(M-485) Hypoxia-Reoxygenation Induces Intercellular Mitochondria Transfer

Introduction:: Peripheral artery disease (PAD) is a condition in which the vascular network is damaged or obstructed, leading to a reduction in oxygen supply to surrounding tissue. PAD affects over 8 million over the age of 40 in the US. The etiology of PAD involves vicious cycles of reactive oxygen species (ROS)-induced oxidative damage to mitochondria, driving the cell death of inflicted myofibers. Intriguingly, as a remnant from the endosymbiotic mitochondrial origin, recent evidence suggests that mitochondria retain the ability to transfer intercellularly, furthering mitochondrial transplantation as a potential means for therapeutic intervention. We hypothesize that during ischemic injury, an intercellular transfer of healthy mitochondria from muscle progenitor cells occurs to rescue and alleviate mitochondrial damage, therefore, regenerating skeletal tissue.


Materials and Methods:: Mitochondria from the mitoDendra transgenic mouse model were isolated to track the transfer of muscle-derived mitochondria. Isolated mitochondria were transferred to cultured myoblasts that underwent cyclic ischemic reperfusion. To induce hypoxia-reoxygenation, myoblast cells were pre-conditioned to a 20%-5%-20% oxygen incubation for 10 minutes in between incubation, for 4 cycles, then cultured at 20% oxygen over time. Changes in mitochondrial morphology were assessed with confocal microscopy, and bioenergetic function was tested using the Seahorse Mito Stress Test. Finally, fibro-adipogenic progenitor cells (FAPs) were co-cultured with hypoxia-injured myoblasts, and the rate of mitochondrial transfer was tracked via live cell imaging. Cell viability and cellular respiration were reassessed in co-cultured groups.


Results, Conclusions, and Discussions:: Based on preliminary in-vivo data, mitochondrial content was significantly upregulated post-ischemic injury. Additionally, following muscle stem cell transplantation, mitochondria efficiently fused with dysfunctional host myofibers, driving the rejuvenation of bioenergetics in skeletal tissue. Intercellular transfer of mitochondria to damaged myofibers was investigated by priming myoblast cells with cyclic ischemic reperfusion. Successful transfer and endocytosis of isolated muscle-derived mitochondria was observed. Additionally, higher transfer and density of novel mitochondria in myoblasts was observed with increasing concentration of transferred, isolated mitochondria. However, no significant changes in bioenergetic function were recorded. Overall, these data indicate that ischemic reperfusion induces intercellular mitochondrial transfer in order to alleviate oxidative stress and rescue dysfunction. This relationship may provide insight into mitochondria-based therapeutics in ischemic-related diseases like PAD, strokes, and cardiomyopathy.


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