Figure 2.

The possible intercellular mitochondrial transfer mechanisms from MSCs to rescue injured cells. (A) The structural components of TNTs formed between MSCs and injured cells contain F-actin and microtubules. (B) Mitochondria can be enveloped in vesicles and transferred to injured cells together with other cytosolic contents. (C) Direct cell-to-cell contact can transfer mitochondria through the formation of gap junction, where gap junctions are transmembrane complexes of connexin proteins. (D) Free mitochondria alone can be internalized by recipient cells without carrier, yet, the exact uptake mechanism remains unknown. (E) Cell fusion is another transfer mechanism, where cytosolic content and organelles such as mitochondria can be shared or exchanged between cells.