Administration of peripheral blood mononuclear cells into the uterine horn to improve pregnancy rate following bovine embryo transfer

Preservation of Simmental bull sperm at 0°C in Tris dilution: effect of dilution ratio and long-distance transport

OBJECTIVE

This study aimed to assess the impact of the dilution ratio of Tris diluent, storage at 0°C, and long-distance transportation on the spermatozoa of Simmental cattle. It also validated the feasibility of the regional distribution of fresh semen.

METHODS

In experiment 1, semen was diluted at four dilution ratios (1:6, 1:9, 1:12, and 1:15) to determine the optimal dilution ratio of Tris diluent. In experiment 2, we assessed sperm viability, progressive motility (objectively assessed by computer-assisted sperm analyzer), and acrosome intactness in Tris dilutions kept at constant 0°C for 1, 3, 6, 9, and 12 days. We compared them to Tianshan livestock dilutions (Commercial diluent). In experiment 3, semen was diluted using Tris diluent, and sperm quality was measured before and after long-distance transport. Artificial insemination of 177 Simmental heifers compared to 156 using Tianshan Livestock dilution.

RESULTS

The outcomes demonstrated that 1:9 was the ideal Tris diluent dilution ratio. The sperm viability, Progressive Motility, and acrosome integrity of both Tris and Tianshan dilutions preserved at 0°C gradually decreased over time. sperm viability was above 50% for both dilutions on d 9, with a flat rate of decline. The decrease in acrosome integrity rate was faster for Tianshan livestock dilutions than for Tris dilutions when stored at 0°C for 1 to 6 days. There was no significant difference (p>0.05) in sperm viability between semen preserved in Tris diluent after long-distance transportation and semen preserved in resting condition. The conception rates for Tris dilution and Tianshan livestock dilution were 49.15% and 46.15% respectively, with no significant difference (p>0.05).

CONCLUSION

This shows that Tris diluent is a good long-term protectant. It has been observed that fresh semen can be successfully preserved for long-distance transport when stored under 0°C conditions. Additionally, it is feasible to distribute semen regionally.

Immunomodulation for unexplained recurrent implantation failure: where are we now?

In brief

Immune dysfunction may contribute to or cause recurrent implantation failure. This article summarizes normal and pathologic immune responses at implantation and critically appraises currently used immunomodulatory therapies.

Abstract

Recurrent implantation failure (RIF) may be defined as the absence of pregnancy despite the transfer of ≥3 good-quality blastocysts and is unexplained in up to 50% of cases. There are currently no effective treatments for patients with unexplained RIF. Since the maternal immune system is intricately involved in mediating endometrial receptivity and embryo implantation, both insufficient and excessive endometrial inflammatory responses during the window of implantation are proposed to lead to implantation failure. Recent strategies to improve conception rates in RIF patients have focused on modulating maternal immune responses at implantation, through either promoting or suppressing inflammation. Unfortunately, there are no validated, readily available diagnostic tests to confirm immune-mediated RIF. As such, immune therapies are often started empirically without robust evidence as to their efficacy. Like other chronic diseases, patient selection for immunomodulatory therapy is crucial, and personalized medicine for RIF patients is emerging. As the literature on the subject is heterogenous and rapidly evolving, we aim to summarize the potential efficacy, mechanisms of actions and side effects of select therapies for the practicing clinician.

Effects of Intrauterine Infusion of Autologous Platelet-Rich Plasma in Women Undergoing Treatment with Assisted Reproductive Technology: a Meta-Analysis of Randomized Controlled Trials

Purpose This meta-analysis was conducted to systematically retrieve relevant randomized controlled trials (RCTs) and evaluate the effects of intrauterine infusion of autologous platelet-rich plasma (PRP) in women with thin endometrium, implantation or pregnancy failure undergoing treatment with assisted reproductive technology (ART).

Methods We conducted a systematic review and meta-analysis of the retrieved RCTs. Studies on the intrauterine infusion of PRP in women undergoing treatment with ART that were published in PubMed, the Cochrane library, Web of Science, and Embase from inception until June 2022 were included. The data were extracted and analyzed independently using the fixed-effects or random-effects model according to heterogeneity.

Results Seven RCTs involving 861 patients (435 in the intervention group and 426 in the control group) were included. The rates of clinical pregnancy (risk ratio [RR]: 2.51; 95% confidence interval [CI]: 2.0–3.13; P < 0.00001), chemical pregnancy (RR: 1.96; 95% CI: 1.58–2.45; P < 0.00001), live births (RR: 7.03; 95% CI: 3.91–12.6; P < 0.00001), and implantation (RR: 3.27; 95% CI: 1.42–7.52; P = 0.005) were significantly higher in the women who received PRP infusion than in the control group. No significant differences were noted in the miscarriage rate (RR: 0.98; 95% CI: 0.39–2.42; P = 0.96) between the two groups.

Conclusion In summary, intrauterine infusion of PRP may be an effective therapy for women with thin endometrium and recurrent implantation failure (RIF) undergoing treatment with ART. More population-based RCTs are warranted to verify the efficacy of our evidence.

Intrauterine administration of peripheral blood mononuclear cells (PBMCs) improves embryo implantation in mice by regulating local Treg/Th17 cell balance

Immune imbalance of Treg/Th17 cells may contribute to recurrent implantation failure (RIF) during in vitro fertilization and embryo transfer (IVF-ET). In this study, we sought to determine the effect of intrauterine administration of mouse PBMCs prior to embryo implantation on endometrial receptivity and embryo implantation, and examine the underlying mechanism of Treg/Th17 cell balance following intrauterine administration of PBMCs. Pregnant mice were randomly divided into three groups: control group, embryo implantation dysfunction (EID) group, and EID with PBMCs group, and the number of embryo implantation sites was recorded during early pregnancy (Pd7.5). The balance of Treg/Th17 cells in the peripheral blood, spleen, and local implantation sites was detected during the peri-implantation period (Pd4.0) and early pregnancy (Pd7.5). The EID group demonstrated a significant decrease in the number of embryo implantation sites, while the EID with PBMCs group demonstrated higher number of embryo implantation sites compared to the EID group. The balance of Treg/Th17 cells in the peripheral blood and spleen tissues was not significantly different between the aforementioned groups. However, the local uterine ratio of the Treg/Th17 cells increased in the EID with PBMCs group compared to that in the EID group. Collectively, we found that intrauterine administration of PBMCs prior to embryo implantation effectively promotes embryo implantation rates. This may be attributed to the improvement in the local immune balance of Treg and Th17 cells compared with the overall immune balance.

The incompletely fulfilled promise of embryo transfer in cattle-why aren't pregnancy rates greater and what can we do about it?

Typically, bovine embryos are transferred into recipient females about day 7 after estrus or anticipated ovulation, when the embryo has reached the blastocyst stage of development. All the biological and technical causes for failure of a female to produce a blastocyst 7 d after natural or artificial insemination (AI) are avoided when a blastocyst-stage embryo is transferred into the female. It is reasonable to expect, therefore, that pregnancy success would be higher for embryo transfer (ET) recipients than for inseminated females. This expectation is not usually met unless the recipient is exposed to heat stress or is classified as a repeat-breeder female. Rather, pregnancy success is generally similar for ET and AI. The implication is that either one or more of the technical aspects of ET have not yet been optimized or that underlying female fertility that causes an embryo to die before day 7 also causes it to die later in pregnancy. Improvements in pregnancy success after ET will depend upon making a better embryo, improving uterine receptivity, and forging new tools for production and transfer of embryos. Key to accelerating progress in improving pregnancy rates will be the identification of phenotypes or phenomes that allow the prediction of embryo competence for survival and maternal capacity to support embryonic development.

Intrauterine administration of autologous hCG- activated peripheral blood mononuclear cells improves pregnancy outcomes in patients with recurrent implantation failure; A double-blind, randomized control trial study

We aimed to investigate the effect of intrauterine administration of autologous hCG-activated PBMCs in RIF women with low Th-17/Treg cell ratio. 248 women with a history of implantation failure volunteered to receive PBMC-therapy. After immunologic consultation and doing flow cytometry analysis, 100 women with at least three IVF/ET failure who had low Th-17/Treg ratio in comparison with healthy control were enrolled in this study. These 100 patients were randomly divided into two groups as PBMC receiving (n = 50) and controls (n = 50). Then PBMCs were obtained from patients and treated with hCG for 48 h. Afterward, PBMCs were administered into the uterine cavity of the patient in the study group, two days before ET. The concentration of inflammatory cytokines was examined in the supernatant of cultured PBMCs after 2, 24, and 48 h of incubation using the ELISA method. The frequency of Th-17, Treg, and the Th-17/Treg ratio was significantly lower in RIF women than the healthy controls (P < 0.0001). The secretion of inflammatory cytokines was significantly higher after 48 h compared to 2 and 24 h (P < 0.0001). The pregnancy and live birth rate were significantly increased in women undergoing the PBMC-therapy compared to control (PBS-injecting) group (P = 0.032 and P = 0.047, respectively). The miscarriage rate was considerably lower in PBMC-therapy group (P = 0.029). Our findings suggest that intrauterine administration of autologous in vitro hCG-activated PBMCs improves pregnancy outcomes in patients with at least three IVF/ET failures.

The Female Response to Seminal Fluid

Seminal fluid is often assumed to have just one function in mammalian reproduction, delivering sperm to fertilize oocytes. But seminal fluid also transmits signaling agents that interact with female reproductive tissues to facilitate conception and .pregnancy. Upon seminal fluid contact, female tissues initiate a controlled inflammatory response that affects several aspects of reproductive function to ultimately maximize the chances of a male producing healthy offspring. This effect is best characterized in mice, where the female response involves several steps. Initially, seminal fluid factors cause leukocytes to infiltrate the female reproductive tract, and to selectively target and eliminate excess sperm. Other signals stimulate ovulation, induce an altered transcriptional program in female tract tissues that modulates embryo developmental programming, and initiate immune adaptations to promote receptivity to implantation and placental development. A key result is expansion of the pool of regulatory T cells that assist implantation by suppressing inflammation, mediating tolerance to male transplantation antigens, and promoting uterine vascular adaptation and placental development. Principal signaling agents in seminal fluid include prostaglandins and transforming growth factor-β. The balance of male signals affects the nature of the female response, providing a mechanism of ‟cryptic female choiceˮ that influences female reproductive investment. Male-female seminal fluid signaling is evident in all mammalian species investigated including human, and effects of seminal fluid in invertebrates indicate evolutionarily conserved mechanisms. Understanding the female response to seminal fluid will shed new light on infertility and pregnancy disorders and is critical to defining how events at conception influence offspring health.

BEEF SPECIES-RUMINANT NUTRITION CACTUS BEEF SYMPOSIUM: Maternal immune modulation prior to embryo arrival in the uterus is important for establishment of pregnancy in cattle1

In 1953, Sir Peter Medawar first recognized the allogeneic properties of a developing conceptus and rationalized that an "immune-tolerant" physiological state must exist during pregnancy. Early theories speculated that the conceptus evaded the maternal immune system completely, but 40 yr after Medawar's observations, Wegmann proposed that the maternal immune system shifts the cytokine profile away from inflammatory cytokine production when an embryo is present. The economic consequences and production losses of subfertile animals have been well documented in studies evaluating calving distribution. Despite advances in understanding infertility or subfertility, few technologies exist to identify subfertile animals or improve fertility beyond hormonal intervention associated with synchronization protocols. Work in rodents and some livestock species indicates that the uterine immune cell population shifts dramatically after copulation and these early immune-modulated events establish a receptive uterine environment. Clearly, as evident in embryo transfer, the presence of a conceptus is sufficient to establish communication for pregnancy establishment but does not rule out the importance of other physiological events to prime the maternal immune system prior to blastocyst arrival in the uterus. In support of this concept, work in our laboratory and by others has demonstrated that autologous intrauterine transfer of peripheral immune cells prior to embryo transfer can increase pregnancy rates and accelerate conceptus development in women and cattle. Understanding aberrant immune regulation in subfertile animals may provide markers for subfertility or targets for clinical intervention to enhance fertility, particularly when using reproductive technologies.

Platelet-rich plasma or blood-derived products to improve endometrial receptivity?

The use of platelet-rich plasma (PRP) to improve endometrial receptivity is gaining increasing attention in assisted reproduction technologies. The authors report that autologous PRP intrauterine administration improves pregnancy and birth rates, particularly in cases of patients presenting poor endometrial growth. Different groups of scientists proposed a similar approach years ago using whole blood-derived products also to improve endometrial receptivity. The important role played by cytokines and growth factors during embryo implantation has been well-known for a long time. These signaling molecules are present and released by blood cells during physiological, normal endometrial growth and implantation. Similar blood mediators are released from platelet granules upon a blood vessel injury. Methods described for PRP preparation for intrauterine administration are not precise, and they seem to be similar to those used to prepare peripheral blood-derived products. Thus, it is possible that when preparing PRP from whole blood, the final plasma product used as "PRP" contains platelets in addition to the important cytokines and growth factors released by the peripheral blood mononuclear cells present in the whole blood. Precise knowledge of the identity, concentration, and effects of the individual blood factors, their origin, whether platelets or blood mononuclear cells, will greatly contribute to improve and to make results obtained in fertility treatments more repeatable.

Intrauterine administration of peripheral mononuclear cells in recurrent implantation failure: a systematic review and meta-analysis

It has been proposed that intrauterine administration of peripheral blood mononuclear cells (PBMCs) modulates maternal immune response through a cascade of cytokines, chemokines and growth factors to favor implantation. We conducted a meta-analysis to verify the effect of intrauterine PBMC administration on the outcome of embryo transfer in women with recurrent implantation failure (RIF). All relevant trials published in PubMed, Web of Science and Cochrane library databases were searched. Two randomized controlled trials and three cohort studies (1173 patients in total) matched the inclusion criteria. No differences in live birth rates were seen between the PBMC-treated patients and controls (OR: 1.65, 95% CI: 0.84–3.25; p = 0.14; I²: 66.3%). The clinical pregnancy rate was significantly higher in women who received intrauterine PBMCs before embryo transfer compared with those who did not (OR: 1.65, 95% CI: 1.30–2.10; p = 0.001, heterogeneity; I²: 60.6%). Subgroup analyses revealed a significant increase in clinical pregnancy rates with the administration of PBMCs in women with ≥3 previous failures compared with controls (OR: 2.69, 95% CI: 1.53–4.72; p = 0.001, I²: 38.3%). In summary, the data did not demonstrate an association between the administration of PBMCs into the uterine cavity before fresh or frozen-thawed embryo transfer and live birth rates in women with RIF. Whether intrauterine PBMC administration significantly changes live birth and miscarriage rates requires further investigation.

Rumen-protected B vitamin complex supplementation during the transition period and early lactation alters endometrium mRNA expression on day 14 of gestation in lactating dairy cows

Greater metabolic demands in high-producing dairy cows are believed to be a cause of sub-fertility in these animals. Previously, supplementation with vitamin B complex molecules has shown benefits in improving milk production, health, and reproductive efficiency of dairy cows. The primary aim of this project was to determine the effects of rumen-protected vitamin B complex supplementation of 100 g of Transition VB (Jefo, St. Hyacinthe, QC, Canada) and 4 g of Lactation VB (VB; Jefo), during the transition and early lactation periods, respectively, compared with a control diet containing no supplementation on d 14 endometrial outcomes of pregnancy. In the vitamin B supplemented cows, we expect to see a change in the mark-up of endometrial genes important for embryo survival before implantation. Multiparous Holstein cows were enrolled into the study 3 wk before parturition and were randomly assigned to either the VB or control treatment. Twice-a-week blood samples, weekly milk samples, and daily feed intake were collected. Cows were enrolled onto a double-ovsynch protocol at 33 ± 3 d postpartum and inseminated by timed artificial insemination. Milk production and components, concentrations of BHB, haptoglobin, and progesterone in serum, and ovarian dynamics were also measured, but no treatment effect was observed. The uterus was flushed on d 14 after artificial insemination (around 72 DIM) for conceptus collection, and endometrial samples were collected at the same time. Overall, 42 cows were flushed and 13 embryos were collected. Analysis of mRNA expression of genes related to embryo development, immune system, adhesion, and regulation of vitamin B molecules showed that OXTR, MUC5B, MUC1, IL1B, SPP, TRD, FZD8, and FOLR1 genes were significantly upregulated in the VB group. Vitamin B supplementation had no effect on the size of the embryo and ovulatory follicle or corpus luteum diameter at embryo collection. In conclusion, the benefits of strategic dietary VB supplementation during the transition and early lactation might be directly linked to endometrial functions required for embryo survival during the peri-implantation period.

Dual Positive Regulation of Embryo Implantation by Endocrine and Immune Systems--Step-by-Step Maternal Recognition of the Developing Embryo

In humans, HCG secreted from the implanting embryo stimulates progesterone production of the corpus luteum to maintain embryo implantation. Along with this endocrine system, current evidence suggests that the maternal immune system positively contributes to the embryo implantation. In mice, immune cells that have been sensitized with seminal fluid and then the developing embryo induce endometrial differentiation and promote embryo implantation. After hatching, HCG activates regulatory T and B cells through LH/HCG receptors and then stimulates uterine NK cells and monocytes through sugar chain receptors, to promote and maintain pregnancy. In accordance with the above, the intrauterine administration of HCG-treated PBMC was demonstrated to improve implantation rates in women with repeated implantation failures. These findings suggest that the maternal immune system undergoes functional changes by recognizing the developing embryos in a stepwise manner even from a pre-fertilization stage and facilitates embryo implantation in cooperation with the endocrine system.

Role of Paternal Antigen-Specific Treg Cells in Successful Implantation

Maternal lymphocytes recognize fetal antigens, so tolerance is necessary to prevent rejection. Seminal plasma is important for induction of paternal antigen-specific Treg cells in the uterine draining lymph nodes and the pregnant uterus. Elimination of Treg cells during implantation or early pregnancy induces implantation failure or fetal resorption in mice. Immunosuppressive therapy with an anti-TNF antibody or the immunosuppressive agent tacrolimus improves the pregnancy rate in women with repeated implantation failure and recurrent pregnancy loss of unknown etiology, suggesting that Treg cells play an essential role in successful implantation and pregnancy in humans.

Influence of Sex on Basal and Dickkopf-1 Regulated Gene Expression in the Bovine Morula

Sex affects function of the developing mammalian embryo as early as the preimplantation period. There were two goals of the current objective. The first was to determine the degree and nature of differences in gene expression between female and male embryos in the cow at the morula stage of development. The second objective was to determine whether DKK1, a molecule known to alter differentiation of the blastocyst, would affect gene expression differently for female and male morulae. In Experiment 1, female and male embryos were treated with DKK1 at Day 5 after insemination. Morulae were harvested 24 h after treatment, pooled in groups of 20 for microarray analysis and RNA subjected to analysis of gene expression by microarray hybridization. There were 662 differentially expressed genes between females and males and 128 of these genes had a fold change ≥ 1.5 between the two sexes. Of the genes upregulated in females, 49.5% were located in the X chromosome. Functional analysis predicted that cell survival was greater in female embryos. Experiment 2 involved a similar design except that transcripts for 12 genes previously reported to be affected by sex, DKK1 or the interaction were quantified by quantitative polymerase chain reaction. Expression of all genes tested that were affected by sex in experiment 1 was affected in a similar manner in Experiment 2. In contrast, effects of DKK1 on gene expression were largely not repeatable in Experiment 2. The exception was for the Hippo signaling gene AMOT, which was inhibited by DKK1. In Experiment 3, embryos produced by fertilization with unsorted sperm were treated with DKK1 at Day 5 and abundance of transcripts for CDX2, GATA6, and NANOG determined at Days 5, 6 and 7 after insemination. There was no effect of DKK1 on expression of any of the three genes. In conclusion, female and male bovine embryos have a different pattern of gene expression as early as the morula stage, and this is due to a large extent to expression of genes in the X chromosomes in females. Differential gene expression between female and male embryos is likely the basis for increased resistance to cell death signals in female embryos and disparity in responses of female and male embryos to changes in the maternal environment.

HCG-Activated Human Peripheral Blood Mononuclear Cells (PBMC) Promote Trophoblast Cell Invasion

Successful embryo implantation and placentation depend on appropriate trophoblast invasion into the maternal endometrial stroma. Human chorionic gonadotropin (hCG) is one of the earliest embryo-derived secreted signals in the peripheral blood mononuclear cells (PBMC) that abundantly expresses hCG receptors. The aims of this study were to estimate the effect of human embryo-secreted hCG on PBMC function and investigate the role and underlying mechanisms of activated PBMC in trophoblast invasion. Blood samples were collected from women undergoing benign gynecological surgery during the mid-secretory phase. PBMC were isolated and stimulated with or without hCG for 0 or 24 h. Interleukin-1β (IL-1β) and leukemia inhibitory factor (LIF) expressions in PBMC were detected by enzyme-linked immunosorbent assay and real-time polymerase chain reaction (PCR). The JAR cell line served as a model for trophoblast cells and was divided into four groups: control, hCG only, PBMC only, and PBMC with hCG. JAR cell invasive and proliferative abilities were detected by trans-well and CCK8 assays and matrix metalloproteinase (MMP)-2 (MMP-2), MMP-9, vascular endothelial growth factor (VEGF), tissue inhibitor of metalloproteinase (TIMP)-1, and TIMP-2 expressions in JAR cells were detected by western blotting and real-time PCR analysis. We found that hCG can remarkably promote IL-1β and LIF promotion in PBMC after 24-h culture. PBMC activated by hCG significantly increased the number of invasive JAR cells in an invasion assay without affecting proliferation, and hCG-activated PBMC significantly increased MMP-2, MMP-9, and VEGF and decreased TIMP-1 and TIMP-2 expressions in JAR cells in a dose-dependent manner. This study demonstrated that hCG stimulates cytokine secretion in human PBMC and could stimulate trophoblast invasion.

Intrauterine insemination of cultured peripheral blood mononuclear cells prior to embryo transfer improves clinical outcome for patients with repeated implantation failures

Implantation failure is a major limiting factor in assisted reproduction improvement. Dysfunction of embryo–maternal immuno-tolerance pathways may be responsible for repeated implantation failures. This fact is supported by immunotropic theory stipulating that maternal immune cells, essentially uterine CD56+ natural killer cells, are determinants of implantation success. In order to test this hypothesis, we applied endometrium immuno-modulation prior to fresh embryo transfer for patients with repeated implantation failures. Peripheral blood mononuclear cells were isolated from repeated implantation failure patients undergoing assisted reproductive technology cycles. On the day of ovulation induction, cells were isolated and then cultured for 3 days and transferred into the endometrium cavity prior to fresh embryo transfer. This immunotherapy was performed on 27 patients with repeated implantation failures and compared with another 27 patients who served as controls. Implantation and clinical pregnancy were increased significantly in the peripheral blood mononuclear cell test versus control (21.54, 44.44 vs. 8.62, 14.81%). This finding suggests a clear role for endometrium immuno-modulation and the inflammation process in implantation success. Our study showed the feasibility of intrauterine administration of autologous peripheral blood mononuclear cells as an effective therapy to improve clinical outcomes for patients with repeated implantation failures and who are undergoing in vitro fertilization cycles.

Seminal Fluid Signalling in the Female Reproductive Tract: Implications for Reproductive Success and Offspring Health

Carriage of sperm is not the only function of seminal fluid in mammals. Studies in mice show that at conception, seminal fluid interacts with the female reproductive tract to induce responses which influence whether or not pregnancy will occur, and to set in train effects that help shape subsequent fetal development. In particular, seminal fluid initiates female immune adaptation processes required to tolerate male transplantation antigens present in seminal fluid and inherited by the conceptus. A tolerogenic immune environment to facilitate pregnancy depends on regulatory T cells (Treg cells), which recognise male antigens and function to suppress inflammation and immune rejection responses. The female response to seminal fluid stimulates the generation of Treg cells that protect the conceptus from inflammatory damage, to support implantation and placental development. Seminal fluid also elicits molecular and cellular changes in the oviduct and endometrium that directly promote embryo development and implantation competence. The plasma fraction of seminal fluid plays a key role in this process with soluble factors, including TGFB, prostaglandin-E, and TLR4 ligands, demonstrated to contribute to the peri-conception immune environment. Recent studies show that conception in the absence of seminal plasma in mice impairs embryo development and alters fetal development to impact the phenotype of offspring, with adverse effects on adult metabolic function particularly in males. This review summarises our current understanding of the molecular responses to seminal fluid and how this contributes to the establishment of pregnancy, generation of an immune-regulatory environment and programming long-term offspring health.

Functions of interferon tau as an immunological regulator for establishment of pregnancy

The establishment of a successful pregnancy requires a "fine quality embryo", "maternal recognition of pregnancy", and a "receptive uterus" during the period of conceptus implantation to the uterine endometrium. In ruminants, a conceptus cytokine, interferon tau (IFNT), a major cytokine produced by the peri-implantation trophectoderm, is known as a key factor for maternal recognition of pregnancy. IFNT can be considered one of the main factors in conceptus-uterus cross-talk, resulting in the rescue of ovarian corpus luteum (CL), induction of endometrial gene expressions, activation of residual immune cells, and recruitment of immune cells. Much research on IFNT has focused on the CL life-span (pregnancy recognition) and uterine gene expression through IFNT and related genes; however, immunological acceptance of the conceptus by the mother has not been well characterized. In this review, we will discuss the progress in IFNT and implantation research made by us and others for over 10 years, and relate this progress to pregnancy in mammalian species other than ruminants.

Intrauterine administration of autologous peripheral blood mononuclear cells increases clinical pregnancy rates in frozen/thawed embryo transfer cycles of patients with repeated implantation failure

Intrauterine administration of autologous peripheral blood mononuclear cells (PBMC) activated by HCG in vitro are reported to improve implantation rates in patients with repeated failure of IVF-ET. In this study, we examined the effects of intrauterine administration of freshly isolated PBMC on clinical pregnancy and the implantation rates of patients who received frozen/thawed embryo transfer by prospective cohort study. Patients who had not achieved a successful pregnancy despite at least one or more IVF-ET sessions were enrolled in this study (n = 253, 253 cycles). Based on the patient's treatment preferences, PBMC were freshly isolated from each patient and then administered to the intrauterine cavity of that patient. Frozen/thawed embryo transfer was performed and the success of implantation in the PBMC-treated group (n = 83, 83 cycles) was compared with that in the non-treated control groups (n = 170, 170 cycles). There were no significant differences in the clinical pregnancy rate (34.9% vs. 32.9%), implantation rate (21.6% vs. 21.1%) and live birth delivery rate (21.7% vs. 21.8%) between PBMC-treated and non-treated groups. However, when the analyses were restricted to patients who had three or more implantation failures, the clinical pregnancy rate and the implantation rate in the PBMC-treated group (42.1% and 25.0%, p<0.05; n = 19 and 32, respectively) were significantly higher than those in the non-treated group (16.7% and 9.4%, p<0.05; n = 36 and 64, respectively). These findings indicate that intrauterine administration of autologous PBMC freshly isolated from patients, effectively improves embryo implantation in patients with three or more IVF failures.

Addition of erythrocytes to in vitro culture medium attenuates the detrimental effects of reactive oxygen species on bovine preimplantation embryo development

Erythrocytes were recently found to improve the early development of mice embryos by their antioxidant effect. The purpose of the present study was to examine the effect of erythrocytes on the in vitro development of bovine in vitro fertilized (IVF) embryos in medium supplemented with reactive oxygen species (ROS). IVF embryos were cultured in CR1aa medium supplemented with oxidizing agents, 0.5mmol/L hypoxanthine and 0.01U/mL xanthine oxidase (HX/XOD), in the presence and absence of erythrocytes (5×10(4) , 5×10(5) , 5×10(6) and 5×10(7) erythrocytes/mL). After 8 days, blastocysts were examined with a stereomicroscope. HX/XOD blocked development to the blastocyst stage (HX/XOD: 0%, control: 33%), but in the presence of both erythrocytes and HX/XOD, blastocyst development was restored to about one-third to two-thirds the normal rate (5×10(5) to 5×10(7) erythrocytes/mL: 12 to 23%). Furthermore, adding erythrocytes or erythrocyte hemolysate to medium without HX/XOD increased the blastocyst rate. These results suggest that the addition of erythrocytes can attenuate the detrimental effects of ROS on embryo development in bovine species as well as in mice.

Macrophage-derived LIF and IL1B regulate alpha(1,2)fucosyltransferase 2 (Fut2) expression in mouse uterine epithelial cells during early pregnancy

Macrophages accumulate within stromal tissue subjacent to the luminal epithelium in the mouse uterus during early pregnancy after seminal fluid exposure at coitus. To investigate their role in regulating epithelial cell expression of fucosylated structures required for embryo attachment and implantation, fucosyltransferase enzymes Fut1, Fut2 (Enzyme Commission number [EC] 2.4.1.69), and Fut4 (EC 2.4.1.214) and Muc1 and Muc4 mRNAs were quantified by quantitative real-time PCR in uterine epithelial cells after laser capture microdissection in situ or after epithelial cell coculture with macrophages or macrophage-secreted factors. When uterine macrophage recruitment was impaired by mating with seminal plasma-deficient males, epithelial cell Fut2 expression on Day 3.5 postcoitus (pc) was reduced compared to intact-mated controls. Epithelial cell Fut2 was upregulated in vitro by coculture with macrophages or macrophage-conditioned medium (MCM). Macrophage-derived cytokines LIF, IL1B, and IL12 replicated the effect of MCM on Fut2 mRNA expression, and MCM-stimulated expression was inhibited by anti-LIF and anti-IL1B neutralizing antibodies. The effects of acute macrophage depletion on fucosylated structures detected with lectins Ulex europaeus 1 (UEA-1) and Lotus tetragonolobus purpureas (LTP), or LewisX immunoreactivity, were quantified in vivo in Cd11b-dtr transgenic mice. Depletion of macrophages caused a 30% reduction in luminal epithelial UEA-1 staining and a 67% reduction in LewisX staining in uterine tissues of mice hormonally treated to mimic early pregnancy. Together, these data demonstrate that uterine epithelial Fut2 mRNA expression and terminal fucosylation of embryo attachment ligands is regulated in preparation for implantation by factors including LIF and IL1B secreted from macrophages recruited during the inflammatory response to insemination.