biostudies-literatureLi WNational Basic Research Program of ChinaNational Natural Science Foundation of Chinae217https://www.ebi.ac.uk/biostudies/studies/S-EPMC10167372biostudies-literatureUnknown4(3)The second polar body (PB2) transfer in assisted reproductive technology is regarded as the most promising mitochondrial replacement scheme for preventing the mitochondrial disease inheritance owing to its less mitochondrial carryover and stronger operability. However, the mitochondrial carryover was still detectable in the reconstructed oocyte in conventional second polar body transfer scheme. Moreover, the delayed operating time would increase the second polar body DNA damage. In this study, we established a spindle-protrusion-retained second polar body separation technique, which allowed us to perform earlier second polar body transfer to avoid DNA damage accumulation. We could also locate the fusion site after the transfer through the spindle protrusion. Then, we further eliminated theMedCommEarlier second polar body transfer and further mitochondrial carryover removal for potential mitochondrial replacement therapy.PMC101673722018YFC1003000320005998187116381901478Cai RXie YMa MLiao XSi JChen LGao HZhang SChen CKuang YLi WYan ZZhao LGuo HYu WLin KWang YLyu QfalseEarlier second polar body transfer and further mitochondrial carryover removal for potential mitochondrial replacement therapy.The second polar body (PB2) transfer in assisted reproductive technology is regarded as the most promising mitochondrial replacement scheme for preventing the mitochondrial disease inheritance owing to its less mitochondrial carryover and stronger operability. However, the mitochondrial carryover was still detectable in the reconstructed oocyte in conventional second polar body transfer scheme. Moreover, the delayed operating time would increase the second polar body DNA damage. In this study, we established a spindle-protrusion-retained second polar body separation technique, which allowed us to perform earlier second polar body transfer to avoid DNA damage accumulation. We could also locate the fusion site after the transfer through the spindle protrusion. Then, we further eliminated the2023-01-01T00:00:00Z2023 Jun2026-07-14T20:07:42.255Z2025-04-06T14:35:12.325ZS-EPMC101673723718082310.1002/mco2.217