Multiscale hydrogel regulates mesenchymal stem cell fate for bone regeneration

<h2>Summary</h2> Hydrogels are commonly utilized as a three-dimensional cell culture platform. High-stiffness hydrogels promote directional cell differentiation, but they may also restrict cellular activity. Here, we report a process utilizing sacrificial templates and nanoparticles for the preparation of multiscale hydrogels with macroporous and locally enhanced stiffness properties. The macroporous hydrogels provide ample space for cells, which facilitates cell activity and proliferation. Chemical doping of the nanoparticles creates a locally stiffness-enhanced region without affecting its macroscopic mechanical properties. This regional stiffness promotes osteogenic differentiation of encapsulated adipose-derived mesenchymal stem cells (ADSCs). Importantly, the functional activity of the ADSCs increases significantly after osteogenic differentiation in hydrogels. Notably, the hydrogels efficiently activate mechanotransduction signals in the ADSCs and influence their fate. In addition, ADSC-loaded multiscale hydrogels promote bone regeneration of rat cranial defects in animal experiments. Collectively, our findings demonstrate that this technique has promising applications in the biomedical field.