Current value of preimplantation genetic aneuploidy screening in IVF

Preimplantation genetic aneuploidy screening (PGS) has been performed during the last decade as a way of enhancing embryo selection in patients with an increased incidence of embryonic numerical chromosome abnormalities (advanced maternal age, recurrent miscarriage and recurrent implantation failure). It has been proposed that the replacement of euploid embryos in these patients would result in a higher implantation and pregnancy rate and a reduced miscarriage rate. Additionally, the transfer of fewer embryos could reduce the chances for multiple pregnancies in all IVF patients. Although, to date, multiple studies have addressed this issue, contradictory results have been encountered. As a result, the effectiveness of aneuploidy screening remains to be established. Moreover, child outcome studies documenting the safety of this procedure are needed. The aim of this review is to summarize the available evidence concerning the use of PGS to determine the current value of the technique.     

中性粒细胞非凋亡性程序化细胞死亡的研究概况

中性粒细胞是机体固有免疫应答的主要效应细胞，也是机体内重要的炎症细胞。中性粒细胞除了凋亡和坏死外，还存在一种非凋亡性程序化细胞死亡形式。该形式具有空泡化，线粒体通透性增大等形态学特征，具有caspase-3、caspase-8非依赖性以及无DNA片段化的生物化学特征。目前尚不知其确切的生物学意义，但它与发育和许多生理／病理现象有关。这些研究成果对于重新认识和定位中性粒细胞程丰化细胞死亡的多样性和复杂性提出了新的思路。     

The Brussels' experience of more than 5 years of clinical preimplantation genetic diagnosis

This paper describes the 5 years' experience of preimplantation genetic diagnosis (PGD) at the Brussels Free University. Our first PGD was carried out in February 1993. Up to October 1998, we carried out 183 PGD cycles on fresh cleavage embryos of 92 couples for 25 different conditions. Patients were treated for autosomal recessive (n = 39), autosomal dominant (n = 65) and X-linked recessive (n = 47) monogenic disorders as well as for autosomal structural aberrations (n = 10), sex chromosome numerical and structural aberrations (n = 21) and a combination of the two latter (n = 1). Specific diagnosis was carried out by polymerase chain reaction (n = 108). Fluorescence in-situ hybridization was used for sexing (n = 64) and structural aberrations (n = 11). We transferred 1.6 +/- 1.1 embryos per cycle, resulting in an implantation rate of 12.0% per replaced embryo. Ongoing pregnancies were achieved in 29 cycles, i.e. 23 singletons, five twins and one dichorionic triplet with an acardius acranius. The ongoing pregnancy rates per cycle, per transfer and per couple were 16.4, 19.9 and 31.5% respectively. While 28 ongoing pregnancies resulted in the births of 34 infants, one pregnancy was terminated after misdiagnosis. The results of 24 PGD were confirmed by prenatal diagnosis or after birth while no information was available in four pregnancies. Our series demonstrates that PGD is a feasible technique by which to avoid the birth of genetically affected children to couples at risk.     

The potential roles for embryotrophic ligands in preimplantation embryo development

Identification of the role(s) extracellular ligands play in regulating the development of the mammalian preimplantation embryo is a controversial area. Unequivocal evidence for their role is complicated by the apparent overlapping actions of multiple ligands. The discovery that the embryo also releases its own repertoire of ligands and expresses their corresponding receptors has further constrained analysis of their roles. Conventional ligand ablation strategies have limited utility when the cell responding to multiple ligands also produces them. The application of methods for identifying signal transduction events that occur in the early embryo in response to ligands has allowed direct assessment of the actions of these putative trophic ligands. A range of ligands induce phosphatidylinositol-3-kinase mediated survival signalling, and this is required for normal embryo development. Survival signalling maintains apoptotic pathways in a latent state within normal somatic cells, and they may fulfill the same role in the early embryo. Survival signals can also mitigate the adverse response of embryos to genotoxic and non-genotoxic stressors. Currently, there is no unequivocal evidence for a direct role of these ligands in the induction of mitosis in the early embryo. Embryotrophic ligands, acting via their specific receptors, to activate a network of effectors to create pro-survival, anti-apoptotic settings within the preimplantation embryo and these are required for normal embryo survival.     

Current concepts in preimplantation genetic diagnosis (PGD): a molecular biologist's view

The first clinically applied preimplantation genetic diagnosis (PGD) was reported more than a decade ago and since then PGD has known an exponential growth. This first report described the use of PCR to sex embryos from couples at risk for X-linked diseases. Not surprisingly, in the first years, the development of PCR-based tests led to PGD for well-known monogenic diseases such as cystic fibrosis and thalassaemia. When fluorescent in-situ hybridization (FISH) was introduced it quickly replaced PCR-based methods, which had led to misdiagnoses, for sexing of embryos. FISH was also quickly introduced for aneuploidy screening, which has as its main aim the improvement of IVF results in patients with poor reproductive outcome, and later for PGD in translocation carriers. In this review, PGD for patients with a pre-existing genetic risk will be discussed, i.e. the monogenic diseases and the translocations, as well as different biopsy methods and promising new developments.     

IL-10 inhibits apoptotic cell death in human T cells starved of IL-2

IL-10 was originally described as an inhibitory factor producedby murine T_h2 lymphocytes that suppresses IFN- production byactivated murine T_h1 lymphocytes. In this study, we have analyzedthe effect of human IL-10 on human T cell death induced by IL-2deprivation. IL-2-dependent T lymphocytes rapidly die when deprivedof IL-2. This cell death was found to involve loss of cell volume,chromatin condensation, and DNA fragmentation, all characteristicof apoptosis. After 2 days incubation in culture medium withoutIL-2, the viability of TM11 cells (a tetanus toxoid-specificT cell line) and of activated peripheral blood T cells decreasedfrom >98% to 34.3 (±2.9) and 39.7 (±5.5)% respectively.Addition of purified human IL-10 (100 U/ml) to these IL-2-starvedcells significantly improved cell viability (66.0±6.0and 73.1±12.3% respectively, P=0.0051). This protectiveeffect of IL-10 was dose-dependent and was neutralized by theanti-human IL-10 mAb 19F1. It was neither accompanied by T cellgrowth stimulation as judged by [³H] thymidine incorporationnor neutralized by anti-IL-2 or anti-IL-2 receptor (CD25) antibodies.Analysis of DNA after separation on agarose gels revealed thatIL-10 inhibits DNA fragmentation in IL-2-starved T cells. Tcells protected from death by IL-10 were indistinguishable fromIL-10-untreated viable T cells in the ability to proliferatein response to IL-2. Thus, another property of IL-10 is to promotethe survival of IL-2-dependent T cells otherwise destined todie by apoptosis.     

细胞自噬的调控与自噬程序性死亡的研究进展

自噬(autophagy)是一种溶酶体依赖性降解途径,涉及细胞内长寿蛋白和受损伤细胞器的降解,其既是细胞保守的自我防御机制,又是一种程序性细胞死亡机制(PCD),与机体的多种疾病有密切关系.自噬具有独特的形态改变和特有的调控通路,自噬的调控涉及到多种机制、如翻译后修饰等.凋亡是研究最清楚的程序性细胞死亡机制,凋亡与细胞自噬程序性死亡之间存在着复杂的关系.对哺乳动物细胞自噬的分子调控机制,自噬程序性细胞死亡过程及其与凋亡的关系等方面进行探讨很有意义.     

Cell death by apoptosis in acute leukaemia

We have previously demonstrated that when freshly isolated childhood T-cell acute lymphoblastic leukaemia cells are incubated in growth medium after isolation from blood, chromatin is rapidly cleaved into nucleosomal sized fragments that are multiples of 200 bp. The fragmentation is similar to that observed in other types of cells undergoing apoptosis or programmed cell death. In this study we describe a more comprehensive approach to the study of DNA fragmentation in leukaemia. Fragmentation was observed in freshly isolated cells from patients with T-cell acute lymphoblastic leukaemia and in one with common acute lymphoblastic leukaemia. Frozen samples of T-cell acute lymphoblastic leukaemia, common acute lymphoblastic leukaemia, and acute myeloid leukaemia cells also showed fragmentation of DNA. However, no fragmentation was evident in normal leukocytes treated under the same conditions. Ultrastructural studies on the isolated leukaemia cells demonstrate that the chromatin cleavage observed biochemically is associated with morphological changes characteristic of apoptosis.     

Culture of preimplantation embryos and its long-term effects on gene expression and phenotype

A growing number of medical, scientific and biotechnological procedures rely on culture of mammalian preimplantation embryos. This review presents currently available data on aberrant offspring development that sometimes arises from commonly applied in-vitro procedures in humans, ruminant species and mice. Comparison between mammalian species reveals similarities in the phenotypic abnormalities that are observed at fetal and perinatal stages of development. In particular, aberrant effects on fetal growth have been observed in multiple studies in which serum complemented the preimplantation culture medium. Although it remains to be determined whether there is a common causal mechanism(s) involved, several hypotheses have been put forward to account for the variety of the observed developmental abnormalities. One of these postulates that culture can result in the epigenetic deregulation of developmentally important genes, and that such epigenetic alterations would affect in particular the expression of genes that are subject to genomic imprinting. Imprinted genes play key roles in the control of fetal growth, and altered imprinting can cause growth defects. Some recent in-vitro culture studies on mice and ruminant species now lend support to this hypothesis.     

骨关节炎软骨细胞的新型程序性死亡

背景：骨关节炎是一种常见的关节退行性疾病,其发生机制复杂,目前尚未阐明。但已有的研究表明,骨关节炎的发生发展与软骨细胞程序性死亡有关。目的：总结骨关节炎软骨细胞新型程序性死亡的研究进展。方法：“Osteoarthritis,Pyroptosis,Necroptosis,Ferroptosis,ROS,L-ROS,Iron-overload”为英文检索词,以“骨关节炎、细胞焦亡、坏死性凋亡、铁死亡、铁超载、脂质活性氧”为中文检索词,使用计算机在CNKI、万方数据库、PubMed、维普数据库检索2012年7月至2022年7月有关于程序性细胞死亡的相关文章,并进行系统地归纳、总结和分析。结果与结论：焦亡与骨关节炎的关系近年来备受关注,目前的研究重点仍是NLRP3炎性小体和脂多糖。有关坏死性凋亡的研究中,骨关节炎的发展也已被证明与受体相互作用蛋白激酶1密切相关,受体相互作用蛋白激酶1有可能是治疗骨关节炎的潜在靶点。铁死亡是一种最新发现的细胞死亡方式,研究发现其通过铁超载和脂质过氧化介导了软骨细胞的死亡,但铁死亡的发生涉及多个基因的表达和调控,具有复杂的信号通路和机制,目前尚未完全阐明。细胞焦亡...     

Rethinking gamete/embryo isolation and culture with microfluidics

IVF remains one of the most exciting modern scientific developments and continues to have a tremendous impact on people's lives. Since its beginnings, scientists have studied and critically analysed the techniques in order to find ways to improve outcomes; however, little has changed with the actual technology and equipment of IVF. Semen is still processed in test tubes and fertilization and culture still occurs in culture dishes. New technological possibilities exist with the burgeoning advancement of microfluidic technology. Microfluidics is based on the behaviour of liquids in a microenvironment. Although a young field, many developments have occurred which demonstrate the potential of this technology for IVF. In this review, we briefly discuss the physical principles of microfluidics and highlight some previous utilizations of this technology, ranging from chemical analysis to cell sorting. We then present the designs and outcomes for microfluidic devices utilized thus far for each step in IVF: gamete isolation and processing, fertilization, and embryo culture. Finally, we discuss and speculate on the ultimate goal of this technology--development of a single, integrated unit for in-vitro assisted reproduction techniques.     

The cytogenetic analysis of human zygotes and preimplantation embryos

A review of cytogenetic studies on human zygotes and preimplantationembryos is presented. This survey documents the high incidenceof chromosomal abnormalities in embryos in vitro. Up to date,914 zygotes and embryos have been karyotyped. The rate of abnormalitiesis significantly higher in morphologically poor-quality embryosthan in good-quality embryos (86.6 and 36.6% respectively).In both groups, aneuploidy is the most frequently observed abnormality.In addition, various types of aberrations such as polyploidy,haploidy, mosaicism or fragmentation are also found. Among tripronucleatedzygotes, 81.9% display chromosomal abnormalities. Data suggestthat some parameters of IVF procedures might be responsiblefor the occurrence of some abnormalities.     

RIP1在细胞程序性死亡中作用的研究进展

近期研究发现受体相互作用蛋白（receptor—interacting protein,RIP）是细胞生存和死亡的重要交叉点,在细胞的凋亡与存活、程序性坏死等过程中发挥着关键性的作用。RIP1为RIP家族中的第一个成员,是一种重要的细胞信号转导调控分子。RIP1的结构与生物学功能及在细胞程序性死亡中的作用具有重要意义。     

Endometrial receptivity markers, the journey to successful embryo implantation

Human embryo implantation is a three-stage process (apposition, adhesion and invasion) involving synchronized crosstalk between a receptive endometrium and a functional blastocyst. This ovarian steroid-dependent phenomenon can only take place during the window of implantation, a self-limited period of endometrial receptivity spanning between days 20 and 24 of the menstrual cycle. Implantation involves a complex sequence of signalling events, consisting in the acquisition of adhesion ligands together with the loss of inhibitory components, which are crucial to the establishment of pregnancy. Histological evaluation, now considered to add little clinically significant information, should be replaced by functional assessment of endometrial receptivity. A large number of molecular mediators have been identified to date, including adhesion molecules, cytokines, growth factors, lipids and others. Thus, endometrial biopsy samples can be used to identify molecules associated with uterine receptivity to obtain a better insight into human implantation. In addition, development of functional in vitro systems to study embryo-uterine interactions will lead to better definition of the interactions existing between the molecules involved in this process. The purpose of this review was not only to describe the different players of the implantation process but also to try to portray the relationship between these factors and their timing in the process of uterine receptivity.     

The role of paf in embryo physiology

Embryo-derived paf (1-o-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is produced by de novo synthesis. This synthesis commences soon after fertilization and persists throughout the preimplantation phase. Paf is produced and released by the embryos of all mammalian species studied to date. Its release from the embryo involves binding to extracellular albumin in a manner that protects paf from enzymatic degradation. Released paf causes a range of alterations in maternal physiology, including platelet activation, changes in oviductal, endometrial and maternal immune function. Paf also acts in an autocrine fashion as a trophic/survival factor for the early embryo. In vitro, supplementation of culture media with paf improves embryo development. Embryo-derived paf's autocrine actions are transduced by 1-o-phosphatidylinositol-3-kinase, which induces characteristic calcium transients within the early embryo. The calcium transients require both the influx of external calcium and release of inositol trisphosphate-dependent internal calcium stores. Buffering these transients compromised embryo development in a manner that was reversed by exogenous paf. Assisted reproductive technologies compromise the production of paf by some embryos and retard the expression of the paf receptor. This deprivation of paf's action is one of the factors limiting the survivability of embryos produced by assisted reproductive technologies. Paf is one of several autocrine and paracrine trophic/survival factors that act on the early embryo. These factors probably act cooperatively and may, to some degree, be mutually redundant. As the earliest-released and the best-described embryotrophin, paf provides an important exemplar for understanding the role of ligand-mediated trophic support of the early embryo.     

Programmed cell death of dendritic cells in immune regulation

Summary: Programmed cell death is essential for the maintenance of lymphocyte homeostasis and immune tolerance. Dendritic cells (DCs), the most efficient antigen-presenting cells, represent a small cell population in the immune system. However, DCs play major roles in the regulation of both innate and adaptive immune responses. Programmed cell death in DCs is essential for regulating DC homeostasis and consequently, the scope of immune responses. Interestingly, different DC subsets show varied turnover rates in vivo. The conventional DCs are relatively short-lived in most lymphoid organs, while plasmacytoid DCs are long-lived cells. Mitochondrion-dependent programmed cell death plays an important role in regulating spontaneous DC turnover. Antigen-specific T cells are also capable of killing DCs, thereby providing a mechanism for negative feedback regulation of immune responses. It has been shown that a surplus of DCs due to defects in programmed cell death leads to overactivation of lymphocytes and the onset of autoimmunity. Studying programmed cell death in DCs will shed light on the roles for DC turnover in the regulation of the duration and magnitude of immune responses in vivo and in the maintenance of immune tolerance.