The trabecular bone response of bisphosphonate immobilized titanium web (TW) was investigated. Apatite thin film was coated onto TW using molecular precursor method. Sintered cylindrical TW was immersed into molecular precursor solution and then heated at 600oC for 2 hr. The immersion and heating process was repeated three times. Apatite coated TW was immersed into the bisphosphonate solution (pamidronate disodium, 5x10-3M) for 24 hr at 37oC. Afterwards, TW, apatite coated TW and bisphosphonate immobilized TW were placed into the trabecular bone of femoral condyles of rabbits. Histological evaluation revealed that new bone formation was recognized inside the porous area of apatite coated TW and bisphosphonate immobilized TW after 12 weeks of implantation, and it appeared that bisphosphonate immobilized TW produced more new bone formation than apatite coated TW. It was suggested that bisphosphonate immobilized TW enhanced the osteogenesis inside area of TW.
Stimulation of the CD3/TCR results within minutes in an increase in T cell adhesion to fibronectin. The biochemical pathways that control TCR-mediated increases in adhesion to fibronectin remain poorly characterized. In this study, the role of the tyrosine kinase in the regulation of adhesion by the CD3/TCR was investigated. CD3 stimulation enhanced adhesion to fibronectin on Jurkat T cells line. Tyrosine kinase inhibitor, PP2, and anti β1 integrin mAb blocked adhesion to fibronectin enhanced by CD3 stimulation on Jurkat T cells. CD3 stimulation did not increase adhesion to fibronectin of the tyrosine kinase ZAP-70-deficient Jurkat T cells line, P116. Furthermore, CD3 stimulation failed to tyrosine phosphorylation of PI3-kinase enzyme AKT on P116 cells. These observations support a model in which the tyrosine kinase activity of ZAP-70 kinase is critical for regulation of β1 integrin activity by CD3/TCR.
The composite scaffold based on a mixture of DNA-chitosan complexes and carbonate apatite particles (DNA-chitosan-apatite complexes) was implanted into cranial bone of rats to evaluate an ability of the bone regeneration. By immersing the DNA-chitosan-apatite complexes disks in simulated body fluid (HBSS) for 3 days, precipitate formation on the disks was observed. Although the precipitates were scattered over the surface of the both DNA-chitosan-apatite complexes and DNA-chitosan complexes disks, early formation of precipitate clusters was observed for the DNA-chitosan-apatite complexes. For the XRD patterns of the DNA-chitosan-apatite complexes after 3 days-immersion in HBSS, the same spectrum for carbonate apatite alone were observed. The implanted DNA-chitosan-apatite complexes disks were gradually fragmentized into small pieces 7 weeks after surgery. Although numerous osteocyte-like cells were observed in these small pieces, the remaining of the carbonate apatite particles could not find in the implanted material. On 12 weeks, the implanted portion was totally replaced by newly generated bone tissues. In contrast, DNA-chitosan complexes disk was capsulated by fibrous connective tissue. No bone formation was observed in the implanted area in the tissue sections examined. It appeared that DNA-chitosan-apatite complexes have a good potential for bone response. The results of this study suggested that degradability of carbonate apatite would play an important role in process of bone generation.
Adiponectin is abundantly present as a plasma protein, and exhibits various biological functions, such as regulating energy homeostasis and increasing insulin sensitivity in the liver and skeletal muscle. Circulating adiponectin includes both a full-length type (AN) and a globular type (gAN). Recent studies have demonstrated both a positive and negative action of adiponectin on bone formation, and it was thought that these different actions might be attributed to different forms of adiponectin. In this study we investigated the gene expression profiles of osteoblasts stimulated by AN or gAN. Osteoblastic differentiation of a murine pro-osteoblastic cell line, MC3T3-E1 cells, was induced by ascorbic acid and β-glycerophosphate with or without recombinant murine gAN or AN. Gene expression profiles were obtained by DNA microarray analysis. Stimulation of AN or gAN showed different gene expression profiles in osteoblasts. The different profiles of up-regulated gene expression in osteoblasts indicated that different forms of adiponectin act on osteoblastic differentiation through different pathways.
The purpose of this study was to evaluate effects of IC50 Ni (2+) ions on human mesenchymal stem cells (hMSC) cultured for one day by 29k full-genome DNA microarray analyses. It became evident that 39 genes of hMSC were up-regulated more than 5-fold, while 24 genes of hMSC were down-regulated less than 0.2-fold. The analyses suggested that (1) for cell protection, cell cycle arrest due to up-regulation of cyclindependent kinase inhibitor genes occurred while Ni (2+) ion intracellular transfer was minimized, (2) hypoxia condition due to down-regulation of channel/transporter related genes caused minor inflammation reaction containing up-regulation of several chemokine ligand genes through MAPK pathway, and (3) intracellular intake of minimum amounts of Ni (2+) ions might take place by up-regulation of zinc finger print protein and ferritin related genes. The master system to regulate the hMSC reaction against Ni (2+) ions needs to be clarified in the future.
Purpose: Osteoblasts, osteogenic factors, and scaffold material are needed in bone regeneration. We examined the physical characteristics and internal structure of porous coral as a scaffold material. Methods: Dried blocks (diameter 4 mm, height 10 mm) of porous coral (stony coral and velvet finger coral) were immersed in 1N NaOH to remove protein. We then measured the specific gravity of the dry blocks, the proportion consisting of internal cavities, and the physical strength (compressive strength, hardness) of the blocks when wet, and compared the physical strength of the coral with that of femurs of Wistar rats. We also observed the exoskeleton and status of internal cavities in these 2 types of coral using micro-CT. Particles of both types of coral were added to human-derived fibroblasts and vascular endothelial cells. Then they were co-cultured for 10 days and the cytotoxicity of these materials was studied. Results: The specific gravity, proportion consisting of cavities, and internal diameters of these cavities were 1.29, 53.1%, and 500 µm, respectively, for stony coral, and 1.40, 50.4%, and 100-200 µm for velvet finger coral. The compressive strength and hardness of stony coral (11.2 MPa, 44.9) and velvet finger coral (12.4 MPa, 61.7) were about 21% and 66% those of rat femur (55.4 MPa, 80.4), respectively. Little cytotoxicity was seen in either of the coral particles in the cell culture test. These findings suggest that these corals would be useful as scaffolding material.