, the DPSCs seeded on Bio-Oss matched the bone regeneration efficacy of BMSCs in vivo and hence appear to be a promising strategy for craniofacial defect repair in future clinical applications.

Background: Mesenchymal stem cell (MSC)-based tissue engineering plays a major role in regenerative medicine. However, the efficiency of MSC transplantation and survival of engrafted stem cells remain challenging. Melatonin can regulate MSC biology. However, its function in the osteogenic differentiation of dental pulp-derived MSCs (DPSCs) remains unclear. We investigated the effects and mechanisms of melatonin on the osteogenic differentiation and bone regeneration capacities of DPSCs. Methods: The biological effects and signaling mechanisms of melatonin with different concentrations on DPSCs were evaluated using a proliferation assay, the quantitative alkaline phosphatase (ALP) activity, Alizarin red staining, a real-time polymerase chain reaction, and a western blot in vitro cell culture model. The in vivo bone regeneration capacities were assessed among empty control, MBCP, MBCP + DPSCs, and MBCP + DPSCs + melatonin preconditioning in four-created calvarial bone defects by using micro-computed tomographic, histological, histomorphometric, and immunohistochemical analyses after 4 and 8 weeks of healing. Results: In vitro experiments revealed that melatonin (1, 10, and 100 μM) significantly and concentration-dependently promoted proliferation, surface marker expression (CD 146), ALP activity and extracellular calcium deposition, and osteogenic gene expression of DPSCs (p < 0.05). Melatonin activated the protein expression of ALP, OCN, and RUNX-2 and inhibited COX-2/NF-κB expression. Furthermore, the phosphorylation of mitogen-activated protein kinase (MAPK) p38/ERK signaling was significantly increased in DPSCs treated with 100 μM melatonin, and their inhibitors significantly decreased osteogenic differentiation. In vivo experiments demonstrated that bone defects implanted with MBCP bone-grafting materials and melatonin-preconditioned DPSCs exhibited significantly greater bone volume fraction, trabecular bone structural modeling, new bone formation, and osteogenesis-related protein expression than the other three groups at 4 and 8 weeks postoperatively (p < 0.05). Conclusions: These results suggest that melatonin promotes the proliferation and osteogenic differentiation of DPSCs by regulating COX-2/NF-κB and p38/ERK MAPK signaling pathways. Preconditioning DPSCs with melatonin before transplantation can efficiently enhance MSCs function and regenerative capacities.

This study reports a carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) composite film that incorporates Calendula officinalis (CO) extract for biomedical applications. The morphological, physical, mechanical, hydrophilic, biological, and antibacterial properties of CMC/PVA composite films with various CO concentrations (0.1%, 1%, 2.5%, 4%, and 5%) are fully investigated using different experiments. The surface morphology and structure of the composite films are significantly affected by higher CO concentrations. X-ray diffraction (XRD) and Fourier transform infrared spectrometry (FTIR) analyses confirm the structural interactions among CMC, PVA, and CO. After CO is incorporated, the tensile strength and elongation upon the breaking of the films decrease significantly. The addition of CO significantly reduces the ultimate tensile strength of the composite films from 42.8 to 13.2 MPa. Furthermore, by increasing the concentration of CO to 0.75%, the contact angle is decreased from 15.8° to 10.9°. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay reveals that the CMC/PVA/CO-2.5% and CMC/PVA/CO-4% composite films are non-cytotoxic to human skin fibroblast cells, which is favorable for cell proliferation. Remarkably, 2.5% and 4% CO incorporation significantly improve the inhibition ability of the CMC/PVA composite films against Staphylococcus aureus and Escherichia coli. In summary, CMC/PVA composite films containing 2.5% CO exhibit the functional properties for wound healing and biomedical engineering applications.

The purpose of this study was to investigate whether the use of HLA as an aqueous binder of hydroxyapatite/beta-tricalcium phosphate (HA-βTCP) particles can reduce the amount of bone graft needed and increase ease of handling in clinical situations. In this study, HA/βTCP was loaded in commercially available crosslinking HLA to form a novel HLA/HA-βTCP composite. Six New Zealand White rabbits (3.0–3.6 kg) were used as test subjects. Four 6 mm defects were prepared in the parietal bone. The defects were filled with the HLA/HA-βTCP composite as well as HA-βTCP particle alone. New bone formation was analyzed by micro-CT and histomorphometry. Our results indicated that even when the HA-βTCP particle numbers were reduced, the regenerative effect on bone remained when the HLA existed. The bone volume density (BV/TV ratio) of HLA/HA-βTCP samples was 1.7 times larger than that of the control sample at week 2. The new bone increasing ratio (NBIR) of HLA/HA-βTCP samples was 1.78 times higher than the control group at week 2. In conclusion, HA-βTCP powder with HLA contributed to bone healing in rabbit calvarial bone defects. The addition of HLA to bone grafts not only promoted osteoconduction but also improved handling characteristics in clinical situations.

This study evaluated the new bone formation potential of micro–macro biphasic calcium phosphate (MBCP) and Bio-Oss grafting materials with and without dental pulp-derived mesenchymal stem cells (DPSCs) and bone marrow-derived mesenchymal stem cells (BMSCs) in a rabbit calvarial bone defect model. The surface structure of the grafting materials was evaluated using a scanning electron microscope (SEM). The multipotent differentiation characteristics of the DPSCs and BMSCs were assessed. Four circular bone defects were created in the calvarium of 24 rabbits and randomly allocated to eight experimental groups: empty control, MBCP, MBCP+DPSCs, MBCP+BMSCs, Bio-Oss+DPSCs, Bio-Oss+BMSCs, and autogenous bone. A three-dimensional analysis of the new bone formation was performed using micro-computed tomography (micro-CT) and a histological study after 2, 4, and 8 weeks of healing. Homogenously porous structures were observed in both grafting materials. The BMSCs revealed higher osteogenic differentiation capacities, whereas the DPSCs exhibited higher colony-forming units. The micro-CT and histological analysis findings for the new bone formation were consistent. In general, the empty control showed the lowest bone regeneration capacity throughout the experimental period. By contrast, the percentage of new bone formation was the highest in the autogenous bone group after 2 (39.4% ± 4.7%) and 4 weeks (49.7% ± 1.5%) of healing (p < 0.05). MBCP and Bio-Oss could provide osteoconductive support and prevent the collapse of the defect space for new bone formation. In addition, more osteoblastic cells lining the surface of the newly formed bone and bone grafting materials were observed after incorporating the DPSCs and BMSCs. After 8 weeks of healing, the autogenous bone group (54.9% ± 6.1%) showed a higher percentage of new bone formation than the empty control (35.3% ± 0.5%), MBCP (38.3% ± 6.0%), MBCP+DPSC (39.8% ± 5.7%), Bio-Oss (41.3% ± 3.5%), and Bio-Oss+DPSC (42.1% ± 2.7%) groups. Nevertheless, the percentage of new bone formation did not significantly differ between the MBCP+BMSC (47.2% ± 8.3%) and Bio-Oss+BMSC (51.2% ± 9.9%) groups and the autogenous bone group. Our study results demonstrated that autogenous bone is the gold standard. Both the DPSCs and BMSCs enhanced the osteoconductive capacities of MBCP and Bio-Oss. In addition, the efficiency of the BMSCs combined with MBCP and Bio-Oss was comparable to that of the autogenous bone after 8 weeks of healing. These findings provide effective strategies for the improvement of biomaterials and MSC-based bone tissue regeneration.