Mitochondrial transfer from adipose-derived regenerative cells contributes therapeutic angiogenesis in a murine hindlimb ischemia model.

OBJECTIVE: Adipose-derived regenerative cells (ADRCs) are promising cell sources for damaged tissue regeneration. The efficacy of therapeutic angiogenesis with ADRC implantation in patients with critical limb ischemia has been demonstrated in clinical studies. There are several possible mechanisms in this process such as cytokines and microRNA. Recently, cell-to-cell transfer of mitochondria gains more attention in regenerative medicine. However, the role of the mitochondrial transfer mechanism in ADRCs in the regeneration of functional tissue perfusion following ischemic injury remains unclear. In this study, we aimed to investigate whether mitochondrial transfer is a potential mechanism of therapeutic angiogenesis in ADRCs using a murine hindlimb ischemia model. METHODS AND RESULTS: In initial studies, the occurrence of mitochondrial transfer of ADRC to endothelial cells and macrophages in a series of pro-angiogenic effects of ADRC was demonstrated in a mouse model of hindlimb ischemia. Subsequently, we comprehensively elucidated the modes of mitochondrial transfer from ADRCs to HUVECs and macrophages mediated by Connexin43-based gap junctions and tunneling nanotubes using time-lapse confocal microscopy and cell sorting techniques. Furthermore, mitochondrial transfer from ADRCs enhanced mitochondrial biogenesis and angiogenesis in vascular endothelial cells and shifted macrophages toward the M2-phenotype. Notably, partially canceled mitochondrial transfer from ADRCs could impede the angiogenic ability of ADRCs in hind limb ischemia. CONCLUSIONS: ADRCs can protect against ischemic limbs, at least in part by mitochondrial transfer via gap junctions and tunneling of nanotubes into injured endothelial cells and macrophages. Additionally, mitochondrial transfer is a potential mechanism for therapeutic angiogenesis with ADRCs in hindlimb ischemia.