Magnetic labeling of physically tunable hydrogel-induced mesenchymal stem cell spheroids with IONPs for MRI tracking and bone regeneration

Bone tissue engineering based on seed cells, biomimetic scaffolds and growth factors emerges as a novel therapeutic option for bone defect. The survival, retention, and function of seed cells after implantation into the defect area are crucial for bone tissue regeneration. However, conventional transplantation of seed cells has limitations such as insufficient transplantation efficiency, survival rate, and cell function. Non-invasive monitoring of engrafted cells to dynamically acquire their growth and differentiation information in vivo presents a challenge in developing tissue engineering applications. Here, we reported magnetically labeled stem cell spheroids induced by physically tunable hydrogel for magnetic resonance imaging (MRI) tracking and bone regeneration. The magnetic stem cell spheroids, integrating spheroid cultivation with the magnetic responsiveness of iron oxide nanoparticles, demonstrated enhanced osteogenic functionality and MRI visibility. This approach is anticipated to facilitate dynamic non-invasive monitoring of cell survival, differentiation, and other status in tissue engineering complexes, thereby expanding its application in visualizing bone defect restoration.