胚胎干细胞体外分化为生殖细胞的研究进展

鼠胚胎干细胞体外已成功诱导分化为生殖细胞和配子,人胚胎干细胞也表现出相似的分化能力。本文重点综述了原始生殖细胞(PGC)的起源和发育、PGC发育的相关因素、体外胚胎干细胞分化为原始生殖细胞和配子的过程及其影响因素、多能成体干细胞分化为生殖细胞等方面。     

干细胞在生殖医学工程中的应用研究进展

<正>干细胞(stem cell)是一种具有多能性或全能性的未分化细胞,它可以来源于胚胎、胎儿,也可以来源于部分成人组织。全能干细胞(即胚胎干细胞)主要来源于哺乳动物早起胚胎内细胞团的一种二倍体细胞,是一种高度未分化细胞,具有全能性或多向性分化潜能,易于进行基因改造操作;多能干细胞(即成体干细胞)为特定组织的干细胞,这类细胞不能产生完整的     

小鼠胚胎干细胞分化为精子细胞的研究进展

胚胎干细胞(ESCs)是一种具有分化发育为三个胚层组织细胞潜能的全能性细胞,哺乳动物的精子起源于原始生殖细胞(PGCs),ESCs可分化为PGCs,并进一步分化为精子细胞。通过在培养基中添加诱导分化因子(如维甲酸等)或与希望诱导分化的目的细胞(如Sertoli细胞等)共培养,并通过鉴别ESCs分化为生殖细胞的各阶段特异性基因标志物c-kit、VASA、DAZL、fragilis、miwi、mil1和mil2等,获取不同阶段的生殖细胞。鼠的ESCs已诱导出了不成熟的精子细胞,但到目前为止尚无成熟精子培养成功,且诱导分化的效率很低。     

不同受体胞质对哺乳动物核移植效果的影响

核移植受体胞质提供了重构核去分化、恢复全能性所需的环境,对重构胚的发育潜能有着重要影响,目前用于核移植的受体胞质有卵母细胞、受精卵、2-细胞期卵裂球以及异种卵母细胞等,其中以去核成熟卵母细胞最为常用。本文从哺乳动物核移植受体的类型、细胞周期等方面,对核移植效果的影响进行综述。     

胚胎干细胞研究进展

胚胎干细胞来源于着床前的囊胚内细胞团或早期胚胎的原始生殖细胞,是一类未分化的全能性(多能性)干细胞,具有无限增殖和分化潜能.人类胚胎干细胞系的成功建立以及其体外诱导分化为特定细胞、组织甚至器官的研究进展,使其在临床应用中显示出诱人的前景.就胚胎干细胞系的建立、定向分化及临床应用等研究现状作一综述.     

胚胎干细胞研究进展

胚胎干细胞来源于着床前的囊胚内细胞团或早期胚胎的原始生殖细胞，是一类未分化的全能性(多能性)干细胞，具有无限增殖和分化潜能。人类胚胎干细胞系的成功建立以及其体外诱导分化为特定细胞、组织甚至器官的研究进展，使其在临床应用中显示出诱人的前景。就胚胎干细胞系的建立、定向分化及临床应用等研究现状作一综述。     

p16基因产物在卵巢恶性生殖细胞肿瘤中的表达

ｐ１６基因产物在卵巢恶性生殖细胞肿瘤中的表达高国兰彭芝兰王和陈爱平姚先莹ｐ１６基因的编码蛋白可特异性抑制ＣＤＫ４激酶（ｃｙｃｌｉｎｄｅｐｅｎｄｅｔｋｉｎａｓｅ４）活性而影响细胞周期的调控。由于ｐ１６基因这一重要的生物学功能以及在多种肿瘤细胞系中有高频...     

干细胞治疗女性压力性尿失禁研究进展

干细胞是(stemcell)是一类具有自我更新和分化潜能的细胞群体,根据其分化潜能分为3类:(1)全能干细胞:具有形成完整个体的分化潜能,如胚胎干细胞(ES)。(2)多能干细胞:具有分化出多种细胞组织的潜能,但失去了发育成完整个体的能力,如骨髓多能造血干细胞。(3)专能     

小干扰RNA沉默胚胎生殖细胞Nanog基因的表达

目的:建立胚胎生殖细胞中沉默多能干细胞特异转录因子Nanog表达的方法。方法:通过检测碱性磷酸酶、SSEA-1和Oct4标志蛋白,鉴定体外培养的胚胎生殖细胞(EG细胞),通过脂质体介导作用,将Nanog特异性小干扰RNA(siRNA)转染EG细胞,应用半定量RT-PCR检测转染24h、36h、48h后EG细胞中Nanog mRNA的表达水平,并应用免疫荧光技术检测转染36h、48h后EG细胞中Nanog蛋白的表达水平。结果:培养细胞具有高度碱性磷酸酶活性,SSEA-1、Oct4阳性,为保持未分化状态的EG细胞。转染后Nanog mRNA和蛋白表达均受到抑制。结论:脂质体介导siRNA能有效沉默EG细胞中Nanog基因的表达,为进一步探讨Nanog对胚胎生殖细胞的调控机制奠定了基础。     

人胚胎干细胞研究与展望

人胚胎干细胞(HESC)是一种具有分化发育成3个胚层组织细胞潜能的全能性细胞,可体外定向诱导分化,为胚胎发育学、遗传学和人类疾病的发病机制与替代治疗提供了宝贵的资源.本文综述了近几年来有关HESC的来源、分离和培养的进展,阐明了HESC的应用前景.     

Embryonic germ cells: when germ cells become stem cells

Embryonic germ cells (EGCs) are pluripotent stem cells derived from primordial germ cells (PGCs). PGCs are progenitors of adult gametes, which diverge from the somatic lineage between late embryonic to early fetal development. First derived in the mouse, EGCs have also been derived from human, chicken, and pig. As pluripotent stem cells, EGCs demonstrate long-term self-renewal via clonal expansion in an undifferentiated state, and differentiate in vitro to form embryoid bodies containing cells that represent all three germ layers as well as mixed cell populations of less differentiated progenitors and precursors. This is also demonstrated in vivo by their formation into experimentally induced teratocarcinomas following transplantation. Furthermore, mice, pig, and chicken EGCs have also been shown to contribute to experimentally produced chimeric animals, including germline transmission. Importantly, EGCs demonstrate normal and stable karyotypes as well as normal patterns of genomic imprinting, including X-inactivation. Transplantation studies have begun in a variety of models in hopes of defining their potential use to treat a wide variety of human conditions, including diabetes and urological and neurological disorders.     

Delayed fertilization of anuran amphibian (Xenopus) eggs leads to reduced numbers of primordial germ cells

Several media were tested for the extent to which they promoted high fertilization efficiencies in ovulated, stripped Xenopus eggs. One medium was selected for maintaining eggs in a 'delayed fertilization' (DelF) condition. DelF eggs displayed several unusual characteristics, including shift of the center of gravity, prominent sperm entrance site, and occasional polyspermy. The frequency of normal pattern formation varied according to the length of time eggs were maintained in the DelF condition. Various developmental abnormalities were observed during gastrulation, neurulation, and organogenesis. Most abnormalities appeared, however, to be related to morphogenesis of the endoderm. Primordial germ cell (PGC) development was examined in DelF eggs which displayed normal external morphological features at the swimming tadpole stage. PGC counts were usually normal in short-duration (eg, 5 hr) DelF eggs, but frequently substantially reduced or completely diminished in longer-duration (eg, 25h) tadpoles. Six spawnings were compared and shown to exhibit considerable variability in fertility, morphogenesis, and PGC development. Yolk platelet shifts and developmental parameters were examined in two additional spawnings. The subcortical cytoplasm in which the germ plasm is normally localized appeared to be disrupted in longer duration DelF eggs. That observation may account for low PGC counts in DelF tadpoles.     

Derivation of germ cells from mouse embryonic stem cells.

Deriving oocytes from mouse embryonic stem (ES) cells in the laboratory would be a major advance in therapeutic cloning from today's insufficient process. The first step in this attempt is to study the precursors - primordial germ cells (PGCs), including their emergence, presentation, migration and differentiation. By comparing various reported antigens of germ cells, we found stage-specific embryonic antigen-1 (SSEA-1) and Octamer-4 (Oct-4) are the most useful markers to verify the growth and maturation of germ cell culture from mice. Transgenic mice with specific antigens such as SSEA-1 or Oct-4 are helpful to pick up colonies and follow PGC differentiation. We also delineate the physiological structure for germ cell development by reviewing important studies which employed re-aggregation methods to make germ cells more mature and ready for clinical use. Although some mysteries about reprogramming and intragonadal signal interactions still remain unsolved, each step in uncovering these mechanisms will bring us closer to establishing an unlimited source of germ cells from ES cells.     

Generation of germ cells from pluripotent stem cells in mammals

Background

The germ cell lineage transmits genetic and epigenetic information to the next generation. Primordial germ cells (PGCs), the early embryonic precursors of sperm or eggs, have been studied extensively. Recently, in vitro models of PGC induction have been established in the mouse. Many attempts are reported to enhance our understanding of PGC development in other mammals, including human.

Methods

Here, original and review articles that have been published on PubMed are reviewed in order to give an overview of the literature that is focused on PGC development, including the specification of in vivo and in vitro in mice, human, porcine, and bovine.

Results

Mammalian PGC development, in vivo and in vitro, have been studied primarily by using the mouse model as a template to study PGC specification in other mammals, including human, porcine, and bovine.

Conclusion

The growing body of published works reveals similarities, as well as differences, in PGC establishment in and between mouse and human.     

Fertilization of mouse oocytes using somatic cells as male germ cells

Female and male mouse somatic cells were injected into mouse F(1) oocytes. The cells used included cumulus cells (female) and muscle derived fibroblasts (male). The ability of the cells to fertilize oocytes and support embryonic development was examined. Following activation of the injected oocytes, two second polar bodies were extruded and two pronuclei were formed, one derived from the oocyte chromosomes and the other from the somatic cell chromosomes in a similar way to that observed following fertilization with secondary spermatocytes. Both second polar bodies contained DNA. The fertilization rates by cumulus cells were 10-29%. This was dependent on the artificial activation protocol and on the age of the oocytes. Older oocytes recovered 16-17 h after human chorionic gonadotrophin (HCG) injection were more likely to produce two second polar bodies and two pronuclei than young oocytes which were retrieved at 13-14 h after HCG injection (P < 0.01). The fertilization rates with fibroblasts were 29% using the most effective activation regime and aged oocytes. Most (80-90%) of the 'zygotes' produced by somatic cells cleaved to two cells in culture and ~50% reached the morula stage. However, the developmental competence of the embryos to reach blastocysts was limited. The present study demonstrates that mouse somatic cells undergo haploidization when injected into metaphase II oocytes, fertilize oocytes as diploid male germ cells and support preimplantation development to a degree.     

Serum lactic dehydrogenase (SLDH) in germ cell malignancies of the ovary

Serum lactic dehydrogenase may be elevated in patients with various neoplasms. In this report the authors describe four patients with ovarian germ cell malignancies who had elevated serum lactic dehydrogenase prior to treatment. There was a consistent correlation between these marker levels and the course of the disease. These preliminary data suggest that measurement of lactic dehydrogenase in sera of patients with ovarian germ cell malignancies may be helpful in assessing the effect of therapy.     

胚胎干细胞与雌性生殖细胞互相转化的研究进展

胚胎干细胞是全能性的干细胞,可以向3个胚层的细胞转化;雌性生殖细胞也被认为是一种"干细胞",因为其将遗传信息从一代传至下一代。两者具有相同和不同的特殊标志物,并且可以通过不同的方法互相转化,为"胚胎干细胞-卵母细胞环路"提出设想。