Abstract: Three dimensionally ordered macroporous sol-gel bioactive glasses (3DOM-BGs)are a type of biomaterial that is both bioactive and resorbable. In this study, 80 % SiO2 – 20 % CaO (molar fraction) 3DOM-BG particles were prepared using a colloidal crystal templating method via a sol-gel process. The as-prepared 3DOM-BG particles can quickly convert to a calcium-deficient, bone-like apatite after soaking in a simulated body fluid (SBF). MC3T3-E1 osteoblastic cells were cultured in the presence of 3DOM-BG particles. Preliminary results from cell studies showed that 3DOM-BG particles are not cytotoxic and are compatible with
MC3T3-E1 osteoblast-like cells in vitro.
Abstract: Marrow mesenchymal cells contain stem cells and can regenerate tissue. We previously reported the clinical application of autologous cultured bone to regeneration therapy. However there is room for improvement in the culture methods; and here, we examined the optimal frequency of medium changing. Marrow cells were collected from the femur of a Fisher 7 week-old male rat. At 2
weeks after primary culture in a standard medium (MEM containing 15% bovine fetal serum), the cultures were trypsinized to prepare a cell suspension and divided into two groups, with or without addition of dexamethasone (Dex) to the osteogenic medium. To investigate optimal frequency, we further divided into 5 sub-groups; no changing (M0), 1 time/week (M1), 2/week (M2), 3/week (M3),
and everyday (M7). After 2 weeks of subculture, the tissue was harvested and then ALP activity and calcium and DNA contents measured. In both of the Dex groups, there was significantly high ALP activity in the higher frequency group; but there was no significant DNA content. Also, in the Dex(+)group, there was a significant increase of calcium content in only the M3 and M7 sub-groups. Thus,
we showed that the osteogenic potential of cultured bone is cultivated by increasing the frequency of medium changing.
Abstract: We have cultured mesenchymal cells (MSC) on various types of ceramic disks and used these tissue-engineered ceramics for hard tissue regeneration. In this approach, observation of cultured cell morphology is important even if culture substrata are calcium phosphate ceramics, which usually show bioactive nature. However, due to the opaque nature of the ceramics, cells observation is very difficult. Here, we demonstrate light microscopic observation of rat MSC cultured
on transparent β-tricalcium phosphate ceramics (β-TCP). The culture was performed in osteogenic medium. Thus, the cell differentiated into bone-forming osteoblasts, which fabricated a mineralized matrix on the ceramic disks. Microscopic observation revealed that the cascade of osteogenic differentiation after attachment/proliferation of MSC on the ceramic disks was similar to that on a
culture grade polystyrene dish. These results confirmed the excellent property of β-TCP for MSC culture leading to hard tissue regeneration.
Abstract: The effect of genistein, a soybean isoflavone, on new bone formation by bone marrow cells from mature humans was examined. After informed consent was obtained from a 55-year-old woman with osteoporosis and lumbar spondylosis deformans，bone marrow cells were collected from her ilium, cultured in the standard medium of MEM containing fetal calf serum and then cultured with or
without the addition of genistein to the bone-forming medium containing dexamethasone etc.． In humans, when genistein was added to the bone-forming medium, genistein (10-7 M and 10-8 M)caused a significant increase in the levels of alkaline phosphatase avtivity and DNA content compared with cells not cultured in genistein． In conclusion，genistein was found to promote bone formation at lower concentrations，and thus may be useful as a bone formation-promoting factor.
Abstract: Samples of zirconia and a bioinert SiO2-containing glass with different surface roughness were immersed into human whole blood for different settling times to investigate the adhesion and attachment of blood cells onto these materials. The cell/material interface was directly observed by scanning electron microscopy (SEM). The results indicate that the blood cells preserved their physiology and attaching capability regardless the type of material, surface roughness, and settling
time. The SEM images strongly indicate the normal function of adhesion proteins.
Abstract: In the current work, we investigated cellular viability, proliferation, and metabolic
activity of rat primary culture osteoblasts in contact with a sample of collagen type I (C) and of this same collagen chemically treated (CTP). The chemical process used here consisted in recover the collagen surface with silica glass obtained from a sol-gel process. The cell viability, the cell death, the alkaline phosphate production and collagen secretion, after 72 hours of incubating the samples with osteoblasts, were measured by MTT assay, propidium iodide, NBT-BCIP assay and SIRCOL
method, respectively. The viability and proliferation of osteoblasts had a significant decrease in the presence of samples when compared to control. The alkaline phosphatase production by the cells had a significant increase in the presence of CTP and collagen secretion by the cells was practically the same when compared to control.
Abstract: The purpose of this study was to evaluate the cell affinity of calcium phosphate glass
scaffold in the system of CaO-CaF2-P2O5-MgO-ZnO, which is already reported that promoted the bone-like tissue formation in vitro and formed new bone in Sprague-Dawley rats. We prepared calcium phosphate glass saffolds with three-dimensionally interconnected pores of 200~500 µm. Commercial HA scaffold was employed as a control in this study. Bone marrow cells were collected from the healthy human donors and cultured within the prepared scaffolds. After 2, 4, 6, and 8 weeks, hMSCs/scaffold were fixed and stained with hematoxylin and eosin. hMSCs were continuously proliferated both in the experimental and control groups at every incubation period. The number of cells was higher in the experimental group than that of the control group, however, there was no significant difference (p>0.05). Extracellular matrices could be observed at the 2nd and 4th days in the
experimental and control groups, respectively. The extracellular matrices were more abundant in the experimental group at all periods. The prepared calcium phosphate glass scaffolds are expected effective in bone tissue engineering.
Abstract: This paper demonstrated a simple technique to seed the hydroxyapatite (HA) ceramic with 2-D cultured cells to establish an advanced mode of HA grafting. The HA beads with a through-hole were fabricated to have an oblate shape to keep an opening of the through-hole contact with 2-D cultured cells layer. The seeding was performed by leaving the HA beads in a culture dish with MG63 cells in culture. The through-hole trapped MG63 cells in a sheet form by 1-day seeding. After 5 days,
the number of trapped cells increased about nine fold, forming cell clumps in the through-hole. The seeding of the HA beads was considered an easy and practical method to provide HA/Cell hybrids that would realize active bone forming orthopedic treatment.
Abstract: In this study, the addition of calcium phosphate powders to an alginate matrix was
evaluated as a strategy to modulate enzyme release-kinetics from alginate microspheres and, simultaneously, to improve cell adhesion to the polymer. Pre-adsorption of the enzyme to the ceramic powders resulted in a more adequate release pattern. The ratio of ceramic-to-polymer had a pronounced effect on osteoblast adhesion to microspheres. Cells were only able to spread on
microspheres with the highest percentage of ceramic (0.4 w/w using a 1.5% w/v alginate solution).
Abstract: For the purpose of mimicking the structure and matching mechanical properties of human cortical bone, a natural composite material, hydroxyapatite (HA) reinforced high density polyethylene (HDPE) has been developed as a bioactive, analogue material for bone replacement. This synthetic composite material is now in clinical use. To understand the deformation behaviour and determine mechanical properties of HA/HDPE composite under different loading modes and loading conditions, tensile and compression tests were performed in the current investigation. It was observed that under tension, HA/HDPE composite exhibited two types of deformation behaviour: ductile and brittle. Under compression, the composite deformed in a ductile manner and did not fracture at high compressive strains. It was found that an increase in HA content resulted in increases in Young’s modulus, compressive modulus, tensile strength and compressive yield
strength of the composite. A higher strain rate led to higher modulus and strength values and lower tensile fracture strains of the composite.