Stem Leydig cells support macrophage immunological homeostasis through intercellular mitochondria transfer in a TRPM7-mediated manner in the testis
As a unique population of testicular mesenchymal stromal cells, stem Leydig cells (SLCs) have shown great promise in the treatment of male hypogonadism. The therapeutic functions of MSCs are largely determined by their reciprocal regulation by immune responses. However, the immunoregulatory properties of SLCs have not been fully studied. Here, we found that transplanted SLCs restored testicular immunological homeostasis via damage signal-triggered transient receptor potential cation channel subfamily member 7 (TRPM7)-mediated mitochondrial transfer to macrophages. Specifically, the results showed that SLCs transplantation restored male fertility and testosterone production in an ischemia?reperfusion injury-induced acute inflammation model. This was achieved mainly via a mechanism involving the prevention of inflammatory cascades but not the differentiation to Leydig cells (LCs), the main testosterone-producing cells. Furthermore, we identified that ROS released from activated macrophages, which are the primary testicular immunocytes, induced nanotube-mediated mitochondrial transfer from SLCs to macrophages via TRPM7. Notably, TRPM7 knockdown by interfering RNA in transplanted SLCs compromised the therapeutic outcomes in both testicular ischemia?reperfusion and testicular aging mouse models. Collectively, SLC rescued testicular damage in testicular ischemia?reperfusion mouse models, and the damage signal activated TRPM7 signaling and induced mitochondrial transfer from SLCs to macrophages, playing important roles in the repair of SLCs. These findings provide insight into the clinical translation of SLCs and suggest that strategies targeting mitochondrial transfer may be effective treatments for patients with male hypogonadism related to immune disorders. Overall design: We analyzed the RNA profiles in mouse primary bone marrow mesenchymal stromal cells (BMSCs) and stem Leydig cells (SLCs)