Abstract: Differences in structural and crystallinity between the lateral and medial regions of the central femoral diaphysis in low-mineral-diet-fed ovariectomized rats were investigated using polarization microscopy and Raman spectral analysis. Eighteen 19-week-old female Wistar rats were divided into 3 groups (Group 1: sham ovariectomy + normal diet group, Group 2: ovariectomy + normal diet group, Group 3: ovariectomy + low-mineral-diet group). Measurements were performed in the lateral and medial regions of the femoral sagittal cross-section at 24 weeks of feeding. On polarization microscopy, tubular structures of haversian and Volkmanns canals and osteocytes were observed in the femur in Groups 1 and 2. In Group 3, the number of these tubular structures in the femur was decreased compared to those in Groups 1 and 2. Moreover, the bone width of the femur decreased in Group 3 compared to those in Groups 1 and 2. On Raman spectral analysis, the peaks of organic and inorganic components were observed in the lateral and medial regions of the femur in all groups. In magnified views of the peak of ν1PO43-spectrum, the peaks in the lateral and medial regions overlapped in Group 1, but the peak of the medial region was about 0.3 and 0.8 cm-1 shifted toward the low wavenumber side compared to those of the lateral region in Groups 2 and 3, respectively. Based on these findings, the influences of reduced estrogen secretion and the low-mineral diet were clarified as differences in the femoral structural and crystallinity on polarization microscopy and Raman spectral analysis. Since highly sensitive detailed point analysis can be performed within a short time using Raman spectral analysis, it may be useful for high-dimensional structural analysis.
Abstract: Ovariectomized rats were fed a diet containing minerals at high concentrations, such as Ca, P, and F (high-mineral diet), and changes in the femoral diaphysis were investigated after 24 weeks. The femur was mainly red and partially orange on the color scale of the 3D-map in Groups A and B, showing a high BMD. The region adjacent to the marrow cavity was yellow, showing a lower BMD than that in the outer region of the femur. In Group C, the red area was small in the outer region and the inner region was mainly yellow and green on the color scale. The inner region adjacent to the marrow cavity showed a view of unevenly resorbed bone, and the BMD was lower than those in Groups A and B. Incorporation of F into the body influences the apatite crystal structure and crystal growth, which subsequently influences adsorption of F to crystals and structural changes. Therefore, it is important to ingest F at the optimum concentration.
Abstract: A surface coating on the polymer polyetheretherketone (PEEK) was developed to improve the osteointegration of an implantation model for cages (implant for spinal fusion). In a process of induction heating the polymer surface was coated with a synthetic biomaterial. The polymer surface melts during the coating process and crawls into the nanoporous structure of the biomaterial. After heat dissipation, a strong connection is reached between polymer and biomaterial. Finally, the model was implanted into New Zealand rabbit femur as control and coated group for 2, 4 and 6 weeks. The evaluation offers a ca. 10% higher bone-to-implant-contact value for the coated group.
Abstract: Studies about silicon-substituted hydroxyapatites exhibit several shortcomings that leave unanswered questions regarding the properties and subsequent biological outcomes generated by this biomaterial. Firstly, samples characterization is often incomplete, meaning that phase purity on the pellet surface is not assured. In fact, ceramic materials used in literature that are claimed to be pure are actually polluted through second phase as superficial polymerized silicate. In this study, we have successfully synthesized a phase pure silicon hydroxyapatite powder Ca10(PO4)5.5(SiO4)0.5(OH)1.5 (Si0.5HA) compressed this powder into pellets, sintered them, and evaluated the biological response of osteoblast cells (C3H10 line) seeded on the pellet surface. Besides, the solubility in aqueous media of HA and Si0.5HA pellets were determined through static experiments. These tests attempt to provide a comprehensive picture of the cellular response to the SiHA material, in order to determine the mechanism by which Si evokes the improved in vitro biological outcomes described in the literature. Results revealed first an equivalent solubility of Si0.5HA and HA pellets, and second that cells do not react favourably to the pure SiHA surface.
Abstract: The osteoblast behaviors on the biomaterial substrates are recognized to play a fundamental role in osteoconduction process. The purpose of this study was to evaluate the in vitro behaviors of osteoblasts cultured on electrically polarized hydroxyapatite (HA), having the enhanced osteobonding abilities. Osteoblasts derived from mouse bone marrow were seeded onto the polarized HA and investigated the proliferation and differentiation. The polarization had effects on the proliferation of osteoblast precursor cells based on the MTT assay. The acceleration was emerged as the early achievement to the confluence on the N-HA and P-HA. The quantitative analysis of the results of ALP and AR-S staining, the charges induced on the HA surface accelerated the differentiation from the osteoblast precursor cells to mature osteoblasts.
Abstract: The treatment of peripheral nerve injuries is still one of the most challenging tasks in neurosurgery, as functional recovery is rarely satisfactory in these patients. The concept behind the use of biodegradable nerve guides is that no foreign material should be left in place after the device has fulfilled its task, so as to spare a second surgical intervention. In a previous study, flexible and biodegradable chitosan-γ-glycidoxypropyltrimethoxysilane (GPTMS) hybrid membranes exhibited better cytocompatibility in terms of osteoblastic cells than chitosan membrane. Porous chitosan hybrid membranes, derived by freeze-drying the hybrid gels, showed that the cells were attached and proliferated both on the surface and into pores. The aim of the present study was to evaluate the influence of these chitosan hybrid membranes in terms of their inflammatory response and remodeling of connective tissue during wound-healing processes before use as a periphery nerve graft. The porous chitosan hybrid membranes showed good biocompatibility and improved posttraumatic axonal regrowth and functional recovery.
Abstract: MC3T3-E1 cell responses, such as cell adhesion and proliferation, to original and bovine serum albumin (BSA) coated disc (original-disc, BSA-disc) of hydroxyapatite (HA) or alpha-type alumina (α-Al2O3) was studied. There was no significant difference in the cell proliferation between BSA-discs and original-discs even after incubated for 14 days, but the cell number at day 14 tended to be higher (p = 0.054) on the BSA-discs of HA than on the original-discs of HA. Incidentally, the amount of adsorbed protein was higher on BSA-discs than on original-discs only until incubated in culture medium for 3 h. BSA adsorption might influence the MC3T3-E1 cell adhesion to HA, as a result the specific adsorption of albumin on HA is likely to affect the expression of the osteoconductivity of materials.
Abstract: Heart disease is the second most common cause of mortality in Japan. Most cases of late stage heart failure can only be effectively treated by a heart transplant. Cardiac tissue engineering is emerging both as a new approach for improving the treatment of heart failure and for developing new cardiac drugs. Apatite-fiber scaffold (AFS) was originally designed as a substitute material for bone. AFS contains two sizes of pores and is appropriate for the three dimensional proliferation and differentiation of osteoblasts. To establish engineered heart tissue, a pluripotent embryonal carcinoma cell line, P19.CL6, was cultured in AFS. P19.CL6 cells seeded into AFS proliferated well. Generally, cardiac differentiation of P19.CL6 cells is induced by treating suspension-cultured cells with dimethyl sulfoxide (DMSO), after which the cells form spheroids. However, our results showed that P19.CL6 cells cultured in AFS differentiated into myocytes without forming spheroidal aggregates, and could be cultured for at least one month. Thus, we conclude that AFS is a good candidate as a scaffold for cardiac tissue engineering.
Abstract: Cytotoxicity and cell behavior to micro / nanoparticles of TiO2 and CuO was evaluated using the viability measurement and time-lapse observation. After cultured, osteoblastic cells MC3T3-E1 were exposed to particles. After 24 hour exposure, their morphology was observed using a SEM and the viability was measured. Cells exposed to TiO2 indicated no or very low decrease of viability. The results were independent of the particle size. On the other hand, the viability of cells exposed to CuO decreased with the concentration, and showed the size dependence. The nanosized CuO indicated higher toxicity compared with micro-sized one. Dynamic behavior of cells exposed to nanoparticles, was succeeded to observe in a time-lapse method for 24 hours. The observation showed that the cells exposed to CuO became dead after forming a spherical shape. This is consistent with the image taken by SEM. Time-lapse observation made it possible to see the dynamic reaction process from cell contact to particles at first, the following cell activity response and finally to cell death, which revealed a considerably different morphology from the static cell observed after fixation by conventional method.
Abstract: The reports on cytotoxic studies of carbon nanotubes (CNTs) increased exponentially. In the present study, we investigate murine macrophage RAW264.7 cell response for the CNTs immobilized on a polystyrene substrate. We prepared CNT-coated dishes, and estimate the interaction of RAW264.7 cells with CNTs by cell adhesion, proliferation assay, and measurement of TNF-α production. As a result, the highest cell adhesion and proliferation was observed on a commercially cell culture polystyrene dish, while CNT-coated dish indicate slightly lower activity of them. Moreover, amount of production of TNF-α on the CNT-coated dishes was considerable lower than that in the case of lipopolysaccharide (LPS) addition as a control. These results indicated that CNT-coated dishes could not show strong cytotoxicity for RAW264.7 cells in vitro.