Injectable silk sericin scaffolds with programmable shape-memory property and neuro-differentiation-promoting activity for individualized brain repair of severe ischemic stroke.

Abstract

Severe ischemic stroke damages neuronal tissue, forming irregular-shaped stroke cavities devoid of supporting structure. Implanting biomaterials to provide structural and functional support is thought to favor ingrowth of regenerated neuronal networks. Injectable hydrogels capable of <i>in situ</i> gelation are often utilized for stroke repair, but challenged by incomplete gelation and imprecise control over end-macrostructure. Injectable shape-memory scaffolds might overcome these limitations, but are not explored for stroke repair. Here, we report an injectable, photoluminescent, carbon-nanotubes-doped sericin scaffold (CNTs-SS) with programmable shape-memory property. By adjusting CNTs' concentrations, CNTs-SS' recovery dynamics can be mathematically calculated at the scale of seconds, and its shapes can be pre-designed to precisely match any irregular-shaped cavities. Using a preclinical stroke model, we show that CNTs-SS with the customized shape is successfully injected into the cavity and recovers its pre-designed shape to well fit the cavity. Notably, CNTs-SS' near-infrared photoluminescence enables non-invasive, real-time tracking after <i>in vivo</i> implantation. Moreover, as a cell carrier, CNTs-SS not only deliver bone marrow mesenchymal stem cells (BMSCs) into brain tissues, but also functionally promote their neuronal differentiation. Together, we for the first time demonstrate the feasibility of applying injectable shape-memory scaffolds for stroke repair, paving the way for personalized stroke repair.