Human polar body transfer eliminates the transmission of inherited mitochondrial DNA variants [methylation]

Although polar body transfer (PBT) has the potential to prevent the transmission of inherited mitochondrial DNA (mtDNA) diseases, the PBT technique is still at an early stage, as no human data are publicly available for PBT. Here, we investigated the comparative values of first and second PBT (PB1T, PB2T), spindle-chromosome and pronuclear transfer (ST, PNT), modified ST and PNT (mST and mPNT) to explore the efficiency and safety of these approaches. A comparative analysis confirmed that PB1T, mST, PB2T and mPNT could be used to donate mtDNA without resulting in significant heteroplasmy or alterations in the methylation profile and gene expression. Importantly, PB1T produced reconstructed embryos and embryonic stem cells (ESCs) in every generation with undetectable donor mtDNA. However, donor mtDNA seems to have a tendency to be amplified in generations of mPNT-ESCs with up to 3% heteroplasmy. These results suggest that PB1T holds great potential in eliminating mtDNA variants. Nine samples, one negative control and one positive control were analysised, each sample replicate three times.