Microfluidic Encapsulation of Genetically Engineered Bone‐marrow‐derived Mesenchymal Stem Cells for Bone Defect Healing

Mesenchymal stem cells (MSCs) hold significant potential for bone healing. Current efforts focus on enhancing stem cell viability and differentiation potential to improve therapeutic outcomes. Here, we transfected bone MSCs (BMSCs) with RUNX2 plasmid nanoparticles (BMSCs^pRUNX2) and encapsulated them into gelatin methacryloyl (GelMA) hydrogel microcarriers (BRGMs) for bone regeneration. As the BRGMs were generated from microfluidics, they possess uniform sizes and good injectability to fit the complex shapes of clinical bone defects. In addition, they can maintain the high cell viability and further osteogenic induction capacity of loaded engineered BMSCs^pRUNX2. Moreover, enhanced osteogenic differentiation of them in vitro was also proved by the detection of osteogenic differentiation genes and proteins expression, staining of alkaline phosphatase, and alizarin red. Based on these features, we have demonstrated satisfactory bone regeneration in situ when the BRGMs were added into 5 mm full-thickness rat calvarial defects for 8 weeks. Therefore, we believed that the proposed microfluidic encapsulation of genetically engineered BMSCs platform is a promising candidate for bone defect healing.