Injectable Modular Cellularized Blocks via Dual-Photocrosslinking for Enhanced Cell Therapy

Cell-based regenerative medicine is limited by poor survival of transplanted cells and the lack of scalable, ready-to-use delivery platforms. Here, we developed an injectable dual-photocrosslinking microsphere (DP-MS) bioink composed of Ru/SPS, o-nitrobenzyl-modified hyaluronic acid (HANB), and gelatin methacryloyl (GelMA). Orthogonal green (525 nm) and UV (365 nm) light enable sequential crosslinking: first to generate cell-laden microspheres, and the second step requires only 10 s to induce inter-microsphere imine bonding without external adhesives. The dual-photocrosslinking strategy preserved inter-microsphere spaces, facilitated rapid vascular ingrowth, and enhanced cell survival. In a subcutaneous implantation model, vascular volume in the DP-MS group was approximately 7-fold greater than that of constructs lacking inter-microsphere voids; furthermore, encapsulated stem cells maintained persistent viability over 14 days. Importantly, this superior performance translated into significantly accelerated bone regeneration in a rat mandibular defect model. This platform thus provides a versatile and scalable strategy for developing cellularized products with clinical translation potential.