Selective expansion and differentiation of antigen-specific CD4+ T-helper cells by engineered extracellular vesicles.

Extracellular vesicles (EVs), particularly small EVs (sEVs), are lipid bilayer vesicles secreted by various cell types and play a key role in intercellular communication. These vesicles are promising tools for cancer immunotherapy owing to their biocompatibility, low immunogenicity, and capacity for targeted drug delivery. In this study, we aimed to assess the potential of engineered antigen-presenting EVs (AP-EVs) to selectively expand and differentiate antigen-specific CD4⁺ T cells. We engineered two types of AP-EVs: AP-EVs-Th1 expressing MHC class II, CD80, and interleukin (IL)-12 on their surface to promote Th1 differentiation, and AP-EVs-Th2 expressing MHC class II, CD80, and IL-4 to induce Th2 differentiation. In vitro experiments demonstrated that AP-EVs successfully induced the antigen-specific proliferation and differentiation of Th1 and Th2 cells, respectively. Notably, in vivo administration of AP-EVs-Th1 significantly enhanced the proliferation and differentiation of tumor antigen-specific Th1 cells, leading to robust anti-tumor effects in a murine melanoma model. These findings highlight the potential of AP-EVs-Th1 for cancer immunotherapy, particularly in augmenting CD4⁺ T cell responses. Furthermore, the versatility and adaptability of EV-based therapies make them beneficial for the development of personalized immunotherapeutic strategies for various cancer types, offering the advantages of targeted immune modulation, ease of use, and reduced risk compared to cell-based therapies.