Clinical Relevance of Secreted Small Noncoding RNAs in an Embryo Implantation Potential Prediction at Morula and Blastocyst Development Stages

Abstract

Despite the improvements in biotechnological approaches and the selection of controlled ovarian hyperstimulation protocols, the resulting pregnancy rate from in vitro fertilization (IVF) protocols still does not exceed 30–40%. In this connection, there is an acute question of the development of a non-invasive, sensitive, and specific method for assessing the implantation potential of an embryo. A total of 110 subfertile couples were included in the study to undergo the IVF/ICSI program. Obtained embryos for transfer into the uterine cavity of patient cohort 1 (n = 60) and cohort 2 (n = 50) were excellent/good-quality blastocysts, and small noncoding RNA (sncRNA) content in the corresponding spent culture medium samples at the morula stage (n = 43) or at the blastocyst stage (n = 31) was analyzed by deep sequencing followed by qRT-PCR in real time. Two logistic regression models were developed to predict the implantation potential of the embryo with 100% sensitivity and 100% specificity: model 1 at the morula stage, using various combinations of hsa_piR_022258, hsa-let-7i-5p, hsa_piR_000765, hsa_piR_015249, hsa_piR_019122, and hsa_piR_008112, and model 2 at the blastocyst stage, using various combinations of hsa_piR_020497, hsa_piR_008113, hsa-miR-381-3p, hsa_piR_022258, and hsa-let-7a-5p. Protein products of sncRNA potential target genes participate in the selective turnover of proteins through the ubiquitination system and in the organization of the various cell cytoskeleton and nucleoskeleton structures, regulating the activity of the Hippo signaling pathway, which determines the fate specification of the blastomers.

Cellular and Molecular Nature of Fragmentation of Human Embryos

“…It is beyond any doubt that, in the near future, a wide panel of the investigations from the fields of experimental and applied embryology should have been targeted at the precisely identifying and comprehensively exploring a broad spectrum of morphological, ultrastructural, biochemical, and molecular determinants responsible for increased incidence of the processes leading to initiation and progression of embryo fragmentation. The thorough characterization of the aforementioned determinants seems to be strongly justified in order to recognize the highly predictable biomarkers related to diminishments in not only molecular quality parameters, but also the extracorporeal and peri-implantation developmental capabilities of the ex vivo produced embryos created by such modern ARTs as in vitro fertilization and intracytoplasmic sperm injection in humans and other mammalian species and somatic cell nuclear transfer (SCNT)-mediated cloning in other mammalian species [114][115][116][117][118][119].…”

Non-Coding RNAs as Biomarkers for Embryo Quality and Pregnancy Outcomes: A Systematic Review and Meta-Analysis

“…Only the cell-free miRNA-20a family [ 42 , 51 , 57 ] was found to be highly concentrated in good-quality or successfully implanted embryos in three studies. However, contradictory results were found in the correlation of four miRNAs, namely, miR-30c [ 42 , 57 ], miR-21-5p [ 51 , 54 ], miR-191 [ 38 , 56 ] and let-7i-5p [ 50 , 52 , 55 ], with pregnancy outcomes ( Table 3 ).…”

“…To evaluate the performance of sncRNAs in predicting IVF outcomes, we further performed a meta-analysis on three studies [ 45 , 55 , 59 ] with raw statistics available. As shown in Figure 2 , the pooled sensitivity and specificity were 0.79 (95% CI 0.72, 0.85) and 0.67 (95% CI 0.52, 0.79), respectively.…”

“…Three members of let-7 , including let-7a-5p [ 55 ], let-7b-5p [ 52 ] and let-7i-5p [ 52 , 55 ], were dysregulated in the SCM of poor-quality and non-implanted embryos. The let-7 family is one of the first miRNA families discovered in C. elegans , and it consists of 12 members in humans [ 83 ].…”

“…Lin-28 is critical to the self-renewal of pluripotent stem cells [ 85 ], while a high level of let-7 is associated with induced cell differentiation and reduced cell proliferation [ 85 , 86 ]. Interestingly, a combination of let-7b-5p and let-7i-5p , together with two piRNAs ( piR-016735 and piR-020381 ), can predict pregnancy outcomes modestly [ 55 ]. Therefore, it is also worth evaluating the practicability of combined extracellular snRNAs in predicting pregnancy outcomes in future research.…”