Evaluation of trabecular bone formation in a canine model surrounding a dental implant fixture immobilized with an antimicrobial peptide derived from histatin.

JH8194 induces osteoblast differentiation, although it was originally designed to improve antifungal activity. This suggests that JH8194 is useful for implant treatment. Therefore, the aim of this study was to evaluate the osseointegration capacity of JH8194-modified titanium dental implant fixtures (JH8194-Fi). The implants were randomly implanted into the edentulous ridge of dog mandibles. Healing abutments were inserted immediately after implant placement. Three weeks later, peri-implant bone levels, the first bone-to-implant contact points, and trabecular bone formation surrounding the implants were assessed by histological and digital image analyses based on microcomputed tomography (microCT). The histological analysis revealed an enhancement of mature trabecular bone around the JH8194-Fi compared with untreated fixtures (control-Fi). Similarly, microCT combined with analysis by Zed View™ also showed increased trabecular bone formation surrounding the JH8194-Fi compared with the control-Fi (Student's t-test, P < 0.05). JH8194 may offer an alternative biological modification of titanium surfaces to enhance trabecular bone formation around dental implants, which may contribute to the transient acquirement of osseointegration and the long-term success of implant therapy.

Titanium immobilized with an antimicrobial peptide derived from histatin accelerates the differentiation of osteoblastic cell line, MC3T3-E1.

The objective of this study was to evaluate the effect of titanium immobilized with a cationic antimicrobial peptide (JH8194) derived from histatin on the biofilm formation of Porphyromonas gingivalis and differentiation of osteoblastic cells (MC3T3-E1). The titanium specimens (Ti) were immobilized with JH8194, according to the method previously described. The colonization of P. gingivalis on JH8194-Ti was significantly lower than that on control- and blocking-Ti. JH8194-Ti enhanced the mRNA expressions of Runx2 and OPN, and ALPase activity in the MC3T3-E1, as compared with those of control- and blocking-Ti. These results, taken together, suggested the possibility that JH8194-Ti may be a potential aid to shorten the period of acquiring osseointegration.

Selection of common markers for bone marrow stromal cells from various bones using real-time RT-PCR: effects of passage number and donor age.

Bone marrow stromal cells (BMSCs) are valuable in tissue engineering and cell therapy, but the quality of the cells is critical for the efficacy of therapy. To test the quality and identity of transplantable cells, we identified the molecular markers that were expressed at higher levels in BMSCs than in fibroblasts. Using numerous BMSC lines from tibia, femur, ilium, and jaw, together with skin and gum fibroblasts, we compared the gene expression profiles of these cells using DNA microarrays and low-density array cards. The differentiation potential of tibia and femur BMSCs was similar to that of iliac BMSCs, and different from jaw BMSCs, but all BMSC lines had many common markers that were expressed at much higher levels in BMSCs than in fibroblasts; several BMSC markers showed discrete expression patterns between jaw and other BMSCs. The common markers are probably useful in routine tests, but their efficacy may depend upon the passage number or donor age. In our study the passage number markedly altered the expression levels of several markers, while donor age had little effect on them. Considering the effects of in vivo location of BMSCs and passage, magnitude of increase in expression levels, and interindividual differences, we identified several reliable markers -- LIF, IGF1, PRG1, MGP, BMP4, CTGF, KCTD12, IGFBP7, TRIB2, and DYNC1I1 -- among many candidates. This marker set may be useful in a routine test for BMSCs in tissue engineering and cell therapy.

Behavior of transplanted bone marrow-derived mesenchymal stem cells in periodontal defects.

BACKGROUND: Recently, there have been an increased number of basic and clinical reports indicating the superior potential of bone marrow-derived mesenchymal stem cells (MSCs) for tissue regeneration. In periodontal treatment, previous animal studies indicated that autotransplantation of bone marrow MSCs into experimental periodontal defects enhanced periodontal tissue regeneration. However, mechanisms for periodontal tissue regeneration with MSCs are still unclear. The purpose of this study was to elucidate the behavior of transplanted MSCs in periodontal defects. METHODS: Bone marrow MSCs were isolated from beagle dogs, labeled with green fluorescent protein (GFP), and expanded in vitro. The expanded MSCs were mixed with atelocollagen (2% type I collagen) at final concentrations of 2 x 10(7) cells/ml and transplanted into experimental Class III periodontal defects. Localizations of GFP and proliferating cell nuclear antigen (PCNA)-positive cells were evaluated by immunohistochemical analysis. RESULTS: Four weeks after transplantation, the periodontal defects were almost regenerated with periodontal tissue. Cementoblasts, osteoblasts, osteocytes, and fibroblasts of the regenerated periodontal tissue were positive with GFP. PCNA-positive cells were present in regenerating connective tissue. CONCLUSION: These findings suggest that transplanted mesenchymal stem cells could survive and differentiate into periodontal tissue cells, resulting in enhancement of periodontal tissue regeneration.

Alveolar bone marrow as a cell source for regenerative medicine: differences between alveolar and iliac bone marrow stromal cells.

UNLABELLED: We isolated and expanded BMSCs from human alveolar/jaw bone at a high success rate (70%). These cells had potent osteogenic potential in vitro and in vivo, although their chondrogenic and adipogenic potential was less than that of iliac cells. INTRODUCTION: Human bone marrow stromal cells (BMSCs) have osteogenic, chondrogenic, and adipogenic potential, but marrow aspiration from iliac crest is an invasive procedure. Alveolar BMSCs may be more useful for regenerative medicine, because the marrow can be aspirated from alveolar bone with minimal pain. MATERIALS AND METHODS: In this study, alveolar bone marrow samples were obtained from 41 patients, 6-66 years of age, during the course of oral surgery. BMSCs were seeded and maintained in culture with 10% FBS and basic fibroblast growth factor. In addition, BMSCs were induced to differentiate into osteoblasts, chondrocytes, or adipocytes in appropriate medium. RESULTS AND CONCLUSION: From a small volume (0.1-3 ml) of aspirates, alveolar BMSCs expanded at a success ratio of 29/41 (70%). The success rate decreased with increasing donor age, perhaps because of age-dependent decreases in the number and proliferative capacity of BMSCs. The expanded BMSCs differentiated into osteoblasts under osteogenic conditions in 21-28 days: the mRNA levels of osteocalcin, osteopontin, and bone sialoprotein, along with the calcium level, in alveolar BMSC cultures were similar to those in iliac cultures. However, unlike iliac BMSC, alveolar BMSC showed poor chondrogenic or adipogenic potential, and similar differences were observed between canine alveolar and iliac BMSCs. Subsequently, human alveolar BMSCs attached to beta-tricalcium phosphate were transplanted into immunodeficient mice. In transplants, new bone formed with osteoblasts and osteocytes that expressed human vimentin, human osteocalcin, and human GAPDH. These findings suggest that BMSCs have distinctive features depending on their in vivo location and that alveolar BMSCs will be useful in cell therapy for bone diseases.

[Cell transplantation for periodontal diseases. A novel periodontal tissue regenerative therapy using bone marrow mesenchymal stem cells].

A major goal of periodontal therapy is to reconstruct healthy periodontium destroyed by periodontal diseases. Basic studies have revealed that transplantation of mesenchymal stem cells (MSC) into periodontal defects promotes regeneration of periodontal tissue. We have developed a novel method for periodontal therapy using MSC. Human bone marrow cells are obtained from the iliac crest and expanded in vitro at Cell and Tissue Engineering Center in Hiroshima University Hospital. MSC are, then, isolated and mixed with Atelocollagen at final concentrations of 2 x 10(7) cells/mL. These MSC in Atelocollagen are transplanted into periodontal osseous defects at the periodontal surgery. The results in all seven patients who received the own MSC transplantation have shown good clinical course. Further basic studies and the continuous clinical trial are needed to prove the effectiveness of the clinical application.

A femoral neck fracture model in rabbits.

A technique was developed to create a reproducible femoral neck fracture in vitro using 5-month-old JW/CSK series male rabbits. Force attenuation of a newly developed damping material was also evaluated using this model. Ten pairs of the femora with smaller deviations in length and weight were harvested and cleaned of soft tissue. Either a right or left of each pair of the specimens was randomly selected and put into either the control or the experimental group, both of which contained equal numbers of the right and left femora. The specimens were attached to an L-shaped plate and embedded in a resin from the proximal diaphysis to the distal end so as to maintain a consistent position of the femora. They were mounted and fixed on a pedestal slanted in the coronal plane at 20 degrees. The impact load testing was conducted using an impact mallet dropped from a height of 3 cm. The impact load was applied onto the femoral head. To the specimens in the experimental group, attenuated impact forces were loaded through the damping material, but those in the control group were subjected to forces directly transmitted without the material. All the impact testing was performed in a temperature and humidity controlled chamber. All of the femoral specimens exposed to the direct impact forces (controlled group) sustained fracture at the neck. The fracture line passed from the base of the femoral head laterally and to the calcar area just proximal to the minor trochanter medially. The location of each fracture line was almost identical among the specimens. None of the specimens that were exposed to the impact force through the damping material (experimental group) sustained fracture macroscopically and roentgenographically.