Fig. 1

Mechanisms of mitochondrial transfer. a Formation of TNTs. Cells move apart and form TNTs with each other. Mitochondria can be transported in TNTs using Miro1 as a dynamic protein. Formation of TNTs can be stimulated via low serum, high glucose concentrations, OGD, or H₂O₂ that activate the ROS/TNF-α/NF-κB/TNFαIp2 pathway. Microvesicles (MVs) ranging from 0.1 to 1 μm containing mitochondria can be released from stem cells and engulfed by recipient cells. Mitochondria without MVs released from stem cells can be engulfed by recipient cells through micropinocytosis. Artificial isolated mitochondria can be engulfed by recipient cells through actin-dependent mitochondria internalization. b Gap junction-mediated mitochondrial transfer. Cells containing Cx43 proteins initially closely contact with target cells, followed by formation of gap junction. ATP adenosine triphosphate, Miro1 mitochondrial Rho-GTPase 1, NF nuclear factor, ROS reactive oxygen species, TNF tumor necrosis factor