A study conducted by the scientists at Oregon Health & Science University in Portland provides hope for people with abnormal embryos looking for infertility treatments. This study was published in the journal Genome Research.
An embryo contains 46 chromosomes, half from each of the parents. In some cases, there is an abnormality present in the embryo. The chromosomes present in the embryo are not perfect as some have more and some have fewer than others.
This abnormality is known as aneuploidy. Aneuploidy is very common and is found in 80% of human embryos.
Aneuploidy is said to be associated with a risk of miscarriage, vitro fertilization failure, birth defects or some genetic disorders. Aneuploidy is also linked to mosaic embryos, which means embryos with both normal and abnormal cells.
There are people who only produce mosaic embryos and are therefore not considered fit candidates for In vitro fertilization (IVF) transfer.
To conduct this study, scientists used a non-human primate model. Scientists used advanced time-lapse imaging and single cell sequencing techniques to track mosaic embryos of a rhesus macaque.
The results indicated a unique relationship between mosaicism and two other biological processes, blastomere exclusion, and cell fragmentation.
Shawn L. Chavez, the lead author of the paper said, “We found that both the blastomeres and their fragments can act as trash bins within the embryo. As DNA-carrying cells divide and/or fragment, the embryo appears to naturally identify which blastomeres have genetic abnormalities and stop them from further development.”
Chavez also said that “By the stage that an embryo would implant into the uterus, these abnormal cells, or DNA have been visibly excluded from the rest of the embryo, suggesting that imperfect IVF embryos could be considered for use in transfer and might have the ability to endure in utero.”
The findings reveal that in patients with only mosaic embryos available for IVF transfer, the embryos can result in normal pregnancies.
According to the scientists, a further study is required to better understand the relationship between aneuploidy, blastomere exclusion and cell fragmentation within the embryo.
The scientists claim that this study confirms that in a non-human primate, mosaic embryos can adapt to their abnormalities and persist in development, resulting in positive IVF outcomes. These results provide hope for people seeking infertility treatments.
The scientists also believe that these findings can help open new paths for testing the efficacy of mosaic human embryos.