Fabrication of boron-containing apatite ceramics via reaction sintering route and their response of lymphocytes for adoptive immunotherapy

Conventional cancer treatments have several challenges, such as side effects and physical decline. Recently, adoptive immunotherapy, which has few side effects, has attracted attention, but the use of expensive drugs has become an issue. In addressing this problem, boron-containing apatite (Ca_9.5+0.5x{(PO₄)_6-x(BO₃)_x}{(BO₂)_1-xO_x} (0 ≤ <i>x</i> ≤ 1); BAp) ceramics, which are referred to as "immunoceramics," have been developed to actively engage the immune system and enhance the activation of CD3+CD8+ cells corresponding to killer T cells. The BAp ceramics have been fabricated via ultrasonic spray pyrolysis (USSP); however, a deviation from the stoichiometric composition occurred when x in the chemical formula was small. Therefore, in this study, the synthesis method was changed from USSP to "reaction sintering". The material properties of the fabricated BAp ceramics confirmed the synthesis of the BAp phase. In particular, the BAp ceramics fabricated by reaction sintering have a composition closer to stoichiometry than those synthesized by USSP. Furthermore, when immune cells derived from mouse spleen were cultured on BAp ceramics, the immune cells cultured on the BAp ceramics fabricated by reaction sintering remarkably increased the percentage of CD3+CD4+ cells corresponding to helper T cells and CD3+CD8+ cells compared with those of BAp ceramics fabricated by USSP. When the BAp ceramics were used to culture the immune cells again, the percentage of CD3+CD4+ cells and CD3+CD8+ cells could be increased as in the first culture. In addition, when BAp ceramics were reused for immune cell culture, they increased the percentage of CD3+CD4+ cells and CD3+CD8+ cells as in the first culture. The BAp ceramics may be expected as a novel culture substrate for adoptive immunotherapy.