Establishment of embryonic stem cell lines from cynomolgus monkey blastocysts produced by IVF or ICSI

Human embryonic stem (ES) cells are predicted to be a valuable source for producing ES-derived therapeutic spare tissues to treat diseases by controlling their growth and differentiation. To understand the regulative mechanisms of their differentiation in vivo and in vitro, ES cells derived from nonhuman primates could be a powerful tool. We established four ES cell lines from cynomolgus monkey (Macaca fascicularis) blastocysts produced by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). The ES cells were characterized by the expression of specific markers such as alkaline phosphatase and stage-specific embryonic antigen-4. They were successfully maintained in an undifferentiated state and with a normal karyotype even after more than 6 months of culture. Pluripotential competence was confirmed by the formation of teratomas containing ectoderm-, mesoderm-, and endoderm- derivatives after subcutaneous injection into SCID mice. Differentiation to a variety of tissues was identified by immunohistochemical analyses using tissue-specific antibodies. Therefore, we established pluripotent ES cell lines derived from monkeys that are widely used as experimental animals. These lines could be a useful resource for preclinical stem cell research, including allogenic transplantation into monkey models of disease.

Targeted disruption of Na+/Ca2+ exchanger gene leads to cardiomyocyte apoptosis and defects in heartbeat

Ca(2+), which enters cardiac myocytes through voltage-dependent Ca(2+) channels during excitation, is extruded from myocytes primarily by the Na(+)/Ca(2+) exchanger (NCX1) during relaxation. The increase in intracellular Ca(2+) concentration in myocytes by digitalis treatment and after ischemia/reperfusion is also thought to result from the reverse mode of the Na(+)/Ca(2+) exchange mechanism. However, the precise roles of the NCX1 are still unclear because of the lack of its specific inhibitors. We generated Ncx1-deficient mice by gene targeting to determine the in vivo function of the exchanger. Homozygous Ncx1-deficient mice died between embryonic days 9 and 10. Their hearts did not beat, and cardiac myocytes showed apoptosis. No forward mode or reverse mode of the Na(+)/Ca(2+) exchange activity was detected in null mutant hearts. The Na(+)-dependent Ca(2+) exchange activity as well as protein content of NCX1 were decreased by approximately 50% in the heart, kidney, aorta, and smooth muscle cells of the heterozygous mice, and tension development of the aortic ring in Na(+)-free solution was markedly impaired in heterozygous mice. These findings suggest that NCX1 is required for heartbeats and survival of cardiac myocytes in embryos and plays critical roles in Na(+)-dependent Ca(2+) handling in the heart and aorta.

Insertional mutation of the murine kisimo locus caused a defect in spermatogenesis

Spermatogenesis is a developmental process that occurs in several phases and is regulated by a large number of gene products. An insertional transgenic mouse mutant (termed kisimo mouse) has been isolated that results in abnormal germ-cell development, showing abnormal elongated spermatids in the lumina of seminiferous tubules. We cloned the disrupted locus of kisimo and identified a novel testis-specific gene, THEG, which is specifically expressed in spermatids and was disrupted in the transgenic mouse. The yeast two-hybrid screening method revealed that THEG protein strongly interacts with chaperonin containing t-complex polypeptide-1epsilon, suggesting that THEG protein functions as a regulatory factor in protein assembly. Our findings indicate that the kisimo locus is essential for the maintenance of spermiogenesis and that a gene expression disorder may be involved in male infertility.

COLLABORATIVE WORK TO EVALUATE TOXICITY ON MALE REPRODUCTIVE ORGANS BY REPEATED DOSE STUDIES IN RATS : 9)TESTICULAR TOXICITY IN MALE RATS GIVEN ADRIAMYCIN FOR TWO OR FOUR WEEKS

The present study was performed to determine whether testicular toxicity can be detected of the administration of adriamycin (ADR), an anticancer drug, for 2 weeks. ADR was intravenously administered to Slc:SD male rats at 1 mg/kg once a week for 4 or 2 weeks, and 2 mg/kg once a week for 2 weeks. Suppression of body weight gain was observed in the 1 mg/kg/week (4 w) and 2 mg/kg/week (2 w) groups. The testes weights in these groups were also lower than those of the control group. On histological examination, a decrease in spermatogonia was observed in the 1 mg/kg/week (4 w) and 2 mg/kg/week (2 w) groups. No abnormalities were detected in the control and 1 mg/kg/week (2 w) groups. Stage analysis of seminiferous tubules was performed for control and 1 mg/kg/week (2 w) groups. In the 1 mg/kg/week (2 w) group, the numbers of spermatogonia in stages II-III, V and XII-XIII were significantly decreased. The numbers of preleptotene spermatocytes in stage VII and zygotene spermatocytes in XII-XIII were also significantly reduced in the same group. These findings suggest that the testicular toxicity of ADR can be detected after 2 weeks administration at a sufficient high dosage, if simplified morphometrical analysis is used.

[Reproductive and developmental toxicity studies of taltirelin hydrate (1) fertility study in rats by oral administration]

Fertility study of taltirelin hydrate, a thyrotropin releasing hormone analogue, was carried out in Wistar rats. Taltirelin hydrate was orally administrated at a dose of 0 (control), 0.15, 1.5, or 15 mg/kg. Male rats were given the drug from 63 days before mating to the day before autopsy (total of 121 days), and female rats were treated from 14 days before mating to day 7 of gestation. The females were sacrificed on day 21 of gestation and pregnancy outcome was determined. In the 15 mg/kg group, wet dog shaking behavior and hyperlocomotion were observed in males and females, and the food consumption was slightly decreased in male rats. These changes induced by taltirelin hydrate were not found in the 0.15 and 1.5 mg/kg groups. No adverse effects of taltirelin hydrate on reproductive function were detected in any groups. In the fetal examination, taltirelin hydrate had no teratogenic, lethal, or growth retardation effects in any groups. These results show that the no-toxic dose levels of taltirelin hydrate are 1.5 mg/kg for general toxicity in parent animals, and 15 mg/kg for reproductive function of parent animals and for development of their fetuses.

[Reproductive and developmental toxicity studies of taltirelin hydrate (4) perinatal and postnatal study in rats by oral administration]

Perinatal and postnatal study of taltirelin hydrate, a thyrotropin releasing hormone analogue, was carried out in Sprague-Dawley rats. Female rats were given taltirelin hydrate at a dose of 0 (control), 0.15, 1.5, or 15 mg/kg from day 17 of gestation to day 20 after delivery. All pregnant rats were allowed to deliver spontaneously and their offspring were examined. In the 15 mg/kg group, the dams showed the central nervous effects such as wet dog shaking during gestation periods. No adverse effect of taltirelin hydrate on the body weight gain, food consumption and reproductive performance was observed in this group. In the 0.15 and 1.5 mg/kg groups, the drug did not have any adverse effects. Taltirelin hydrate did not have any adverse effects on viability, growth, physical differentiation, functional and behavioral development (coordinated activity, auditory function, emotionality, learning ability, and spontaneous motor activity), and reproductive performance of F1 offspring, and development of F2 fetuses. These results show that the no-toxic dose levels of taltirelin hydrate are 1.5 mg/kg for general toxicity in dams, and 15 mg/kg for reproductive function of dams and for their offspring.

[Reproductive and developmental toxicity studies of taltirelin hydrate (2) teratogenicity study in rats by oral administration]

Teratogenicity study of taltirelin hydrate, a thyrotropin releasing hormone analogue, was carried out in Wistar rats. Female rats were orally given taltirelin hydrate at a dose of 0 (control), 0.15, 1.5, or 15 mg/kg from day 7 to day 17 of gestation. Twenty-seven female rats in each group were sacrificed on day 21 of gestation and their fetuses were examined. The remaining 13 female rats in each group were allowed to deliver spontaneously and their newborns were examined. In the 15 mg/kg group, the dams (P) showed wet dog shaking behavior and hyperlocomotion. No adverse effect of taltirelin hydrate on the body weight gain, food consumption, water intake, and reproductive performance was observed in this group. In the 0.15 and 1.5 mg/kg groups, taltirelin hydrate did not show any adverse effects. In F1 generation groups, taltirelin hydrate had no teratogenic, lethal, or growth retardation effects in any groups. There were also no adverse effects of taltirelin hydrate on postnatal development, emotionality, coordinated activity, sensitivity, learning ability, and reproductive performance of F1 offspring, and development of F2 fetuses. These results show that the no-toxic dose levels of taltirelin hydrate are 1.5 mg/kg for general toxicity in dams, and 15 mg/kg for reproductive function of dams (P) and for development of F1 generation.

[Reproductive and developmental toxicity studies of taltirelin hydrate (3) teratogenicity study in rabbits by oral administration]

Teratogenicity study of taltirelin hydrate, a thyrotropin releasing hormone analogue, was carried out in Japanese white rabbits. Female rabbits were orally given taltirelin hydrate at a dose of 0 (control), 0.15, 1.5, or 15 mg/kg from day 6 to day 18 of gestation. Females were sacrificed on day 29 and their fetuses were examined. Neither death nor adverse effects on food consumption in dams were found in any dose groups. In the 15 mg/kg group, rapid breathing and decreased body weight gain in dams were temporally observed. No adverse effect of taltirelin hydrate on reproductive function was detected in any groups. In the fetal examination, taltirelin hydrate had no teratogenic, lethal, or growth retardation effects in any groups. These results show that the no-toxic dose levels of taltirelin hydrate are 1.5 mg/kg for general toxicity in dams, and 15 mg/kg for reproductive function of dams and for development of their offspring.

Effects of adriamycin, an anticancer drug showing testicular toxicity, on fertility in male rats

Adriamycin (ADR), an anticancer drug,was intravenously administered to Slc:SD male rats at doses of 0, 1 and 2 mg/kg once a week for 4 or 9 weeks before pairing, and the treatment period and parameters suitable for detection of male fertility disorder were examined. No adverse effects were observed on the copulation index, fertility index and spermatozoa, but testicular weights were low in the 1 and 2 mg/kg groups after 4-week treatment. In the 2 mg/kg group after 9-week treatment, 11 of 12 males had died or became moribund, and no successful pregnancies were observed. The males in the 1 and 2 mg/kg groups after 9-week treatment had decreased weights of the genital organs, an extremely decreased number of sperm and low sperm motility as well as a low implantation rate and a decreased number of live fetuses. Microscopically, the numbers of spermatogonia were decreased in the 1 and 2 mg/kg groups after 4-week treatment, whereas the numbers of even spermatozoa were diminished and genital organs showed atrophy after 9-week treatment. These results indicate that 4-week treatment before pairing is sufficient to detect effects of ADR on the testis, especially on spermatogonia, and that microscopic findings and testis weight are appropriate parameters for detection of male fertility disorders.

Comparison of electron irradiation diets and gamma irradiation diets for reproductive effects on rats

Rats were maintained on 50 kGy electron irradiation diets. Effects of the diets on reproductive performance of parents and developmental performance of fetuses (F1 and F2) were studied by comparison with data in rats maintained on gamma irradiation diets, as control animals, and the background data of our facility. As the result, no specific changes were observed in the group maintained on electron irradiation diets. Electron irradiation diets sterilized under the condition of 50 kGy irradiation in the present study, as well as the existing gamma irradiation diets, were found to be useful for breeding and nursing rats.