We generated a three-dimensional collagen scaffold coated with carbon nanotubes (CNTs) and β-tricalcium phosphate (β-TCP) nanoparticles and histologically evaluated tissue behavior toward the nanomodified scaffold after subcutaneous tissue implantation in rat. Scanning electron microscopy images of the nanomodified scaffold showed that the collagen surface was enveloped by a meshwork of CNTs and dispersed β-TCP nanoparticles. Histological observations indicated that application of CNTs and β-TCP nanoparticles increased cell and blood vessel penetration into the collagen scaffold. CNTs consistently stimulated giant cell aggregation. In addition, CNTs and β-TCP application to the scaffold significantly promoted the DNA content of infiltrating cells and scaffold biodegradation compared to the untreated scaffold. The nanomodified scaffold coated with CNTs and β-TCP nanoparticles would be beneficial for tissue engineering therapy.
Cysteine knot proteins (CKPs) with cysteine-rich domain mainly inhibit bone formation induced by Bone morphogenetic protein (BMP). We identified a novel CKP, von Willebrand factor C domain containing 2 (VWC2), and investigated the effect of VWC2 on bone formation. When VWC2 was added to MC3T3-E1 osteoblastic cell culture, the extent of matrix mineralization and alkaline phosphatase activity were significantly increased. The newly formed bone area was increased and mineral apposition rate was enhanced by VWC2 when applied to mouse cranial bone defect in vivo. VWC2 addition also increased the expression of key osteogenic markers Osterix and Runt-related transcription factor 2 (Runx2) in primary osteoblast cells. In conclusion, VWC2 positively regulates bone formation possibly through Osterix and Runx2 upregulation.
Human γδ T cells are subdivided into two main subsets, Vδ1 and Vδ2 T cells, based on the expression of the Vδ T cell receptor (TCR) subunit. Most peripheral blood γδ T cells express both Vδ2 and Vγ9 TCR subunits. Vγ9Vδ2 T cells are known to play a key role in immunity against microbial infection and tumors via recognition of non-peptide phospho-antigens. Here, we investigated the antigen-independent cytokine-dependent activation of ex vivo expanded Vγ9Vδ2 T cells. We found that IL-15, but not IL-2, induced cell division in ex vivo expanded Vγ9Vδ2 T cells in the absence of antigen stimulation.
Psoralen ultraviolet A (PUVA) therapy using the cytotoxicity of ultraviolet radiation combined with 8-methoxypsoralen (8-MOP) is performed in the field of dermatology. As there are many disorders common to the oral mucosa and skin, treatments for refractory disorders of the skim may also be applicable to oral mucosal disorders. We, therefore, performed phototoxicity tests using 8-MOP primarily on cultured cells from oral tissues.
The cell lines used were the mouse Balb/3T3, rat osteosarcoma UMR-106, rat squamous cell carcinoma SCC-158, human oral squamous cell carcinoma HSC-2, and human tongue squamous cell carcinoma HSC-3 and HSC-4. 8-MOP was added to the culture medium in 2-dimensional culture and 3-dimensional culture using porcine Type I collagen gel. The cells were irradiated with ultraviolet light at 375 nm using an LED irradiation system. The control group was not irradiated. After 24-hour static culture, the cell survival rate was determined by MTT assay.
In 2-dimensional culture, strong phototoxicity tended to be observed in cells derived from tumors. In 3-dimensional culture, phototoxicity varied in strength among cell types, and it was milder than in 2-dimensional culture, suggesting insufficient transmission of ultraviolet light to cells through the collagen gel. In cultured cells derived from tumors, the effects of photoirradiation varied among cell lines. As collagen may have inhibited transmission of ultraviolet light, a method to more efficiently deliver ultraviolet light to cells in deep areas of the body is needed.
Pure titanium surface is strongly bound to the bone when embedded as a dental implant, with high biocompatibility to the soft tissue around the implant. However, the mechanical strength of Ti-6Al-4V alloy is superior to that of pure titanium. Titanium alloy products account for about 40% of all implant products in Japan. Of the composition elements of Ti-6Al-4V alloy, vanadium has a higher toxicity than the others. Ti-6Al-4V alloys are employed in various titanium alloy implant products. In the present study, cell differentiation and proliferation levels were examined with a polished Ti-6Al-4V alloy in three-dimensional ES cell culture on collagen, demonstrating no developmental toxicity of Ti-6Al-4V alloy. However, Ti-6Al-4V alloy powder corroded with a hydrofluoric acid solution had effects on the differentiation and proliferation of ES cells.
It has been reported that RE-06 experimentally produced as a remineralization-accelerating agent by GC Corp., induces remineralization of demineralized dentin. We analyzed the effect of RE-06 on odontoblast-like cell (MDPC-23) by determining cell proliferation and gene expression related to mineralization.
A new media with RE-06 liquid-A, B and a mixture were exposed into the MDPC-23 cells respectively. The cells were then incubated for 1, 2 and 4 days. Then mRNA expression of BMP-2, 4 and Cbfa1 genes were analyzed by RT-PCR. Cell proliferation was done of MDPC-23, and was measured after 1, 2 and 4 days.
For the group containing liquid-A, BMP-2 and 4 were expressed only on day 2. Cbfa1 expression was seen only during day 2 and 4.
For the group with mixed A and B, BMP-2 and Cbfa1 were expressed at day 1 and 2 and BMP-4 was expressed on all days. Cell proliferation containing RE-06 was lower compared to the control. No cell growth was observed in liquid-A or with mixed A and B. These findings suggest that RE-06, particularly liquid-A regulates the expression of mineralization–related genes and inhibits the growth of MDPC-23 cells.
Phototoxicity, i.e., cytotoxicity caused by light irradiation, is due to the biological effects of active oxygen and free radicals, generated by energy released upon the excitement of chemical substances by ultraviolet irradiation, and those of photoexcited chemical substances. We have already conducted a phototoxicity test on 8-MOP using six cell types, including mouse-derived 3T3 cells and human oral cavity-derived tumor cells, demonstrating potent phototoxicity in oral cancer-derived cells.
Since hyperkeratosis occurs in some oral mucosal diseases as in inflammatory keratosis (psoriasis), a phototoxicity test was conducted with human keratinocytes. As a result, the phototoxicity of 8-MOP was demonstrated in two-dimensional culture, and was more significant in three-dimensional culture.
This study compared bone regeneration ability following non-demineralized dentin granule transplantation and autogenous bone grafting. A critical-sized bone defect was created at the center of the calvaria in rats, and autologous bone and dentin were transplanted. All specimens were evaluated microradiographically and histologically. Computed tomography (CT) analysis revealed no difference in the amount of hard tissue between the dentin-transplanted group and the autologous bone-grafted group 8 weeks after surgery. Tissue analysis revealed that the defect was almost entirely replaced with new bone in the autogastric bone-grafted group 8 weeks after surgery. About half of the dentin granules remained in the dentin-transplanted group, and the rest were replaced with autologous bone. These results suggest that dentin was slowly replaced by new bone while securing the space at the transplantation site, even after a long period of transplantation.
The preservatives added to cosmetics and quasi-medicines inhibit the growth and bacteriostasis of microorganisms. However, since they also have effects on cells, their safety and effects on the human body are of marked concern. In this study, therefore, the relationship between the preservative efficacy and cytotoxicity of preservatives was basically investigated from the viewpoint of cosmetic safety management. Two common preservatives, whose skin stimulation or contact dermatitis tests have been reported, were used. Especially, the inhibition of bacteria growth and bacteriostasis of the very common methyl para-hydroxybenzoate were examined in comparison with phenoxyethanol. The preservative efficacy tests showed a decrease in the survival rate of microorganisms and a different tendency for each type of bacteria and preservative. In the case of concurrent use, a synergistic effect was observed. On the other hand, in cytotoxicity tests, the cell survival rate in the methyl para-hydroxybenzoate solution decreased gradually at first, and then markedly dropped with an increase in the concentration of the preservative, contrarily to the proportional decrease in the phenoxyethanol. In the case of concurrent use, the cell survival rate in the phenoxyethanol solution decreased slightly more than on single use, because of the effect of the initially added methyl para-hydroxybenzoate. In this study, it was found that quite different tendency existed in the relationship between the preservative efficacy and cytotoxicity of each preservative.