睾丸支持细胞对精原干细胞发育的调节

精原干细胞(spermatogonial stem cells,SSCs)是位于睾丸曲精小管基膜上既能自我更新,又能定向分化的一类原始精原细胞.鉴于其独具的生物学特性,SSCs研究在干细胞生物学、医学、畜牧业等领域均具有重要意义,但目前有关其更新、分化的调控机制仍不清楚.干细胞的发育受其外部特定发育环境及其内在因素的综合调控.最近以睾丸支持细胞为主要结构组分的发育环境对SSCs行为的调控研究备受关注且取得快速进展.综合相关报道,主要就哺乳动物睾丸支持细胞对SSCs更新、分化的调节进行了评述,以期为本领域及其他干细胞研究提供借鉴.     

哺乳动物精原干细胞体外分离培养研究进展

精原干细胞(spermatogonial stem cells,SSCs)作为成体干细胞的一种,具有高度自我更新和分化潜能。近几年研究发现,SSCs的体外培养是表观遗传基础研究、精子发生机制深入探索以及治疗雄性不育的基础条件。本文根据国内外SSCs相关研究,对哺乳动物SSCs的生物学特性、体外分离培养和鉴定等作一综述,以期为哺乳动物SSCs和其他干细胞的长期体外培养以及建系提供一定的借鉴。     

哺乳动物精原干细胞的分子标记及调控

精原干细胞(spermatogonial stem cells,SSCs)是一群生活在睾丸特殊微环境中并能自我更新和具有多向分化潜能的细胞,是精子发生的基础。近年来,通过对SSCs表面的α6-和β1-整合素、CD9、GFRA1等主要标记分子,以及对GDNF、Plzf、泛素、LIF等决定SSCs自我更新和分化的多种细胞因子和基因的研究发现,目前在SSCs的分离、鉴定和生物学特性方面已获得新的成果。本文简述了目前哺乳动物SSCs主要的标记分子及自我更新与分化的调控机理,以期为该领域及其他干细胞研究提供一定的借鉴。     

精原干细胞微环境研究进展

精原干细胞(spermatogonia stem cells, SSCs)是一类在睾丸中具有长期自我更新和分化潜能的生殖细胞(germ cells, GCs),即位于基底膜上的组织干细胞,其自我更新和分化受到周围微环境的调控。近年来对SSCs的研究取得了一系列重要进展,为临床治疗部分男性不育患者带来了曙光。其中,微环境对SSCs的调节功能的研究尤为重要,微环境负责整合不同类型的细胞成分、细胞外基质、细胞外调节分子及激素等对SSCs的作用,从而调节SSCs命运。关于SSCs微环境的研究已开始逐步成为干细胞研究的主要内容之一。本文主要对小鼠(Mus musculus)SSCs微环境的细胞组成、调控因子以及特点等研究现状进行了综述,为深入研究SSCs微环境的结构和功能提供背景资料,希望在未来能够通过多种研究模式复用,发现更为丰富的细胞表型和微环境因子。     

哺乳动物精原干细胞自我更新调控的研究进展

精原干细胞（spermatogonial stem cells,SSCs）具有自我更新和分化的功能,这两种功能的平衡协调不仅能维持其自身数量的稳定,还能满足雄性动物精子生成的需要。近几年,由于细胞培养技术、基因工程技术、生殖细胞移植技术的建立和完善,使SSCs自我更新调控机制的研究取得了许多突破,主要体现在蛋白调控因子和微小RNA分子以及DNA甲基化新作用的发现等方面。该文将着重围绕调控SSCs自我更新的外源性细胞因子和内源性转录因子等蛋白因子进行综述,以期为哺乳动物SSCs的深入研究提供借鉴。     

精原干细胞命运调控的研究进展

精原干细胞(spermatogonial stem cells, SSCs)是体内一类特殊的成体干细胞,它的自我更新和分化平衡决定着雄(男)性持续一生的精子发生过程,是遗传信息在物种间世代稳定传递的基础。半个世纪以来,对SSCs的识别、培养、移植和命运调控相关分子机制的研究极大拓展了人们对其生物学特性的认知。该综述将介绍SSCs研究的相关历史、重要里程、进展和依然面临的瓶颈问题,以期为生育力拯救、干细胞基因改造、濒危动物多样性保护、畜牧业生产等研究和应用提供参考。     

哺乳动物精原干细胞的增殖分化及其移植技术的应用

精原干细胞(spermatogonial stem cells,SSCs)是指位于睾丸生精小管基膜上既能自我更新以维持自身群体数量恒定,又能定向分化形成精母细胞,最终形成精子的一类成体干细胞.鉴于其独具的生物学特性,SSCs的研究在干细胞生物学、医学、畜牧业等领域均具有重要意义.通过其建立转基因动物模型,对研究精子的发生机制、重建不育个体的生精功能等都有着重要意义.综述了哺乳动物SSCs的形态特性,增殖分化特性及其调控因素,简述了SSCs移植技术的应用.     

猪精原干细胞研究进展

精原干细胞（spermatogonial stem cells,SSCs）是雄性生殖系干细胞,位于睾丸曲细精管基膜上,既具有自我更新潜能,又具有定向分化潜能,是自然状态下出生后动物体内在整个生命过程中进行自我更新并能将基因传递至子代的惟一成体干细胞。根据国内外最新相关进展,系统评述了猪SSCs分离纯化、体外培养及移植等方面的现状及问题。     

胶质细胞源性神经营养因子引发精原干细胞自我更新的信号通路

胶质细胞源性神经营养因子(glial cell line-derived neurotrophic factor,GDNF)是TGF-β超家族的一个相关成员。哺乳动物睾丸曲细精管内支持细胞分泌的GDNF,能促进精原干细胞(spermatogonial stem cells,SSCs)的自我更新与增殖。SSCs去分化诱导产生的多能干细胞已被广泛应用于再生医学领域,且SSCs在制作转基因动物、男性不育治疗和体外实施精子发生过程等方面,具有极大的应用价值。所以,GDNF引发SSCs自我更新的作用机理非常值得探索。通过对GDNF引发SSCs自我更新的信号通路进行系统梳理,我们发现了如下的作用过程:GDNF与GFR-α1特异性结合,活化Ret蛋白酪氨酸激酶,随后激活Ras/ERK1/2、PI3K-Akt和SFK信号通路,促进SSCs的自我更新;同时,在该过程中还存在信号通路间的交联对话现象。     

表观遗传修饰与干细胞分化调控

干细胞具有自我更新和多种分化潜能的特性。干细胞向分化细胞的转变涉及到基因表达模式的改变,与自我更新有关的基因关闭．与细胞特化有关的基因激活。表观遗传调控机制,包括DNA甲基化、组蛋白修饰和微RNA（microRNA）介导的基因调控,在多个层面上控制发育过程中基因表达。近年研究表明,动态的表观遗传调控机制在干细胞自我更新和分化中起关键作用。     

哺乳动物精原干细胞的研究进展

精原干细胞是雄性体内可以永久维持的成体干细胞,它具有自我更新和分化的能力,保证了雄性个体生命过程中精子发生的持续进行,从而实现将遗传信息传递给下一代。精原千细胞不仅可在体外实现长期培养或诱导分化为各级生精细胞,并且可在特定条件下将其诱导去分化成为多能性干细胞。同样,这种多能性干细胞如同胚胎干细胞,可被诱导形成造血细胞、神经元细胞、肌细胞等多种类型细胞。鉴于其独具的生物学特性,精原干细胞在揭示精子的发生机制、治疗雄性不育和转基因动物等研究中具有重要价值。该文对精原干细胞在生物学特性、纯化培养、移植、体外诱导分化及其相关调控方面的各项研究进行了小结,综述了近年来的研究历程和最新研究成果。     

Spermatogonial stem cells, infertility and testicular cancer

The spermatogonial stem cells (SSCs) are responsible for the transmission of genetic information from an individual to the next generation. SSCs play critical roles in understanding the basic reproductive biology of gametes and treatments of human infertility. SSCs not only maintain normal spermatogenesis, but also sustain fertility by critically balancing both SSC self-renewal and differentiation. This self-renewal and differentiation in turn is tightly regulated by a combination of intrinsic gene expression within the SSC as well as the extrinsic gene signals from the niche. Increased SSCs self-renewal at the expense of differentiation result in germ cell tumours, on the other hand, higher differentiation at the expense of self-renewal can result in male sterility. Testicular germ cell cancers are the most frequent cancers among young men in industrialized countries. However, understanding the pathogenesis of testis cancer has been difficult because it is formed during foetal development. Recent studies suggest that SSCs can be reprogrammed to become embryonic stem (ES)-like cells to acquire pluripotency. In the present review, we summarize the recent developments in SSCs biology and role of SSC in testicular cancer. We believe that studying the biology of SSCs will not only provide better understanding of stem cell regulation in the testis, but eventually will also be a novel target for male infertility and testicular cancers.     

哺乳动物精原干细胞的操作技术及应用

精原干细胞(spermatogonial stem cells,SSCs)具有高度的自我更新能力和分化潜能。精原干细胞移植技术作为精原干细胞研究的重要手段,已成为一种新兴的动物繁殖技术,能够提高雄性动物的生殖能力。该技术是从适龄雄性供体动物中采集精原干细胞,注射入受体动物的生精小管中使其产生精子。通过对精原干细胞的体外培养、遗传修饰及移植等操作,可以为探讨精子的发生机制、重建不育个体的精子发生、生产转基因动物提供新的途径;同时为提高优良品种家畜的生产效率、保护野生动物资源及不育症的治疗提供了一种新的方法;在医学、生物学及动物科学方面有着广泛地应用。通过对培养体系的不断完善,筛选、移植方法的不断改进,可获得更高的移植成功率。本文将从利用精原干细胞法生产转基因动物的优势,精原干细胞的形态特性和增殖分化特性,精原干细胞的移植技术和影响移植效率的关键因素,精原干细胞的体外培养,以及相关操作技术的应用与前景展望等方面做一概述。     

Capacity for stochastic self-renewal and differentiation in mammalian spermatogonial stem cells

Mammalian spermatogenesis is initiated and sustained by spermatogonial stem cells (SSCs) through self-renewal and differentiation. The basic question of whether SSCs have the potential to specify self-renewal and differentiation in a cell-autonomous manner has yet to be addressed. Here, we show that rat SSCs in ex vivo culture conditions consistently give rise to two distinct types of progeny: new SSCs and differentiating germ cells, even when they have been exposed to virtually identical microenvironments. Quantitative experimental measurements and mathematical modeling indicates that fate decision is stochastic, with constant probability. These results reveal an unexpected ability in a mammalian SSC to specify both self-renewal and differentiation through a self-directed mechanism, and further suggest that this mechanism operates according to stochastic principles. These findings provide an experimental basis for autonomous and stochastic fate choice as an alternative strategy for SSC fate bifurcation, which may also be relevant to other stem cell types.     

生精干细胞的研究进展

生精干细胞（spermatogonial stem cells,Sscs）是动物出生后保持分裂能力的生殖细胞,其通过自身复制从而终生存在,并不停地进行减数分裂而分化成精子。然而,最近的研究发现生精干细胞具有一定的多能性,在体外可被培养和诱导成多能性细胞,显示生精干细胞是再生医学和细胞治疗疾病的另一理想祖细胞来源。该综述将着重讨论生精干细胞的多能性研究情况和相关问题。     

Homing efficiency and proliferation kinetics of male germ line stem cells following transplantation in mice

Stem cells in the male germ line (spermatogonial stem cells [SSCs]) are an important target for male fertility restoration and germ line gene modification. To establish a model system to study the biology and the applications of SSCs in mice, I used a sequential transplantation strategy to analyze the process by which SSCs colonize the stem cell niche after transplantation and to determine the efficiency of the process (homing efficiency). I further analyzed the proliferation kinetics of SSCs after colonization. The number of SSCs gradually decreased during the homing process, and only 12% of SSCs successfully colonized the niche on Day 7 after transplantation, but the number of SSCs increased by Day 14. Thus, homing efficiency of adult mouse SSCs is 12%. These results indicate that SSCs are rapidly lost upon transplantation and require approximately 1 wk to settle into their niches before initiating expansion. Using this SSC homing efficiency, I calculated that approximately 3000 SSCs exist in one normal adult testis, representing approximately 0.01% of total testis cells. Between 7 days and 1 mo after transplantation, SSCs proliferated 7.5-fold. However, they did not significantly proliferate thereafter until 2 mo, and only 8 SSCs supported one colony of donor-derived spermatogenesis from 1 to 2 mo. These results suggest that self-renewal and differentiation of SSCs are strictly regulated in coordination with the progress of an entire unit of regenerating spermatogenesis.     

Male germ line stem cells have an altered potential to proliferate and differentiate during postnatal development in mice

Spermatogonial stem cells (SSCs) continuously support spermatogenesis after puberty. However, accumulating evidence suggests that SSCs differ functionally during postnatal development. For example, mutant mice exist in which SSCs support spermatogenesis in the first wave after birth but cease to do so thereafter, resulting in infertility in adults. Studies using a retroviral vector have shown that the vector transduces pup SSCs more efficiently than adult SSCs, which suggests that pup SSCs divide more frequently. Thus, it is hypothesized that the SSCs in pup and adult testes have different characteristics. As an approach to testing this hypothesis in the present study, we investigated the proliferation kinetics of pup SSCs (6-9 days old) and their self-renewal/differentiation patterns for the first 2 mo after transplantation, and compared them to those of adult SSCs. Using serial transplantation, we found that the number of pup SSCs declined over the first week after transplantation. Thereafter, it increased ~4-fold by 1 mo and ~9-fold by 2 mo after transplantation, which indicates that pup SSCs continuously proliferate from 1 wk to 2 mo after transplantation. Compared to the proliferation of SSCs derived from adult intact testes, that of pup SSCs was lower at 1 mo but similar at 2 mo, indicating the delayed proliferation of pup SSCs. However, the pup SSCs regenerated spermatogenic colonies at 1 mo that were similar in length to those of SSCs from adult intact testes. Therefore, these results suggest that some functional differences exist in SSCs during postnatal development, and that these differences may affect the abilities of SSCs to self-renew and differentiate.     

KnockoutTM SR无血清培养基支持小鼠精原干细胞的短期存活(简报)

精原干细胞(spermatogonial stem cells,SSCs)是睾丸内具有自我复制和分化为精子潜能的干细胞,它的体外培养是精子发生机理研究和制作转基因动物等的新途径[1,2].近几年的研究表明,SSCs在体外的自我增殖需要GDNF(glial cell line-derived neu-rotrophie factor)因子和饲养层细胞等的支持[3-10].并且睾丸支持细胞(Sertoli's cells)和血清都导致培养的SSCs分化[1,6].因此,使用无血清培养基培养高度纯化的SSCs是培养成败的关键之一.