Chun Kyu Lim

Clinical outcomes of preimplantation genetic diagnosis (PGD) and analysis of meiotic segregation modes in reciprocal translocation carriers

Balanced reciprocal translocation is the most common chromosome rearrangement, with an incidence of 1 out of 625 newborns. In reciprocal translocation carriers, genetically unbalanced gametes can be produced through three principal modes of segregation: adjacent‐1, adjacent‐2 and 3:1. In this study, we reviewed 133 cycles of preimplantation genetic diagnosis (PGD) for 65 couples with reciprocal translocation and analyzed pregnancy outcomes and the meiotic segregation mode of gametes of the translocation carriers using fluorescent in situ hybridization (FISH). We found that 285 of 1,508 embryos (18.9%) were normal or balanced. Thirty‐three clinical pregnancies, including eight spontaneous abortions (21.6% per couple), were established. According to the meiotic segregation analysis, the frequencies of 3:1 and 4:0 segregation modes were significantly higher (P < 0.05) in female carriers, and the frequencies of adjacent‐1 and chaotic segregation modes were significantly higher (P < 0.05) in male carriers. Our results indicate that meiotic segregation might be affected by the carriers sex but not by the carriers age or breakpoints.

Differential cytotoxic effects of mono-(2-ethylhexyl) phthalate on blastomere-derived embryonic stem cells and differentiating neurons

Potential applications of embryonic stem (ES) cells are not limited to regenerative medicine but can also include in vitro screening of various toxicants. In this study, we established mouse ES cell lines from isolated blastomeres of two-cell stage embryos and examined their potential use as an in vitro system for the study of developmental toxicity. Two ES cell lines were established from 69 blastomere-derived blastocysts (2.9%). The blastomere-derived ES (bm-ES) cells were treated with mono-(2-ethylhexyl) phthalate (MEHP) in an undifferentiated state or after directed differentiation into early neural cell types. We observed significantly decreased cell viability when undifferentiated bm-ES cells were exposed to a high dose of MEHP (1000 microM). The cytotoxic effects of MEHP were accompanied by increased DNA fragmentation, nuclear condensation, and activation of Caspase-3, which are biochemical and morphological features of apoptosis. Compared to undifferentiated bm-ES cells, considerably lower doses of MEHP (50 and 100 microM) were sufficient to induce cell death in early neurons differentiated from bm-ES cells. At the lower doses, the number of neural cells positive for the active form of Caspase-3 was greater than that for undifferentiated bm-ES cells. Thus, our data indicate that differentiating neurons are more sensitive to MEHP than undifferentiated ES cells, and that undifferentiated ES cells may have more efficient defense systems against cytotoxic stresses. These findings might contribute to the development of a new predictive screening method for assessment of hazards for developmental toxicity.

Fertilization and pregnancy potential of immature oocytes from stimulated intracytoplasmic sperm injection cycles

Objective We evaluated the fertilization potential of immature oocytes obtained from controlled ovarian hyperstimulation cycles of patients undergoing ICSI. Methods We retrospectively analyzed 463 ICSI cycles containing at least one immature oocyte at oocyte denudation. ICSI was performed on mature oocytes at oocyte denudation (metaphase-II [MII] oocytes) and the oocytes that extruded the first polar body between oocyte denudation and ICSI (MI-MII oocytes). Fertilization and early embryonic development were compared between MII and MI-MII oocytes. To investigate the pregnancy potential of MI-MII oocytes, the pregnancy outcome was analyzed in 24 ICSI cycles containing only immature oocytes at retrieval. Results The fertilization rate of MI-MII oocytes (37.0%) was significantly lower than that of MII oocytes (72.3%). The rates of delayed embryos and damaged embryos did not significantly differ. Eighty-one immature oocytes were retrieved in 24 cycles that retrieved only immature oocytes and 61 (75.3%) of them were in the MI stage. ICSI was performed on 36 oocytes (59.0%) that extruded the first polar body before ICSI and nine MI-MII oocytes (25.0%) were fertilized. Embryo transfers were performed in five cycles. Pregnancy was observed in one cycle, but it ended in biochemical pregnancy. Conclusion In ICSI cycles, oocytes that extruded the first polar body between denudation and ICSI can be used as a source of oocytes for sperm injection. However, their fertilization and pregnancy potential are lower than that of mature oocytes. Therefore, ovarian stimulation should be performed carefully for mature oocytes obtained at retrieval, especially in cycles with a small number of retrieved oocytes.

Effect of testicular spermatozoa on embryo quality and pregnancy in patients with non-obstructive azoospermia

Abstract This study was performed to assess and compare the outcomes of testicular sperm extraction (TESE)-intracytoplasmic sperm injection (ICSI) using spermatozoa from fresh and frozen testicular tissue from men with subgroups of non-obstructive azoospermia (NOA). A total of 110 cycles of TESE-ICSI were performed. Patients were classified into one of the following NOA subgroups: hypospermatogenesis (HS), maturation arrest (MA), or Sertoli cell-only syndrome (SCO). Laboratory (fertilization, cleavage stage of embryo, and good quality embryo) and clinical (pregnancy, clinical pregnancy, implantation, and delivery) outcomes were assessed. No statistically significant differences were observed in any of the other measured parameters between the three subgroups of NOA. No significant differences in laboratory outcomes were observed between spermatozoa from fresh and frozen testicular spermatozoa; however, statistically significant differences were observed in the pregnancy and implantation rates between groups (p < 0.05). The outcomes of using spermatozoa retrieved from fresh testicular tissue in each of the three subgroups were also compared; although clinical outcomes showed low results, no significant differences were observed between the three subgroups. Similarly, no significant differences were observed in spermatozoa retrieved from frozen testicular tissue. Once spermatozoa have been successfully obtained, acceptable laboratory outcomes can be achieved for NOA, whether or not the spermatozoa are cryopreserved. However, satisfactory clinical outcomes may be more difficult to achieve as the results showed in each group of fresh and frozen testicular spermatozoa. Therefore, achieving acceptable clinical pregnancy results and efficient cryopreservation of testicular spermatozoa should be considered in patients with NOA.

Comparison of the clinical outcomes of day 4 and 5 embryo transfer cycles

Objective The majority of embryo transfers (ETs) to date have been performed on day 3 to reduce the potential risk of developmental arrest of in vitro cultured embryos before ET. Development of sequential media has significantly improved culture conditions and allowed blastocyst transfer on day 5. While day 5 ET provides higher clinical pregnancy outcomes with reduced risks of multiple pregnancies, it still has potential risks of developmental arrest of IVF embryos. The aim of this study was to evaluate the clinical outcomes of day 4 ETs and compare the efficacy of day 4 ET with day 5 ET. Methods From 2006 to 2009, a total of 747 fresh IVF-ET cycles were retrospectively analyzed (day 4, n=440 or and day 5, n=307). The cycles with any genetic factors were excluded. The rates of matured oocytes, fertilization, good embryos, and clinical pregnancy of the two groups were compared. The chi-square test and t-test were used for statistical analysis. Results There were no significant differences between the two groups with respect to the mean age of the females and rates of matured oocytes. The pregnancy outcomes of day 4 ET (40.7%) were similar to those of day 5 ET (44.6%). The implantation rate of day 5 ET (24.2%) was significantly higher than that of day 4 ET (18.4%) (p=0.003). Conclusion Day 4 ET can be chosen to avoid ET cancellation in day 5 ET resulting from suboptimal circumstances in the IVF laboratory, but the decremented quality of embryos for transfer and the decreased pregnancy rate must be taken into consideration.