Role of reactive oxygen species (ROS) in the regulation of adipogenic differentiation of human maxillary/mandibular bone marrow-derived mesenchymal stem cells.

BACKGROUND: Maxillary/mandibular bone marrow-derived mesenchymal stem cells (MBMSCs) exhibit a unique property of lower adipogenic potential than other bone marrow-derived MSCs. However, the molecular mechanisms regulating the adipogenesis of MBMSCs remain unclear. This study aimed to explore the roles of mitochondrial function and reactive oxygen species (ROS) in regulating the adipogenesis of MBMSCs. METHODS AND RESULTS: MBMSCs exhibited significantly lower lipid droplet formation than iliac BMSCs (IBMSCs). Moreover, the expression levels of CCAAT/enhancer-binding protein ß (C/EBPß), C/EBPδ, and early B cell factor 1 (Ebf-1), which are early adipogenic transcription factors, and those of peroxisome proliferator-activated receptor-γ (PPARγ) and C/EBPα, which are late adipogenic transcription factors, were downregulated in MBMSCs compared to those in IBMSCs. Adipogenic induction increased the mitochondrial membrane potential and mitochondrial biogenesis in MBMSCs and IBMSCs, with no significant difference between the two cell types; however, intracellular ROS production was significantly enhanced only in IBMSCs. Furthermore, NAD(P)H oxidase 4 (NOX4) expression was significantly lower in MBMSCs than in IBMSCs. Increased ROS production in MBMSCs by NOX4 overexpression or treatment with menadione promoted the expression of early adipogenic transcription factors but did not induce that of late adipogenic transcription factors or lipid droplet accumulation. CONCLUSIONS: These results suggest that ROS may be partially involved in the process of MBMSC adipogenic differentiation from undifferentiated cells to immature adipocytes. This study provides important insights into the tissue-specific properties of MBMSCs.

Elucidation of adipogenic differentiation regulatory mechanism in human maxillary/mandibular bone marrow-derived stem cells.

OBJECTIVE: This study aims to investigate the underlying molecular mechanisms that regulate the adipogenic differentiation of maxillary/mandibular bone marrow-derived mesenchymal stem cells (MBMSCs). DESIGN: MBMSCs and iliac bone marrow-derived MSCs (IBMSCs) were compared for osteogenic, chondrogenic, and adipogenic differentiation. Cell surface antigen expression was examined using flow cytometry, and stem cell marker expression was assessed using real-time polymerase chain reaction (PCR). Various adipogenic regulatory factors' expression was evaluated using real-time PCR and western blotting. RESULTS: No significant differences in cell surface antigen profiles or stem cell marker expression in MBMSCs and IBMSCs were observed. MBMSCs and IBMSCs displayed similar osteogenic and chondrogenic potentials, whereas MBMSCs showed significantly lower adipogenic potentials than those shown by IBMSCs. Expression of CCAAT/enhancer binding protein ß (C/EBPß), C/EBPδ, early B-cell factor 1 (Ebf-1), and Krüppel-like factor 5 (KLF5), which are early adipogenic differentiation factors, was suppressed in MBMSCs compared to that in IBMSCs. Peroxisome proliferator-activated receptor-γ (PPARγ) and C/EBPα, which play important roles in the terminal differentiation of adipocytes, was lower in MBMSCs than that in IBMSCs. Furthermore, the level of zinc finger protein 423 (Zfp423), which is involved in the commitment of undifferentiated MSCs to the adipocyte lineage, was significantly lower in MBMSCs than that in IBMSCs. CONCLUSIONS: MBMSCs are negatively regulated in the commitment of undifferentiated MSCs to the adipocyte lineage (preadipocytes) as well as in the terminal differentiation of preadipocytes into mature adipocytes. These results may elucidate the site-specific characteristics of MBMSCs.

Efficacy of bone grafting materials in preserving the alveolar ridge in a canine model.

Preservation of the alveolar ridge after tooth extraction is an essential component for ideal implant positioning. Furthermore, preservation of bone around the implant after implant placement is an essential component for implant treatment. We aimed to evaluate the efficacy of bone grafting materials in preserving the alveolar ridge after implant placement. Implants were placed in regenerated bone without grafting material or with beta-tricalcium phosphate, bovine bone substitute, or carbonate apatite transplantation. In all groups, the bone healed and the implants were successfully placed within the bone. No significant differences in insertion torque and implant stability quotient values were found. The amount of bone around the implant 5 weeks after implant placement was significantly reduced in the bovine bone substitute group; however, implants placed in regenerated bone achieved sufficient initial fixation and osseointegration.

Efficacy of chitinase-3-like protein 1 as an in vivo bone formation predictable marker of maxillary/mandibular bone marrow stromal cells.

INTRODUCTION: Maxillary/mandibular bone marrow stromal cells (MBMSCs) are a useful cell source for bone regeneration in the oral and maxillofacial region. To further ensure the clinical application of MBMSCs in bone regenerative therapy, it is important to determine the bone formation capacity of MBMSCs before transplantation. The aim of this study is to identify the molecular marker that determines the in vivo bone formation capacity of MBMSCs. METHODS: The cell growth, cell surface antigens, in vitro and in vivo bone formation capacity of MBMSCs were examined. The amount of chitinase-3-like protein 1 (CHI3L1) secreted into the conditioned medium was quantified. The effects of CHI3L1 on the cell growth and osteogenic differentiation potential of MBMSCs and on the cell growth and migration of vascular endothelial cells and fibroblasts were examined. RESULTS: The cell growth, and in vitro and in vivo bone formation capacity of the cells treated with different conditions were observed. MBMSCs that secreted a large amount of CHI3L1 into the conditioned medium tended to have low in vivo bone formation capacity, whereas MBMSCs that secreted a small amount of CHI3L1 had greater in vivo bone formation capacity. CHI3L1 promoted the migration of vascular endothelial cells, and the cell growth and migration of fibroblasts. CONCLUSION: Our study indicates that the in vitro osteogenic differentiation capacity of MBMSCs and the in vivo bone formation capacities of MBMSCs were not necessarily correlated. The transplantation of high CHI3L1 secretory MBMSCs may suppress bone formation by inducing fibrosis at the site. These results suggest that the CHI3L1 secretion levels from MBMSCs may be used as a predictable marker of bone formation capacity in vivo.