Labeling of mitochondria for detection of intercellular mitochondrial transfer

The phenomenon of intercellular transfer of mitochondria has been reported and has attracted significant interest in recent years. The phenomena involve a range of physiological and pathological conditions, such as tumor growth, immunoregulation, and tissue regeneration. There is speculation on the potential restoration of cellular energy status through the transfer of healthy mitochondria from donor cells to cells with impaired mitochondria. Multiple mechanisms and routes of mitochondria transfer have been suggested, including direct cell-to-cell connections, extracellular vesicles, and cell fusion. However, there is limited understanding regarding the precise mechanisms behind mitochondrial transfer, particularly the initiation signals and the associated processes. In order to explore these fundamental mechanisms of mitochondrial transfer, it is imperative to employ techniques that enable direct labeling of mitochondria. Here, we present a detailed methodology utilizing fluorescent protein tagging to visualize mitochondria. The molecular biological techniques applied in this study entail the precise localization of mitochondria with reduced cytotoxicity. This approach facilitates the direct observation of transferred mitochondria through fluorescent and confocal microscopy. The described method can be readily implemented in other mammalian cell types with few modifications, enabling the continuous monitoring of mitochondrial trafficking processes over an extended period.