Safety and Risks · Procedure-Attributable Risk
de Waal E et al., 2015 · Human molecular genetics
Assisted reproductive technologies (ART) are associated with several complications including low birth weight, abnormal placentation and increased risk for rare imprinting disorders. Indeed, experimental studies demonstrate ART procedures independent of existing infertility induce epigenetic perturbations in the embryo and extraembryonic tissues. To test the hypothesis that these epigenetic perturbations persist and result in adverse outcomes at term, we assessed placental morphology and methylation profiles in E18.5 mouse concepti generated by in vitro fertilization (IVF) in two different genetic backgrounds. We also examined embryo transfer (ET) and superovulation procedures to ascertain if they contribute to developmental and epigenetic effects. Increased placental weight and reduced fetal-to-placental weight ratio were observed in all ART groups when compared with naturally conceived controls, demonstrating that non-surgical embryo transfer alone can impact placental development. Furthermore, superovulation further induced overgrowth of the placental junctional zone. Embryo transfer and superovulation defects were limited to these morphological changes, as we did not observe any differences in epigenetic profiles. IVF placentae, however, displayed hypomethylation of imprinting control regions of select imprinted genes and a global reduction in DNA methylation levels. Although we did not detect significant differences in DNA methylation in fetal brain or liver samples, rare IVF concepti displayed very low methylation and abnormal gene expression from the normally repressed allele. Our findings suggest that individual ART procedures cumulatively increase placental morphological abnormalities and epigenetic perturbations, potentially causing adverse neonatal and long-term health outcomes in offspring.
Safety and Risks · Procedure-Attributable Risk
de Waal E et al., 2012 · Human molecular genetics
We previously demonstrated that intracytoplasmic sperm injection (ICSI), a type of assisted reproductive technology (ART), can induce epimutations and/or epimutant phenotypes in somatic tissues of adult mice produced by this method. In the present study, we compared the occurrence of epimutations in mice produced by natural conception, ICSI and somatic cell nuclear transfer. Surprisingly, we observed the highest frequency of epimutations in somatic tissues from ICSI-derived mice. We also observed a delay in reprogramming of the maternal allele of the imprinted H19 gene in spermatogonia from juvenile ICSI-derived male mice. These observations led us to hypothesize that the exposure of the maternal gametic genome to exogenous gonadotropins during the endocrine stimulation of folliculogenesis (superovulation) may contribute to the disruption of the normal epigenetic programming of imprinted loci in somatic tissues and/or epigenetic reprogramming in the germ line of ensuing offspring. To test this hypothesis, we uncoupled superovulation from ICSI by subjecting female mice to gonadotropin stimulation and then allowing them to produce offspring by natural mating. We found that mice produced in this way also exhibited epimutations and/or epimutant phenotypes in somatic tissues and delayed epigenetic reprogramming in spermatogenic cells, providing evidence that gonadotropin stimulation contributes to the induction of epimutations during ART procedures. Our results suggest that gonadotropin stimulation protocols used in conjunction with ART procedures should be optimized to minimize the occurrence of epimutations in offspring produced by these methods.
Safety and Risks · Procedure-Attributable Risk
Rivera RM et al., 2008 · Human molecular genetics
In vitro culture of mouse embryos results in loss of imprinting. The aim of the present study was to examine how two of the techniques commonly used during assisted reproduction, namely embryo culture and embryo transfer, affect genomic imprinting after implantation in the mouse. F1 hybrid mouse embryos were subjected to three experimental conditions: control (unmanipulated), embryo transfer and in-vitro-culture followed by embryo transfer. Concepti were collected on d9.5 of development and allelic expression determination of ten imprinted genes (H19, Snrpn, Igf2, Kcnq1ot1, Cdkn1c, Kcnq1, Mknr3, Ascl2, Zim1, Peg3) was performed. Although control concepti had monoallelic imprinted gene expression in all tissues, both manipulated groups had aberrant expression of one or more imprinted genes in the yolk sac and placenta. Culture further exacerbated the effects of transfer by increasing the number of genes with aberrant allelic expression in extraembryonic, as well as embryonic tissues. Additionally, placentae of both groups of manipulated concepti exhibited reduced levels of Igf2 mRNA and increased levels of Ascl2 mRNA when compared with their unmanipulated counterparts. Furthermore, we show that biallelic expression of Kcnq1ot1 coincided with loss of methylation on the maternal allele of the KvDMR1 locus, a phenotype often associated with the human syndrome Beckwith-Wiedemann. In conclusion, our results show that even the most basic manipulation used during human-assisted reproduction, namely, embryo transfer, can lead to misexpression of several imprinted genes during post-implantation development. Additionally, our results serve as a cautionary tale for gene expression studies in which embryo transfer is used.
Cancer and Fertility · Hormone Sensitive Cancer and Reproductive Care
Chen C et al., 2024 · Critical reviews in oncology/hematology
The effects of ovarian stimulation on breast and gynecological tumor incidence remain controversial. Therefore, the aim of this meta-analysis was to study the risk of cancer in ovarian stimulation. Of the 22713 studies initially identified, 28 were eligible for inclusion. The results revealed that the impact of ovarian cancer (RR = 1.33, [1.05; 1.69]) and cervical cancer (RR = 0.67, [0.46; 0.97]) is significant among the overall effects. In subgroup analysis, in the nulliparous population (RR = 0.81 [0.68; 0.96]) was the protective factor for the breast cancer. In the Caucasians subgroup (RR = 1.45, [1.12; 1.88]), the ovarian cancer incidence was statistically significant. In the Asian subgroup (RR = 1.51, [1.00; 2.28]), the endometrial cancer incidence was statistically significant. In the subgroup of Asians (RR = 0.55 [0.44; 0.68]) and the multiparous population (RR = 0.31, [0.21; 0.46]), them can be the statistically protective factor for the cervical cancer.