Anti-apoptotic effect of insulin-like growth factor (IGF)-I and its receptor in porcine preimplantation embryos derived from in vitro fertilization and somatic cell nuclear transfer

Pig Cloning Using Somatic Cell Nuclear Transfer

Porcine cloning technology can be used to produce progenies genetically identical to the donor cells from high-quality breeding pigs. In addition, genetically modified pigs have been produced by somatic cell nuclear transfer using genetically modified porcine fetal fibroblasts. The method of preparing genetically modified pigs is critical for establishing pig models for human diseases, and for generating donor animals for future xenotransplantation. This chapter describes detailed procedures for generating cloned pigs using fetal fibroblasts as nuclear donors.

Application of the modified handmade cloning technique to pigs

Although somatic cell nuclear transfer (SCNT) is frequently employed to produce cloned animals in laboratories, this technique is expensive and inefficient. Therefore, the handmade cloning (HMC) technique has been suggested to simplify and advance the cloning process, however, HMC wastes many oocytes and leads to mitochondrial heteroplasmy. To solve these problems, we propose a modified handmade cloning (mHMC) technique that uses simple laboratory equipment, i.e., a Pasteur pipette and an alcohol lamp, applying it to porcine embryo cloning. To validate the application of mHMC to pig cloning, embryos produced through SCNT and mHMC are compared using multiple methods, such as enucleation efficiency, oxidative stress, embryo developmental competence, and gene expression. The results show no significant differences between techniques except in the enucleation efficiency. The 8-cell and 16-cell embryo developmental competence and Oct4 expression levels exhibit significant differences. However, the blastocyst rate is not significantly different between mHMC and SCNT. This study verifies that cloned embryos derived from the two techniques exhibit similar generation and developmental competence. Thus, we suggest that mHMC could replace SCNT for simpler and cheaper porcine cloning.

Insulin-like growth factor-1 overexpression increases long-term survival of posttrauma-born hippocampal neurons while inhibiting ectopic migration following traumatic brain injury

Cellular damage associated with traumatic brain injury (TBI) manifests in motor and cognitive dysfunction following injury. Experimental models of TBI reveal cell death in the granule cell layer (GCL) of the hippocampal dentate gyrus acutely after injury. Adult-born neurons residing in the neurogenic niche of the GCL, the subgranular zone, are particularly vulnerable. Injury-induced proliferation of neural progenitors in the subgranular zone supports recovery of the immature neuron population, but their development and localization may be altered, potentially affecting long-term survival. Here we show that increasing hippocampal levels of insulin-like growth factor-1 (IGF1) is sufficient to promote end-stage maturity of posttrauma-born neurons and improve cognition following TBI. Mice with conditional overexpression of astrocyte-specific IGF1 and wild-type mice received controlled cortical impact or sham injury and bromo-2'-deoxyuridine injections for 7d after injury to label proliferating cells. IGF1 overexpression increased the number of GCL neurons born acutely after trauma that survived 6 weeks to maturity (NeuN+BrdU+), and enhanced their outward migration into the GCL while significantly reducing the proportion localized ectopically to the hilus and molecular layer. IGF1 selectively affected neurons, without increasing the persistence of posttrauma-proliferated glia in the dentate gyrus. IGF1 overexpressing animals performed better during radial arm water maze reversal testing, a neurogenesis-dependent cognitive test. These findings demonstrate the ability of IGF1 to promote the long-term survival and appropriate localization of granule neurons born acutely after a TBI, and suggest these new neurons contribute to improved cognitive function.

Supplementing Maturation Medium With Insulin Growth Factor I and Vitrification-Warming Solutions With Reduced Glutathione Enhances Survival Rates and Development Ability of in vitro Matured Vitrified-Warmed Pig Oocytes

The present study sought to determine whether in vitro maturation (IVM) of pig oocytes in a medium supplemented with insulin growth factor-I (IGF-I) and subsequent vitrification with or without reduced glutathione (GSH) affect their quality and developmental competence, and the expression of genes involved in antioxidant, apoptotic and stress responses. In Experiment 1, cumulus-oocyte complexes were matured in the absence or presence of IGF-I (100 ng·mL⁻¹) and then vitrified-warmed with or without 2 mM of GSH. Maturation rate was evaluated before vitrification, and oocyte viability, DNA fragmentation and relative transcript abundances of BCL-2-associated X protein (BAX), BCL2-like1 (BCL2L1), heat shock protein 70 (HSPA1A), glutathione peroxidase 1 (GPX1) and superoxide dismutase 1 (SOD1) genes were assessed in fresh and vitrified-warmed oocytes. In Experiment 2, fresh and vitrified-warmed oocytes were in vitro fertilized and their developmental competence determined. Whereas the addition of IGF-I to maturation medium had no effect on oocyte maturation, it caused an increase in the survival rate of vitrified-warmed oocytes. This effect was accompanied by a concomitant augment in the relative transcript abundance of HSPA1A and a decrease of BAX. Furthermore, the addition of GSH to vitrification-warming media increased survival rates at post-warming. Likewise, the action of GSH was concomitant with an increase in the relative abundance of GPX1 and a decrease of BAX transcript. Blastocyst rates of vitrified-warmed oocytes did not differ from their fresh counterparts when IGF-I and GSH were combined. In conclusion, supplementing maturation medium with 100 ng·mL⁻¹ IGF-I and vitrification-warming solutions with 2 mM GSH improves the quality and cryotolerance of IVM pig oocytes, through a mechanism that involves BAX, GPX1 and HSPA1A expression.

Embryotropic effects of vascular endothelial growth factor on porcine embryos produced by in vitro fertilization

Current research suggests that supplementing in vitro culture (IVC) media with vascular endothelial growth factor (VEGF) may have beneficial effects on the development of porcine embryos in vitro. However, the molecular signaling mechanisms underlying this effect are unclear. Therefore, we aimed to investigate the effects of VEGF on molecular signaling events during in vitro embryonic development of porcine embryos. Porcine oocytes matured in vitro were fertilized, and the resultant zygotes were cultured with 5 ng/mL of VEGF supplemented with or without fetal bovine serum from day 4 till day 7. Without VEGF and/or FBS served as the control group. Real-time quantitative PCR was used to detect expression patterns of apoptosis- and oxidative stress-related genes in day 7 blastocysts (BLs). Early-stage apoptosis was detected by annexin-V assays in day 2 and day 7 embryos. We found that the addition of VEGF throughout the culture period with or without FBS supplementation significantly improved embryo survival and development. Supplementation with VEGF in the IVC medium significantly increased early BL formation (p < 0.05), although addition of FBS on day 4 significantly increased hatched BL formation (p < 0.05) regardless of VEGF supplementation. However, supplementation of media with both VEGF and FBS increased the formation of expanded BLs synergistically. The average total cell numbers per BL were significantly (p < 0.05) higher in embryos supplemented with VEGF and FBS than in those supplemented with either VEGF or FBS alone. We also found that accumulation of reactive oxygen species in VEGF-treated embryos was significantly lower (p < 0.05) than that in untreated embryos. The mRNA levels of caspase-3 were significantly lower (p < 0.05), and those of Bcl-2 and Nrf-2 were significantly higher (p < 0.05) in embryos grown in VEGF-supplemented media than in embryos grown in non-supplemented media. Furthermore, on day 2, the numbers of viable embryos (44.06 ± 3.94%) and blastomeres (67.18 ± 3.60%) were significantly higher (p < 0.05), and the numbers of early apoptotic embryos (55.94 ± 3.94) and blastomeres (23.23 ± 4.22) were significantly lower (p < 0.05) in VEGF-treated BLs than in controls. Furthermore, the numbers of early apoptotic cells in BLs on day 7 were also significantly lower (p < 0.05) in VEGF-treated BLs than in controls. Overall, our results indicate that supplementing IVC media with VEGF during in vitro culture of porcine embryos increases their developmental potential.

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.

High serum IGF-1 levels are associated with pregnancy loss following frozen-thawed euploid embryo transfer cycles

An elevated level of insulin growth factor (IGF-1) in rat uterine fluid has been shown to exert detrimental effects of embryo development possibly leading to an increase in pregnancy loss. Interestingly, the administration of somatostatin to rats undergoing superovulation reduced IGF-1 levels in uterine luminal fluid and thus reversed its deleterious effects on embryo development and increased the number of normal embryos. Therefore, we investigated whether serum levels of IGF-1 correlate with the incidence of pregnancy loss following IVF. To account for aneuploidy and the effect of hormonal supplementation on serum IGF levels, we only included natural frozen-thawed euploid embryo transfer (N-FET) cycles. Sera collected in the follicular phase (cycle day 10) were tested for levels of IGF-1, IGF-2, and IGF-binding protein 1 (IGFBP-1) using quantitative ELISA. A total of 156 N-FET cycles were included: 120 resulted in a live birth whereas 36 led to a first trimester pregnancy loss. Women with a pregnancy loss had significantly higher serum IGF-1 levels compared to those who achieved a live birth (18.0 ± 1.1 vs. 14.6 ± 0.7 ng/mL, respectively). The two groups had comparable serum IGF-2 and IGFBP-1 levels. There was no significant difference in maternal age, body mass index, gravidity, parity, number of prior miscarriages, peak endometrial thickness, or infertility diagnosis between the two groups. In conclusion, women undergoing euploid blastocyst transfer with elevated serum IGF-1 concentrations may be at increased risk of pregnancy loss. This may constitute a novel molecular explanation of pregnancy loss of euploid conceptus.

Dual effect of fetal bovine serum on early development depends on stage-specific reactive oxygen species demands in pigs

Despite the application of numerous supplements to improve in vitro culture (IVC) conditions of mammalian cells, studies regarding the effect of fetal bovine serum (FBS) on mammalian early embryogenesis, particularly in relation to redox homeostasis, are lacking. Herein, we demonstrated that early development of in vitro-produced (IVP) porcine embryos highly depends on the combination of FBS supplementation timing and embryonic reactive oxygen species (ROS) requirements. Interestingly, FBS significantly reduced intracellular ROS levels in parthenogenetically activated (PA) embryos regardless of the developmental stage. However, the beneficial effect of FBS on early embryogenesis was found only during the late phase (IVC 4-6 days) treatment group. In particular, developmental competence parameters, such as blastocyst formation rate, cellular survival, total cell number and trophectoderm proportion, were markedly increased by FBS supplementation during the late IVC phase. In addition, treatment with FBS elevated antioxidant transcript levels during the late IVC phase. In contrast, supplementation with FBS during the entire period (1-6 days) or during the early IVC phase (1-2 days) greatly impaired the developmental parameters. Consistent with the results from PA embryos, the developmental competence of in vitro fertilization (IVF) or somatic cell nuclear transfer (SCNT) embryos were markedly improved by treatment with FBS during the late IVC phase. Moreover, the embryonic stage-specific effects of FBS were reversed by the addition of an oxidant and were mimicked by treatment with an antioxidant. These findings may increase our understanding of redox-dependent early embryogenesis and contribute to the large-scale production of high-quality IVP embryos.

Big Animal Cloning Using Transgenic Induced Pluripotent Stem Cells: A Case Study of Goat Transgenic Induced Pluripotent Stem Cells

Using of embryonic stem cells (ESCs) could improve production traits and disease resistance by improving the efficiency of somatic cell nuclear transfer (SCNT) technology. However, robust ESCs have not been established from domestic ungulates. In the present study, we generated goat induced pluripotent stem cells (giPSCs) and transgenic cloned dairy goat induced pluripotent stem cells (tgiPSCs) from dairy goat fibroblasts (gFs) and transgenic cloned dairy goat fibroblasts (tgFs), respectively, using lentiviruses that contained hOCT4, hSOX2, hMYC, and hKLF4 without chemical compounds. The giPSCs and tgiPSCs expressed endogenous pluripotent markers, including OCT4, SOX2, MYC, KLF4, and NANOG. Moreover, they were able to maintain a normal karyotype and differentiate into derivatives from all three germ layers in vitro and in vivo. Using SCNT, tgFs and tgiPSCs were used as donor cells to produce embryos, which were named tgF-Embryos and tgiPSC-Embryos. The fusion rates and cleavage rates had no significant differences between tgF-Embryos and tgiPSC-Embryos. However, the expression of IGF-2, which is an important gene associated with embryonic development, was significantly lower in tgiPSC-Embryos than in tgF-Embryos and was not significantly different from vivo-Embryos.

Stem Cell-Derived Bioactive Materials Accelerate Development of Porcine In Vitro-Fertilized Embryos

Stem cells show the capability to proliferate in an undifferentiated state with long-term self-renewal, which gives the cells advantages for use as bioactive material (BM) for embryo culture in vitro. The objective of this experiment was to investigate the effect of two BMs-human adipose tissue-derived mesenchymal stem cell BM (hAT-MSC-BM) and human embryonic stem cell-derived BM (hESC-BM)-on porcine embryo development compared to commonly used bovine serum albumin (BSA) or serum treatment groups. In vitro-fertilized (IVF) embryos were cultured in PZM-5 with 4 mg/mL BSA until day 4 and equally divided into four groups. Starting from day 4 (until day 6), each group was treated with the following protein additives: 4 mg/mL BSA (control), 10% fetal bovine serum (FBS), 10% hAT-MSC-BM, or 10% hESC-BM. Our results show FBS- and two other BM-treated groups showed significant increases in blastocyst formation rate, hatching rate, and total cell number compared with the control group (p<0.05). The hAT-MSC-BM and hESC-BM treatment groups presented better-quality embryo development, especially from the middle expanding stage to hatching. In particular, the hAT-MSC-BM-treated group showed the highest developmental potential of all groups and formed the most expanding-stage blastocysts. The relative expression of reprogramming-related transcription factor (POU5F1, SOX2, DPPA5, and CDH1), antioxidant (PRDX5), and apoptosis (BCL2L1 and BIRC5) genes also increased in two types of BMs compared to the control. In addition, we investigated the protein synthesis of the tight junction- and gap junction-related genes, connexin 43 and zonula occludens-1 (ZO-1); these increased more than in the control. These results demonstrate that stem cell-derived BMs accelerate porcine preimplantation embryo development and that the BMs would be helpful in the development of preimplantation embryos.

Association of in vitro fertilization outcome with circulating insulin-like growth factor components prior to cycle initiation

OBJECTIVE

Components of the insulin-like growth factor (IGF) system enhance in vitro embryo quality and implantation rates in both animal models and human in vitro fertilization (IVF). We evaluated whether differences in serum levels of these components in women prior to initiation of an IVF cycle would be predictive of subsequent outcome.

STUDY DESIGN

In this retrospective study sera from women obtained at day 2 of their IVF cycle (at baseline before stimulation) were assayed for IGF-I, IGF-II, and IGF binding protein (BP)-1 by enzyme-linked immunosorbent assay. Samples from 54 women with a live birth, 38 with a transient biochemical pregnancy, 45 with a spontaneous abortion, 54 who did not become pregnant, and 35 who had an ectopic pregnancy were available for analysis. Associations between the assays and outcome were evaluated by the Kruskal-Wallis test and receiver operating characteristic analysis.

RESULTS

There were no differences in the number of oocytes retrieved, oocyte quality, fertilization rates, or embryo grade between groups. Median concentrations of IGF-I were elevated in women with a live birth (29.1 ng/mL) as compared to women with a biochemical pregnancy (25.6 ng/mL), with spontaneous abortion (21.2 ng/mL), who were not pregnant (18.7 pg/mL), or who had an ectopic pregnancy (4.2 pg/mL) (P < .001). Conversely, median levels of IGF-II were reduced in women with a live birth (294.5 ng/mL) as opposed to 357.5, 393.6, 407.2, and 426.9 ng/mL in women with a biochemical pregnancy, with ectopic pregnancy, with spontaneous abortion, or who were not pregnant, respectively (P < .001). Median IGFBP-1 concentrations were markedly elevated in women with a live birth (23.6 ng/mL) compared to 18.3, 14.1, 13.8, and 9.5 ng/mL in women with a biochemical pregnancy, with spontaneous abortion, who were not pregnant, or with an ectopic pregnancy (P < .001). The combination of IGF-I and IGFBP-1 best predicted the occurrence of a live birth with an area under the curve of 0.892.

CONCLUSION

Maternal serum levels of IGF-I, IGF-II, and IGFBP-1 prior to initiation of an IVF cycle are correlated with the likelihood of a live birth. Alterations in maternal IGF system components may influence oocyte quality or the success of early postfertilization events and embryo implantation.

The evolution of porcine embryo in vitro production

The in vitro production of porcine embryos has presented numerous challenges to researchers over the past four decades. Some of the problems encountered were specific to porcine gametes and embryos and needed the concerted efforts of many to overcome. Gradually, porcine embryo in vitro production systems became more reliable and acceptable rates of blastocyst formation were achieved. Despite the significant improvements, the problem of polyspermic fertilization has still not been adequately resolved and the embryo in vitro culture conditions are still considered to be suboptimal. Whereas early studies focused on increasing our understanding of the reproductive processes involved, the technology evolved to the point where in vitro-matured oocytes and in vitro-produced embryos could be used as research material for developing associated reproductive technologies, such as SCNT and embryo cryopreservation. Today, the in vitro procedures used to mature oocytes and culture embryos are integral to the production of transgenic pigs by SCNT. This review discusses the major achievements, advances, and knowledge gained from porcine embryo in vitro production studies and highlights the future research perspectives of this important technology.

Generation of transgenic pigs by cytoplasmic injection of piggyBac transposase-based pmGENIE-3 plasmids

The process of transgenesis involves the introduction of a foreign gene, the transgene, into the genome of an animal. Gene transfer by pronuclear microinjection (PNI) is the predominant method used to produce transgenic animals. However, this technique does not always result in germline transgenic offspring and has a low success rate for livestock. Alternate approaches, such as somatic cell nuclear transfer using transgenic fibroblasts, do not show an increase in efficiency compared to PNI, while viral-based transgenesis is hampered by issues regarding transgene size and biosafety considerations. We have recently described highly successful transgenesis experiments with mice using a piggyBac transposase-based vector, pmhyGENIE-3. This construct, a single and self-inactivating plasmid, contains all the transpositional elements necessary for successful gene transfer. In this series of experiments, our laboratories have implemented cytoplasmic injection (CTI) of pmGENIE-3 for transgene delivery into in vivo-fertilized pig zygotes. More than 8.00% of the injected embryos developed into transgenic animals containing monogenic and often single transgenes in their genome. However, the CTI technique was unsuccessful during the injection of in vitro-fertilized pig zygotes. In summary, here we have described a method that is not only easy to implement, but also demonstrated the highest efficiency rate for nonviral livestock transgenesis.

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

OBJECTIVE

The aim of this study is to determine the effects of insulin-like growth factor-1 (IGF-1) and the mRNA expression of IGF-1 receptor (IGF-1R) during the in vitro development of cat embryos cultured in groups versus singly.

METHODS

Cumulus-oocyte complexes (COCs) were matured and fertilized in vitro with frozen-thawed semen. Cleaved embryos (48h post-fertilization) were randomly assigned to one of the following treatments: 1) group embryo culture without IGF-1 (10 embryos per 50μl droplet), 2) single-embryo culture without IGF-1, and 3) to 6) single-embryo culture (50μl droplet per embryo) supplemented with different concentrations of IGF-1 (5, 25, 50 and 100ng/ml, respectively). During in vitro culture, the embryos were analyzed for development to the morula, blastocyst and hatching blastocyst stage. Relative mRNA expression of IGF-1R was also examined by qPCR at the morula and blastocyst stages. In addition, the mRNA expression of IGF-1R in morula-stage embryos treated with IGF-1 was determined. The influence of IGF-1 to preimplantation embryo development was then explored by co-incubation with 0.5μM IGF-1R inhibitor (Picropodophyllin; PPP).

RESULTS

Group embryo culture led to a significantly higher blastocyst development rate compared with single-embryo culture (P<0.05). The poor development of singly cultured embryos coincided with the significantly lower IGF-1R expression in morulae than in group-cultured morulae. IGF-1 (25 or 50ng/ml) supplementation significantly improved the blastocyst formation rate of single embryos to a level similar to group culture by promoting the morula-to-blastocyst transition. IGF-1 supplementation (25 or 50ng/ml) of singly cultured embryos upregulated the expression of IGF-1R mRNA in morula-stage embryos to the same level as that observed in group-cultured embryos (without IGF-1). The beneficial effects of IGF-1 on singly cultured embryo were (P<0.05) suppressed by PPP even in the group culture embryo without growth factor supplementation.

CONCLUSION

IGF-1 supplementation improves the developmental competence of feline embryos cultured individually and also increases IGF-1R gene expression to levels similar to group-cultured embryos.

Effect of human adipose tissue-derived mesenchymal-stem-cell bioactive materials on porcine embryo development

Human adipose tissue-derived mesenchymal stem cells (hAT-MSCs) secrete bioactive materials that are beneficial for tissue repair and regeneration. In this study, we characterized human hAT-MSC bioactive material (hAT-MSC-BM), and examined the effect of hAT-MSC-BM on porcine embryo development. hAT-MSC-BM was enriched with several growth factors and cytokines, including fibroblast growth factor 2 (FGF2), vascular endothelial growth factor A (VEGFA), and interleukin 6 (IL6). Among the various concentrations and days of treatment tested, 10% hAT-MSC-BM treatment beginning on culture Day 4 provided the best environment for the in vitro growth of parthenogenetic porcine embryos. While the addition of 10% fetal bovine serum (FBS) increased the hatching rate and the total cell number of parthenogenetic porcine embryos compared with the control and hAT-MSC culture medium group, the best results were from the group cultured with 10% hAT-MSC-BM. Mitochondrial activity was also higher in the 10% hAT-MSC-BM-treated group. Moreover, the relative mRNA expression levels of development and anti-apoptosis genes were significantly higher in the 10% hAT-MSC-BM-treated group than in control, hAT-MSC culture medium, or 10% FBS groups, whereas the transcript abundance of an apoptosis gene was slightly lower. Treatment with 10% hAT-MSC-BM starting on Day 4 also improved the development rate and the total cell number of in vitro-fertilized embryos. This is the first report on the benefits of hAT-MSC-BM in a porcine embryo in vitro culture system. We conclude that hAT-MSC-BM is a new, alternative supplement that can improve the development of porcine embryos during both parthenogenesis and fertilization in vitro.

Ascorbic acid improves the developmental competence of porcine oocytes after parthenogenetic activation and somatic cell nuclear transplantation

In this study, a dose-response assessment was performed to understand the relation between supplementation of media with L-ascorbic acid or vitamin C and porcine oocyte maturation and the in vitro development of parthenotes (PA) and handmade cloned (HMC) embryos. Various concentrations (0, 25, 50 and 100 µg/ml) of vitamin C supplemented in in vitro maturation (IVM) and culture (IVC) media were tested. None of these vitamin C additions affected nuclear maturation of oocytes, yet supplementation at 50 µg/ml led to significantly increased intracellular glutathione (GSH) levels and reduced reactive oxygen species (ROS). When cultured in IVM- and/or IVC-supplemented media, the group supplemented with 50 µg/ml of vitamin C showed improved cleavage rates, blastocyst rates and total cell numbers per blastocyst (P<0.05) compared with other groups (control, 25 µg/ml and 100 µg/ml). In contrast, supplementation with 50 µg/ml vitamin C decreased (P<0.05) the apoptosis index as compared with the groups supplemented with 100 µg/ml. In addition, even with a lower blastocyst rate to start with (37.6 vs. 50.3%, P<0.05), supplementation of HMC embryos with vitamin C ameliorated their blastocyst quality to the extent of PA embryos as indicated by their total cell numbers (61.2 vs. 59.1). Taken together, an optimized concentration of vitamin C supplementation in the medium not only improves blastocyst rates and total cell numbers but also reduces apoptotic indices, whereas overdosages compromise various aspects of the development of parthenotes and cloned porcine embryos.

Porcine granulocyte-macrophage colony-stimulating factor improves the in vitro development of cloned porcine embryos

We examined the effects of porcine granulocyte-macrophage colony-stimulating factor (pGM-CSF) on the in vitro development of porcine embryos produced by somatic cell nuclear transfer (SCNT) for the first time. We evaluated the effects of pGM-CSF on SCNT-derived blastocyst formation and investigated gene expression. A total of 522 cloned embryos in 6 replicates were treated with 10 ng/ml pGM-CSF during in vitro culture (IVC). This treatment significantly (P<0.05) increased blastocyst formation and total cell number in blastocysts compared with the control (12.3% and 41.4 vs. 9.0% and 34.7, respectively). However, there was no effect on cleavage rate. The numbers of cells in the inner cell mass and trophectoderm were significantly higher in the pGM-CSF treatment group (6.0 and 43.0, respectively) compared with the control (4.4 and 31.9, respectively). Treatment with 10 ng/ml pGM-CSF significantly increased POU5F1 and Cdx2 mRNA expression in blastocysts. In addition, Bcl-2, Dnmt1 and proliferating cell nuclear antigen (PCNA) mRNA expression were upregulated in blastocysts in the pGM-CSF supplemented group compared with the control. These results suggest that pGM-CSF improves the quality and developmental viability of porcine SCNT embryos by regulating transcription factor expression.

The effect of horse serum on in vitro development of porcine parthenogenetic embryos

The objective of this study was to examine the effect of different sera and serum-like substances on the preimplantation development of porcine parthenogenetic embryos. Chemically activated (calcium ionophore A23187+cytochalasin B) pig oocytes were pre-cultured for five days. On day 5, the parthenogenetic embryos were treated with porcine follicular fluid (PFF), fetal bovine serum (FBS), horse serum (HS) or porcine serum albumin (PSA), and were cultured two more days. Horse serum was found to be the most effective protein source in enhancing parthenote development judging by blastocyst formation and hatching. Next, three different concentrations of HS (10, 20 and 30%) were used to determine the optima HS concentration needed to improve the development of porcine parthenogenetic embryos. All HS concentrations increased the blastocyst cell number and decreased the incidence of blastocyst apoptotic cells with 20% being the most effective. In conclusion, horse serum enhanced parthenogenetic embryo development and the quality of porcine parthenogenetic embryos.

Media composition: growth factors

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

Knockdown of IGF-IR by siRNA injection during bovine preimplantation embryonic development

This study aimed to assess the efficiency and effects of insulin-like growth factor receptor-1 (IGF-IR) siRNA knockdown during bovine preimplantation embryonic development. In oocytes injected with IGF-IR siRNA, the relative IGF-IR mRNA levels compared to controls were 28% and 46% at 6 and 24 h after injection, respectively. With respect to the injection of IGF-IR siRNA in zygotes, 24 h after injection the relative levels of IGF-IR mRNA and protein in the two-cell embryos were 74% and 78% of those in the controls, respectively. IGF-IR siRNA reduced blastocyst formation (23.2%) compared to siRNA controls (33.0%) and uninjected oocytes (35.4%; P < 0.05) and the number of viable cells per IGF-IR siRNA-treated blastocyst (64 ± 3) was significantly reduced, compared to control siRNA and uninjected blastocysts (81 ± 3 and 116 ± 4; P < 0.01). In conclusion, IGF-IR siRNA knockdown reduces the development of bovine embryos, and microinjection in zygotes can decrease blastocyst cell number.

Smaller fetal size in singletons after infertility therapies: the influence of technology and the underlying infertility

OBJECTIVE

To determine whether fetal size differences exist between matched fertile and infertile women and among women with infertility achieving pregnancy through various treatment modalities.

DESIGN

Retrospective cohort study with propensity score analysis.

SETTING

Tertiary care center and affiliated community hospitals.

PATIENT(S)

1,246 fertile and 461 infertile healthy women with singleton livebirths over a 10-year period.

INTERVENTION(S)

Infertile women conceiving without medical assistance, with ovulation induction, or with in vitro fertilization.

MAIN OUTCOME MEASURE(S)

Birthweight; secondary outcomes included crown-rump length, second-trimester estimated fetal weight, and incidence of low birth weight and preterm delivery.

RESULT(S)

Compared with matched fertile women, infertile women had smaller neonates at birth (3,375 ± 21 vs. 3,231 ± 21 g) and more low-birth-weight infants (relative risk = 1.68, 95% confidence interval, 1.06, 2.67). Neonates conceived via ovulation induction were the smallest among the infertility subgroups compared with the neonates of fertile women (3,092 ± 46 vs. 3,397 ± 44 g). First-trimester fetal size was smaller in infertile versus fertile women (crown-rump length 7.9 ± 0.1 vs. 8.5 ± 0.1 mm). Within the infertility subgroups, no differences in fetal or neonatal size were found.

CONCLUSION(S)

The inherent pathologic processes associated with infertility may have a larger impact on fetal growth than infertility therapies.

Sonic hedgehog supplementation of oocyte and embryo culture media enhances development of IVF porcine embryos

We investigated the expression of sonic hedgehog (SHH) receptor PTCH1 and its co-receptor smoothened (SMO) in fertilized porcine embryos. Effects of exogenous SHH on embryonic development and expressions of survival- and pluripotency-related genes were also determined. We found that PTCH1 and SMO are expressed from two-cell to blastocyst embryos. When oocytes or fertilized embryos were respectively cultured in the maturation or embryo culture medium supplemented with SHH (0.5 μg/ml), their blastocyst rates and total cell numbers increased (P<0.05) compared with the untreated control. When cultured simultaneously in thein vitromaturation (IVM) andin vitroculture (IVC) media supplemented with SHH, the oocytes gained increased blastocyst rates and total cell numbers in an additive manner, with reduced apoptotic indices (P<0.05). Interestingly, SHH treatment did not affect the expression of theBCL2L1(BCL-XL) gene, yet reducedBAXexpression. Blastocysts cultured with various SHH regimes had similar pluripotency-related gene (POU5F1(OCT-4) andCDX2) expression levels, but blastocysts derived from SHH treatment during IVM had higherZPF42(REX01) expression (P<0.05). The highestZPF42expression was observed in the blastocysts derived from SHH-supplemented IVC and from dual IVM and IVC treatments. The levels of acetylated histone 3 (AcH3K9/K14) increased in the two-cell and the four-cell embryos when IVM and/or IVC media were supplemented with SHH (P<0.05). Our findings indicate that SHH conferred a beneficial effect on preimplantation development of porcine embryos, particularly when both IVM and IVC media were supplemented with SHH, and the effects may be further carried over from IVM to the subsequent embryonic development.

Sonic Hedgehog improves in vitro development of porcine parthenotes and handmade cloned embryos

This study investigated the expression of Sonic Hedgehog (Shh) signaling pathway and its effect on porcine parthenogenetic (PA) embryo development. The Shh receptor Patched (Ptc1) and co-receptor Smoothened (Smo) were expressed at various stages of PA porcine embryos, at both mRNA and protein levels. Furthermore, the transcriptional activator Gli1 mRNA was first present in the 2-cell stage embryos, and was readily detected at the 4-cell stage and beyond. Culture medium supplemented with 0.5 μg/mL Shh optimized blastocyst rates (58.6 vs. 41.1%; P < 0.05) and the total number of cells per blastocyst (56.4 vs. 45.6 cells; P < 0.05); however, this response was prevented by simultaneous addition of 1 mM cyclopamine (an Shh inhibitor). Moreover, blastocysts that developed in medium containing 0.5 μg/mL Shh had lower apoptotic indices and reduced DNA damage (evaluated by TUNEL and comet assays, respectively). Based on Western-blot analysis, expression of phosphorylated Akt protein in Shh-treated blastocysts was higher than that of the control group (1.22- vs. 0.66-fold, P < 0.05), and less total PARP-1/2 protein was accumulated (0.7-fold, P < 0.05) in treated blastocysts compared to untreated controls. Furthermore, supplementation of Shh (1 μg/mL) also supported development of handmade cloned embryos (50.3 vs. 26.8%; P < 0.05) with reduced apoptotic rates (2.8 vs. 6.3%; P < 0.05). We inferred that the Shh signaling pathway existed in porcine PA embryos and we concluded that Shh supplementation improved the quality and developmental competence of early PA embryos, at least in part, by increasing cell proliferation and reducing apoptosis of the developing embryos.

Increased apoptosis in bovine blastocysts exposed to high levels of IGF1 is not associated with downregulation of the IGF1 receptor

The hypothesis that high concentrations of IGF1 can impair embryo development was investigated in a bovine in vitro model to reflect conditions in polycystic ovary syndrome (PCOS) patients. Embryos were either cultured in the absence or presence of a physiological (100 ng/ml) or supraphysiological (1000 ng/ml) IGF1 concentration. Cell allocation, apoptosis, transcript and protein expression of selected genes involved in apoptosis, glucose metabolism and the IGF system were analysed. Supraphysiological IGF1 concentration did not improve blastocyst formation over controls, but induced higher levels of apoptosis, decreased TP53 protein expression in the trophectoderm and increased the number of cells in the inner cell mass (ICM). The increase in ICM cells corresponded with an increase in IGF1 receptor (IGF1R) protein in the ICM. A small, but significant, percentage of blastocysts displayed a hypertrophic ICM, not observed in controls and virtually absent in embryos treated with physiological concentrations of IGF1. Physiological IGF1 concentrations increased total IGF1R protein expression and upregulated IGFBP3 transcripts leading to an increase in blastocyst formation with no effects on cell number or apoptosis. In conclusion, the results support the hypothesis of detrimental effects of supraphysiological IGF1 concentrations on early pregnancy. However, our results do not support the premise that increased apoptosis associated with high levels of IGF1 is mediated via downregulation of the IGF1R as previously found in preimplantation mouse embryos. This in vitro system with the bovine preimplantation embryo reflects critical features of fertility in PCOS patients and could thus serve as a useful model for in-depth mechanistic studies.

Effects of activin A on the in vitro development and mRNA expression of bovine embryos cultured in chemically-defined two-step culture medium

The purpose of the present study was to evaluate the effects of activin A on the developmental competence of in vitro fertilized (IVF) bovine embryos derived from a two-step defined culture system (C1/C2 medium) during the early or later stages of embryo development. To evaluate the effects of activin A on transcriptional levels, we analysed genes related to blastocyst hatching and implantation and to activin signalling pathway in IVF embryos. Cumulus-oocyte complexes were matured for 22 h and fertilized in vitro. Presumptive zygotes were cultured in the presence or absence of activin A during early (0-120 h, C1) or later (120-192 h, C2) stages. Although the developmental competence of embryos cultured with activin A in C1 medium was not significantly different from their corresponding controls, development to blastocysts (22.4% vs 34.7%; p < 0.05) and the blastocyst hatching rate (9.3% vs 22.4%; p < 0.05) in C2 medium supplemented with 100 ng/ml activin A were significantly higher than in the control group. To evaluate the effect of activin A on transcription, the relative expression levels of genes related to blastocyst hatching and implantation (Na/K-ATPase, E-cad and Glut-1) as well as activin signalling pathway (ActRII, ActRIIB and Smad2) were analysed. Compared to control medium, gene expression of Na/K-ATPase, E-cad, Glut-1, ActRII and ActRIIB was increased in medium supplemented with activin A. In conclusion, this study suggests that activin A, during the later stage of in vitro bovine embryo development, can enhance in vitro development of embryos by increasing hatching rates and affecting expression levels of genes related to hatching and implantation in defined culture medium.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Effects of insulin-like growth factor-1 on cellular and molecular characteristics of bovine blastocysts produced in vitro

Addition of insulin-like growth factor-1 (IGF-1) to culture medium increases the proportion of bovine embryos that develop to the blastocyst stage and increases embryo survival following transfer to heat-stressed, lactating dairy cows. The objective of the present study was to determine molecular and cellular correlates of these actions of IGF-1. Embryos were produced in vitro and cultured for 7 days with or without 100 ng/ml IGF-1. On d 7 after insemination, grade 1 expanded blastocysts were harvested and used to determine total cell number, percent apoptosis, cell allocation to the inner cell mass and trophectoderm, and the relative abundance of several developmentally important gene transcripts. There was no significant effect of IGF-1 treatment on blastocyst cell number, the proportion of blastomeres that were apoptotic, or the number of cells in the inner cell mass and trophectoderm. However, differences in the relative abundance of several mRNA transcripts were observed between control and IGF-1 treated embryos. Addition of IGF-1 increased (P < 0.02) amounts of mRNA for IGF binding protein-3 and desmocollin II and tended (P < 0.08) to increase amounts of mRNA for Na/K ATPase and Bax. Moreover, IGF-1 treatment decreased (P < 0.05) steady-state amounts of transcripts for heat shock protein 70 and tended (P < 0.08) to reduce amounts of IGF-1 receptor mRNA. In conclusion, increased survival of embryos treated with IGF-1 does not appear due to effects on cell number, percent apoptosis, or cell allocation. Addition of IGF-1 to culture can, however, alter expression of several transcripts which may be important for embryo development and survival following transfer.

Single gene mutations causing SGA

The growth hormone-insulin-like growth factor-I (GH-IGF-I) axis plays a key role in intra-uterine growth and development. This review will describe the consequences of genetic defects in various components of the GH-IGF-I axis on intra-uterine growth and development. Animal knockout experiments have provided evidence for the GH-independent secretion of IGF-I and its effect in utero. Reports of patients with a deletion or mutation of the IGF-I and IGF1R genes have provided insight into the role of intra-uterine IGF-I in the human. Homozygous defects of the IGF-I gene have dramatic effects on intra-uterine growth and development, whereas heterozygous defects of the IGF1R gene have a more variable clinical presentation. The phenotype in relation to the genotype of the different disorders will be reviewed in this chapter.