Use of reverse transcription-polymerase chain reaction to detect embryonic interleukin-1 system messenger RNA in individual preimplantation mouse embryos co-cultured with Vero cells

Simultaneous detection of two growth factors from human single-embryo culture medium by a bead-based digital microfluidic chip

The measurement of growth factors released in a culture medium is considered to be an attractive non-invasive approach, apart from the embryo morphology, to identify the condition of an embryo development after fertilization in vitro (IVF), but the available embryo culture medium in the current method is only a few microlitres. This small sample volume, also of small concentration, makes difficult the application of a conventional detection method, such as an enzyme-linked immunosorbent assay (ELISA). A reliable detection of the growth factor from each embryo culture medium of such a small concentration hence remains a challenge. Here for the first time we report the results of measurement of not just one, but two, growth factors, human IL-1β and human TNF-α, from an individual droplet of embryo culture medium with a bead-based digital microfluidic chip. The required sample volume for a single measurement is only 520 nL; the total duration of the on-chip process is less than 40 min. Using the culture media of human embryos with normal morphologic features, we found that the concentrations of TNF-α change little from day 3 to day 5-6, but the concentrations of IL-1β for some embryos might double from day 3 to day 5-6. For other embryos even with similar normal morphologic features, some growth factors, such as IL-1β, might exhibit different expressions during the culture period. Those growth factors could serve to distinguish the development conditions of each embryo, not merely from an observation of embryo morphology.

Cytokines and Blastocyst Hatching

Blastocyst implantation into the uterine endometrium establishes early pregnancy. This event is regulated by blastocyst- and/or endometrium-derived molecular factors which include hormones, growth factors, cell adhesion molecules, cytokines and proteases. Their coordinated expression and function are critical for a viable pregnancy. A rate-limiting event that immediately precedes implantation is the hatching of blastocyst. Ironically, blastocyst hatching is tacitly linked to peri-implantation events, although it is a distinct developmental phenomenon. The exact molecular network regulating hatching is still unclear. A number of implantation-associated molecular factors are expressed in the pre-implanting blastocyst. Among others, cytokines, expressed by peri-implantation blastocysts, are thought to be important for hatching, making blastocysts implantation competent. Pro-inflammatory (IL-6, LIF, GM-CSF) and anti-inflammatory (IL-11, CSF-1) cytokines improve hatching rates; they modulate proteases (MMPs, tPAs, cathepsins and ISP1). However, functional involvement of cytokines and their specific mediation of hatching-associated proteases are unclear. There is a need to understand mechanistic roles of cytokines and proteases in blastocyst hatching. This review will assess the available knowledge on blastocyst-derived pro-inflammatory and anti-inflammatory cytokines and their role in potentially regulating blastocyst hatching. They have implications in our understanding of early embryonic loss and infertility in mammals, including humans.

Expression and localization of interleukin 1 beta and interleukin 1 receptor (type I) in the bovine endometrium and embryo

The interleukin-1 (IL1) system likely mediates mammalian embryo-maternal communication. In cattle, we have reported that the uterine fluid of heifers carrying early embryos shows downregulated IL1 beta (IL1B), which could lead to reduced NFkB expression and dampening of maternal innate immune responses. In this work, we assessed the expression of IL 1 beta (IL1B) and its receptor, interleukin 1 receptor type I (IL1R1) in the bovine endometrium and embryos by RT-PCR, immunohistochemistry and Western blot at the time of blastocyst development. Day 8 endometrium, both collected from animals after transfer of day 5 embryos (ET) and sham transferred (ST), showed IL1B and IL1R1 mRNA transcription and protein co-localization. Similarly, day 8 blastocyst, from ET animals and entirely produced in vitro, showed IL1R1 mRNA transcription and IL1B and IL1R1 protein co-localization. IL1B mRNA was detected in the analyzed blastocysts, but at very low levels that precluded its quantification. IL1B and IL1R1 immunostaining was observed in luminal epithelial cells, glandular epithelium and stromal cells. The presence of embryos increased endometrial IL1B protein locally, while no differences regarding IL1R1 protein and IL1B and IL1R1 mRNA were detected. These results suggest that the early preimplantation bovine embryo in the maternal tract might interact with the maternal immune system through the IL1 system. Such a mechanism may allow the embryo to elicit local endometrial responses at early stages, which are required for the development of a receptive endometrium.

Influence of cumulus cell coculture and cumulusaided embryo transfer on embryonic development and pregnancy rates

OBJECTIVE

In this study, we aimed to evaluate the influence of autologous cumulus oocyte complex (COC) coculture on embryonic development and quality, and investigate the implantation and pregnancy rates after cumulus-aided embryo transfer in the ICSI-ET cycles.

MATERIAL AND METHODS

Ninety five consecutive infertile women undergoing their first cycle of IVF teratment were included in the study. The cases were divided into two groups. Group 1 consisted of 48 women undergoing ICSI, along with autologous cumulus embryo coculture and cumulus-aided emryo transfer. Group 2 comprised 47 consecutive patients who consented to undergo ICSI and in whom autologous cumulus embryo coculture and cumulus-aided embryo transfer were not performed. Implantation and pregnancy rates were compared between the two groups.

RESULTS

The demographic data and controlled ovarian hyperstimulation parameters were similar in the two groups. The fertilization and cleavage rates were found to be higher in group 1 when compared with group 2 (p=0.03 and 0.001, respectively). There were no statistical significant differences for the implantation and clinical pregnancy rates between the two groups.

CONCLUSION

Usage of autologous COCs as coculture may improve fertilization and cleavage rates. However, cumulus-aided embryo transfer does not produce an increase in implantation and pregnancy rates.

Deletion of the Isg15 gene results in up-regulation of decidual cell survival genes and down-regulation of adhesion genes: implication for regulation by IL-1beta

The ubiquitin homolog interferon stimulated gene 15 (ISG15) is up-regulated in the endometrium in response to pregnancy in primates, ruminants, pigs, and mice. ISG15 covalently attaches to intracellular proteins (isgylation) and regulates numerous intracellular responses. We hypothesized that ISG15 depletion (Isg15(-/-)) alters decidual tissue gene expression and that IL-1beta induces ISG15 expression and isgylation in cultured murine decidual explants and human uterine fibroblasts (HuFs). After studying the reproductive phenotype, contrary to earlier reports, up to 50% of the fetuses die between 7.5 and 12.5 d post coitum (dpc) in Isg15(-/-) mothers when mated to Isg15(-/-) fathers. Using microarray analysis, over 500 genes are differentially regulated in 7.5 dpc deciduas from Isg15(-/-) compared with Isg15(+/+) mice. The gene for interferon-inducible protein 202b, which functions in cell-survival mechanisms, was up-regulated (mRNA and protein) in deciduas from Isg15(-/-) mice. Culture of Isg15(+/+) mouse decidual explants (7.5 dpc) with IL-1beta decreased Isg15 mRNA but increased free and conjugated ISG15. In predecidual HuF cells, IL-1beta treatment increased ISG15 mRNA and isgylation. Additionally, IL-1beta up-regulated expression of enzymes (HERC5, UBCH8) that coordinate the covalent conjugation of ISG15 to target proteins, as well as the gene that encodes the deisglyation enzyme UBP43 in HuF cells. In conclusion, deletion of Isg15 gene results in 50% fetal loss after 7.5 dpc, which can be explained through differential decidual gene expression that is functionally tied to cell survival and adhesion pathways. This fetal death also might relate to impaired IL-1beta signaling, because ISG15 and isgylation are induced by IL-1beta in human and murine endometrial stromal cells.

Mammalian embryo co-culture: Trials and tribulations of a misunderstood method

Embryo-somatic cell co-culture was devised over 40 years ago in an attempt to improve the development and viability of mammalian preimplantation embryos generated and cultured in vitro. While initial endeavours were successful in this respect, other studies soon highlighted a number of significant long-term detrimental impacts of this approach. Surprisingly little is known about the mechanisms underlying the beneficial effects of co-culture, although the production of embryotrophic compounds, modulation of nutrient profile, protection against culture-induced stress and/or toxin clearance are all contenders. The extent to which the inadvertent exposure of embryos to serum accounts for many of these effects remains open to question. Although the popularity of somatic cell co-culture has recently declined in favour of the use of sequential media due to concerns associated with its risk of disease transmission and long-term sequelae, we argue that complete dismissal of this technique is ill advised, given that our limited understanding of basic somatic cell interactions has prevented us from fully exploiting its potential. In this respect, there is some merit in focussing future research strategies based on reconstructed maternal tract tissue. Although the use of co-culture in clinical practice is unacceptable and its implementation in domestic species for commercial purposes should be viewed with diffidence, this technique can still provide a wealth of information on the development of novel, more physiological embryo in vitro culture systems. The proviso for acquiring such information is to gain a fuller understanding of the culture requirements/biochemistry of somatic cells and their interaction with the early conceptus.

Interleukin-18 system messenger RNA and protein expression in human endometrium during the menstrual cycle

OBJECTIVE

To investigate the IL-18 system, including IL-18, IL-18 receptor (IL-18R), IL-18 binding protein (IL-18BP), and IL-18 precursor (proIL-18), mRNA and protein expression in human endometrium during the menstrual cycle.

DESIGN

Controlled study.

SETTING

Clinical and academic research setting in a university medical center.

PATIENT(S)

Human endometrium was obtained from surgical specimens of normal cycling women undergoing hysterectomy for benign reasons.

INTERVENTION(S)

A total of 24 human endometrium samples were obtained at proliferative and secretory phase from surgical specimens of normal cycling women undergoing hysterectomy. Quantitative competitive polymerase chain reaction (QC PCR) and immunohistochemistry were performed.

MAIN OUTCOME MEASURE(S)

The differences of IL-18 system mRNA and the ratio of antagonist to agonist in both proliferative and secretory phases of endometrium were analyzed.

RESULT(S)

Our results showed a complete IL-18 system, including mRNA expression and protein production in both proliferative and secretory phases of the endometrium. The QC PCR demonstrated that both IL-18 and IL-18R decreased and IL-18BP increased mRNA expression in human endometrium in secretory phase compared with proliferative phase. A positive correlation of IL-18 and IL-18R in human endometrium was demonstrated in proliferative phase but not in secretory phase. In addition, there is a significantly higher ratio of IL-18BP to IL-18 mRNA levels in secretory endometrium compared with proliferative phase endometrium (P<.05).

CONCLUSION(S)

The expression and ratio of IL-18 antagonist to agonist may be responsible for embryo implantation.

Cumulus coculture and cumulus-aided embryo transfer increases pregnancy rates in patients undergoing in vitro fertilization

OBJECTIVE

To evaluate the effect of the use of cumulus-aided embryo transfer on pregnancy rates. To study the proximity of expanded cumulus cells to the developing embryo. To document by light microscopy the anchoring of day 3 to day 4 embryos by the expanded cumulus cells. To demonstrate by transmission electron microscopy the cellular activity of the expanded cumulus cells. To evaluate the expression of growth factors (vascular endothelial growth factor, interleukin-6, insulin-like growth factor I) that are secreted by the cumulus cells.

DESIGN

A comparative study of a group of women undergoing cumulus coculture and cumulus-aided embryo transfer, with those who underwent cumulus coculture but did not undergo cumulus-aided embryo transfer. The endpoint was the achievement of pregnancy.

SETTING

Department of Infertility Management and Assisted Reproduction, Jaslok Hospital and Research Centre, Mumbai, India.

PATIENT(S)

Five hundred seventeen women undergoing treatment for infertility using intracytoplasmic sperm injection and embryo transfer and fulfilling set criteria. To validate our initial results, we conducted a similar study on 208 women where randomization was performed.

INTERVENTION(S)

Embryos were cocultured with the patient's own cumulus cells and were transferred into the uterus with approximately 30 microL of the expanded cumulus cells.

MAIN OUTCOME MEASURE(S)

Pregnancy, implantation, and multiple gestation rates.

RESULT(S)

Our study demonstrated a significant increase in the implantation rate in the study group (group A) of 25.6% versus 14.5% in the control group (group B) and a significant increase in the pregnancy rate in the study group (group A) of 47.6% versus 34% achieved in the control group (group B). Although the incidence of multiple gestation was similar (38.6% in the study group and 32.9% in the control group), the higher-order multiple gestation rate was significantly more in the study group as compared with the control group (18.1% vs. 2.4%). Similar pregnancy and implantation rates were observed in the randomized study.

CONCLUSION(S)

This study demonstrates the efficacy of cumulus-aided embryo transfer, using autologous cumulus cells. It indicates a significant increase in implantation and pregnancy rates. The results suggest that cumulus cells play an important role in embryonic development, and that they may provide a mechanism to improve embryo-uterine adhesion by physical proximity, and by secreting cytokines and growth factors required to aid the implantation process.

Expression of porcine endometrial prostaglandin synthase during the estrous cycle and early pregnancy, and following endocrine disruption of pregnancy

Porcine trophoblast attachment to the uterine surface is associated with increased conceptus and endometrial production of prostaglandins. Conceptus secretion of estrogen on Day 12 of gestation is important for establishment of pregnancy; however, early (Days 9 and 10) exposure to exogenous estrogens results in embryonic mortality. Present studies established the temporal and spatial pattern of endometrial PTGS1 (prostaglandin-endoperoxide synthase 1) and PTGS2 expression during the estrous cycle and early pregnancy and determined the effect of early estrogen treatment on endometrial PTGS expression in pregnant gilts. Endometrial PTGS1 mRNA expression increased 2- to 3-fold after Day 10 of the estrous cycle and pregnancy, whereas PTGS2 mRNA expression increased 76-fold between Days 5 and 15 of the estrous cycle and pregnancy. Increased expression of the PTGS2 transcript was detected in the lumenal epithelium after Day 10 in both cyclic and pregnant gilts. There was a 10- and 20-fold increase in endometrial PTGS2 protein expression between Days 5 and 18 of the estrous cycle and pregnancy respectively. Administration of estrogen on Days 9 and 10 of gestation increased endometrial PTGS2 mRNA and protein on Day 10, but decreased PTGS2 mRNA and protein in lumenal epithelium (LE) on Day 12 of gestation compared to vehicle-treated gilts. The present study demonstrates that an increase in uterine epithelial PTGS2 expression occurs after Day 10 of the estrous cycle and early pregnancy in the pig. The conceptus-independent increase in the uterine LE indicates that a novel pathway exists for endometrial induction PTGS2 expression before conceptus elongation and attachment to the uterine surface. Epithelial expression of PTGS2 may serve as one of the signals for placental attachment and embryo survival in the pig. Early administration of estrogen on Days 9 and 10 of pregnancy alters endometrial PTGS2 mRNA and protein expression, which may, at least in part, represent a mechanism by which endocrine disruption of pregnancy causes total embryonic loss during implantation in the pig.

Interleukin-1 system messenger ribonucleic acid and protein expression in human fallopian tube may be associated with ectopic pregnancy

OBJECTIVE

To investigate the interleukin-1 (IL-1) system mRNA and protein expression in human fallopian tubes with ectopic pregnancies.

DESIGN

A controlled study.

SETTING

Clinical and academic research setting in a university medical center.

PATIENT(S)

Women undergoing salpingectomy for fallopian tube with ectopic pregnancy and women undergoing tubal ligation.

INTERVENTION(S)

Paired segments of human fallopian tubes containing an ectopic pregnancy and parafallopian tube segments adjacent to the ectopic pregnancy were collected from five women undergoing laparoscopic salpingectomy. Segments of fallopian tubes from four women undergoing tubal ligation were used as control tissues. Quantitative competitive polymerase chain reaction (QC-PCR) and immunohistochemistry were performed.

MAIN OUTCOME MEASURE(S)

The differences of IL-1 system mRNA and the ratio of IL-1beta to IL-1 receptor antagonist (IL-1ra) in both fallopian tubes with ectopic pregnancies and normal controls were analyzed.

RESULT(S)

A complete IL-1 system mRNA and protein expression was identified in both fallopian tubes with ectopic pregnancies and normal controls. As QC-PCR demonstrated, IL-1beta mRNA expression was decreased, and IL-1ra and IL-1 receptor type 1 were increased in fallopian tubes with ectopic pregnancies in comparison with normal control tubes. In para-ectopic tubes, IL-1 receptor type 1 mRNA was statistically significantly increased in comparison with normal controls. There was a lower ratio of IL-1beta to IL-1ra at mRNA in fallopian tubes with ectopic pregnancies.

CONCLUSION(S)

These results suggest that an inappropriate ratio of IL-1beta to IL-1ra and a higher expression of its receptor in fallopian tubes may possibly be implicated to the implantation of an ectopic pregnancy in the oviduct.

Regulation of embryonic implantation

The preimplantation embryo produces several factors during its development to signal its presence to the maternal organism. This paper will focus on the role of two distinctive cytokine and growth factor systems (interleukin-1 (IL-1) system and the vascular endothelial growth factor (VEGF) system) during early embryonic development and implantation. IL-1 receptor is expressed in the endometrium of various species and antagonising the biological effects of IL-1 leads to implantation failure in mice. We could show that this is due to an endometrial, not an embryonic effect. Furthermore, we could detect the expression of all components of the IL-1 system in preimplantation embryos from mice and humans. We could show a possible influence of IL-1 on other systems involved in embryonic implantation, including invasion (MMPs/TIMPs) and angiogenesis (VEGF), therefore suggesting a role of this cytokine family during early embryonic development. Immediately after contact to the endometrium, the embryo must induce angiogenesis to ensure its survival, VEGF is a potent angiogenetic growth factor. We have shown a cyclic regulation of the soluble VEGF-receptor, sflt, in human endometrium and have detected the expression of the transmembraneous VEGF-receptors, Flt-1 and kinase insert domain containing receptor (KDR) throughout the menstrual cycle. Furthermore, we have shown that the VEGF gene is one of the earliest genes activated during human preimplantation embryo development, giving rise to the assumption that VEGF is crucial for embryonic development.

Matrix metalloproteinase and tissue inhibitor of matrix metalloproteinase expression in human preimplantation embryos

OBJECTIVE

To examine human embryos at various stages of preimplantation development for simultaneous expression of matrix metalloproteinases (MMPs) and tissue inhibitor of matrix metalloproteinases (TIMPs).

DESIGN

mRNAs of specific MMPs and TIMPs were examined in single human embryos, at different stages of preimplantation development, by reverse transcription-polymerase chain reaction (RT-PCR). Single embryo immunohistochemistry was applied to examine the protein expression.

SETTING

University-affiliated IVF-ET program.

PATIENT(S)

Couples, attending the university-affiliated IVF-ET program, electing to donate poor prognosis embryos with anomalous morphology.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The expression of MMP-1, MMP-2, MMP-9, TIMP-1, TIMP-2, and TIMP-3 in preimplantation embryos.

RESULT(S)

The MMP-2 mRNA was expressed consistently during development from one-cell to blastocyst stage. The TIMP-1 and TIMP-3 mRNAs were detected in embryos at all stages; however, in the later preimplantation developmental stages, an increasing proportion of embryos expressing TIMP-1 and TIMP-3 mRNA were noted. The MMP-1, MMP-9, and TIMP-2 mRNAs were detected in only a minority of human embryos studied. Immunohistochemistry showed MMP-1 and TIMP-1 protein expression in preimplantation embryos.

CONCLUSION(S)

The existence of MMP and TIMP mRNA expression in human preimplantation embryos argues for a role for these metalloproteinases and their inhibitors during the process of implantation in humans.

Interleukin-1beta regulation of gonadotropin-releasing hormone messenger ribonucleic acid in cultured human endometrial stromal cells

OBJECTIVE

To investigate the role of interleukin-1beta (IL-1beta) in regulating GnRH mRNA expression in cultured human endometrial stromal cells using a modified semiquantitative competitive reverse transcription and polymerase chain reaction (PCR).

DESIGN

A controlled study.

SETTING

Clinical and academic research setting in a university medical center.

PATIENT(S)

Women undergoing hysterectomy for nonmalignant indications.

INTERVENTION(S)

Confluent stromal cell cultures treated with steroid hormones were stimulated with IL-1beta and attenuated by anti-IL-1beta antibody or IL-1 receptor antagonist.

MAIN OUTCOME MEASURE(S)

The human endometrial stromal cell expression of GnRH and its receptor were determined by PCR. Interleukin-1beta-mediated regulation of stromal cell GnRH mRNA expression was determined by quantitative competitive PCR.

RESULT(S)

The GnRH and GnRH receptor mRNA expression were amplified in cultured stromal cells by PCR and two rounds of nested PCR, respectively. Treatment with IL-1beta stimulated stromal cell GnRH mRNA expression at concentrations of IL-1beta above 10 IU/mL. Recombinant IL-1 receptor antagonist and anti-IL-1beta antibody attenuated the increase of gene expression of GnRH initiated by IL-1beta.

CONCLUSION(S)

These results provide indirect evidence that IL-1beta may play a crucial role at the level of embryo-maternal interaction by regulating stromal cell expression of GnRH and its receptor, both known to be important in mediating trophoblast invasion and placental hormone regulation.

Possible Role of Interferon-.TAU. on In Vitro Development of Bovine Embryos

The effect of interferon-tau on in vitro development of bovine embryos was investigated. After in vitro fertilization, embryos developed to the morula stage were cultured for 3 days in TCM-199 or CR1 medium containing BSA or FCS supplemented with or without recombinant IFN-tau produced by a baculovirus expression system. Addition of baculovirus-expressed IFN-tau (100 ng/ml) significantly promoted development to the blastocyst stage in both culture media. Addition of E. coli expressed IFN-tau (2 microg/ml) also significantly promoted the embryonic development. Supplementation of BSA or FCS did not affect the growth-promoting effect of IFN-tau. To determine whether the growth-promoting effect of IFN-tau is related to the interferon type I receptors that bind to type I interferon such as IFN-alpha, embryos were cultured with IFN-alpha. Although IFN-alpha significantly promoted the development, a much higher concentration (25 microg/ml) was required than IFN-tau. A reverse transcription polymerase chain reaction analysis revealed the expression of mRNA encoded type-I IFN receptor subunit from morula to blastocyst stage embryos. The overall results suggest a novel function for IFNs in promoting embryonic development and the effect may be related to type-I IFN receptor expressed in the early stages of preimplantation embryos.

Vero cells, but not oviductal cells, increase the hatching frequency and total cell count of mouse blastocysts partly by changing energy substrate concentrations in culture medium

PURPOSE

To investigate the embryotrophic mechanisms of Vero and oviductal cells coculture.

METHODS

Mouse embryos were cultured in Chatot, Ziomek, and Bavister medium (CZB), in modified CZB media (MM) with nutrient concentrations adjusted to that found in conditioned media after different periods of Vero cells or oviductal cells culture, in reconstituted medium (RM) containing the purified > 100-kDa components of Vero cell conditioned medium that had been reconstituted with CZB medium, and cocultured with Vero cells with an interposing membrane.

RESULTS

The blastulation rate was not different among embryos cultured in different Vero-cell-derived MMs. Nine-hour Vero-cell-derived MM significantly increased the total cell number and hatching frequency of the embryos. There was no difference in these parameters with oviductal-cell-derived MMs. The RM of Vero cells did not possess embryotrophic activity. The presence of a porous membrane between Vero cells and embryos did not affect the embryotrophic activity of coculture.

CONCLUSIONS

Vero cells, but not oviductal cells, improved mouse embryo development partly by modifying the energy substrate concentration in culture medium.

Gonadotropin-releasing hormone messenger ribonucleic acid and protein expression in Vero cells

PURPOSE

Interleukin-1 (IL-1) is a major regulator of local cellular interactions during embryonic implantation. We hypothesized that gonadotropin-releasing hormone (GnRH) may also play a role in the embryonic/epithelial dialogue during early implantation. To examine this hypothesis, we examined the ability of IL-1 to regulate GnRH mRNA and protein expression in Vero cells.

METHODS

Viable Vero cells (1 x 10(5)/well) were cultured in multiple-well tissue culture plates for in vitro studies and in 4-well chamber slides for immunohistochemical study. Confluent Vero cells were cultured with increasing concentrations of recombinant human IL-1 beta for an additional 24 hr. Vero cell expression of GnRH and GnRH receptor mRNAs was measured with polymerase chain reaction (PCR) and nested PCR, respectively. GnRH protein expression was validated by immunohistochemistry study. The quantitative level of GnRH mRNA expression regulated by IL-1 beta in Vero cells was determined by quantitative competitive PCR (QC PCR) with standard curve methodology.

RESULTS

RT-PCR revealed beta-actin, GnRH, and GnRH receptor mRNA expression in Vero cell cultures. Immunostaining confirmed the presence of GnRH protein in Vero cells. Quantitative PCR demonstrated IL-1 beta up-regulation of Vero cell GnRH mRNA expression (p < 0.05).

CONCLUSIONS

These results suggest that Vero cell mRNA and protein expression of GnRH may play a substantial role in early embryo/epithelial dialogue during embryo coculture, with an embryotrophic effect due to expression of GnRH by Vero cells.

Interleukin (IL)-1beta regulation of IL-1beta and IL-1 receptor antagonist expression in cultured human endometrial stromal cells

The interleukin (IL)-1 system is a major regulator of local cellular interactions during embryonic implantation. Because IL-1beta and IL receptor antagonist (IL-1ra) are both expressed in human endometrium, we hypothesized that an appropriate ratio of IL-1beta to IL-1ra might favor the process of embryo implantation. Therefore, we investigated IL-1 regulation of the quantitative ratio of IL-1beta/IL-1ra messenger RNA (mRNA) expression in human endometrial stromal cells using quantitative competitive PCR, as well as intracellular protein expression after stromal cell solubilization. Confluent stromal cell cultures were stimulated with human IL-1beta (0-1000 IU/mL) for 24 h. After 24 h, total RNA was extracted, reverse transcribed, and coamplified by PCR with a defined amount of internal standard. The quantitative ratio was determined by the density of target to the internal standard. After culture with IL-1beta for 24 and 48 h, stromal cells were solubilized, and the intracellular protein levels of IL-1beta and IL-1ra were measured by enzyme-linked immunosorbent assay. The IL-1beta and IL-1ra mRNA were both up-regulated, and IL-1R tI mRNA was down-regulated, by IL-1beta in a dose-dependent manner. The quantitative ratio of IL-1beta to IL-1ra mRNA was constant with the presence of increasing concentrations of IL-1beta (1-1000 IU/mL). IL-1beta and IL-1ra protein was not detected in conditioned media of cultures before addition of IL-1beta. IL-1beta and IL-1ra protein levels increased with increasing amounts of IL-1beta after solubilization of stromal cells. The IL-1beta was detectable after 12 h of culture, in comparison with IL-1ra, which was detectable after 24 h of IL-1beta stimulation. These results suggest that IL-1 may play a crucial role in embryo-maternal interaction by regulating stromal cell expression of IL-1beta and IL-1ra, resulting in an appropriate ratio during the process of embryonic implantation.

Expression of vascular endothelial growth factor mRNA in human preimplantation embryos derived from tripronuclear zygotes

OBJECTIVE

To detect the expression of vascular endothelial growth factor (VEGF) mRNA and/or secretion of VEGF protein by human preimplantation embryos.

DESIGN

Human preimplantation embryos not suitable for uterine transfer were examined for beta-actin and VEGF mRNA expression. Culture media from normally fertilized and developing preimplantation embryos were assessed for VEGF protein secretion.

SETTING

Clinics and academic research laboratories at the Departments of Obstetrics and Gynecology at the Stanford University, Palo Alto, California and the Heinrich-Heine-University, Düsseldorf, Germany.

PATIENT(S)

Couples undergoing IVF by intracytoplasmic sperm injection for various reasons.

INTERVENTION(S)

Six unfertilized oocytes and 33 pathologically fertilized (tripronucleic, 3PN) preimplantation embryos were examined for VEGF mRNA expression, and 16 embryos were examined for VEGF protein secretion.

MAIN OUTCOME MEASURE(S)

Embryonic expression of VEGF mRNA and VEGF protein as determined by reverse transcription (RT)/nested polymerase chain reaction (PCR) and ELISA.

RESULT(S)

VEGF mRNA and protein could not be detected in unfertilized oocytes. However, 30/33 preimplantation embryos did express VEGF mRNA (11/12 10-to-16-cell embryos, 3/4 morulae, 11/12 early blastocysts, 5/5 hatched blastocysts). The VEGF protein level was below the sensitivity of the ELISA.

CONCLUSION(S)

Production of VEGF may give the embryo the ability to induce neoangiogenesis at the implantation site, thus creating an environment necessary for its survival.

The role of gonadotropin-releasing hormone in murine preimplantation embryonic development

Previous studies have established the presence of an extrahypothalamic GnRH in a variety of tissues. GnRH receptor is known to be present in the placenta, which produces and secretes the decapeptide from the very early stages of placentation. We hypothesized that GnRH may play a role in the preimplantation development of embryos. To examine this hypothesis, we assessed GnRH and GnRH receptor messenger RNA (mRNA; RT-PCR) and protein expression (Immunohistochemistry) in preimplantation murine embryos at various developmental stages. Furthermore, preimplantation murine embryos were cultured with GnRH agonist and antagonist in vitro to assess the influence of GnRH analogs on embryo development. GnRH is expressed in the developing mouse embryo from morula to hatching blastocyst stages at the mRNA and protein levels. GnRH receptor mRNA is also present in the developing embryos studied. Preimplantation embryonic development was significantly enhanced by incubation with increasing concentrations of GnRH agonist and is significantly decreased by GnRH antagonist compared with that in the control group. Moreover, GnRH antagonist (5 and 10 microM) was able to completely block embryo development. The deleterious effect of GnRH antagonist on embryo development was reversed by increasing concentrations of the agonist, as determined by the number of embryos reaching the blastocyst stage.

Ontogeny of expression of a receptor for platelet-activating factor in mouse preimplantation embryos and the effects of fertilization and culture in vitro on its expression

Platelet-activating factor (PAF; 1-o-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent ether phospholipid. It is one of the preimplantation embryo's autocrine growth/survival factors. It may act via a G protein-linked receptor on the embryo; however, the evidence for this is conflicting. The recent description of the intracellular form of the PAF:acetlyhydrolase enzyme as having structural homology with G proteins and Ras also suggests this as a potential intracellular receptor/transducer for PAF. This study used reverse transcription-polymerase chain reaction to examine the ontogeny of expression of the genes for these proteins in the oocyte and preimplantation-stage embryo. Transcripts for the G protein-linked PAF receptor were detected in the late 2-cell-stage embryo and in all stages from the 4-cell stage to blastocysts. They were also present in unfertilized oocytes and newly fertilized zygotes but only at relatively low levels. The incidence of expression was generally low and variable in late zygotes and early 2-cell embryos. Expression past the 2-cell stage was alpha-amanitin sensitive. The results indicated that mRNA for this receptor is a maternal transcript that was degraded during the zygote-2-cell stage. New expression of the receptor transcript required activation of the zygotic genome. Fertilization of embryos in vitro caused this transcript not to be expressed in the zygote. Culture of zygotes (irrespective of their method of fertilization) caused expression from the zygotic genome to be retarded by more than 24 h. This retardation did not occur if culture commenced at the 2-cell stage. The transcripts for the subunits of intracellular PAF:acetylhydrolase were not detected in oocytes or at any stage of embryo development examined, despite their being readily detected in control tissue. This study confirms the presence of the G protein-linked PAF receptor in the 2-cell embryo and describes for the first time its normal pattern of expression during early development. The adverse effects of in vitro fertilization (IVF) and embryo culture on the expression of this transcript may be a contributing factor for the poor viability of embryos produced in this manner. The reduced expression of PAF-receptor mRNA following IVF predicts that such embryos may have a deficiency in autocrine stimulation and also suggests that supplementation of growth media with exogenous PAF would be only partially beneficial. The effect of IVF and culture may also explain the conflicting literature.

Different pattern of interleukin-1 beta-(IL-1 beta), interleukin-1 receptor antagonist- (IL-1ra) and interleukin-1 receptor type I- (IL-1R tI) mRNA-expression in single preimplantation mouse embryos at various developmental stages

The interleukin-1 (IL-1) system has been shown to play an important role in human and murine embryo implantation. Recent studies have documented immunohistochemical evidence of interleukin-1 beta (IL--1 beta), interleukin-1 receptor antagonist (IL-1ra) and interleukin-1 receptor type I (IL-1R tI) in human preimplantation embryos and protein levels of interleukin-1 alpha (IL-1 alpha), IL-1 beta and IL1ra in human preimplantation embryo culture fluid have been correlated with successful implantation and pregnancy. Our aim in this study was to detect IL-1 beta, Il-1ra and Il-1R tI mRNA in single preimplantation mouse embryos and to describe the frequency of positive mRNA-expression at different developmental stages. B6C3F1-mice, 12 weeks old were pregnant mare serum gonadotropin (PMSG)/human chorionic gonadotropin (hCG)-stimulated and mated. Animals were sacrificed at day 0.5, and zygotes were flushed from the tubes and cultured in HAMs-F10 medium. 2-cell- (2C-), 8-cell- (8C-), morula- (M-), early blastocyst- (EB-) and hatching blastocyst- (HB-) stage embryos were examined by one round of reverse transcriptase (RT) followed by two rounds of polymerase chain reaction (PCR) carried out on individual mouse embryos for beta-actin (internal standard), IL-1 beta, IL-1ra and IL-1R tI-mRNAs. The frequencies of positive mRNA-expressions were as follows (2C/8C/M/EB/HB); beta-actin: 91/96/100/100/98%; IL-1b: 0/0/2.5/6.25/19; IL-1ra; 0/5/30/41/74% and IL-1R tI: 0/0/10/20/25%. The incidence of IL-1ra mRNA expression increased with developmental stage. IL-1ra mRNA seems to be expressed in a very high percentage (74%) of embryos near the time of implantation, whereas the percentage of IL-1 beta-mRNA positive embryos is surprisingly low (19%).