Use of recombinant leukemia inhibitory factor in embryo implantation

Progesterone: The Key Factor of the Beginning of Life

Progesterone is the ovarian steroid produced by the granulosa cells of follicles after the LH peak at mid-cycle. Its role is to sustain embryo endometrial implantation and ongoing pregnancy. Other biological effects of progesterone may exert a protective function in supporting pregnancy up to birth. Luteal phase support (LPS) with progesterone is the standard of care for assisted reproductive technology. Progesterone vaginal administration is currently the most widely used treatment for LPS. Physicians and patients have been reluctant to change an administration route that has proven to be effective. However, some questions remain open, namely the need for LPS in fresh and frozen embryo transfer, the route of administration, the optimal duration of LPS, dosage, and the benefit of combination therapies. The aim of this review is to provide an overview of the uterine and extra-uterine effects of progesterone that may play a role in embryo implantation and pregnancy, and to discuss the advantages of the use of progesterone for LPS in the context of Good Medical Practice.

Optimizing the culture environment and embryo manipulation to help maintain embryo developmental potential

With increased use of comprehensive chromosome screening (CCS), the question remains as to why some practices do not experience the same high levels of clinical success after implementation of the approach. Indeed, the debate surrounding the efficacy and usefulness of blastocyst biopsy and CCS continues. Importantly, several variables impact the success of an assisted reproductive technology cycle. Transfer of a euploid embryo is but one factor in an intricate system that requires numerous steps to occur successfully. Certainly, the culture environment and the manipulations of the embryo during its time in the laboratory can impact its reproductive potential. Environmental stressors ranging from culture media to culture conditions and even culture platform can impact biochemical, metabolic, and epigenetic patterns that can affect the developing cell independent of chromosome number. Furthermore, accompanying procedures, such as biopsy and vitrification, are complex and, when performed improperly, can negatively impact embryo quality. These are areas that likely still carry room for improvement within the IVF laboratory.

Media composition: growth factors

Despite the fact that the fundamental principle underlying the most common method of culture media constitution is that of mimicking the natural environment of the preimplantation embryo, one major difference that remains between current embryo culture media and in vivo conditions is the absence of growth factors in vitro. Numerous growth factors are known to be present in the in vivo environment of human and nonhuman preimplantation embryos, often with peak concentrations corresponding to when fertilization and preimplantation embryo growth would occur. Although these growth factors are found in very small concentrations, they have a profound effect on tissue growth and differentiation through attachment to factor-specific receptors on cell surfaces. Receptors for many different growth factors have also been detected in human preimplantation embryos. Preimplantation embryos themselves express many growth factors. The growth factors and receptors are metabolically costly to produce, and thus their presence in the environment of the preimplantation embryo and in the embryo respectively strongly implies that embryos are designed to encounter and respond to the corresponding factors. Studies of embryo coculture also indirectly suggest that growth factors can improve in vitro development. Several animal and human studies attest to a probable beneficial effect of addition of growth factors to culture media. However, there is still ambiguity regarding the exact role of growth factors in embryonic development, the optimal dose of growth factors to be added to culture media, the combinatorial effect and endocrine of growth factors in embryonic development.

The importance of growth factors for preimplantation embryo development and in-vitro culture

PURPOSE OF REVIEW

The present paper reviews evidence that preimplantation embryos are naturally exposed and designed to respond to growth factors during preimplantation development.

RECENT FINDINGS

Recent studies have demonstrated that in-vivo human preimplantation embryos are exposed to a mixture of many different growth factors, expressed by the follicles, oviducts and endometrium. Receptors for many of these growth factors have also been shown to be expressed by preimplantation embryos, suggesting a functional role during preimplantation development. Studies of in-vitro fertilization in both animals and humans indicate that in-vitro culture of embryos in conventional media lacking growth factors can result in suboptimal growth and a variety of short-term and long-term developmental abnormalities. Studies of embryo coculture indirectly suggest that growth factors can improve in-vitro development. Many studies of defined growth factor supplements demonstrate that their inclusion in culture media can substantially improve preimplantation development and efficacy of in-vitro fertilization, and may reduce long-term developmental abnormalities as well.

SUMMARY

Embryos are naturally exposed to a complex mixture of growth factors that play an important role in preimplantation embryo development and that are likely to be of substantial benefit if added to in-vitro culture media.

Recombinant human leukemia inhibitory factor does not improve implantation and pregnancy outcomes after assisted reproductive techniques in women with recurrent unexplained implantation failure

In this randomized, double-blind, placebo-controlled, multicenter study, women (n = 149) with a history of at least two unexplained implantation failures after assisted reproductive techniques received recombinant human leukemia inhibitory factor, 150 microg SC twice daily for 7 days, or placebo. The clinical pregnancy rate after ET was significantly lower in patients receiving recombinant human leukemia inhibitory factor than in those receiving placebo (17.6% vs. 34.0%, respectively).

Leukemia inhibitory factor gene mutations in the population of infertile women are not restricted to nulligravid patients

OBJECTIVE

Leukemia inhibitory factor (LIF) is one of the key cytokines in the embryo implantation regulation. We investigated the prevalence of the LIF gene mutations in the population of infertile women that consisted of nulligravid and secondary infertile patients.

STUDY DESIGN

We designed a LIF gene mutation screening method that is based on the Temperature Gradient Gel Electrophoresis (TGGE). The population to screen consisted of 176 infertile women including group A of 147 nulligravid women and group B of 29 women with secondary infertility that had a history of either miscarriage or an ectopic pregnancy but no live births. The control population was comprised of 75 healthy fertile subjects. The groups of fertile controls and infertile patients were compared for statistically significant differences using the t-test.

RESULTS

Six potentially functional LIF gene mutations, the G to A transitions at the position 3400 leading to the valin to methionin exchange at codon 64 (V64M) in the AB loop region of the LIF protein, were detected. All of the six positive women were infertile. Four of them were nulligravid and two of them had history of spontaneous conception followed by early miscarriage. No positive TGGE samples were identified in the control group, which means that the frequency of functionally relevant mutations of the LIF gene in infertile women is significantly enhanced in comparison with controls (P<0.05, t-test).

CONCLUSION

The results suggest that the LIF gene mutations affect fertility. Even though they occur infrequently, their impact on molecular events during early phases of pregnancy should be further established.

Role of the leukemia-inhibitory factor gene mutations in infertile women: the embryo-endometrial cytokine cross talk during implantation--a delicate homeostatic equilibrium

Locally secreted cytokines of both the embryonic and the endometrial origin control the implantation process. The defects in their signaling that lead to unfavorable environment within the uterus may cause embryo implantation failure. The leukemia inhibitory factor (LIF), interleukin-11 (IL-11) as well as IL-12/IL-15/IL-18 system are regarded to be important signaling vectors. LIF plays an essential role in the preimplantation embryo development and the blastocyst implantation and its gene mutations in women contribute to the implantation failure and subsequent infertility. IL-11 signaling has been shown to be required for the uterine decidualization response as well as for the hatching and attachment of blastocysts. The IL-12/IL-15/IL-18 system interacts with endometrial leukocytes, particularly with NK cells, and influences directly the local angiogenesis and tissue remodeling. Differences in the levels of endometrial leukocytic subpopulations and in the patterns of intra-uterine cytokine concentrations that are observed between fertile and infertile women contribute to infertility probably by affecting the embryonic maternal dialogue during the implantation and early placentation period. Focusing on this cross talk promises to open new era in assisted reproduction techniques that will be based on diagnostics of missing signaling molecules and impairments of uterine receptivity as well as on therapeutic applications of individualized embryo culture and transfer media.

Population pharmacokinetic modelling of Emfilermin (recombinant human leukaemia inhibitory factor, r-hLIF) in healthy postmenopausal women and in infertile patients undergoing in vitro fertilization and embryo transfer

AIMS

The aim of this analysis was to develop a population pharmacokinetic model for Emfilermin (recombinant human leukaemia inhibitory factor, r-hLIF) following subcutaneous administration to healthy postmenopausal women and to infertile patients undergoing in vitro fertilization and embryo transfer (IVF-ET).

METHODS

Data from three studies, a single and a repeat dose Phase I study in postmenopausal women as well as a proof of concept study in patients undergoing in vitro fertilization and embryo transfer were combined and analyzed. The structural pharmacokinetic model was developed using the rich data from the Phase I studies and the full pharmacostatistical model was then derived using all the data.

RESULTS

The pharmacokinetics of r-hLIF after repeated subcutaneous administration were described by a one-compartment disposition model with a zero order input. The duration of the absorption phase was short (0.8 h) and invariant. The apparent clearance in postmenopausal women was 57 l h(-1) (CV = 17%). In in vitro fertilization and embryo transfer patients, the apparent clearance was decreased by 35% compared with postmenopausal women. The apparent volume of distribution was 235 l (interindividual CV = 28%) and exhibited an interoccasion variability of 23%. It increased (for weight above 62 kg) or decreased (for weight below 62 kg) by 29% for every 10 kg body weight. The median posthoc estimates of apparent clearance and volume of distribution and their variability were consistent with the population estimates. In postmenopausal women, the results were consistent with those obtained by noncompartmental analysis. The residual variability on r-hLIF serum concentrations was 20%.

CONCLUSIONS

The pharmacokinetics of r-hLIF after repeated SC administration were described by a one compartment disposition model, with zero order input, in postmenopausal women and those undergoing IVF or intracytoplasmic sperm injection and embryo transfer. Absorption of r-hLIF was rapid as was its subsequent clearance. The apparent volume of distribution of r-hLIF was moderate to high, depended on body weight and showed interoccasion variability.