Insulin-like growth factor-1 (IGF-1) enhances developmental competence of cat embryos cultured singly by modulating the expression of its receptor (IGF-1R) and reducing developmental block

LIF-IGF Axis Contributes to the Proliferation of Neural Progenitor Cells in Developing Rat Cerebrum

In rodent models, leukemia inhibitory factor (LIF) is involved in cerebral development via the placenta, and maternal immune activation is linked to psychiatric disorders in the child. However, whether LIF acts directly on neural progenitor cells (NPCs) remains unclear. This study performed DNA microarray analysis and quantitative RT-PCR on the fetal cerebrum after maternal intraperitoneal or fetal intracerebral ventricular injection of LIF at day 14.5 (E14.5) and determined that the expression of insulin-like growth factors (IGF)-1 and -2 was induced by LIF. Physiological IGF-1 and IGF-2 levels in fetal cerebrospinal fluid (CSF) increased from E15.5 to E17.5, following the physiological surge of LIF levels in CSF at E15.5. Immunostaining showed that IGF-1 was expressed in the cerebrum at E15.5 to E19.5 and IGF-2 at E15.5 to E17.5 and that IGF-1 receptor and insulin receptor were co-expressed in NPCs. Further, LIF treatment enhanced cultured NPC proliferation, which was reduced by picropodophyllin, an IGF-1 receptor inhibitor, even under LIF supplementation. Our findings suggest that IGF expression and release from the NPCs of the fetal cerebrum in fetal CSF is induced by LIF, thus supporting the involvement of the LIF-IGF axis in cerebral cortical development in an autocrine/paracrine manner.

Effects of embryonic stem cell-conditioned medium on the preimplantation development of mouse embryos

The production of high-quality embryos in the laboratory and a successful pregnancy are closely related to the condition and contents of oocyte and embryo culture media. In this study, we investigated the effects of embryonic stem cell-conditioned medium (ESCCM) and embryonic stem cells growth medium (ESCGM) compared with potassium-enriched simplex optimized medium (KSOM) on preimplantation embryo development stages during natural or in vitro fertilization (IVF). Birth rate of pups was measured. To obtain mature oocytes, and 2-cell and 8-cell embryos, human chorionic gonadotropin (HCG) was injected 48 h after i.p. injection of 5 units of pregnant mare serum gonadotropin. Mature oocytes were obtained from non-mated female mice 14 h after HCG injection. To obtain 2-cell and 8-cell embryos, mated female mice, 1 day and 3 days, respectively, after HCG injection, were used. Mature oocytes were fertilized in HTF medium. Embryos obtained from natural or in vitro fertilization were cultured in experimental media, ESCCM and ESCGM, or KSOM as the control culture medium. Embryos that developed to the blastocyst stage were transferred to the uteri of pseudopregnant mice and effects of the experimental media on embryo viability were determined. ESCCM and ESCGM could not pass the embryo after the 2-cell stage, but they were suitable for the development of the embryo from the 8-cell stage to the blastocyst. It can be concluded that the embryo has various requirements at different stages of development.

An investigation of mechanisms underlying mouse blastocyst hatching: a ribonucleic acid sequencing study

OBJECTIVE

To investigate the regulatory mechanisms and signaling molecules underlying hatching in mouse embryos.

DESIGN

Experimental laboratory study using a mouse embryo model.

SETTING

University-based basic scientific research laboratory.

ANIMALS

A total of 40 B6C3F1 × B6D2F1 mouse embryos were used in this study.

INTERVENTION(S)

Frozen/thawed mouse embryos, at the 8-cell stage, were cultured in vitro for 2 days. The resulting hatching and prehatching blastocysts were then used for complementary deoxyribonucleic acid (cDNA) library preparation and ribonucleic acid (RNA) sequencing analysis (n = 8 for each group). Differentially expressed genes were then used for downstream functional analysis. In addition, a list of genes related to developmental progression in humans was used to identify genes that were potentially related to the hatching of human embryos.

MAIN OUTCOME MEASURE(S)

Differentially expressed genes, enriched Gene Ontology terms and canonical pathways, clustered gene networks, activated upstream regulators, and common genes between a gene list of hatching-related genes in mice and a gene list associated with developmental progression in humans.

RESULT(S)

A total 275 differentially expressed genes were identified between hatching and prehatching blastocysts: 230 up-regulated and 45 down-regulated genes. Functional enrichment analysis suggested that blastocyst hatching in vitro is an adenosine triphosphate (ATP)-dependent process that involves protein biosynthesis and organization of the cytoskeleton. Furthermore, by regulating cell motility, the RhoA signaling pathway (including Arpc2, Cfl1, Gsn, Pfn1, Tpi1, Grb2, Tmsb10, Enah, and Rnd3 genes) may be a crucial signaling pathway during hatching. We also identified a cluster of genes (Krt8, Krt7, Cldn4, and Aqp3) that exerted functional roles in cell-cell junctions and water homeostasis during hatching. Moreover, some growth factors (angiotensinogen and fibroblast growth factor 2) and endocrine factors (estrogen receptor and prolactin) were predicted to be involved in the regulation of embryo hatching. In addition, we identified 81 potential genes that are potentially involved in the hatching process in human embryos.

CONCLUSION(S)

Our analysis identified potential genes and molecular regulatory pathways involved in the blastocyst hatching process in mice; we also identified genes that may potentially regulate hatching in human embryos. Our findings enhance our knowledge of embryo development and provide useful information for further exploring the mechanisms underlying embryo hatching.

IGF-I Medium Supplementation Improves Singly Cultured Cat Oocyte Maturation and Embryo Development In Vitro

Embryo production is a routine procedure in several species. However, in felids, the effectiveness of this approach is far behind that in the majority of laboratory species. The development of a suitable environment starts with the proper composition of culture media. Therefore, for the improvement of assisted reproduction techniques and their outcome in cats, this is an urgent task. As the addition of insulin-like growth factors (IGF-I, IGF-II) or granulocyte-macrophage colony-stimulating factor (GM-CSF) was beneficial in other mammalian species, this study aims to check whether these components, combined with other factors (such as type of fertilisation or type of culture) can provide a benefit in the felid culture system in current use. Thus, these supplements, in different concentrations and combinations, were merged with the use of two fertilisation techniques and randomly assigned to single or group culturing. The results showed that the addition of IGF-I and/or GM-CSF produced an increase in morula and blastocyst rate in a single culture system. In particular, the supplementation with 20 ng/mL of IGF-I incremented the maturation rate by 10% and significantly increased the morula and blastocyst rates in single culturing. This result is especially remarkable for wild felids, where only a few oocytes and/or embryos are available.

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.

p66Shc is associated with hydrogen peroxide-induced oxidative stress in preimplantation sheep embryos

The low efficiency of in vitro embryo production is associated with oxidative stress induced by suboptimal culture conditions. p66Shc is a 66-kDa protein of the ShcA (Src homologous-collagen homolog) adaptor protein family, which is involved in signaling pathways involved in oxidative stress regulation, apoptosis induction, and aging. However, the functional role of p66Shc during the preimplantation development of sheep embryos is not understood. Our results showed that early-cleavage (≤28 hr) embryos had a higher developmental potential than late-cleavage (>28 hr) embryos. The poor quality of these late-cleavage embryos was associated with increased the transcripts and protein of p66Shc and decreased mitochondrial activity. In addition, exogenous hydrogen peroxide-induced oxidative stress significantly increased p66Shc protein abundance and suppressed embryonic development, which was ameliorated by antioxidant treatment. Notably, oxidative stress induced the nuclear localization of p66Shc and phosphorylated (Ser-36) p66Shc. Collectively, these observations suggest that p66Shc may be playing an important role in the regulation of oxidative stress during the preimplantation development of sheep embryos.

The effect of blastocyst transfer on newborn sex ratio and monozygotic twinning rate: an updated systematic review and meta-analysis

RESEARCH QUESTION

Is blastocyst transfer (BT) associated with a higher offspring secondary sex ratio and monozygotic twinning (MZT)?

DESIGN

A systematic search of PubMed/MEDLINE, Embase, Web of Science, Cochrane Library and Google Scholar databases was carried out for studies published between 1995 and May 2017 using relevant keywords and a meta-analysis performed on selected studies. The analysis was performed using Stata 12.0; odds ratios (OR) and 95% confidence intervals (CI) were used to assess the results for binary studies. Subgroup analyses and meta-regression were also conducted.

RESULTS

Twenty-six studies published between 2001 and May 2017 (sex ratio: 13, MZT: 12, and both sex ratio and MZT: 1) were identified. The analysis showed a significantly higher M/F ratio at birth (OR = 0.89, 95% CI: 0.86 to 0.93, I² = 19.8%) and a higher risk of MZT (OR = 0.37, 95% CI: 0.22 to 0.60, I² = 75.2%) after BT compared with cleavage-stage embryo transfer (CT). Furthermore, a subgroup analysis was performed based on studies published after 2009; results were found to be consistent with the 2009 meta-analysis.

CONCLUSIONS

This meta-analysis provides an update and stronger evidence to support the observation that BT is associated with a higher proportion of males and an increased risk of MZT. In clinical practice, these BT-associated neonatal outcomes should be taken into account when counselling infertility patients.

Effects of vitrification and a Rho-associated coiled-coil containing protein kinase 1 inhibitor on the meiotic and developmental competence of feline oocytes

Oocyte cryopreservation is the technique of choice for the long-term storage of female gametes. However, it induces an irreversible loss of oocyte viability and function. We examined the effects of vitrification and a Rho-associated coiled-coil containing protein kinase 1 (ROCK1) inhibitor (ROCKi) on the meiotic and developmental competence of feline oocytes. We examined the expression of LIM kinase (LIMK) 1 and 2, with and without ROCKi treatment. Cumulus oocyte complexes (COCs) were matured in vitro with 0, 10, 20, and 40 µM ROCKi. The oocytes were subsequently assessed for maturation rate and embryo development following in vitro fertilization. We repeated the COC experiment, but vitrified and warmed the COCs prior to culture. We detected LIMK1 and LIMK2 expression in feline oocytes, which could be downregulated by ROCKi treatment. The ROCKi at 10 µM affected neither meiotic nor developmental competence (P > 0.05, versus control). However, high concentrations of ROCKi during maturation induced meiotic arrest at metaphase I. Appropriate concentrations of ROCKi significantly improved the normal fertilization rate of vitrified warmed oocytes (49.4 ± 3.4%) compared with that of the control (42.8 ± 8.6%, P < 0.05). The ROCKi also significantly improved the embryo cleavage rate (36.1 ± 3.8%) as compared with the non-treated control (27.4 ± 2.5%, P < 0.05). Thus, this study revealed that the main mediators of the ROCK cascade (LIM kinases) are expressed in feline oocytes. The ROCKi (10 µM) did not compromise the meiotic or developmental competence of feline oocytes. In addition, 10 µM ROCKi improved the cytoplasmic maturation of vitrified–warmed oocytes as indicated by their fertilization competence.

Epidermal growth factor improves developmental competence and embryonic quality of singly cultured domestic cat embryos

This study examined the influence of EGF on the expression of EGF receptors (EGFR) and developmental competence of embryos cultured individually versus those cultured in groups. Cat oocytes were in vitro matured and fertilized (IVM/IVF), and cleaved embryos were randomly assigned to one of seven culture conditions: one group each in which embryos were subjected to group culture supplemented with or without 5 ng/ml EGF and five groups in which embryos were subjected to single-embryo culture supplemented with EGF (0, 5, 25, 50 or 100 ng/ml). Morulae, blastocysts and hatching blastocysts were assessed at days 5 and 7; post IVF, respectively, and total blastocyst cell numbers were assessed at day 7. Relative mRNA expressions of EGFR of 2–4-cell embryos, 8–16-cell embryos, morulae and blastocysts cultured in groups or singly with or without EGF supplementation were examined. OCT3/4 and Ki67 in blastocysts derived from the group or single-embryo culture systems with or without EGF supplementation were localized. A higher rate of embryos cultured in groups developed to blastocysts than individually incubated cohorts. Although EGF increased blastocyst formation in the single-embryo culture system, EGF did not affect embryo development in group culture. Expression levels of EGFR decreased in morulae and blastocysts cultured with EGF. An increased ratio of Ki67-positive cells to the total number of cells in the blastocyst was observed in singly cultured embryos in the presence of EGF. However, EGF did not affect the expression of OCT3/4. These findings indicate that EGF enhanced developmental competence of cat embryos cultured singly by stimulating cell proliferation and modulating the EGFR expression at various developmental stages.