Supplementary data.xlsx

Telomere length(TL) is important for the maintaining the individual health of a species. However, recent studies have indicated that the telomere length of somatic cells can be drastically decreased in the offspring receiving in vitrofertilization (IVF) therapy, however, the underlying molecular mechanism remains unknown. Sirt6 is a NAD+-dependent epigenetic regulator that has recently been found to play an important role in maintaining telomere stability. Here, we report for the first time that NAD+ levels are significantly lower in blastocysts cultured in vitro than that in blastocysts developed in vivo, leading to impaired Sirt6 function, further triggering telomere shortening of the inner cell mass and possibly affecting newborn offspring. This phenotype could be effectively mitigated by supplementation with nicotinamide mononucleotide (NMN), a precursor of NAD+, during in vitro culture, while it could not be achieved in Sirt6 conditional knockout embryos. Furthermore, mtROS accumulation and epigenetic modifications may also be involved in this process. Our results reveal the mechanism by which in vitro culture induces telomere shortening in preimplantation embryos, providing a potential target for improving in vitro culture conditions.