Challenges to Widespread Use of Fertility Preservation Facilities for Pediatric Cancer Patients in Japan.

Purpose: Although fertility preservation for pediatric cancer patients is becoming more widespread in Japan, some facilities do not provide sufficient information regarding fertility. This study aimed to elucidate the problems pertaining to the lack of information about fertility among patients. Methods: Based on a 2020 survey, seminars addressing fertility preservation were held from the Designated Pediatric Cancer Care Hospitals in each of the seven blocks in Japan to their partner hospital (pediatric cancer hospitals). The seminar consisted of lectures and group discussions, and a questionnaire was also administered after each seminar. Results: In the group discussions, a lack of explanations to patients and explanatory materials for children were cited as issues by many facilities. The survey results revealed a lack of material explaining fertility preservation and a lack of knowledge among health care providers. There were also many requests to use the patient explanation videos presented at the seminar. Conclusion: The results indicate that further education for health care providers by seminar and other sources and enhancement of explanatory materials are important for fertility preservation in pediatric cancer hospitals in Japan.

High doses of intravenous immunoglobulin stimulate regulatory T cell and suppress natural killer cell in women with recurrent pregnancy loss.

The aim was to evaluate whether natural killer (NK) cells and regulatory T (Treg) cells were involved in mechanisms underlying beneficial effects of a high dose of intravenous immunoglobulin (IVIG) on recurrent pregnancy losses (RPL) of unexplained etiology. In a double-blind, randomized, placebo-controlled trial of IVIG (400 mg/kg, for 5 days in 4-6 weeks of gestation) in women with RPL, blood samples were collected pre-infusion, one week after infusion (1 w), and eight weeks of gestation/when miscarried (8 w). Levels of NK and Treg cells in peripheral blood were compared between women with IVIG (n = 50) and placebo (n = 49), and between women with IVIG who gave live birth (n = 29) and those who had miscarriage with normal chromosome (n = 12). Effector Treg cell percentages in IVIG group at 1 w (mean 1.43 % vs. 1.03 %) and at 8 w (1.91 % vs. 1.18 %) were higher than those in placebo group (p < 0.01). Total Treg cell percentages in IVIG group at 1 w (4.75 % vs. 4.08 %) and at 8 w (5.55 % vs. 4.47 %) were higher than those in placebo group (p < 0.05). In women with live birth, total Treg cell percentages increased at 8 w (5.52 %, p < 0.001) compared with pre-infusion (4.54 %) and 1 w (4.47 %), while NK cell activity decreased at 1 w (20.18 %, p < 0.001) compared with pre-infusion (26.59 %). IVIG increased Treg cell percentages and suppressed NK cell activity very early in pregnancy, and these were associated with subsequent live birth. Stimulation of Treg cells and suppression of NK cell activity very early in pregnancy may be a mechanism of pharmacological effects of high dose IVIG.

Pathological variants in genes associated with disorders of sex development and central causes of hypogonadism in a whole-genome reference panel of 8380 Japanese individuals.

Disorders of sex development (DSD) comprises a congenital condition in which chromosomal, gonadal, or anatomical sex development is atypical. In this study, we screened for pathogenic variants in 32 genes associated with DSDs and central causes of hypogonadism (CHG) in a whole-genome reference panel including 8380 Japanese individuals constructed by Tohoku Medical Megabank Organization. Candidate pathogenic (P) or likely pathogenic (LP) variants were extracted from the ClinVar, InterVar, and Human Gene Mutation databases. Ninety-one candidate pathological variants were found in 25 genes; 28 novel candidate variants were identified. Nearly 1 in 40 (either ClinVar or InterVar P or LP) to 157 (both ClinVar and InterVar P or LP) individuals were found to be carriers of recessive DSD and CHG alleles. In these data, genes implicated in gonadal dysfunction did not show loss-of-function variants, with a relatively high tendency of intolerance for haploinsufficiency based on pLI and Episcore, both of which can be used for estimating haploinsufficiency. We report the types and frequencies of causative variants for DSD and CHG in the general Japanese population. This study furthers our understanding of the genetic causes and helps to refine genetic counseling of DSD and CHG.

Intraoperative Placement of an Absorbable Spacer Prior to Radiation Therapy for a Malignant Peripheral Nerve Sheath Tumor.

A 7-year-6-month-old female was diagnosed with a pelvic malignant peripheral nerve sheath tumor and lymph node metastases. Tumorectomy was performed after four cycles of chemotherapy. A 33-mm cystic lesion was observed around the left iliac muscle after three cycles of postoperative chemotherapy, and proton beam therapy (PBT) was recommended. She was referred for absorbable spacer (AS) placement. The left ovarian appendage (OA) was resected due to the direct tumor infiltration. The right OA was fixed to the uterosacral ligament. The AS was fixed to the lateral pelvis. The PBT (70.3 Gy relative biological effectiveness) was performed successfully with the AS, and she also had the reproducing possibility due to prevention of severe irradiation damage of the right OA. AS eliminated the surgical removal of spacers and enabled us high-dose PBT for residual tumor without severe irradiation damage including infertility.

Intravenous immunoglobulin treatment in women with four or more recurrent pregnancy losses: A double-blind, randomised, placebo-controlled trial.

Background: There is no effective treatment for women with unexplained recurrent pregnancy loss (RPL). We aimed to investigate whether treatment with a high dose of intravenous immunoglobulin (IVIG) in early pregnancy can improve pregnancy outcomes in women with unexplained RPL. Methods: In a double-blind, randomised, placebo-controlled trial, women with primary RPL of unexplained aetiology received 400 mg/kg of IVIG daily or placebo for five consecutive days starting at 4-6 weeks of gestation. They had experienced four or more miscarriages except biochemical pregnancy loss and at least one miscarriage of normal chromosome karyotype. The primary outcome was ongoing pregnancy rate at 22 weeks of gestation, and the live birth rate was the secondary outcome. We analysed all women receiving the study drug (intention-to-treat, ITT) and women except those who miscarried due to fetal chromosome abnormality (modified-ITT). This study is registered with ClinicalTrials.gov number, NCT02184741. Findings: From June 3, 2014 to Jan 29, 2020, 102 women were randomly assigned to receive IVIG (n = 53) or placebo (n = 49). Three women were excluded; therefore 50 women received IVIG and 49 women received placebo in the ITT population. The ongoing pregnancy rate at 22 weeks of gestation (31/50 [62·0%] vs. 17/49 [34·7%]; odds ratio [OR] 3·07, 95% CI 1·35-6·97; p = 0·009) and the live birth rate (29/50 [58·0%] vs. 17/49 [34·7%]; OR 2·60, 95% CI 1·15-5·86; p = 0·03) in the IVIG group were higher than those in the placebo group in the ITT population. The ongoing pregnancy rate at 22 weeks of gestation (OR 6·27, 95% CI 2·21-17·78; p < 0·001) and the live birth rate (OR 4·85, 95% CI 1·74-13·49; p = 0·003) significantly increased in women who received IVIG at 4-5 weeks of gestation as compared with placebo, but these increases were not evident in women who received IVIG at 6 weeks of gestation. Four newborns in the IVIG group and none in the placebo group had congenital anomalies (p = 0·28). Interpretation: A high dose of IVIG in very early pregnancy improved pregnancy outcome in women with four or more RPLs of unexplained aetiology. Funding: The Japan Blood Products Organization.

Association of fish intake with menstrual pain: A cross-sectional study of the Japan Environment and Children's Study.

The relationship between fish eating habits and menstrual pain is unknown. Elucidating this relationship can inform dietary guidance for reproductive age women with menstrual pain. The aim of this study was to clarify the relationship between fish intake frequency/preference and menstrual pain. This cross-sectional study was conducted at the Miyagi Regional Center as an adjunct study of the Japan Environment and Children's Study, and 2060 eligible women (mean age, 31.9 years) participated. Fish intake frequency ("< 1 time/week," "1 time/week," "2-3 times/week," or "≥ 4 times/week"), preference ("like," "neutral," or "dislike"), and menstrual pain (no/mild or moderate-to-severe) were assessed at 1.5 years after the last delivery through self-administered questionnaires. The association between fish intake frequency/preference and prevalence of moderate-to-severe menstrual pain was evaluated through logistic regression analyses. Our results show that, compared with the "< 1 time/week" (38.0%) group, the "1 time/week" (26.9%), "2-3 times/week" (27.8%), and "≥ 4 times/week" (23.9%) groups showed a lower prevalence of moderate-to-severe menstrual pain (p < 0.01). The prevalence of moderate-to-severe menstrual pain was 27.7%, 27.6%, and 34.4% in the "like," "neutral," and "dislike" groups, respectively. Multivariate logistic regression showed that frequent fish intake was associated with a lower prevalence of moderate-to-severe menstrual pain ("1 time/week": odds ratio [OR] = 0.59; 95% confidence interval [CI], 0.41-0.86, "2-3 times/week": OR = 0.64; 95% CI, 0.45-0.90 and "≥ 4 times/week": OR = 0.52; 95% CI, 0.34-0.80; trend p = 0.004). Multivariate logistic regression showed no association between fish preference and moderate-to-severe menstrual pain ("dislike" vs "like": OR = 1.16; 95% CI, 0.78-1.73). There was a significant negative association between fish intake frequency and menstrual pain. It is suggested that fish intake can reduce or prevent menstrual pain.

Association between maternal infertility treatment and child neurodevelopment: findings from the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study in Miyagi and Iwate Prefectures, Japan.

OBJECTIVES: This study aimed to examine the association between infertility treatment and neurodevelopment in children at 2 and 3.5 years of age. DESIGN: Prospective cohort study. SETTING AND PARTICIPANTS: The study population consisted of mother-child pairs who participated in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study in Miyagi and Iwate Prefectures, Japan. Pregnant women were recruited in obstetric clinics or hospitals and their children were followed up by the questionnaire. OUTCOME MEASURES: The children's neurodevelopmental outcomes were assessed at 2 and 3.5 years of age using the Ages and Stages Questionnaire, third edition (ASQ-3), which consists of questions on five developmental domains. We performed a multivariate logistic regression analysis of the association between infertility treatment (including ovulation induction (OI), artificial insemination with husband's sperm (AIH) and assisted reproductive technology (ART)) and the clinical range of ASQ-3. RESULTS: Of 9655 mother-child pairs, 273 (2.8%) and 487 (5.0%) were conceived through OI/AIH and ART, respectively. The odds of having developmental delays at 2 years of age were higher in children conceived through OI/AIH (OR, 1.36; 95% CI 1.00 to 1.85) and ART (OR, 1.36; 95% CI 1.07 to 1.72) than in those conceived naturally. Additionally, OI/AIH and ART were significantly associated with communication (OR, 1.93; 95% CI 1.25 to 2.98) and gross motor (OR, 1.50; 95% CI 1.08 to 2.09) delays, respectively. There were no statistically significant differences in the odds of having developmental delays at 3.5 years of age in children conceived through OI/AIH (OR, 1.13; 95% CI 0.79 to 1.61) and ART (OR, 1.03; 95% CI 0.78 to 1.37). CONCLUSION: In this study, we found a significant association between infertility treatment and children's neurodevelopment at 2 years of age, whereas no statistically significant differences were found at 3.5 years of age.

Exploration of the Cytoplasmic Function of Abnormally Fertilized Embryos via Novel Pronuclear-Stage Cytoplasmic Transfer.

In regular IVF, a portion of oocytes exhibit abnormal numbers of pronuclei (PN) that is considered as abnormal fertilization, and they are routinely discarded. However, it is known that abnormal ploidy still does not completely abandon embryo development and implantation. To explore the potential of cytoplasm from those abnormally fertilized oocytes, we developed a novel technique for the transfer of large cytoplasm between pronuclear-stage mouse embryos, and assessed its impact. A large volume of cytoplast could be efficiently transferred in the PN stage using a novel two-step method of pronuclear-stage cytoplasmic transfer (PNCT). PNCT revealed the difference in the cytoplasmic function among abnormally fertilized embryos where the cytoplasm of 3PN was developmentally more competent than 1PN, and the supplementing of fresh 3PN cytoplasm restored the impaired developmental potential of postovulatory "aged" oocytes. PNCT-derived embryos harbored significantly higher mitochondrial DNA copies, ATP content, oxygen consumption rate, and total cells. The difference in cytoplasmic function between 3PN and 1PN mouse oocytes probably attributed to the proper activation via sperm and may impact subsequent epigenetic events. These results imply that PNCT may serve as a potential alternative treatment to whole egg donation for patients with age-related recurrent IVF failure.

Effects of localisation of uterine adenomyosis on outcome of in vitro fertilisation/intracytoplasmic sperm injection fresh and frozen-thawed embryo transfer cycles: a multicentre retrospective cohort study.

BACKGROUND: Uterine adenomyosis is a benign disease, common among women in their 40 and 50 s, characterised by ectopic endometrial tissue in the uterine myometrial layer. Adenomyosis causes infertility and has a negative effect on the outcomes of in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) embryo transfer (ET) cycles. It has also been reported to have different characteristics depending on the adenomyotic lesion localisation. The effect of its localisation on IVF/ICSI-ET outcomes is unclear. This study aimed to investigate whether adenomyotic lesion localisation, assessed using magnetic resonance imaging (MRI), was associated with outcomes of IVF/ICSI-ET cycles. METHODS: This multicentre, joint, retrospective cohort study analysed the medical records of 67 infertile patients with adenomyosis who underwent IVF/ICSI with fresh and frozen-thawed ET at five participating facilities from January 2012 to December 2016 and for whom MRI data were available. Fifteen patients were excluded; therefore, the MRI data of 52 patients were evaluated by two radiologists. We assessed the localisation of and classified adenomyotic lesions into advanced (invades the full thickness of the uterine myometrium), extrinsic (localised on the serosal side), and intrinsic (localised on the endometrial side) subtypes. RESULTS: There were 40 advanced, nine extrinsic, and three intrinsic cases, and the outcomes of 100, 27, and nine ET cycles, respectively, were analysed. Pregnancy loss/clinical pregnancy and live birth rates of the advanced, extrinsic, and intrinsic groups were 64 % (16/25) and 9 % (9/100), 33.3 % (3/9) and 22.2 % (6/27), and 50 % (1/2) and 11.1 % (1/9), respectively. A logistic regression analysis adjusted for age, prior miscarriage, and body mass index showed that the extrinsic group had fewer pregnancy losses (odds ratio 0.06; 95 % confidence interval [CI]: 0.00-0.54, p = 0.026) and more live births (odds ratio 6.05; 95 % CI: 1.41-29.65, p = 0.018) than the advanced group. CONCLUSIONS: Adenomyotic lesions exert different effects on IVF/ICSI-ET outcomes. Thus, MRI assessments of adenomyosis in infertile patients are beneficial. Establishment of treatment plans based on adenomyotic lesion localisation should be considered.

Abnormal early folliculogenesis due to impeded pyruvate metabolism in mouse oocytes†.

Fetal ovarian germ cells show characteristic energy metabolism status, such as enhanced mitochondrial metabolism as well as glycolysis, but their roles in early folliculogenesis are unclear. We show here that inhibition of pyruvate uptake to mitochondria by UK5099 in organ cultures of fetal mouse ovaries resulted in repressed early folliculogenesis without affecting energy production, survival of oocytes, or meiosis. In addition, the abnormal folliculogenesis by UK5099 was partially rescued by α-ketoglutarate and succinate, intermediate metabolites in the TCA cycle, suggesting the importance of those metabolites. The expression of TGFß-related genes Gdf9 and Bmp15 in ovarian germ cells, which are crucial for folliculogenesis, was downregulated by UK5099, and the addition of recombinant GDF9 partially rescued the abnormal folliculogenesis induced by UK5099. We also found that early folliculogenesis was similarly repressed, as in the culture, in the ovaries of a germ cell-specific knockout of Mpc2, which encodes a mitochondria pyruvate carrier that is targeted by UK5099. These results suggest that insufficient Gdf9 expression induced by abnormal pyruvate metabolism in oocytes results in early follicular dysgenesis, which is a possible cause of defective folliculogenesis in humans.

Estimation of the carrier frequencies and proportions of potential patients by detecting causative gene variants associated with autosomal recessive bone dysplasia using a whole-genome reference panel of Japanese individuals.

Bone dysplasias are a group of rare hereditary diseases, with up to 436 disease types. Perinatal diagnosis is clinically important for adequate personalized management and counseling. There are no reports focused on pathogenic variants of bone dysplasias in the general population. In this study, we focused on autosomal recessive bone dysplasias. We identified pathogenic variants using whole-genome reference panel data from 3552 Japanese individuals. For the first time, we were able to estimate the carrier frequencies and the proportions of potential patients. For autosomal recessive bone dysplasias, we detected 198 pathogenic variants of 54 causative genes. We estimated the variant carrier frequencies and the proportions of potential patients with variants associated with four clinically important bone dysplasias: osteogenesis imperfecta (OI), hypophosphatasia (HPP), asphyxiating thoracic dysplasia (ATD), and Ellis-van Creveld syndrome (EvC). The proportions of potential patients with OI, ATD, and EvC based on pathogenic variants classified as "pathogenic" and "likely pathogenic" by InterVar were closer to the reported incidence rates in Japanese subjects. Furthermore, the proportions of potential patients with HPP variants classified as "pathogenic" and "likely pathogenic" in InterVar and "pathogenic" in ClinVar were closer to the reported incidence rates. For bone dysplasia, the findings of this study will provide a better understanding of the variant types and frequencies in the Japanese general population, and should be useful for clinical diagnosis, genetic counseling, and personalized medicine.

Interannual Changes in the Prevalence of Intimate Partner Violence Against Pregnant Women in Miyagi Prefecture After the Great East Japan Earthquake: The Japan Environment and Children's Study.

This study aimed to clarify the interannual changes in intimate partner violence against pregnant women after the March 11, 2011 Great East Japan Earthquake in target areas of Miyagi Prefecture that were damaged by the earthquake and tsunami. Because of this disaster, in Miyagi Prefecture, approximately 12,000 people died or went missing, and approximately 238,000 buildings were destroyed. According to the U.S. Geological Survey, the Great East Japan Earthquake is the fourth largest earthquake in the world and the largest in Japan since 1900. The present study was part of the Japan Environment and Children's Study. Data from June 2011 to May 2014 of 79,222 pregnant women were analyzed, calculating the prevalence of physical and mental intimate partner violence in the inland, north coastal, and south coastal areas of Miyagi. These prevalence rates were compared with nationwide rates of intimate partner violence in 2011 using univariate and logistic regression analyses. After the disaster, the incidence of mental intimate partner violence increased in the south coastal area and then improved later (19.4%, 13.1%, and 13.3% for south coastal area, and 13.8%, 13.8%, and 13.1% for nationwide in 2011, 2012, and 2013, respectively). However, in the north coastal area, the incidence of physical intimate partner violence increased after the disaster and then improved later (2.7%, 1.5%, and 1.3% for north coastal area, and 1.4%, 1.3%, and 1.1% for nationwide in 2011, 2012, and 2013, respectively). In the inland area, however, the prevalence of both mental and physical intimate partner violence was consistently higher than nationwide rates after the disaster.

Successful pregnancy and vaginal delivery after laparoscopic excision of a congenital uterine cervical diverticulum: A case report.

Uterine cervical diverticulum is a very rare malformation. Affected patients are reported to have infertility issues and problems during the perinatal period. A 32-year-old nulliparous woman visited another obstetrics and gynecology hospital because of infertility. A cyst branching out from the uterine cervix was discovered. Subsequently, she conceived via assisted reproductive technology, but the uterine cyst was left untreated. Eventually, the pregnancy was terminated due to an enlarged uterine cyst and several birth defects. She was referred to our hospital where she was diagnosed with a uterine cervical diverticulum. We excised the diverticulum via a laparoscopic approach. Afterward, she became pregnant and delivered a baby vaginally at 37 weeks. To our knowledge, this is the first report of successful delivery after laparoscopic diverticulum excision. We recommend cervical diverticulum excision before pregnancy because of the potential adverse events associated with cervical diverticulum during pregnancy.

A Preclinical Evaluation towards the Clinical Application of Oxygen Consumption Measurement by CERMs by a Mouse Chimera Model.

We have developed an automated device for the measurement of oxygen consumption rate (OCR) called Chip-sensing Embryo Respiratory Measurement system (CERMs). To verify the safety and the significance of the OCR measurement by CERMs, we conducted comprehensive tests using a mouse model prior to clinical trials in a human in vitro fertilization (IVF) program. Embryo transfer revealed that the OCR measured by CERMs did not compromise the full-term development of mice or their future fertility, and was positively correlated with adenosine triphosphate (ATP) production and the mitochondrial membrane potential (ΔΨm), thereby indirectly reflecting mitochondrial oxidative phosphorylation (OXPHOS) activity. We demonstrated that the OCR is independent of embryo morphology (the size) and number of mitochondria (mitochondrial DNA copy number). The OCR correlated with the total cell numbers, whereas the inner cell mass (ICM) cell numbers and the fetal developmental rate were not. Thus, the OCR may serve as an indicator of the numbers of trophectoderm (TE) cells, rather than number or quality of ICM cells. However, implantation ability was neither correlated with the OCR, nor the embryo size in this model. This can probably be attributed to the limitation that chimeric embryos contain non-physiological high TE cells counts that are beneficial for implantation. CERMs can be safely employed in clinical IVF owing to it being a safe, highly effective, non-invasive, accurate, and quantitative tool for OCR measurement. Utilization of CERMs for clinical testing of human embryos would provide further insights into the nature of oxidative metabolism and embryonic viability.

Sarcoidosis of the fallopian tube: A rare case study with confirmed Propionibacterium acnes infection.

Sarcoidosis is a systemic granulomatous disease that is most commonly manifested in the pulmonary system. Though the entire etiology of sarcoidosis remains unknown, it has been reported that Propionibacterium acnes (P. acnes) has been isolated from sarcoid lesions. Herein, we report a case of salpingitis arising from sarcoidosis. A female patient aged 37 years, gravida 2 para 0, who had been diagnosed with sarcoidosis at the age of 36 years, underwent laparoscopic right salpingectomy due to obvious right hydrosalpinx with recurrent refractory right lower abdominal pain. The pathological diagnosis was granulomatous salpingitis of the right fallopian tube suspecting sarcoidosis. Immunocytochemistry using a specific monoclonal antibody against P. acnes lipoteichoic acid (PAB antibody) revealed PAB-positive reaction in sarcoid granuloma. This is the first case of sarcoidosis that the presence of P. acnes was shown in sarcoid lesions in the fallopian tube.

Preconception dysmenorrhea as a risk factor for psychological distress in pregnancy: The Japan Environment and Children's Study.

BACKGROUND: Dysmenorrhea influences emotional distress as well as physical suffering in young non-pregnant women. The aim of this study was to assess the potential association between preconception dysmenorrhea and the development of psychological distress during pregnancy. METHODS: This study was a part of the Japan Environment and Children's Study (JECS), a nationwide birth cohort study conducted between 2011 and 2014 in Japan. A total of 87,102 pregnant Japanese women with no psychological distress (Kessler 6-item psychological distress scale [K6] score ≤ 12) in early pregnancy were eligible. Among these, 7626 had mild and 1638 had severe preconception dysmenorrhea. The prevalence and risk of maternal psychological distress (K6 scores ≥ 13) in the second or third trimester were compared among preconception dysmenorrhea severity groups. RESULTS: A higher percentage of women with mild (2.6%) or severe preconception dysmenorrhea (3.6%) suffered psychological distress during pregnancy compared to that in women without dysmenorrhea (2.1%). A multilevel logistic regression model, adjusting for baseline characteristics and the K6 score at enrollment, showed that the severity of dysmenorrhea was associated with psychological distress (mild dysmenorrhea: adjusted odds ratio [aOR], 1.154; 95% confidence interval [95% CI], 0.980-1.359; and severe dysmenorrhea: aOR, 1.457; 95% CI, 1.087-1.951). LIMITATIONS: Information about dysmenorrhea was obtained during early pregnancy. The JECS did not have clear diagnostic criteria for dysmenorrhea. CONCLUSIONS: Preconception dysmenorrhea is associated with an elevated incidence of psychological distress during pregnancy. Additionally, expectant mothers with a history of severe dysmenorrhea symptoms before pregnancy have a higher risk of developing psychological distress.

Mitochondrial replacement therapy and assisted reproductive technology: A paradigm shift toward treatment of genetic diseases in gametes or in early embryos.

BACKGROUND: Recent technological development allows nearly complete replacement of the cytoplasm of egg/embryo, eliminating the transmission of undesired defective mitochondria (mutated mitochondrial DNA: mtDNA) for patients with inherited mitochondrial diseases, which is called mitochondrial replacement therapy (MRT). METHODS: We review and summarize the mitochondrial biogenesis and mitochondrial diseases, the research milestones and future research agenda of MRT and also discuss MRT-derived potential application in common assisted reproductive technology (ART) treatment for subfertile patients. MAIN FINDINGS: Emerging techniques, involving maternal spindle transfer (MST) and pronuclear transfer (PNT), have demonstrated in preventing carryover of the unbidden (mutated) mtDNA in egg or in early embryos. The House of Parliament in the United Kingdom passed regulations permitting the use of MST and PNT in 2015. Furthermore, the Human Fertilization and Embryology Authority (HFEA) to granted licenses world first use of those techniques in March 2017. However, recent evidence demonstrated gradual loss of donor mtDNA and reversal to the nuclear DNA-matched haplotype in MRT derivatives. CONCLUSION: While further studies are needed to clarify mitochondrial biogenesis responsible for reversion, ruling in United Kingdom may shift the current worldwide consensus that prohibits gene modification in human gametes or embryos, toward allowing the correction of altered genes in germline.

Development of a new clinically applicable device for embryo evaluation which measures embryo oxygen consumption.

STUDY QUESTION: Does a new system-the chip-sensing embryo respiration monitoring system (CERMs)-enable evaluation of embryo viability for potential application in a clinical IVF setting? SUMMARY ANSWER: The system enabled the oxygen consumption rate of spheroids, bovine embryos and frozen-thawed human embryos to be measured, and this rate corresponded to the developmental potential of embryos. WHAT IS ALREADY KNOWN: To date, no reliable and clinically suitable objective evaluation methods for embryos are available, which circumvent the differences in inter-observer subjective view. Existing systems such as the scanning electrochemical microscopy (SECM) technique, which enables the measurement of oxygen consumption rate in embryos, need improvement in usability before they can be applied to a clinical setting. STUDY DESIGN, SIZE, DURATION: This is a prospective original research study. The feasibility of measuring the oxygen consumption rate was assessed using CERMs for 9 spheroids, 9 bovine embryos and 30 redundant frozen-thawed human embryos. The endpoints for the study were whether CERMs could detect a dissolved oxygen gradient with high sensitivity, had comparable accuracy to the SECM measuring system with improved usability, and could predict the development of an embryo to a blastocyst by measuring the oxygen consumption rate. The relationship between the oxygen consumption rate and standard morphological evaluation was also examined. PARTICIPANTS/MATERIALS, SETTING, METHODS: We developed a new CERMs, which enables the oxygen consumption rate to be measured automatically using an electrochemical method. The device was initially used for measuring a dissolved oxygen concentration gradient in order to calculate oxygen consumption rate using nine spheroids. Next, we evaluated data correlation between the CERMs and the SECM measuring systems using nine bovine embryos. Finally, the oxygen consumption rates of 30 human embryos, which were frozen-thawed on 2nd day after fertilization, were measured by CERMs at 6, 24, 48, 72 and 96 h after thawing with standard morphological evaluation. Furthermore, the developed blastocysts were scored using the blastocyst quality score (BQS), and the correlation with oxygen consumption rate was also assessed. MAIN RESULTS AND THE ROLE OF CHANCE: The device enabled the oxygen consumption rate of an embryo to be measured automatically within a minute. The oxygen concentration gradient profile showed excellent linearity in a distance-dependent change. A close correlation in the oxygen consumption rates of bovine embryos was observed between the SECM measuring system and CERMs, with a determination coefficient of 0.8203 (P = 0.0008). Oxygen consumption rates of human embryos that have reached the blastocyst stage were significantly higher than those of arrested embryos at 48, 72 and 96 h after thawing (P = 0.039, 0.004 and 0.049, respectively). Thus, in vitro development of frozen-thawed human embryos to the blastocyst stage would be predicted at 48 h after thawing (day 4) by measuring the oxygen consumption using CERMs. Although a positive linear relationship between BQS and the oxygen consumption rate was observed [the determination coefficient was R(2) = 0.6537 (P = 0.008)], two blastocysts exhibited low oxygen consumption rates considering their relatively high BQS. This suggests that morphology and metabolism in human embryos might not correlate consistently. LIMITATIONS, REASONS FOR CAUTION: Transfer of the embryo and pregnancy evaluation was not performed. Thus, a correlation between oxygen consumption and the in vivo viability of embryos remains unknown. Clinical trials, including embryo transfer, would be desirable to determine a threshold value to elect clinically relevant, quality embryos for transfer. We utilized frozen-thawed human embryos in this study. The effect of these manipulations on the respiratory activity of the embryo is also unknown. WIDER IMPLICATIONS OF THE FINDINGS: Selection of quality embryos, especially in a single embryo transfer cycle, by CERMs may have an impact on obtaining better clinical outcomes, albeit with clinical trials being required. Furthermore, the early determination of quality embryos by CERMs may enable the omission of long-term in vitro embryo culture to the blastocyst stage. CERMs is scalable technology that can be integrated into incubators and/or other embryo evaluation systems, such as the time-lapse systems, due to its chip-based architecture. Thus, CERMS would enable automatic measurement of oxygen consumption, under 5% CO2, in the near future, in order to reduce oxidative stress from exposure to atmospheric air. STUDY FUNDING/COMPETING INTERESTS: This study was supported by grants from the Health and Labor Sciences Research Grant (H24-Hisaichiiki-Shitei-016). The authors have no conflicts of interest. TRIAL REGISTRATION NUMBER: Not applicable.