Stem cell factor/c-Kit signaling in in vitro cultures supports early mouse embryonic development by accelerating proliferation via a mechanism involving Akt-downstream genes

Sex differences in human pre-gastrulation embryos

Human fetuses exhibit notable sex differences in growth rate and response to the intrauterine environment, yet their origins and underlying mechanisms remain uncertain. Here, we conduct a detailed investigation of sex differences in human pre-gastrulation embryos. The lower methylation and incomplete inactivation of the X chromosome in females, as well as the sex-specific cell-cell communication patterns, contribute to sex-differential transcription. Male trophectoderm is more inclined toward syncytiotrophoblast differentiation and exhibits a stronger hormone secretion capacity, while female trophectoderm tends to retain cytotrophoblast program with stronger mitochondrial function as well as higher vasculogenesis and immunotolerance signals. Male primitive endoderm initiates the anterior visceral endoderm transcriptional program earlier than females. The cell cycle activities of the epiblast and primitive endoderm are higher in males compared to females, while the situation is opposite in the trophectoderm. In conclusion, our study provides in-depth insights into the sex differences in human pre-gastrulation embryos and contributes to unraveling the origins of the sex differences in human fetal development.

Asprosin-mediated regulation of ovarian functions in mice: An age-dependent study

Asprosin is a recently discovered adipokine reported to be involved in the modulation of mammalian gonadal functions. Preliminary investigations suggest its role in regulation of ovarian functions in rodents as well as bovids. In addition, increased levels of the adipokine during human ovarian pathophysiologies implicate it in disease progression and severity. The present study evidenced high expression of asprosin in ovaries of juvenile, pubertal and adult mice while expression was significantly low in ageing ovaries. Further, asprosin stimulated expression of markers for ovarian folliculogenesis (Scf, c-Kit, Gdf9, Bmp6, Fshr, Lhr) and steroidogenesis (3β-Hsd) in adult mice. In addition to exploring concentration-dependent effect of asprosin, the study implicates asprosin as an age-dependent modulator of ovarian functions as treatment of ovaries with asprosin led to upregulation of Fshr, c-Kit, Bmp6, and Gdf9 in both adult and juvenile ovaries, Lhr only in adults while that of Scf only in juvenile ovaries. The current study is first to report an age-dependent expression and role of asprosin in murine ovaries.

Optimization of human recombinant granulocyte-colony stimulating factor supplementation during in vitro production of porcine embryos to improve the efficiency of resource utilization of poor-quality cumulus-oocyte complexes

Granulocyte colony-stimulating factor (G-CSF), a pleiotropic cytokine, is secreted by the reproductive tract. Furthermore, our previous study indicated that human recombinant G-CSF (hrG-CSF) supplementation during porcine oocyte in vitro maturation (IVM) or during embryo in vitro culture (IVC) improved their quality and development potential when using cumulus-oocyte complexes (COCs) with more than three cumulus cell layers (CCL >3). Thus, in this study, we investigate the optimal conditions of hrG-CSF supplementation throughout the in vitro production (IVP: IVM + IVC) system to improve the embryo production efficiency of "poor-quality (CCL ≤3)" oocytes. COCs were classified into two groups according to the number of CCL (>3 and ≤3) and embryonic viability was analyzed after treatment with hrG-CSF during IVC. The mRNA transcription levels of G-CSF in COCs were compared based on their type and the period of IVM. Finally, developmental capacity and quality were evaluated after treatment with hrG-CSF for different periods of IVP. No marked effects on the developmental potential of embryos when using CCL ≤3 type COCs were observed after supplementing hrG-CSF only during IVC. Moreover, the mRNA transcription level of G-CSF increased gradually with IVM culture time and was higher in CCL ≤3 COCs than in >3. Supplementing hrG-CSF only during the IVM period resulted in the best embryo developmental potential, while supplementing hrG-CSF during the IVP period resulted in the best quality embryos, reflected in the increased total cell number and decreased apoptotic nuclei index of blastocysts. These findings indicate that "poor-quality" COCs may have a greater demand for G-CSF than "good-quality", meanwhile hrG-CSF supplementation throughout IVP improves resource utilization efficiency in poor-quality COCs.

Stem cell factor's role in enhancing the quality of fertilized and cloned porcine embryos for improved embryonic stem cell derivation

Stem cell factor (SCF), a cytokine growth factor, is expressed in various tissues of the male and female reproductive organs, including the testis, ovary, and endometrium. Its primary function involves cell survival, differentiation, and proliferation, achieved through its binding to the c-kit receptor. This study aimed to scrutinize the effects of SCF treatment during in vitro culture (IVC) on both the developmental potential and the efficiency of establishing embryonic stem cells (ESCs) from fertilized and cloned porcine embryos. The rates of cleavage and blastocyst formation exhibited no significant differences between fertilized and cloned embryos, even with the addition of SCF. However, it's worth noting that embryos cloned with Cloud eGFP as donor cells demonstrated notably increased rates of hatched blastocysts when treated with SCF, and this increase was statistically significant (p < 0.05). Furthermore, following the complete dissection of the blastocysts, although there was no significant difference in the SCF-treated group, the area of expansion was significantly reduced (p < 0.01) in the group treated with the antagonistic blocker (ACK2) compared to both the control and SCF-treated groups. These outcomes suggest that the SCF/c-kit signaling pathway might play a pivotal role in embryo implantation. As anticipated, the efficiency of deriving ESCs was significantly higher (p < 0.01) in the group subjected to SCF treatment (12.82 ± 1.02%) compared to the control group (5.41 ± 2.25%). In conclusion, this study highlights the crucial role of SCF in enhancing the quality of porcine embryos, a vital step in obtaining high-quality ESCs.

C-kit signaling promotes human pre-implantation 3PN embryonic development and blastocyst formation

BACKGROUND

Although in vitro culture system has been optimized in the past few decades, the problem of few or no high quality embryos has been still not completely solved. Accordingly, fully understanding the regulatory mechanism of pre-implantation embryonic development would be beneficial to further optimize the in vitro embryo culture system. Recent studies have found the expression of c-kit in mouse embryo and its promotion effects on mouse embryonic development. However, it is unclear the expression, the role and the related molecular regulatory mechanism of c-kit in human pre-implantation embryo development. Therefore, the present study is to determine whether c-kit is expressed in human pre-implantation embryos, and to investigate the possible regulatory mechanism of c-kit signaling in the process of embryonic development.

METHODS

The present study includes human immature oocytes and three pronucleus (3PN) embryos collected from 768 women (28-32 ages) undergoing IVF, and normal 2PN embryos collected from ICR mice. Samples were distributed randomly into three different experimental groups: SCF group: G-1™ (medium for culture of embryos from the pro-nucleate stage to day 3) or G-2™ (medium for culture of embryos from day3 to blastocyst stage) + HSA (Human serum album) solution + rhSCF; SCF + imanitib (c-kit inhibitor) group: G-1™ or G-2™ + HSA solution + rhSCF + imanitib; SCF + U0126 (MEK/ERK inhibitor) group: G-1™ or G-2™ + HSA solution + rhSCF + U0126; Control group: G-1™ or G-2™ + HSA solution + PBS; The rate of good quality embryos at day 3, blastulation at day 6 and good quality blastulation at day 6 were analysis. RT-PCR, western blot and immunofluorescence staining were applied to detect the target genes and proteins in samples collected from human or mice, respectively.

RESULTS

c-kit was expressed ubiquitously in all human immature oocytes, 3PN embryos and 3PN blastocysts. In the experiment of human 3PN embryos, compared with other groups, SCF group showed obviously higher rate of good quality at day 3, better rate of blastocyst formation at day 6 and higher rate of good quality blastocyst formation at day 6. Furthermore, we observed a higher ETV5 expression in SCF group than that in other groups. Similar results were also found in animal experiment. Interestingly, we also found a higher phosphorylation level of MEK/ERK signal molecule in mice embryos from SCF group than those from other groups. Moreover, inhibition of MEK/ERK signaling would remarkably impeded the mice embryonic development, which might be due to the reduced ETV5 expression.

CONCLUSIONS

The present study firstly revealed that c-kit signaling might promote the human pre-implantation embryonic development and blastocyst formation by up-regulating the expression of ETV5 via MEK/ERK pathway. Our findings provide a new idea for optimizing the in vitro embryo culture condition during ART program, which is beneficial to obtain high quality embryos for infertile patients.

Annexin A8 (ANXA8) regulates proliferation of porcine endometrial cells via Akt signalling pathway

Annexin A8 (ANXA8) gene, a member of the annexin family, encodes an anticoagulant protein involved in blood coagulation cascade and acts as an indirect inhibitor of the thromboplastin-specific complex. However, little is known about the function of ANXA8 in porcine endometrial cells so far. Here, ANXA8 mRNA was found to be abundant in porcine endometrium on days 11-13 of pregnancy. Real-time RT-PCR analysis indicated that the mRNA expression of the leukaemia inhibitory factor (LIF) and the epidermal growth factor (EGF) was upregulated by ANXA8 in porcine endometrial cells. Immunofluorescence technology and cell cycle analysis revealed that ANXA8 promoted the proliferation of endometrial cells, as evidenced by the abundant proliferating cell nuclear antigen (PCNA) expression and an increase in the S phase. Western blot analysis results indicated that ANXA8 activated the phosphorylation of the target protein kinase B (Akt) protein. Immunofluorescence technology results showed that the PCNA protein had no significant change in porcine endometrial cells with both ANXA8 overexpression and the addition of Akt inhibitor. Furthermore, the number of implantation sites was significantly reduced by injection of mus-siRNA-ANXA8 into the uterine horn of mice. Collectively, these results suggest that ANXA8 promotes the proliferation of endometrial cells through the Akt signalling pathway.

Stem cell factor-induced AKT cell signaling pathway: Effects on porcine trophectoderm and uterine luminal epithelial cells

Stem cell factor (SCF) is a multipotent growth factor that elicits diverse biological actions in various aspects of embryogenesis and animal development. The aim of the present study was to assess SCF-induced intracellular signaling and cellular activities in porcine trophectoderm (pTr) and uterine luminal epithelial (pLE) cells which are well known as useful to elucidate developmental events. SCF induced abundances of p-AKT, p-P70RSK and RPS6 proteins in pTr cells reached to their maximum, and then returned to basal levels by 120min. In pLE cells, SCF induced protracted effect to increase AKT phosphorylation which was well correlated with the time course for P70RSK and RPS6 phosphorylation. LY294002 (an inhibitor of AKT) decreased SCF-induced p-AKT, p-P70RSK and p-RPS6 proteins. Also, immunofluorescence analyses revealed that p-RPS6 was abundant within the cytoplasm of SCF-treated cells, but p-RPS6 was present only at basal levels in cells treated with LY294002. In the presence of LY294002, both SCF-stimulated transient and sustained AKT phosphorylation were inhibited in pLE cells. Furthermore, SCF increased migration of pTr and pLE cells, but LY294002 significantly reduced this effect of SCF. In conclusion, results of the present study suggest that SCF secreted by the endometrium induces autocrine/paracrine signaling responses that stimulate migration of pTr and pLE cells through activation of the AKT cell signaling pathway. Those results support the hypothesis that SCF is a critical regulatory factor for conceptus development and implantation during pregnancy in pigs.

Increased SCF in Follicular Fluid and Granulosa Cells Positively Correlates With Oocyte Maturation, Fertilization, and Embryo Quality in Humans

Stem cell factor (SCF), which is derived from granulosa cells (GCs), plays a key role in the process of follicular development and oocyte maturation. The present study aimed to explore whether the levels of SCF in follicular fluid (FF) and GCs can be used as a potential marker for predicting oocyte developmental potential. Follicular fluid and GC samples from 150 female patients undergoing intracytoplasmic sperm injection were collected in this study. The SCF concentrations in FFs and SCF messenger RNA (mRNA) in GCs were evaluated by using enzyme-linked immunosorbent assay and real-time polymerase chain reaction, respectively. The results showed that the levels of SCF protein and mRNA were significantly associated with oocyte maturation, normal fertilization, cleavage, and embryo quality. Moreover, the levels of SCF protein and mRNA in pregnancy group were also higher than those in the nonpregnancy group. The cutoff value of SCF in FF for predicting high-quality embryo was 1.346, with a sensitivity of 57.8% and a specificity of 72.4%, and the cutoff value of SCF in GCs for predicting high-quality embryo was 6.650, with a sensitivity of 64.4% and a specificity of 78.1%. In conclusion, our results showed a positive and statistically significant relationship between SCF level and oocyte maturation, normal fertilization, cleavage, embryo quality, and clinical pregnancy. Therefore, the levels of SCF in FF and GCs might be considered as a new marker for predicting oocyte developmental potential.

The impact of inflammatory cells in malignant ascites on small intestinal ICCs' morphology and function

Malignant ascites is one of the common complication at the late stage of abdominal cancers, which may deteriorate the environment of abdominal cavity and lead to potential damage of functional cells. Interstitial cells of Cajal (ICCs) are mesoderm-derived mesenchymal cells that function normal gastrointestinal motility. The pathological changes of ICCs or the reduced number may lead to the motility disorders of gastrointestinal tract. In this study, through analysis of malignant ascites which were obtained from cancer patients, we found that inflammatory cells, including tumour-infiltrating lymphocytes, accounted for 17.26 ± 1.31% and tumour-associated macrophages, occupied 19.06 ± 2.27% of total cells in the ascites, suggesting these inflammatory cells, in addition to tumour cells, may exert important influence on the tumour environment of abdominal cavity. We further demonstrated that the number of mice ICCs were significant decreased, as well as morphological and functional damage when ICCs were in the simulated tumour microenvironment in vitro. Additionally, we illustrated intestinal myoelectrical activity reduced and irregular with morphological changes of ICCs using the mice model of malignant ascites. In conclusion, our data suggested that inflammatory cells in malignant ascites may damage ICCs of the small intestine and lead to intestinal motility disorders.

Female tract cytokines and developmental programming in embryos

In the physiological situation, cytokines are pivotal mediators of communication between the maternal tract and the embryo. Compelling evidence shows that cytokines emanating from the oviduct and uterus confer a sophisticated mechanism for 'fine-tuning' of embryo development, influencing a range of cellular events from cell survival and metabolism, through division and differentiation, and potentially exerting long-term impact through epigenetic remodelling. The balance between survival agents, including GM-CSF, CSF1, LIF, HB-EGF and IGFII, against apoptosis-inducing factors such as TNFα, TRAIL and IFNg, influence the course of preimplantation development, causing embryos to develop normally, adapt to varying maternal environments, or in some cases to arrest and undergo demise. Maternal cytokine-mediated pathways help mediate the biological effects of embryo programming, embryo plasticity and adaptation, and maternal tract quality control. Thus maternal cytokines exert influence not only on fertility and pregnancy progression but on the developmental trajectory and health of offspring. Defining a clear understanding of the biology of cytokine networks influencing the embryo is essential to support optimal outcomes in natural and assisted conception.

Improvement of mouse embryo quality by myo-inositol supplementation of IVF media

OBJECTIVE

Myo-inositol (myoIns) has a positive role in mammalian development and human reproduction. Since experiments on farming species suggest a similar role in preimplantation development, we evaluated the hypothesis that the inclusion of myoIns in human embryo culture media would produce an increase in embryo quality in IVF cycles, using the mouse embryo assay.

METHODS

To determine the effect of myoIns on completion of preimplantation development in vitro, one-cell embryos of the inbred C57BL/6N mouse strain were produced by ICSI, cultured in human fertilization media in the presence of myoIns (myoIns+) or in its absence (myoIns-) and evaluated morphologically. Daily progression through cleavage stages, blastocyst production and expansion and blastomere number at 96 hours post fertilization were assessed.

RESULTS

Compared to myoIns- embryos, myoIns+ embryos displayed a faster cleavage rate and by the end of preimplantation development, the majority of myoIns+ blastocysts was expanded and formed by a higher number of blastomeres.

CONCLUSION

The presence of myoIns resulted in both an increase in proliferation activity and developmental rate of in vitro cultured early mouse embryos, representing a substantial improvement of culture conditions. These data may identify myoIns as an important supplement for human embryo preimplantation culture.