[Mitochondrial therapy: a new strategy for treating mitochondrion-associated diseases].

Mitochondrion is a multifunctional organelle in cells and responsible for energy production, cell apoptosis and various life processes. Dysfunctional mitochondria are associated with hundreds of diseases. Increasing evidences have shown that extracellular mitochondria can be endocytosed by cells, directly into cells, and then play roles in cells. Mitochondria are the organelles that are extremely sensitive to oxygen content and pH of microenvironment that induces the adverse effect based on the cellular environment: mitochondria will increase cell survival and viability when they arrive in cells of physiological environment, but mitochondria will cause cell death when they enter the hypoxic and acidic tumor tissues, because they can produce a large amounts of oxygen free radicals. The pharmacological feature of environmental responsiveness of mitochondria could make them as a potential biological drug to kill cancer cells and restore the function of damaged tissues. Currently, mitochondria are used in the treatment of central nervous system diseases (Parkinson's disease, depression, schizophrenia, etc.), peripheral system diseases (ischemic myocardial injury, fatty liver, emphysema, etc.) and tumor. In this review, we summarize the research progress, medical application and challenges of mitochondrial therapy.