Mesenchymal stem cells (MSCs) have become important seed cells in therapy because of their immunosuppressive function and anti-inflammatory effects. MSCs exert immunosuppressive effects through direct contact or paracrine action. The paracrine functions of MSCs are at least partially mediated by exosomes, which are membrane vesicles, carrying abundant proteins, nucleic acids and other active molecules. MSC-exos have heterogeneity. The exosomes from different donors, tissues generations of MSCs carry different bioactive molecules. These cargos are transferred to recipient cells by endocytosis or binding to proteins on the receptor surface to mediate intercellular communication between different cell types and affect the functions of the recipient cells. Exosomes play an important role in the regulation of the immune system. Exosomes derived from MSCs (MSC-exos) carry immunomodulatory effectors or transmit active signal molecules to regulate the biological activities of immune cells and thus mediating immune suppression, especially on macrophages and T cells. Mitochondria and autophagy-related pathways are also associated with MSC-exos immunosuppressive effects.

间充质干细胞（MSCs）因其免疫抑制功能和抗炎作用已成为治疗中重要的种子细胞。间充质干细胞通过直接接触或旁分泌作用发挥免疫抑制作用。MSCs 的旁分泌功能至少部分由外泌体介导，外泌体是一种膜囊泡，携带丰富的蛋白质、核酸和其他活性分子。MSC-exos 具有异质性。来自不同供体、组织代间充质干细胞的外泌体携带不同的生物活性分子。这些货物通过内吞作用或与受体表面的蛋白质结合转移到受体细胞，以介导不同细胞类型之间的细胞间通讯并影响受体细胞的功能。外泌体在免疫系统的调节中起重要作用。来自间充质干细胞的外泌体（MSC-exos）携带免疫调节效应子或传递活性信号分子以调节免疫细胞的生物活性，从而介导免疫抑制，尤其是对巨噬细胞和T细胞的免疫抑制。线粒体和自噬相关通路也与 MSC-exos 免疫抑制作用有关。