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Hydroxyapatite (HAp) is similar to the main inorganic components of bone and tooth enamel. Furthermore, it possesses biocompatibility, making it suitable for clinical use in artificial bones. This study aimed to verify whether the preferred orientation of HAp influences osteogenesis. Using the templated grain growth method, we successfully fabricated HAp ceramics with a preferred orientation to m (a)-planes (aHAp) and examined the effects of this orientation on bone differentiation. Osteosarcoma-derived osteoblasts (MG-63) were cultured on aHAp and HAp ceramics made from commercially available powder (iHAp). Electron backscatter diffraction analysis revealed the crystal orientation distribution of HAp ceramics and the numerous exposed a-planes of aHAp. The MG-63 cultured on aHAp exhibited significantly higher alkaline phosphatase activity, a marker of early bone differentiation, compared to iHAp. Furthermore, the two-dimensional electrophoresis results indicated that the expressed proteins differed between aHAp and iHAp. These results indicate that controlling HAp's crystal structure may promote the osteogenic potential of osteoblasts. In this study, we propose that the a-plane of HAp promotes bone differentiation during the early stages, presenting a promising approach for novel biomaterials, such as high-performance artificial bones. [ABSTRACT FROM AUTHOR]

Recent research has focused on immunotherapy with no side effects as an innovative medical treatment for cancer. However, typical drugs for immunotherapy are very expensive. Here, we propose the use of immunoceramics that activate immune cells by contact with their surface. Previous studies demonstrated that polymers, including the phenylboronic acid group, could activate lymphocytes. This activation may be due to the interaction between the sugar chains in cells and the OH group in B(OH)3 formed via the dissociation of the BO2 group. We have clarified that boron-containing apatite (BAp) activated lymphocytes in vitro. In this study, we fabricated the ceramic surfaces using the CaO-P2O5-SiO2-B2O3 system (CPSB ceramics) containing BAp as a main crystalline phase. The results of the in vitro evaluation indicated that killer T cells in splenocytes cocultured with the CPSB ceramics were more numerous than in splenocytes cocultured on a control surface. The results of the in vivo evaluation indicated that the CPSB ceramics significantly inhibited tumor growth when CD8-positive T cells were cultured on individual ceramics and subsequently injected into tumor-bearing mice. The present CPSB ceramics are expected to be a valuable biomaterial for immunotherapy. [ABSTRACT FROM AUTHOR]

We have previously reported that a novel bioresorbable self‐setting injectable bone paste composed of hydroxyapatite/collagen bone‐like nanocomposite (HAp/Col) and (3‐glycidoxypropyl)trimethoxysilane (GPTMS) was successfully prepared and was replaced with new bone within 3 months of implantation in defects created in porcine tibia. In this study, the HAp/Col‐GPTMS paste was implanted into bone defects in rat tibiae to investigate the initial kinetics and bone tissue response. Even though more than 35% of GPTMS molecules should be eluted rapidly from directly injected pastes according to previously reported cell culture tests, in this study, energy‐dispersive X‐ray spectrometry did not detect Si (GPTMS) deposition in tissues surrounding the paste at 1 day postimplantation. Further, no abnormal inflammatory responses were observed in the surrounding tissues over the test period for both directly injected and prehardened pastes. Companying these observations with the results of the previous animal test (in which the paste was fully resorbed and was substituted with new bone), the eluted GPTMS resolved in no harm in vivo from the initial to final (completely resorbed) stages. Material resorption rates calculated from X‐ray microcomputed tomography (μ‐CT) images decreased with increasing in GPTMS concentration. Histological observations indicated that tartrate‐resistant acid phosphatase (TRAP) active cells, (assumed to be osteoclasts), exist on the periphery of pastes. This result suggested that the paste was resorbed by osteoclasts in the same way as the HAp/Col. Since a good correlation was observed between TRAP active areas in histological sections and material resorption rate calculated from μ‐CT, the TRAP activity coverage ratio offers the possibility to estimate the osteoclastic resorption ratio of materials, which are replaced with bone via bone remodeling process. [ABSTRACT FROM AUTHOR]

Ex vivo tissue engineering is an effective therapeutic approach for the treatment of severe cartilage diseases that require tissue replenishment or replacement. This strategy demands scaffolds that are durable enough for long‐term cell culture to form artificial tissue. Additionally, such scaffolds must be biocompatible to prevent the transplanted matrix from taking a toll on the patient's body. From the viewpoint of structure and bio‐absorbability, a β‐tricalcium phosphate (β‐TCP) fiber scaffold (βTFS) is expected to serve as a good scaffold for tissue engineering. However, the fragility and high solubility of β‐TCP fibers make this matrix unsuitable for long‐term cell culture. To solve this problem, we developed an alginate‐coated β‐TCP fiber scaffold (βTFS‐Alg). To assess cell proliferation and differentiation in the presence of βTFS‐Alg, we characterized ATDC5 cells, a chondrocyte‐like cell line, when grown in this matrix. We found that alginate coated the surface of βTFS fiber and suppressed the elution of Ca2+ from β‐TCP fibers. Due to the decreased solubility of βTFS‐Alg compared with β‐TCP, the former provided an improved scaffold for long‐term cell culture. Additionally, we observed superior cell proliferation and upregulation of chondrogenesis marker genes in ATDC5 cells cultured in βTFS‐Alg. These results suggest that βTFS‐Alg is suitable for application in tissue culture. [ABSTRACT FROM AUTHOR]

Population ageing has increased the incidence of osteoporosis, which is mainly treated by using artificial bone. To practically utilise an artificial bone, it is necessary to synthesise bioceramics and evaluate their physical and biological properties, which requires animal experiments. To refine these properties, bioceramics must be evaluated repeatedly, which requires more time, money, and animal sacrifice. In a previous study, a machine learning model was used to predict the bone formation rate as a function of synthesis conditions, physical properties, and implant conditions before performing any animal experiments. However, the model did not consider bioceramic structure, which may be an important predictor of bone formation rate. In this study, we used scanning electron microscope (SEM) images of artificial bones to analyse their structural properties and extract important features for predicting bone formation rate, including grain size and contour, and latent variables were transformed using an autoencoder constructed with SEM images. The features and latent variables were used as inputs for a machine learning model predicting bone formation rate. The coefficient of determination of the proposed model was higher than that of the conventional model, thus confirming that a highly accurate model to predict bone formation rate can be constructed using important features in SEM images. [ABSTRACT FROM AUTHOR]

Hydroxyapatite and β-tricalcium phosphate have been clinically applied as artificial bone materials due to their high biocompatibility. The development of artificial bones requires the verification of safety and efficacy through animal experiments; however, from the viewpoint of animal welfare, it is necessary to reduce the number of animal experiments. In this study, we utilized machine learning to construct a model that estimates the bone-forming ability of bioceramics from material fabrication conditions, material properties, and in vivo experimental conditions. We succeeded in constructing two models: 'Model 1′, which predicts material properties from their fabrication conditions, and 'Model 2′, which predicts the bone-formation rate from material properties and in vivo experimental conditions. The inclusion of full width at half maximum (FWHM) in the feature of Model 2 showed an improvement in accuracy. Furthermore, the results of the feature importance showed that the FWHMs were the most important. By an inverse analysis of the two models, we proposed candidates for material fabrication conditions to achieve target values of the bone-formation rate. Under the proposed conditions, the material properties of the fabricated material were consistent with the estimated material properties. Furthermore, a comparison between bone-formation rates after 12 weeks of implantation in the porcine tibia and the estimated bone-formation rate. This result showed that the actual bone-formation rates existed within the error range of the estimated bone-formation rates, indicating that machine learning consistently predicts the results of animal experiments using material fabrication conditions. We believe that these findings will lead to the establishment of alternative animal experiments to replace animal experiments in the development of artificial bones. [ABSTRACT FROM AUTHOR]