goro kuramoto

OBJECTIVE: To evaluate the impact of assisted sperm fusion insemination (ASFI), a microinsemination method using sperm bound to the zona pellucida (ZP-sperm) without penetrating the oocyte membrane, compared with conventional intracytoplasmic sperm injection (C-ICSI), on fertilization and embryonic development. DESIGN: Prospective clinical sibling-oocyte study. SUBJECTS: A total of 197 oocytes from 24 patients who underwent 35 oocyte retrieval cycles from January 2023 to April 2024 were analyzed. Patients who underwent retrieval of both, at least 2 metaphase II (MII) oocytes and at least 1 immature or degenerated oocyte, were recruited. INTERVENTION: Metaphase II oocytes were alternately allocated to 2 groups: ASFI and C-ICSI groups. To obtain ZP-sperm for ASFI, immature or degenerated oocytes were incubated with 10,000 motile sperm for 3 hours. After harvesting the ZP-sperm, it was pressed onto the membrane of an MII oocyte for 10 seconds in the ASFI group. Conventional intracytoplasmic sperm injection was performed conventionally in the C-ICSI group. MAIN OUTCOME MEASURES: The rates of 2 pronuclei (2PN), degeneration, blastocyst formation, and usable embryos, defined as the total number of transferred or cryopreserved embryos divided by the number of MII oocytes, were compared between the 2 groups. RESULTS: The 2PN rate of the ASFI group was 88.0% (73/83), which was significantly higher than that of the C-ICSI group (70.2% [80/114]). In addition, a significantly lower degeneration rate was observed in the ASFI group (0% [0/83]) than in the C-ICSI group (8.8% [10/114]). The blastocyst formation rate was equivalent in the 2 groups (ASFI group, 63.9% [39/61]; C-ICSI group, 62.0% [44/71]). However, the usable embryo rate was significantly higher in the ASFI group (45.8% [38/83]) than in the C-ICSI group (28.1% [32/114]). CONCLUSION: The ASFI group yielded significantly higher 2PN and lower degeneration rates than the C-ICSI group. Consequently, the ASFI group experienced a higher number of embryos usable for implantation, although there was no significant difference in the blastocyst formation rate between the 2 groups. Further studies with a larger number of cases will be needed for more general application of these findings.

Infertility in women is associated with various uterine and ovarian disorders. Treatment strategies for infertility can range from medications to embryo implantation through assisted reproductive technology (ART). ART has enabled considerable progress; however, there is currently no treatment to replace the endometrium itself. Decidualization requires a complex interaction between endometrial tissue and estrogen and progesterone. We aimed to create a three-dimensional endometrial-like tissue model using in-vitro cell sheet engineering with rat endometrium, and culture cells at different progesterone concentrations to mimic local concentrations. Histological and morphological changes revealed that development of the endometrial-like tissue was not proportional to progesterone concentrations in terms of thickness, number of endometrial glands, or area fraction of intimal glands. These results suggest that decidualization may not be commensurate with the local endometrial progesterone concentration. Notably, the number of endometrial glands increased in the high concentration group and compaction occurred, indicating that the endometrial conditions in the high concentration group may be most conducive to increase pregnancy rates. These findings suggest that there may be an "optimal progesterone concentration" for decidualization, application of which may lead to new strategies for improving pregnancy rates in women with infertility.

RESEARCH QUESTION: This study aimed to retrospectively evaluate the efficacy of a hyaluronan-enriched transfer medium (HETM) for transfer failures and transfer of frozen embryos that have been graded as C at the time of transfer according to the Gardner classification of trophectoderm (TE). DESIGN: This study included 365 cycles of unsuccessful frozen-thawed embryo transfers in hormone replacement cycles graded C according to the Gardner classification of TE at the time of transfer. Clinical pregnancy rates were compared using the χ2 test, with the patients divided into two groups: one whose transfers did include HETM (HETM group) and one whose transfers did not include HETM (control group). As a subgroup analysis, patients with a TE grade of C at the time of transplantation were divided into two groups: those aged 39 years or younger and those aged 40 years or older at the time of transplantation. The clinical pregnancy rates of the groups with and without HETM were then compared. RESULTS: No difference in the clinical pregnancy rates between the HETM and control groups was observed. CONCLUSIONS: Hyaluronic acid is believed to favor implantation by promoting adhesion between the embryo and the endometrium, and there are reports of improved implantation and pregnancy rates as a result of HETM. However, the present results suggest limited effectiveness for HETM. Further case series should be conducted, and the suitability of its use as a treatment should be investigated.