Nuclear Reprogramming Through Oxygen-Independent Metabotype Purges Dysfunctional Mitochondrial Heteroplasmy

Technology #2012-007

Mitochondrial disease is inherited through maternal transmission of mutated mitochondrial DNA (mtDNA) with disease phenotypes determined by the unpredictable mixture of mutant and wild-type mtDNA. Mitochondrial heteroplasmy is dependent upon stochastic segregation of mtDNA into discrete units during early embryogenesis as mtDNA replication is shut off during blastomere expansion. Since nuclear reprogramming resets a somatic cell into a primitive pluripotent ground state, we have herein demonstrated that bioengineering induced pluripotent stem (iPS) cells triggers a reduction in mtDNA dependency and results in the ability to isolate isogenic iPS clones that have purged mutated forms of mtDNA. In fact, with successful nuclear reprogramming we were able to maintain a stable iPS cell line that did not contain any detectable levels of mutant mtDNA in dramatic contrast to the 50% heteroplasmy of starting patient-derived fibroblasts. Thus, nuclear reprogramming with metabotype conversion to oxygen-independent and glycolytic-dependency produced isogenic pluripotent stem cell lines with healthy mitochondria! genotypes. This novel discovery opens a new field of biomedical research to enable patient-specific iPS cells to provide a spectrum of bioengineered heteroplasmy that includes autologous cell lines cured of disease-causing mutations and thus can be leveraged for therapeutic and diagnosic strategies for mitochondrial medicine.