Mitochondrial gene replacement in primate offspring and embryonic stem cells

Abstract

Mitochondria are found in all eukaryotic cells and contain their own genome (mtDNA). Unlike the nuclear genome which is derived from both the egg and sperm at fertilization, the mtDNA in the embryo are derived almost exclusively from the egg, i.e. is of maternal origin. Mutations in mtDNA contribute to a diverse range of still incurable human diseases and disorders. To establish preclinical models for new therapeutic approaches, we demonstrate here that the mitochondrial genome can be efficiently replaced in mature nonhuman primate oocytes by spindle-chromosomal complex transfer from one egg to an enucleated, mitochondrial-replete egg. The reconstructed oocytes with the mitochondrial replacement were capable of supporting normal fertilization, embryo development and produced healthy offspring. Genetic analysis confirmed that nuclear DNA in the three infants born so far originated from the spindle donors while mtDNA came from the cytoplast donors. No contribution of spindle donor mtDNA was detected in offspring. Spindle replacement is shown here as an efficient protocol replacing the full complement of mitochondria in newly generated embryonic stem cell lines. This approach may offer a reproductive option to prevent mtDNA disease transmission in affected families.