Fig. 1.

Schematic illustration for the principles of bone defects filling and repair by MMSC. The MMSs are not only of the desired physicochemical properties to meet the requirement of injectable bone cement for clinical application, but also can be cured into a 3D interconnected porous scaffold conducive to cells and tissue ingrowth in situ. Moreover, the controllable biodegradation of MMSC continuously provides increasing space while the release of magnesium ions induces a tissue repair favourable immunoregulation via the M2 phenotype polarization of macrophages for the consecutive vascularization and new bone formation.