title: Internalization of isolated functional mitochondria: involvement of macropinocytosis.
abstract: In eukaryotic cells, mitochondrial dysfunction is associated with a variety of human diseases. Delivery of exogenous functional mitochondria into damaged cells has been proposed as a mechanism of cell transplant and physiological repair for damaged tissue. We here demonstrated that isolated mitochondria can be transferred into homogeneic and xenogeneic cells by simple co-incubation using genetically labelled mitochondria, and elucidated the mechanism and the effect of direct mitochondrial transfer. Intracellular localization of exogenous mitochondria was confirmed by PCR, real-time PCR, live fluorescence imaging, three-dimensional reconstruction imaging, continuous time-lapse microscopic observation, flow cytometric analysis and immunoelectron microscopy. Isolated homogeneic mitochondria were transferred into human uterine endometrial gland-derived mesenchymal cells in a dose-dependent manner. Moreover, mitochondrial transfer rescued the mitochondrial respiratory function and improved the cellular viability in mitochondrial DNA-depleted cells and these effects lasted several days. Finally, we discovered that mitochondrial internalization involves macropinocytosis. In conclusion, these data support direct transfer of exogenous mitochondria as a promising approach for the treatment of various diseases.
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medical Science, Kyoto Prefectural University School of Medicine, Kyoto, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Kitani
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kami
authors.forename: Satoaki
authors.initials: S
authors.lastname: Matoba
authors.forename: Satoshi
authors.initials: S
authors.lastname: Gojo
mesh_terms: D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D002584:Cervix Uteri / Q000166:cytology / Q000502:physiology*; D004272:DNA, Mitochondrial / Q000235:genetics; D004717:Endometrium / Q000166:cytology / Q000502:physiology*; D004734:Energy Metabolism; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D021621:Imaging, Three-Dimensional; D008648:Mesoderm / Q000166:cytology / Q000502:physiology*; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D008928:Mitochondria / Q000378:metabolism / Q000637:transplantation* / Q000648:ultrastructure; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology*; D010873:Pinocytosis; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D004272:DNA, Mitochondrial
keywords: macropinocytosis; mitochondrial transfer; rho0 cells