Effect of human leukemia inhibitory factor on in vitro development of parthenogenetic bovine morulae

Culture systems: embryo co-culture

During the 1970s, domestic animal biotechnology, i.e., embryo transfer in farm animals, was confronted with the problem of embryonic developmental arrest observed in vitro, especially during the cycle in which maternal to zygotic transition (MZT) cycle takes place. In farm animals, obtaining blastocysts is mandatory, as transfer at earlier stages results in expulsion of the embryo from the vagina. In humans, the first attempts to obtain blastocysts with classical culture media were disappointing, and the use of a coculture strategy was naturally tempting: the first significant results of successful blastocyst development were obtained in the early 1980s, using trophoblastic tissue as a feeder layer in order to mimic an autocrine embryotrophic system. The next supporting cell systems were based on oviduct epithelial cells and uterine cells in order to achieve a paracrine effect. Non-hormone dependence was then demonstrated with the use of prepubertal cells, and finally with the use of established cell lines of nongenital origin (African Green Monkey Kidney, Vero cells). The embryotrophic properties are linked to features of "transport epithelia." Vero cells have been extensively used in human ART, and most of our knowledge about the human blastocyst was gathered with the use of this technology. Coculture is still in current use, but with systems that employ autologous uterine cells. Results following the use of this technology in human ART are superior to those observed with the use of sequential media. The benefit is linked to the release of free radical scavengers and growth factors by the feeder cells. In animal biotechnology, an important part of the "precious embryos," i.e., those resulting from cloning technology, involves coculture with buffalo rat liver (BRL) cells or Vero cells.

Autologous embryo–cumulus cells co-culture and blastocyst transfer in repeated implantation failures: a collaborative prospective randomized study

In repeated implantation failure, the co-culture of human embryos with somatic cells has been reported to promote the improvement of embryos quality, implantation and pregnancy rate. It was reported that feeder cells can be more beneficial to the oocyte and embryo by detoxifying the culture medium and supporting embryo development via different pathways. In this study, 432 patients, each with a minimum of three repeated implantation failures, were accepted for a prospective randomized study with or without autologous cumulus cell embryo co-culture and transfer at day 3 or day 5–6. We also investigated the expression of leukaemia inhibitor factor (LIF) and platelet activating factor receptor (PAF-R) on day 3 confluent cumulus cells. The statistic analysis of the data showed significant difference of implantation and clinical pregnancy rates between classical culture and day 3 compared with co-culture and day 5–6 transfer. The molecular analysis showed that cumulus cells express the LIF and the PAF-R genes and confirmed the possible positive role of growth factors and cytokines in early embryo development. Embryo co-culture systems with autologous cells can be beneficial in routine in vitro fertilization for embryo selection and implantation improvement. More molecular investigations need to be done to improve elucidation of the complex dialogue between the embryo and feeder cells prior to implantation and to understand the involved biological function and molecular process during embryo development.

Effect of supplementation of leukemia inhibitory factor and epidermal growth factor on murine embryonic development in vitro, implantation, and outcome of offspring

OBJECTIVES

To evaluate the supplementation of leukemia inhibitory factor (LIF) or epidermal growth factor (EGF) in a single culture system (IVF50) and a sequential culture system (IVF50-S2) to determine whether they had any additional benefit on embryo development and implantation.

DESIGN

Prospective controlled animal study.

SETTING

University research laboratory.

SUBJECT(S)

Two-cell embryos from F1(CBA x C57BL) mice.

INTERVENTION(S)

Embryos were randomly cultured in different growth factor-treated or untreated in vitro systems.

MAIN OUTCOME MEASURE(S)

Blastocyst formation and morphology, total cell numbers of day 5 blastocysts, birth rates, and characteristics of the offspring.

RESULT(S)

The beneficial effects of LIF or EGF on blastocyst development and morphology were observed only in IVF50 medium but not in sequential IVF50-S2 media. In addition, blastocysts generated from the LIF-supplemented cultures had higher total cell numbers and higher total birth rates after transfer compared to those from IVF50 medium alone. No significant effect on fetal development was observed but pups born after treatment in LIF-supplemented sequential cultures had prolonged gestation and increased birth weights.

CONCLUSION(S)

The beneficial effects of LIF and EGF on in vitro blastocyst development are mainly seen under suboptimal culture conditions (simple medium only) and their effects are masked in an improved in vitro system (sequential culture media). Supplementation of culture media with such factors, however, is still an attractive approach in enhancing embryo viability through increased total cell numbers. The beneficial effect of LIF in improving implantation and subsequent increased birth rates should be further explored.

Cytokines during early pregnancy of mammals: a review

This article reviews the function of cytokines during early pregnancy of mammals including the human species. Investigations concerning conceptus and other secretory proteins, their meaning for maternal recognition and maintenance of pregnancy, fetal and placental growth and differentiation, adhesion, invasion and implantation are discussed, and differences between laboratory rodents, carnivores, artiodactyls, horses and human beings elucidated and summarized. Finally topics that might be of interest for further research are emphasized.