MicroRNAs secreted by human preimplantation embryos and IVF outcome.

OBJECTIVE: To generate an effective embryo prediction model and identify a non-invasive evaluation method by analyzing microRNAs (miRNAs) in embryo culture medium. DESIGN: Analysis of microRNA profiles from spent culture medium of blastocysts with good morphology that did or did not result in pregnancy. SETTING: Clinical and experimental research. PATIENTS: Sixty patients who underwent thawed embryo transfer of blastocysts after intracytoplasmic sperm injection. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The association of miRNA abundance levels secreted by blastocysts in culture medium and implantation success. RESULTS: Our RNA sequencing analysis found a total of 53 differentially expressed miRNAs in the culture media of pregnancy and non-pregnancy groups. Twenty-one miRNAs were analyzed for their potential to predict implantation success. Eight miRNAs (hsa-miR-191-5p, hsa-miR-320a, hsa-miR-92a-3p, hsa-miR-509-3p, hsa-miR-378a-3p, hsa-miR-28-3p, hsa-miR-512-5p, and hsa-miR-181a-5p) were further extracted from the results of a logistic regression analysis of qPCR Ct values. A prediction model for high-quality blastocysts was generated using the eight miRNAs, with an average accuracy of 0.82 by 5-fold cross validation. CONCLUSION: We isolated blastocyst miRNAs that may predict implantation success and created a model to predict viable embryos. Increasing the number of investigated cases and further studying the effect of each miRNA on embryonic development is needed to refine the miRNA-based predictive model.

Examination of clinical factors affecting intrauterine microbiota.

PURPOSE: Following reports of an increase in implantation and pregnancy continuation rates by a higher percentage of Lactobacillus in the intrauterine microbiota, it has received attention in infertility treatment. This study aimed to examine Japanese women for intrauterine microbiota. METHODS: The clinical background factors in women that influence the abundance of Lactobacillus in the bacterial microbiota were examined. We included 147 patients (31 and 116 in the follicular and luteal phase, respectively), from June 2018 to June 2020, who underwent their first intrauterine microbiota test and had not used antibiotics for at least 4 weeks before the test. In the luteal phase, we compared the background factors of women in cases with 90% or more and less than 90% of Lactobacillus. Differences in the intrauterine microbiota were examined during the follicular and luteal phases. RESULTS: The proportion of Lactobacillus tended to be low among women aged 36 years and older with a history of childbirth (P = 0.0631). Some bacteria were only detected during the follicular and luteal phases, and the bacterial microbiota may change during the menstrual cycle. CONCLUSION: Bacterial microbiota in the uterus may differ between the follicular and luteal phases. Furthermore, it was shown that the rate of Lactobacillus may be lower in women (older than 36 years) who had given birth, indicating that intrauterine microbiological testing may be considered for these women in clinical practice. LAY SUMMARY: Good implantation and pregnancy continuation rates have been reported when the proportion of the bacteria Lactobacillus is high in the uterus (intrauterine) bacterial population (microbiota). In this study, we assessed whether the clinical background of Japanese women (age, history of pregnancy and childbirth, and presence of gynecological or hormonal disorders) affect the proportion of intrauterine microbiota. Intrauterine samples were collected and sequenced to evaluate the intrauterine microbiota and the composition ratio of each bacterium. Comparing the percentage of Lactobacillus in the latter phase of the menstrual cycle with the clinical background, it was found that the percentage tended to be lower in women with a history of childbirth. We compared the intrauterine microbiota between the first phase and latter phase of the menstrual cycle and revealed that it may differ between the two phases. Advances in the development of criteria for assessing intrauterine microbiota are expected.