An injectable hydrogel microsphere-integrated training court to inspire tumor-infiltrating T lymphocyte potential

Although tumor-infiltrating T lymphocytes (TIL-Ts) play a crucial role in solid tumor immunotherapy, their clinical application has been limited because of the immunosuppressive microenvironment. Herein, we developed an injectable hydrogel microsphere-integrated training court (MS-ITC) to inspire the function of TIL-Ts and amplify TIL-Ts, through grafting with anti-CD3 and anti-CD28 antibodies and bovine serum albumin nanoparticles encapsulated with IL-7 and IL-15. MS-ITC provided the T-cell receptor and co-stimulatory signals required for TIL-Ts activation and IL-7/IL-15 signals for TIL-Ts expansion. Afterward, the MS-ITC was injected locally into the osteosarcoma tumor tissue in mice. MS-ITC suppressed the growth of primary osteosarcoma by more than 95 %, accompanied with primed and expanded TIL-Ts in the tumor tissues, compromising significantly increased CD8⁺ T and memory T cells, thereby enhancing the anti-tumor effect. Together, this work provides an injectable hydrogel microsphere-integrated training platform capable of inspiring TIL-Ts potential for a range of solid tumor immunotherapy.