EPO-modified bone marrow MSCs alleviate asthma inflammation through enhanced mitochondrial activation and transfer by upregulating HO-1

Bone marrow mesenchymal stem cells (BM-MSCs) can rejuvenate injured cells through mitochondrial transfer. Our previous study has highlighted the ability of erythropoietin (EPO)-modified BM-MSCs (EPO-BM-MSCs) to relieve asthmatic inflammation. Here, we elucidated whether EPO-BM-MSCs improve asthmatic phenotype by mitochondrial transfer and investigated the underlying mechanism. EPO-BM-MSCs and different modified EPO-BM-MSCs were generated. Ovalbumin (OVA)-induced asthma mouse models were established, and mtCC1-2 cells were treated with CoCl2 to mimic in vitro asthmatic phenotype. EPO-BM-MSC engraftment and mitochondrial transfer from EPO-BM-MSCs to epithelial cells were assessed by fluorescent microscopy and flow cytometry. Mitochondrial membrane potential, ROS production and tunnelling nanotube (TNT) formation were detected by flow cytometry or fluorescent microscopy. Intratracheal transplantation of EPO-BM-MSCs alleviated airway inflammation, asthmatic phenotype, and mitochondrial dysfunction in the lungs of OVA-induced asthma mice. Moreover, EPO-BM-MSCs had more efficient effects than BM-MSCs. EPO-BM-MSCs diminished CoCl2-triggered mitochondrial dysfunction in mtCC1-2 cells in vitro, which could be reversed by the inhibitors of TNT formation. When CoCl2-stimulated mtCC1-2 cells were co-cultured with EPO-BM-MSCs, TNT formation significantly increased. EPO-BM-MSCs were validated to donate mitochondria to mtCC1-2 cells through intercellular TNTs in vitro and pulmonary epithelial cells in vivo. EPO-BM-MSCs-upregulated HO-1 contributed to enhanced mitochondrial transfer and improved anti-inflammatory efficacy. Additionally, M-sec promoted intercellular TNT formation and Miro1 enhanced mitochondrial transfer from EPO-BM-MSCs to mtCC1-2 cells. Our findings demonstrate that EPO-BM-MSCs rescue epithelial cell injury by mitochondrial donation by upregulating HO-1 to alleviate asthma inflammation, providing novel evidence for the therapeutic potential of EPO-BM-MSCs in asthma.