Bioceramics Enhance the Anti-Tumor Activity of Immune Cells in Adoptive Immunotherapy

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.