Abstract: In 2020, the Centers for Disease Control and Prevention reported that only 45% of embryo transfer procedures result in live birth deliveries. Aneuploidy is a common cause of embryo developmental failure, although low-range mosaicism of aneuploidy has displayed some developmental capabilities. The current methods of preimplantation genetic testing for aneuploidy (PGT-A) often overlook the possibility of genetic mosaicism within an embryo. Furthermore, studies have not demonstrated favorable effects of PGT-A on improving live birth rates. Recent research has identified microRNA (miRNA) markers in trisomy cell lines that may serve as predictors for developmental potential. Similarly, these miRNAs released by mammalian embryos into the culture media are essential, unbiased, and non-invasive markers for evaluating embryo quality. However, using human embryos as a research model raises ethical challenges. To address the ethical considerations of our research, we have successfully generated blastoids from naïve-like human induced pluripotent stem cells (hiPSC) of Trisomy 21 (Tri21) origin. An isogenic subclone with corrected ploidy status (Disomy 21; Di21) was included as an euploid control. Blastoids generated from Tri21 hiPSC exhibited a fluid-filled cavity and the self-organization of three primary cell lineages, comparable to those created from Di21 hiPSC. miRNA markers associated with developmental competence (e.g., miR-191, miR-320a, miR-372, and miR-16) were evaluated in blastoids and their spent culture media fractions using RT-qPCR. Elevated levels of miR-320a, -372, and -16 were observed in the spent culture media fraction of Tri21-origin blastoids compared to those of Di21 origin, suggesting a differential miRNA profile correlating with ploidy status. Our study demonstrates that blastoids generated from hiPSCs of known aneuploid status present a promising and ethically sound model of aneuploid human embryos. We highlight the potential of these models in providing valuable insights into identifying miRNA markers of developmental competency.
Funding Source: Canadian Institutes of Health Research (CIHR), Children’s Health Research Institute (CHRI)
