Influence of lithium ion doping and mitoxantrone hydrochloride loading on the structure and in vitro biological properties of mesoporous bioactive glass microspheres in the treatment of multiple myeloma

Multiple myeloma (MM) is an incurable plasma cell hematologic tumor in which bone pain is a typical symptom. The current main treatment methods not only easily cause multidrug resistance but also cause bacterial infections. Therefore, improving multidrug resistance and bacterial infection during MM therapy and repairing bone defects caused by bone pain are necessary. In this work, we propose a drug delivery platform of lithium-doped  bioactive glass microspheres (7Li-MBGs) with a mesoporous structure (2–5 nm) and a high specific surface area (636 m 2 /g) to achieve these functions. Interestingly, lithium ions are network modifier doped into the silicon-oxygen network. This in turn affects the dissolution and release behavior of silicon ions in the MBGs network. Thus, the bioactive response as well as drug release of the MBGs were enhanced. During this process, hydroxyapatite easily forms on the surface, which has a therapeutic effect on bone defects caused by MM. The drug (mitoxantrone hydrochloride, MTO) release mechanism is diffusion-driven, suggesting that drug/platform interactions are key determinants of release kinetics and depend on the release medium environment and platform structure. In vitro antibacterial and cytotoxicity experiments proved that the synergistic effect of Li ions and the MTO improved the antibacterial ability of the MBGs (> 98%) and the ability to treat MM. Therefore, the proposed 7Li-MBGs drug delivery platform can effectively release drugs in the long-term, repair bone defects, inhibit bacterial growth and tumor cell activity, and provide new ideas for the treatment of MM.