For instance, efficient cartilage repair was achieved without requiring cell transplantation in a rabbit model of cartilage defect by injecting photopolymerizable acrylated HA containing KTG-loaded NPs. This hybrid system recruited chondrocytes as well as stem cells (bone marrow and synovium-derived), promoted their differentiation into chondrocytes and resulted in efficient defect filling. Three months after surgery, the biomechanical properties (i.e., reduced modulus and hardness values) of the repaired cartilage were similar to those of intact tissue, allowing it to withstand external pressure. Concomitant loading of drugs with cells, either simply dispersed or encapsulated within NPs, has been an attractive approach to achieve higher therapeutic efficacy. For instance, stem cells were embedded into an ALG matrix along with berberine-loaded CS NPs, resulting in an effective scaffold capable of promoting substantial functional recovery after injection at the site of spinal cord injury in rats. In another example, IL-15 and Chimeric Antigenic Receptor -T cells (CAR-T) cells were coloaded in a hybrid hydrogel with the aim to build an inflammatory niche. When SC administered, this approach outperformed intravenous and peritumoral conventional administration of CAR-T cells in terms of anticancer activity against a murine model of solid tumor, whether closely located to the injection site of the hydrogel or distant. This revealed an abscopal effect, which could acquire relevance in the treatment of inaccessible or metastatic tumors (Figure ). Figure T cells administered with different delivery methods. (e) Schematic illustrating tumor placement of SC and distal SC treatments alongside representative luminescent imaging of tumors using in vivo imaging. Adapted with permission. Copyright 2022 American Association for the Advancement of Science.