Three-dimensional spheroids of mesenchymal stem/stromal cells promote osteogenesis by activating stemness and Wnt/β-catenin.

Mesenchymal stem/stromal cells (MSCs) are multipotent and self-renewal cells that are widely used in regenerative medicine. The culture of three-dimensional (3D) spheroid MSCs more accurately mimics the biological microenvironment. However, it is unclear which key molecules are responsible for the cell fate control of MSCs during 3D spheroid formation and their impact on the functional characteristics of these stem cells. Furthermore, it remains unclear what effects 3D spheroid MSC transplantation has on new bone formation compared with that of 2D monolayer MSCs. We assessed whether the osteogenerative potential of 3D spheroid MSCs is greater than that of 2D monolayer MSCs in vitro. In addition, to elucidate the ability of 3D spheroid MSCs to regenerate bone, we examined the effects of transplanting wild-type (WT) or knockout (KO) spheroid MSCs on new bone formation in mice calvarial defect model in vitro. The 3D spheroid MSC culture dramatically upregulated into stemness markers compared with the 2D monolayer MSC culture. In contrast, BMP-2 significantly increased the osteogenesis-related molecules in the 3D spheroid MSCs but, in turn, downregulated the stemness markers. BMP-2 activated Smad1/5 together with Wnt/β-catenin in 3D spheroid MSCs. Transplantation of these MSCs into aged mice with calvarial defects promoted new bone formation compared with that of 2D monolayer MSCs. In contrast, transplantation of 3D or 2D β-catenin knockout MSCs induced little new bone formation. The 3D spheroid MSC culture had higher stemness compared with the 2D monolayer MSC culture. The culture of 3D spheroid MSCs rapidly promoted osteoblastogenesis and bone formation through synergistic activation of the Wnt/β-catenin pathway in vitro. The transformation of 3D spheroid, but not 2D monolayer, MSCs promoted new bone regeneration in vivo. These results indicate that transplantation of 3D spheroid MSCs in regeneration therapy contributes to a shorter regenerative healing process, including new bone formation.福岡歯科大学2019年

The Effects of Implant Surface Characteristics on Surrounding Bone: A Comparative Study of Two Types of Surface Characteristics

The aims of this study were to create experimental implants by coating rough plastic surfaces with a thin layer of titanium, and to use the experimental implants in an animal experiment to investigate whether differences in the surface characteristics of the implant affect the peri-implant bone reaction during the period of osseointegration. Titanium rods of diameter 1.6 mm and length 7 mm were treated by acid etching (AE) or sandblasting followed by acid etching (SA), and replicas were made from plastic. Experimental implants were created by depositing a thin layer of titanium on the plastic replicas by DC-magnetron sputtering, and the surface characteristics of the experimental implants were evaluated. The experimental implants were placed in the tibias of eight-week-old male SD rats. The rats were sacrificed and the implants harvested at 3, 5, 10, 14, 21 and 28 days after implant placement. The samples were examined by optical microscopy and micro-CT to confirm peri-implant new bone growth. Examination of the experimental implants by SEM imaging showed that the different surface conditions (SA and AE) had been faithfully recreated. TEM observation and XPS analysis confirmed that the coating was titanium. The surface roughness of SA and AE was 2.68±0.536 μm and 0.47±0.069 μm, respectively. With AE, the BMD of peri-implant trabecular bone showed that bone mineralization progressed not on the surface of the implant but at sites a small distance away. At day 28 after placement of the implant, when osseointegration was complete, the BMD value in the region near the implant surface was higher in SA than in AE. Furthermore, the BV/TV value was high at an earlier stage in SA than AE. The results showed that the SA surface was better than the AE surface for achieving osseointegration.福岡歯科大学2013年

Enhancement of jaw bone regeneration via ERK1/2 activation using dedifferentiated fat cells.

Mesenchymal stem/stromal cells (MSCs) are multipotent and self-renewing cells that are extensively used in tissue engineering. Adipose tissues are known to be the source of two types of MSCs; namely, adipose tissue-derived MSCs (ASCs) and dedifferentiated fat (DFAT) cells. Although ASCs are sometimes transplanted for clinical cytotherapy, the effects of DFAT cell transplantation on mandibular bone healing remain unclear.The authors assessed whether DFAT cells have osteogenerative potential compared with ASCs in rats in vitro. In addition, to elucidate the ability of DFAT cells to regenerate the jaw bone, the authors examined the effects of DFAT cells on new bone formation in a mandibular defect model in (i) 30-week-old rats and (ii) ovariectomy-induced osteoporotic rats in vivo.Osteoblast differentiation with bone morphogenetic protein 2 (BMP-2) or osteogenesis-induced medium upregulated the osteogenesis-related molecules in DFAT cells compared with those in ASCs. BMP-2 activated the phosphorylation signaling pathways of ERK1/2 and Smad2 in DFAT cells, but minor Smad1/5/9 activation was noted in ASCs. The transplantation of DFAT cells into normal or ovariectomy-induced osteoporotic rats with mandibular defects promoted new bone formation compared with that seen with ASCs.DFAT cells promoted osteoblast differentiation and new bone formation through ERK1/2 and Smad2 signaling pathways in vitro. The transplantation of DFAT cells promoted new mandibular bone formation in vivo compared with that seen with ASCs. These results suggest that transplantation of ERK1/2-activated DFAT cells shorten the mandibular bone healing process in cytotherapy.福岡歯科大学2020年

Intramedullary injury combined with osteoporosis therapeutics regulates targeted local osteogenesis.

福岡歯科大学2022年

Degradation rate of DNA scaffolds and bone regeneration.

Scaffolds implanted into bone defect sites must achieve optimal biodegradation rates while appropriately filling the void as new bone formation progresses. We recently developed a unique biomaterial consisting of salmon deoxyribose nucleic acid (DNA) and protamine, which can be used as an osteoconductive scaffold for tissue engineering. The aim of the present study was to elucidate how the degradation rate of the scaffold affects bone regeneration. We examined the relationships between the degradation rate of salmon DNA scaffolds and new bone formation using a rat skin flank subcutaneous model and rat calvarial defect model. The degradation rates of the scaffolds were proportional to the durations of pretreatment with ultraviolet (UV) light irradiation. The biodegradation rates of the scaffolds were also dependent on the duration of UV irradiation, as tested a subcutaneous tissue implantation. Scaffolds irradiated with UV light for 0.5 h maintained gradual biodegradation of phosphate compared with scaffolds irradiated for 0 or 3 h. In the calvarial defect model, we found that new bone formation was higher in rats treated with scaffolds irradiated with UV light for 0.5 h compared with those irradiated with UV light for 0 or 3.0 h. The present results suggest that bioengineering of scaffolds for biodegradation is important to regenerate bone. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018.福岡歯科大学2017年

Bone Morphogenetic Protein-2 Accelerates Osteogenic Differentiation in Spheroid-Derived Mesenchymal Stem Cells

福岡歯科大学2018年

Photothermal stress triggered by near infrared-irradiated carbon nanotubes promotes bone deposition in rat calvarial defects.

The bone regenerative healing process is often prolonged, with a high risk of infection particularly in elderly and diseased patients. A reduction in healing process time usually requires mechanical stress devices, chemical cues, or laser/thermal therapies. Although these approaches have been used extensively for the reduction of bone healing time, the exact mechanisms involved in thermal stress-induced bone regeneration remain unclear. In this study, we investigated the effect of optimal hyperthermia on rat calvarial defects in vivo and on osteogenesis in vitro. Photothermal stress stimulation was carried out using a new photothermal device, composed of an alginate gel including in carbon nanotubes and their irradiator with near-infrared light. Photothermal stress (15 min at 42℃, every day), trigged by near-infrared-induced carbon nanotube, promoted bone deposition in critical-sized calvarial defects compared with nonthermal stress controls. We recently reported that our novel DNA/protamine complex scaffold induces bone regeneration in calvarial defects. In this study, photothermal stress upregulated bone deposition in DNA/protamine-engrafted calvarial defects. Furthermore, photothermal stress significantly induced expression of osteogenic related genes in a time-dependent manner, including alkaline phosphatase, osterix, and osteocalcin. This was observed in DNA/protamine cells, which were expanded from regenerated tissue engrafted into the DNA/protamine scaffold, as well as in human MG63 preosteoblasts. In summary, this novel carbon nanotube-based photothermal stress approach upregulated expression of osteogenic-related genes in preosteoblasts, resulting in promotion of mineral deposition for enhanced bone repair.福岡歯科大学2014年

Osteogenic Evaluation of DNA/Protamine Complex Paste in Rat Cranial Defects

福岡歯科大学2013年