Faculty Bibliography

BACKGROUND CONTEXT: The beneficial therapeutic effects of selected low energy, time varying pulsed electromagnetic fields (PEMFs) have been documented to treat therapeutically resistant problems of the musculoskeletal system. PEMFs promote fracture healing in non-unions. We have found that both bone morphogenetic protein-2 (BMP-2) and PEMF (Spinal-Stim by Orthofix, Inc.) separately stimulated proliferation of rat osteoblastic cells (Selvamurugan et al, 2007) in culture. This effect was additive when both agents were combined. Early osteoblastic differentiation genes were stimulated by PEMF treatment; whereas both the early and late differentiation genes were stimulated by BMP-2 treatment. When both treatments were combined, additive effects were found on both alkaline phosphatase and osteocalcin gene expression and this was more pronounced with daily PEMF treatment. Thus, PEMF has effects on both the proliferating and differentiating osteoblast. Our present work investigated the effects of PEMF (Cervical-Stim by Orthofix, Inc.) on human bone marrow mesenchymal stem cells (hBMMSCs) differentiated to osteoblastic cells and human bone marrow monocytic cells (hBMMs) differentiated to osteoclasts as well as some of the mechanisms of action of PEMF. METHODS: Fresh human bone marrow samples were obtained from the iliac crest of female subjects of different ages. Mononuclear cells were purified by running through Ficoll-Hypaque, and the cells then plated to allow the mesenchymal cells to adhere and expand in proliferation medium, aMEM with 15% fetal bovine serum. Colonies formed, and were expanded for experiments. Human BMMSCs from the second to sixth passages were used for experiments. To obtain human osteoclasts, the fresh mononuclear cells were incubated overnight and the next day non-adherent cells were plated into multiwell plates. All osteoclastic cultures were supplemented with 25 ng/ml M-CSF. Osteoclasts were induced by addition of 35 ng/ ml RANKL. After 9 days incubation multinuclear cells wer!

Osteoblast differentiation is tightly regulated by post transcriptional regulators such as microRNAs (miRNAs). Several bioactive materials including nano-bioglass ceramic particles (nBGC) influence differentiation of the osteoblasts, but the molecular mechanisms of nBGC-stimulation of osteoblast differentiation via miRNAs are not yet determined. In this study, we identified that nBGC-treatment stimulated miR-30c expression in human osteoblastic cells (MG63). The bioinformatics tools identified its regulatory network, molecular function, biological processes and its target genes involved in negative regulation of osteoblast differentiation. TGIF2 and HDAC4 were found to be its putative target genes and their expression was down regulated by nBGC-treatment in MG63 cells. Thus, this study advances our understanding of nBGC action on bone cells and supports utilization of nBGC in bone tissue engineering.

INTRODUCTION: Histological studies of immature human permanent necrotic teeth with or without apical periodontitis after revascularization have not been reported. This case report describes the histological findings of tissue formed in the canal space of an immature permanent tooth #9 with irreversible pulpitis without apical periodontitis after revascularization. METHODS: An immature human permanent tooth #9 was fractured 3.5 weeks after revascularization and could not be retained. The tooth was extracted and prepared for routine histological and immunohistochemical evaluation in order to examine the nature of tissue formed in the root canal following the revascularization procedure. RESULTS: At 3.5 weeks after revascularization, more than one half of the canal was filled with loose connective tissue similar to the pulp tissue. A layer of flattened odontoblast-like cells lined along the predentin. Layers of epithelial-like cells, similar to the Hertwig's epithelial root sheath, surrounded the root apex. No hard tissue was formed in the canal. CONCLUSIONS: Based on the histological findings in the present case, regeneration of pulp-like tissue is possible after revascularization. In this case, both the apical papilla and the Hertwig's epithelial root sheath survived in an immature permanent tooth despite irreversible pulpitis but without apical periodontitis.

Bisphosphonates are therapeutic agents in the treatment of post-menopausal osteoporosis. Although they have been associated with delayed healing in injured tissues, inappropriate femoral fractures, and osteonecrosis of the jaw (ONJ), the pathophysiological mechanisms involved are not clear. Our hypothesis is that alendronate, a member of the N-containing bisphosphonates, indirectly inhibits osteoblast function through the coupling of osteoclasts to osteoblasts by ephrinB-EphB interaction. We found that alendronate increased gene and protein expression of ephrinB1 and EphB1, as well as B3, in femurs of adult mice injected with alendronate (10 microg/100 g/wk) for 8 weeks. Alendronate suppressed the expression of bone sialoprotein (BSP) and osteonectin in both femurs and bone marrow osteoblastic cells of mice. After elimination of pre-osteoclasts from bone marrow cells, alendronate did not affect osteoblast differentiation, indicating the need for pre-osteoclasts for alendronate's effects. Alendronate stimulated EphB1 and EphB3 protein expression in osteoblasts, whereas it enhanced ephrinB1 protein in pre-osteoclasts. In addition, a reverse signal by ephrinB1 inhibited osteoblast differentiation and suppressed BSP gene expression. Thus, alendronate, through its direct effects on the pre-osteoclast, appears to regulate expression of ephrinB1, which regulates and acts through the EphB1, B3 receptors on the osteoblast to suppress osteoblast differentiation.

The current study involves fabrication and characterization of bio-composite scaffolds containing chitosan (CS), nano-hydroxyapatite (nHAp) and Cu-Zn alloy nanoparticles (nCu-Zn) by freeze drying technique. The fabricated composite scaffolds (CS/nHAp and CS/nHAp/nCu-Zn) were characterized by SEM, EDX, XRD and FT-IR studies. The addition of nCu-Zn in the CS/nHAp scaffolds significantly increased swelling, decreased degradation, increased protein adsorption, and increased antibacterial activity. The CS/nHAp/nCu-Zn scaffolds had no toxicity towards rat osteoprogenitor cells. So the developed CS/nHAp/nCu-Zn scaffolds have advantageous and potential applications over the CS-nHAp scaffolds for bone tissue engineering.