Improved development of very-poor-quality human preembryos by coculture with human fallopian ampullary cells

Development of bovine embryos in vitro in coculture with murine mesenchymal stem cells and embryonic fibroblasts

Despite the progress on development of new culture media, in vitro-produced embryos still display lower quality when compared to the in vivo-produced counterparts. Coculture has been reconsidered as an alternative to improve embryo quality. Mesenchymal stem cells (MSC) and murine embryonic fibroblasts (MEF) have been extensively used as feeder layers due to their capacity to release growth factors. In the present study we investigated the effect of these feeder layers in oocyte maturation and/or embryo development under in vitro conditions. Oocytes were matured in control (CTRL) conditions or in coculture with MSC or MEF. In vitro fertilization and embryo culture until fourth day were performed in CTRL condition for all groups. Embryos from fourth day on were then cultured until the eighth day in CTRL or in coculture system. No significant differences for metaphase II stage and apoptosis in oocytes were found among the groups. There was also no difference among the groups when we evaluated blastocyst formation on the seventh and eighth day, with exception of a higher hatched blastocyst rate in the group maturated and cultivated in CTRL condition when compared to the group matured and cocultured with MSC. Also no difference was observed in the number of cells in the whole embryos, in the inner cell mass, in the trophoblast and at apoptotic stage on the eighth day. We conclude that coculture with MSC or MEF during maturation and/or embryo development do not enhance the in vitro production of bovine embryos.

The expression of activins, their type II receptors and follistatin in human Fallopian tube during the menstrual cycle and in pseudo-pregnancy

BACKGROUND

The Fallopian tube (FT) is the site of fertilization and early embryonic development. We have previously reported the expression of activins, their receptors and follistatin by the FT. Here, our aim was to study the expression of tubal activins, their type II receptors and follistatin during the menstrual cycle and following exposure to hCG in vivo.

METHOD

A set of 30 FTs were collected from cycling women (n = 12) at different stages of the cycle (n = 4 in each stage) and pseudo-pregnant women (n = 3) at the time of hysterectomy for benign disease. The pseudo-pregnant women were injected with hCG in the days leading up to hysterectomy, and pseudo-pregnancy was confirmed by the persistence of amenorrhea, the presence of corpus luteum and decidualization of the endometrium. FT specimens were examined using immunohistochemistry and quantitative RT-PCR.

RESULTS

The expression of activin βA- and βB-subunits, activin type IIA and IIB receptors, and follistatin varied throughout the menstrual cycle, being lowest in the follicular phase and highest in the luteal phase. These results were demonstrated at the mRNA and protein level by quantitative RT-PCR and immunohistochemistry (P< 0.05). HCG injection rescued the expression of the candidate molecules from falling to the follicular stage levels but the expression remained lower than in the luteal phase.

CONCLUSIONS

We suggest that activins play a role in tubal physiology and early embryonic development. Additionally, exposure of the tubal epithelium to hCG modulates the expression of tubal activins.

Impact of chromosomal abnormalities on preimplantation embryo development

OBJECTIVES

To evaluate the influence of numerical chromosomal abnormalities on preimplantation embryo development.

METHODS

This study includes 6936 embryos from 1245 women undergoing preimplantation genetic diagnosis (PGD). Indications for aneuploidy screening were: recurrent miscarriages, implantation failure, severe male factor, advanced maternal age, and mixed causes. Embryo biopsy was performed on day 3, and embryos were co-cultured until day 5, when embryo transfer was performed.

RESULTS

In the aneuploidy screening regimen, normal euploid embryos showed significantly higher blastocyst rates (68.2%) compared to chromosomally abnormal (42.8%, p < 0.0001) and mosaic (53.7%, p < 0.0001) embryos. Among aneuploid embryos for autosomes, higher blastocyst rates were observed in trisomies than monosomies, although only statistically significant in patients over 36 years of age (50.8 vs 38.9%; p < 0.0001). In contrast, in embryos with sex chromosomes aneuploidy, similar blastocyst rates were observed between trisomies and monosomy X.

CONCLUSION

Embryos with certain types of chromosomal abnormalities were negatively selected during preimplantation embryo development. Despite this selection, a remarkable percentage of chromosomally abnormal embryos can develop normally to blastocyst stage with high probability of implantation and pregnancy.

Human Embryo Culture

Human embryonic stem cells (hESCs) are derived from preimplantation embryos. Approximately 60% of human embryos are blocked during in vitro development. Although statistics are inconclusive, experience demonstrates that hESCs are more effectively derived from high-quality embryos. In this way, optimal human embryo culture conditions are a crucial aspect in any derivation laboratory. Embryos can be cultured solely with sequential media or cocultured on a monolayer of a given cell type. This chapter explores general aspects of human embryonic development, the concept of sequential culture and coculture, and specific protocols and procedures in which the authors are experienced, including the results obtained.

Chromosomal abnormalities and embryo development in recurrent miscarriage couples

BACKGROUND

Chromosomal abnormalities are an important cause of spontaneous abortion and recurrent miscarriage (RM). Therefore, we have analysed the incidence of chromosomal abnormalities and embryo development in patients with RM.

METHODS

Preimplantation genetic diagnosis (PGD) was performed on 71 couples with RM and 28 couples undergoing PGD for sex-linked diseases (control group). Chromosomes 13, 16, 18, 21, 22, X and Y were analysed by fluorescence in-situ hybridization.

RESULTS

The implantation rate in RM patients was 28% and three patients (13%) miscarried. The percentage of abnormal embryos was significantly increased (P < 0.0001) in RM patients compared with controls (70.7 versus 45.1%). All of the embryos were abnormal in 19 cycles (22.1%) and repeated PGD cycles yielded similar rates of chromosomal abnormalities in 14 couples. Anomalies for chromosomes 16 and 22 were significantly higher (P < 0.01) in RM cases. In the RM population, euploid embryos reached the blastocyst stage more frequently than abnormal embryos (61.7 versus 24.9%; P < 0.0001).

CONCLUSIONS

RM is associated with a higher incidence of chromosomally abnormal embryos, of which some are able to develop to the blastocyst stage. IVF plus PGD is an important step in the management of these couples, but the technique has to move towards a full chromosome analysis.