Mitochondrial transfer between eukaryotic animal cells and its physiologic role

Experiments recently reported by the Prockop laboratory show that some form of mitochondrial transfer can occur among cells in vitro and can have a physiologic role by rescuing the respiration of respiration-deficient cells. However, these results do not establish whether it was only mtDNA or whole functional mitochondria that were transferred, or if the latter, whether the mitochondria were transferred through direct cytoplasmic transport or as discrete vesicles. Two hypotheses are discussed here concerning the physiologic role of mitotransfer (the first is preferred): (a) respiration-competent mitochondria transfer from respiration-competent cells to respiration-deficient cells with damaged mitochondria (the "entropy" scenario); and (b) respiration-competent mitochondria transfer from predominantly respiration-deficient cells to respiration-competent cells, which provide a more favorable host environment (the "selfish" scenario).