Bexarotene selectively activates retinoid X receptor, which is a commonly used anticancer agent for cutaneous T-cell lymphoma. In this study, we aimed to investigate the anticancer effect of bexarotene and its underlying mechanism in ovarian cancer in vitro. The ES2 and NIH:OVACAR3 ovarian cancer cell lines were treated with 0, 5, 10, or 20 µM of bexarotene. After 24 h, cell number measurement and lactate dehydrogenase (LDH) cytotoxicity assay were performed. The effect of bexarotene on CDKN1A expression, cell cycle-related protein, cell cycle, pyroptosis, and apoptosis was evaluated. Bexarotene reduced cell proliferation in all concentrations in both the cells. At concentrations of > 10 µM, extracellular LDH activity increased with cell rupture. Treatment using 10 µM of bexarotene increased CDKN1A mRNA levels, decreased cell cycle-related protein expression, and increased the sub-G1 cell population in both cells. In ES2 cells, caspase-4 and GSDME were activated, whereas caspase-3 was not, indicating that bexarotene-induced cell death might be pyroptosis. A clinical setting concentration of bexarotene induced cell death through caspase-4–mediated pyroptosis in ovarian cancer cell lines. Thus, bexarotene may serve as a novel therapeutic agent for ovarian cancer.

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Study question This study aimed to analyze whether hyaluronan as an alternative to polyvinylpyrrolidone (PVP) for sperm immobilization, aspiration, and injection into the ooplasm improves ICSI outcomes. Summary answer The use of hyaluronan solution as an alternative to PVP improves the blastocyst formation rate and good quality blastocyst formation rate compared to PVP. What is known already The PVP solution facilitates ICSI procedures, such as sperm immobilization, aspiration, and injection into the ooplasm. However, it has been reported that injection of a small amount of PVP along with the sperm into the ooplasm negatively affects subsequent embryo development. Hyaluronan is a natural component of the extracellular matrix of the cumulus-oocyte complex. Balaban et al. (2003) reported that hyaluronan can replace PVP during ICSI procedures in the early embryo transfer cycle without adversely affecting pregnancy outcomes. This study analyzed whether using hyaluronan-based solution for the ICSI procedure would improves blastocyst development compared with ICSI using PVP. Study design, size, duration This retrospective study analyzed clinical medical reports at Takahashi Women’s Clinic, Japan. We included 4002 oocytes retrieved from 411 patients under 39 years of age who underwent ICSI using autologous oocytes between December 2019 and August 2021. Of the oocytes used for ICSI, 1909 underwent sperm aspiration and injection into the ooplasm with hyaluronan (Sperm Slow; Origio), and 2093 oocytes with 7% PVP (NakaMedical). We did not perform preimplantation genetic testing-aneuploidy for any cycles. Participants/materials, setting, methods We used PVP droplets for sperm selection under 400× magnification in both groups. In hyaluronan-ICSI, the selected sperm were transferred to a hyaluronan droplet and washed three times. The sperm was then aspirated with hyaluronan, and ICSI was performed. In PVP-ICSI, all procedures were performed using PVP. The ICSI and embryo transfer outcomes were compared between hyaluronan-ICSI and PVP-ICSI by logistic regression analysis considering patient age, BMI, and basal level of anti-mullerian hormone. Main results and the role of chance Normal fertilization rates were 74.3% (1556/2093) in PVP-ICSI and 75.5% (1442/1909) in hyaluronan-ICSI. There was no significant difference in the normal fertilization rate between PVP-ICSI and hyaluronan-ICSI groups (p = 0.437, aOR:1.06, 95% CI: 0.92–1.22). We cultured 1323 2PN embryos in PVP-ICSI and 1237 2PN embryos in hyaluronan-ICSI until the blastocyst stage. Blastocyst formation rates were 48.1% for PVP-ICSI and 52.3% for hyaluronan-ICSI, and this difference was statistically significant (aOR, 1.20; 95% CI: 1.02–1.40; p = 0.024). Moreover, the good grade (Gardner criteria ≧BB) blastocyst formation rates were significantly higher in the hyaluronan-ICSI group (36.9% and 41.0%, aOR: 1.21, 95% CI: 1.03–1.42, p = 0.022). During the study period, we performed 163 and 169 cryo-thawed blastocyst transfer cycles in PVP-ICSI and hyaluronan-ICSI, respectively. The clinical pregnancy rate (50.9% vs. 54.4%, aOR: 1.19, 95% CI: 0.77–1.83, p = 0.443) and miscarriage rate (19.3% vs. 13.0%, aOR: 0.66, 95% CI: 0.3–1.44, p = 0.295) after embryo transfer were not significantly different between PVP-ICSI and hyaluronan-ICSI. Limitations, reasons for caution The study was conducted at a single IVF center, and the oocytes included in this study were collected from patients aged < 39 years. Embryo transfer result is based on ongoing pregnancy, while the live birth data for all pregnancies are not yet available. Wider implications of the findings Hyaluronan facilitates ICSI procedures such as sperm immobilization, aspiration, and injection. Moreover, the hyaluronan improves blastocyst development. The present study indicates that using hyaluronan as an alternative to PVP during the ICSI procedure is recommended. Trial registration number not applicable

Study question Do oocytes with narrow perivitelline space have poor clinical outcomes after ICSI? Summary answer After ICSI, oocytes with narrow perivitelline space have an increased degeneration rate and decreased rates of 2PN and embryo development. What is known already Several studies reported that oocytes with dysmorphologies, such as zona pellucida (ZP) abnormalities and cytoplasmic inclusions (vacuoles, smooth endoplasmic reticulum cluster, refractile bodies), have poor developmental potential in IVF/ICSI. In research on perivitelline space (PVS), many studies have focused on the PVS with fragmentation as well as large PVS. On the other hand, oocytes with narrow perivitelline space (narrow PVS oocytes) are considered to have an immature cytoplasm, but there are few reports on the relationship between narrow PVS oocytes and clinical outcomes. In this study, we retrospectively analyzed the effect of narrow PVS oocytes on ICSI outcomes. Study design, size, duration This retrospective single-center study analyzed 11149 MII oocytes that underwent ICSI between January 2018 and October 2021. We observed the PVS of MII oocytes during ICSI, and oocytes with sufficient PVS between the ZP and cytoplasm were determined to be non-narrow PVS oocytes. Oocytes without sufficient PVS from any angle (PVS was observed only around the first polar body) were defined as narrow PVS oocytes. Participants/materials, setting, methods After ICSI, oocytes were cultured in ONESTEP medium (NakaMedical, Tokyo, Japan). Embryos that developed into blastocysts were used for single vitrified-warmed blastocyst transfer (SVBT). We compared the rates of degeneration, 2PN, cleavage, blastocyst formation, good-grade (Gardner’s criteria ≥BB) blastocyst, top-grade blastocyst (Gardner’s criteria=AA), and clinical pregnancy (presence of a gestational sac) between oocytes with narrow and non-narrow PVS. Logistic regression analysis with consideration of patient age, BMI, and basal AMH was performed for each outcome. Main results and the role of chance Of the 11149 MII oocytes, 570 and 10579 were determined to be narrow and non-narrow PVS oocytes, respectively. Narrow PVS oocytes showed significantly higher degeneration rates (aOR: 1.52, 95% CI: 1.12–2.06, p<0.01) and lower 2PN rates (aOR: 0.77, 95% CI: 0.64–0.93, p<0.01) after ICSI compared to non-narrow PVS oocytes. Furthermore, rates of cleavage (aOR: 0.52, 95% CI: 0.31–0.87, p<0.05), blastocyst formation (aOR: 0.56, 95% CI: 0.45–0.70, p<0.01), good-grade blastocyst formation (aOR: 0.59, 95% CI: 0.46–0.76, p<0.01), and top-grade blastocyst formation (aOR:0.625, 95% CI:0.45–0.86, p<0.01), were significantly lower in the narrow PVS oocytes. Of the blastocysts developed, 32 and 1439 blastocysts from narrow PVS oocytes and non-narrow PVS oocytes, respectively, were used for SVBT. The clinical pregnancy rate was not significantly different between blastocysts developed from narrow (aOR: 0.52, 95% CI, 0.22–1.22, p = 0.131) and non-narrow PVS oocytes. However, in blastocysts developed from narrow PVS oocytes, clinical pregnancy was confirmed only in top-grade blastocysts (58.8% [10/17]), and blastocysts of other grades did not result in pregnancy (0% [0/15]). Limitations, reasons for caution The limitation of this study is that it was a retrospective analysis conducted at a single IVF center. It is necessary to confirm the reproducibility at other facilities because the evaluation of PVS differs among embryologists and IVF centers. Therefore, a prospective multicenter study is needed. Wider implications of the findings We found that the narrow PVS oocytes showed poor outcomes after ICSI. While a good pregnancy rate could be expected if a top-grade blastocyst from such oocytes was obtained and transferred, the embryonic development rate of narrow PVS oocytes is low. Trial registration number Not applicable

Purpose To analyze whether the morphokinetics algorithm based on data from day 5 blastocyst transfer (KIDScoreD5 version 3) can predict the pregnancy rate of both day 5 and day 6 blastocyst transfers. Methods The relationship between KIDScoreD5 and clinical pregnancy rate was evaluated using the Cochran–Armitage test and receiver‐operating characteristic (ROC) curve analysis. Results A positive correlation was observed between the KIDScoreD5 value and clinical pregnancy rate for both day 5 ( p = 0.0003) and day 6 blastocysts ( p = 0.0019) using the Cochrane–Armitage test. ROC curve analysis showed that the area under the curve (AUC) of KIDScoreD5 for clinical pregnancy was 0.627 (0.575–0.677, p < 0.0001) for day 5 blastocysts and 0.685 (0.571–0.780, p = 0.0009) for day 6 blastocysts. The combined analysis of both day 5 and day 6 blastocysts also showed an AUC of 0.680 (0.636–0.720, p < 0.0001), suggesting that it is possible to select embryos that are more likely to result in pregnancy. Conclusions KIDScoreD5 could predict pregnancy not only in day 5 blastocysts but also in day 6 blastocysts. When both day 5 and day 6 blastocysts are vitrified, embryo selection by KIDScoreD5 is possible with a high prediction ability of pregnancy.