神澤 信行

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.

Protein adsorption is essential for determining material biocompatibility and promoting adherent cell growth. In this study, we focused on the a-plane structure of hydroxyapatite (HAp). This a-plane structure closely resembles the crystal plane where apatite is exposed in long bones. We conducted protein adsorption experiments using HAp ceramics with a preferred orientation to a-planes (aHAp), employing bovine serum albumin (BSA), lysozyme, and fetal bovine serum (FBS) as protein models to mimic the in vivo environment. Higher zeta potential and contact angle values were found in aHAp than in HAp ceramics fabricated from commercial HAp powder (iHAp). Bradford-quantified protein adsorption revealed BSA adsorption of 212 ng·mm−2 in aHAp and 28.4 ng mm−2 in iHAp. Furthermore, the Bradford-quantified protein adsorption values for FBS were 2.07 μg mm−2 in aHAp and 1.28 µg mm−2 in iHAp. Two-dimensional electrophoresis (2D-PAGE) showed a higher number of protein-derived major spots in aHAp (37 spots) than in iHAp (12 spots). Mass spectrometry analysis of the resulting 2D-PAGE gels revealed proteins adsorbed on aHAp, including secreted frizzled-related protein 3 and vitamin K epoxide reductase complex 1, which are involved in cellular bone differentiation. Overall, these proteins are expected to promote bone differentiation, representing a characteristic property of aHAp.