Nanoparticle encapsulated core-shell hydrogel for on-site BMSCs delivery protects from iron overload and enhances functional recovery.

The local microenvironment may influence the success of stem cell therapy. Iron overload occurs in many hemorrhagic injuries due to hemolysis and hemoglobin degradation, which not only mediates local cell injury, but also induces damage to the transplanted cells. Here, an injectable nanoparticle encapsulated core-shell hydrogel was fabricated for simultaneous iron overload clearance and bone marrow mesenchymal stem cells (BMSCs) transplantation following intracerebral hemorrhage (ICH). The iron chelator-loaded low-molecular-weight keratin hydrogel with quick degradation property was selected as the outer shell to eliminate iron overload, and BMSCs implantation with high-molecular-weight keratin hydrogel was selected as the inner core. The epidermal growth factor and the basic fibroblast growth factor were entrapped within the poly (lactic-co-glycolic acid) (PLGA) nanoparticle, which was then encapsulated into the core hydrogel to support the BMSC growth and differentiation. The core-shell hydrogel can be easily formed by programmed injections, and the core-shell hydrogel displayed a strong protective effect against the toxicity of hemoglobin in cell experiments. Furthermore, more BMSCs survived in the core-shell hydrogel group in vivo as compared to that in the core hydrogel group and the vehicle group. Less iron deposition and ventricular enlargement, lower brain water content, and faster neurological recovery were also observed. The data demonstrated that this core-shell hydrogel is an effective strategy for promoting transplanted cell survival under the condition of an iron overload.