The present invention relates to a method using a cell penetrating peptide (Pep-1) for labeling and delivering mitochondria separated from healthy cells to replace damaged mitochondria. At present, microinjection of mitochondria into cells can only process one cell at a time, and therefore, this technique is limited to embryo related research and relevant applications. The advantages of the said peptide-mediated mitochondrial delivery system (PMD) include less steps with more efficiency, where a number of cells can be treated following one labeling process the delivery process can be easily controlled, there is no cell toxicity after delivery under appropriate conditions, and delivery efficiency is over 80% depending on different cell types. Mitochondria delivered by the PMD system will move to the original mitochondrial location in the cells and will not be catalyzed in lysosomes thus, the therapeutic effects can last at least one week.
