经睾丸网移植小鼠精原干细胞的研究

目的研究经睾丸网移植小鼠同种精原干细胞的可行性。方法经~(60)Co-γ射线全身照射后,在基因型相似的Balb/c小鼠间经睾丸网进行精原干细胞移植,移植后3个月,观察其生精恢复情况。结果形态学证实,成功移植的小鼠精原干细胞生精过程部分恢复。结论在基因型相似的Balb/c小鼠间经睾丸网进行精原干细胞移植是可行的。     

Plasticity of male germline stem cells and their applications in reproductive and regenerative medicine

Spermatogonial stem cells (SSCs), also known as male germline stem cells, are a small subpopulation of type A spermatogonia with the potential of self-renewal to maintain stem cell pool and differentiation into spermatids in mammalian testis. SSCs are previously regarded as the unipotent stem cells since they can only give rise to sperm within the seminiferous tubules. However, this concept has recently been challenged because numerous studies have demonstrated that SSCs cultured with growth factors can acquire pluripotency to become embryonic stem-like cells. The in vivo and in vitro studies from peers and us have clearly revealed that SSCs can directly transdifferentiate into morphologic, phenotypic, and functional cells of other lineages. Direct conversion to the cells of other tissues has important significance for regenerative medicine. SSCs from azoospermia patients could be induced to differentiate into spermatids with fertilization and developmental potentials. As such, SSCs could have significant applications in both reproductive and regenerative medicine due to their unique and great potentials. In this review, we address the important plasticity of SSCs, with focuses on their self-renewal, differentiation, dedifferentiation, transdifferentiation, and translational medicine studies.     

Defect in germ cells, not in supporting cells, is the cause of male infertility in the jsd mutant mouse: proliferation of spermatogonial stem cells without differentiation

C57BL/6 (B6)-jsd/jsd male mice are sterile because of lack of spermatogenesis. To find the cause of the deficient spermatogenesis, we have examined whether the mutation phenotype is the result of a defect in germ cells or in supporting cells using germ cell transplantation. In the seminiferous tubules of B6-jsd/jsd mutant mice, donor germ cells derived from the wild type GFP transgenic mouse (B6-+/+GFP) were able to undergo complete spermatogenesis, indicating that the juvenile spermatogonial depletion (jsd/jsd) mouse possesses normal supporting cell functions. In contrast, undifferentiated spermatogonia derived from B6-jsd/jsd mice were unable to differentiate in the seminiferous tubules of W/W v mice, even if the mutant germ cells successfully settled in the tubules. These results demonstrate that the deficiency in spermatogenesis of B6-jsd/jsd mice can be ascribed to a defect in spermatogonia but not in their supporting cell environment. Furthermore, the defect in B6-jsd/jsd spermatogonia is not in their ability to proliferate, but in their differentiation and may result from their hypersensitivity to high concentrations of androgen in the testis.     

Enrichment and transplantation of spermatogonial stem cells

Spermatogenesis is a complex, highly organized process originated from stem cell spermatogonia. Because there are very few stem cells and they can only be defined by their function, the identification and isolation of these cells has been very difficult. By using a spermatogonial transplantation assay system, we have identified α₆-and β₁-integrin expression on stem cells, and cells isolated with these antigens were significantly enriched in stem cells. This is the first demonstration of spermatogonial stem cell-associated antigens. Analysis of two infertile mouse models, Steel/Steel^Dickie (Sl/Sl^d) and experimental cryptorchidism, showed that the number of stem cells is reduced in Sl/Sl^d testis. Whereas cryptorchid testes are greatly enriched for stem cells, and one in 200 cells is a stem cell. These techniques will provide an important starting point for further purification and characterization of spermatogonial stem cells.     

Stage-specific degeneration of germ cells in the seminiferous tubules of non-obese diabetic mice

The cause of fertility problems in insulin-dependent diabetes is largely unknown. To evaluate the role of autoimmunity-associated phenomena in the testis as a possible cause of the derangement in spermatogenesis, the stage-specific apoptosis of germ cells in the insulitis phase of pre-diabetes was quantified in the testes of non-obese diabetic (NOD) mice. The seminiferous epithelium of normal BALB/c and NOD mice contained cells positive for in-situ end-labelling (ISEL) of DNA. ISEL-positive germ cells formed clusters in the seminiferous epithelium of the NOD mice in marked contrast to the seminiferous epithelium of the BALB/c mice, which contained only individual cells positive for ISEL. ISEL-positive cells were present in the basal and luminal compartments of the epithelium. Ultrastructural analysis and demonstration of externalized phosphatidyl serine confirmed that the cells were undergoing apoptosis. The ultrastructurally apoptotic cells included spermatogonia, spermatocytes and spermatids. In cytological squash preparations of segments of seminiferous tubules from NOD mice aged 17–20 weeks, the number of ISEL-positive cells/mm tubule was significantly lower in segments at stages I–II of the seminiferous epithelial wave but higher at stages III–IV in comparison to BALB/c mice. The numbers of ISEL-positive cells/mm tubule in the other stages were similar in the two strains of mice. Analysis of ³²P-3' -end labelled DNA from the testes showed that the BALB/c mice had relatively more DNA fragmentation than did the NOD mice. These data suggest that autoimmune insulitis in the NOD mice is associated with increased amounts and abnormal stage distribution of apoptosis in the seminiferous epithelium, resulting in derangement of spermatogenesis.     

Renal differentiation from adult spermatogonial stem cells

Abstract

There is considerable interest in the use of multi-potent stem cells in kidney tissue regeneration. We studied if spermatogonial stem cells have the ability to undergo kidney differentiation. Spermatogonial stem cell differentiation was induced using in vitro and ex vivo co-culture techniques. Conditioned media from human kidney fibroblasts induced the expression of epithelial and endothelial lineages in spermatogonial stem cells, consistent with nephrogenesis. Furthermore, we showed that these cells up-regulated renal tubular-specific markers alkaline phosphatase, mineralocorticoid receptor, renal epithelial sodium channel and sodium-glucose transporter-2 (p?<?0.05). GFP-labeled spermatogonial stem cells were engrafted into metanephric kidney organ cultures harvested from E12.5 mouse embryos. After 5 days of organ culture, focal anti-GFP staining was detectable in all inoculated kidneys demonstrating integration of spermatogonial stem cells into the developing kidney (p?<?0.01). Histological assessment showed early nephron-like architecture. In summary, we show that spermatogonial stem cells have the potential to generate renal tissue and lay the foundations for further investigations into a novel therapeutic approach for renal insufficiency.     

Clinically relevant aspects of stem cell technologies: current state of play

The emergence of stem cell technologies and their potential applications in regenerative medicine have generated immense interest by both the lay public and clinicians. Unproven and unregulated cell‐based therapies are commercially available both in Australia and internationally, and reports of patient uptake (stem cell tourism) and associated morbidity are increasingly frequent. Clinicians in all fields will require an enhanced understanding of the basic science principles and current state of play in regenerative medicine in order to effectively counsel patients regarding these therapies in the setting of both commercial ventures and clinical trials. This review aims to concisely highlight the key clinically pertinent features of these trials and briefly discuss the specific therapeutic potential, mechanism of action and risks associated with these variables.     

Reproductive stem cell research and its application to urology

Abstract:   Germ cells are defined by their innate potential to transmit genetic information to the next generation through fertilization. Males produce numerous sperm for long periods to maximize chances of fertilization. Key to the continuous production of large numbers of sperm are germline stem cells and their immediate daughter cells, functioning as transit amplifying cells. Recently, it has become possible to expand germline stem cells of rodents in vitro . In addition, multipotent stem cells, which are functionally the same as embryonic stem cells, have been established from neonatal mouse testes. These stem cells derived from the testis should contribute to biological research and technologies. On the other hand, the nature of human spermatogenesis is largely unknown due to the lack of an appropriate experimental system. However, the prevailing testicular sperm extraction procedure unraveled hitherto unknown facets of human spermatogenesis. The establishment of a culturing method for human spermatogonial stem cells in hopefully the near future would be a great benefit for achieving further insight into human spermatogenesis and should lead to more sophisticated diagnostic and therapeutic clinical measures for male infertility.     

Annexin A7在精原干细胞中的表达研究

目的:探讨Annexin A7在睾丸中的表达,尤其是在精原细胞各亚型中的分布。方法:采用原核表达法制备了Annexin A7的重组蛋白,质谱鉴定后用其吸附Annexin A7抗体,并用W estern印迹及免疫组化的方法检测了Annexin A7的表达。结果:研究发现Annexin A7于青春期前的小鼠睾丸中主要在精原细胞中表达,并有一定发育依赖性;在成年睾丸中主要表达于As及Apr精原细胞,且与分化型精原干细胞(SSCs)的分子标志Stra8的共表达也进一步证实上述结果。结论:Annexin A7是As及Apr精原干细胞的内在因子,可参与SSCs的生物学功能。     

Transplantation of mesenchymal stem cells in a canine disc degeneration model

Transplantation of mesenchymal stem cells (MSCs) is effective in decelerating disc degeneration in small animals; much remains unknown about this new therapy in larger animals or humans. Fas‐ligand (FasL), which is only found in tissues with isolated immune privilege, is expressed in IVDs, particularly in the nucleus pulposus (NP). Maintaining the FasL level is important for IVD function. This study evaluated whether MSC transplantation has an effect on the suppression of disc degeneration and preservation of immune privilege in a canine model of disc degeneration. Mature beagles were separated into a normal control group (NC), a MSC group, and the disc degeneration (nucleotomy‐only) group. In the MSC group, 4 weeks after nucleotomy, MSCs were transplanted into the degeneration‐induced discs. The animals were followed for 12 weeks after the initial operation. Subsequently, radiological, histological, biochemical, immunohistochemical, and RT‐PCR analyses were performed. MSC transplantation effectively led to the regeneration of degenerated discs. FACS and RT‐PCR analyses of MSCs before transplantation demonstrated that the MSCs expressed FasL at the genetic level, not at the protein level. GFP‐positive MSCs detected in the NP region 8 weeks after transplantation expressed FasL protein. The results of this study suggest that MSC transplantation may contribute to the maintenance of IVD immune privilege by the differentiation of transplanted MSCs into cells expressing FasL. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:589–600, 2008     

Expression of BCL-2 family genes in germ cells undergoing apoptosis during the first wave of spermatogenesis in the rat

Apoptosis is a key event controlling sperm output both in normal and pathological conditions. However, the mechanisms involving germ cell apoptosis is far from being understood. In this work, we have immunoisolated germ cells undergoing apoptosis by taking advantage of the up-regulation of Fas, a dead receptor involved in apoptosis induction in these cells. Analysis of specific markers showed that this cell population is composed of spermatogonia and meiotic spermatocytes. We measured the mRNA levels of several apoptosis-inducing proteins belonging to the BCL-2 family (BAX, BAD, PUMA, BOK and BAK) as well as those that prevent apoptosis (BCL-2, BCL-W and BCL-XL). Results showed that apoptotic germ cells have elevated mRNA levels of all studied genes (both pro and anti-apoptotic) compared with non-apoptotic cells. Our data would help to define the molecular mechanisms involving germ cell apoptosis under physiological conditions.     

人胚胎干细胞来源的成纤维细胞支持无动物源污染条件下的人精原干细胞生长

精原干细胞在人出生后可以连续分裂以支持精子形成,将遗传信息传递给下一代。在本文中,我们成功地从睾丸组织中分离并鉴别人精原干细胞的一种新方法,并在人胚胎干细胞来源的成纤维细胞上扩增人精原干细胞。在这种人胚胎干细胞来源的成纤维细胞上可维持大量的人精原干细胞并且在组合生长因子,特别是胶质细胞来源的神经生长因子存在的条件下扩增至少2个月。细胞表面标志分析显示这些精原干细胞具有高水平的碱性磷酸酶的表达并保持了高水平的胚胎特异阶段抗原SSEA-1,OCT4和CD49f的表达。用逆转录PCR反应检测出OCT4,SOX3,STRA8基因的表达。这些数据清晰地表明运用人胚胎干细胞来源的成纤维细胞来支持人精原干细胞的一个新的策略,并排除了异源物种的污染。这个系统提供了新的机会去了解干细胞巢对于控制精原干细胞自我更新的调节机制,并将对于精原干细胞潜在的临床应用提供有用的精原干细胞。     

精原干细胞增殖和分化相关因子的研究进展

临床上,非梗阻性无精子症患者由于睾丸中没有精子而无法进行辅助生殖治疗,精原干细胞方面的研究,可能为这部分患者带来希望。本文就近年来精原干细胞增殖分化的分子调控机制进行综述。     

Identification of a novel testis-specific gene and its potential roles in testis development／spermatogenesis

Aim: To identify and characterize a novel gene with potential roles in testis development and spermatogenesis.Methods: A cDNA microarray was constructed from a human testis large insert cDNA library and hybridized with probes of human or mouse adult and fetal testes. Differentially expressed genes were isolated and sequenced. RT-PCR was used to test the tissue distribution of the genes of interest and in situ hybridization was performed to localize the gene expression in the mouse testis. A range of bioinformatical programs including Gene Runner, SMART, NCBI Blast and Emboss CpGPlot were used to characterize the new gene‘s feature. Results: A novel testis-specific gene,NYD-SPS, was differentially expressed in fetal and adult testes. The deduced protein structure of NYD-SP5 was found to contain an IQ motif (a short calmodulin-binding motif containing conserved lie and Gin residues), a Carbamate kinase-like domain, a Zn-dependent exopeptidase domain and a lactate dehydrogenase (LDH) C-terminal-like domain. RT-PCR analysis revealed that NYD-SP5 was predominantly expressed in the testis but not in other 15 tissues examined. In situ hybridization and RT-PCR examinations revealed that the expression of NYD-SP5 was confined in the male germ cell but not present in the somatic cell in the testes. Conclusion: NYD-SP5 is a newly found testisspecific gene with potential roles in testis development and spermatogenesis through a calmodulin-activated enzyme.     

Characteristics of spermatogonial stem cells derived from neonatal porcine testis

The aim of this study was to isolate and characterise porcine spermatogonial stem cells (PSSCs). The putative porcine germline stem cells from testis were isolated successfully by an improving way of enrichment with lymphocyte separation medium (LSM). Results from RT‐PCR analyses showed that PSSCs were positive for OCT4, SOX2, NANOG, PGP9.5, c‐MYC, KEL4 and PRDM‐14 which are multipotent stem cell markers. At the protein level, the results of immunofluorescence analyses showed that PSSCs were positive for OCT4, PGP9.5, SOX2 and CD29. We successfully differentiated these PSSCs into adipocytes and muscle cells and then defined their characteristics, including morphology, surface stem cell markers, and mechanical properties. But the experiment of teratoma formation was negative. The results indicated the PSSCs could be multipotent. Atomic force microscopy was used to characterise the morphological and mechanical properties of undifferentiated PSSCs, as well as the differentiated adipocytes and muscle cells, which could be potentially useful for distinguishing PSSCs from differentiated cells.     

小鼠同种生精干细胞移植后的形态学观察

目的 研究同种生精干细胞移植的后的形态学变化。方法 在不采用免疫抑制剂的条件下,在基因型相似的封闭群昆明白小鼠间进行同种生精干细胞移植,移植后3个月,观察其生精恢复情况。结果 形态学证实,成功移植的小鼠生精功能基本恢复正常。结论 在基因型类似的昆明白小鼠进行同种生精干细胞移植是可行的。     

Regenerative cell therapy for the treatment of hyperbilirubinemic Gunn rats with fresh and frozen human induced pluripotent stem cells-derived hepatic stem cells

Pluripotent stem cells have been investigated as a renewable source of therapeutic hepatic cells, in order to overcome the lack of transplantable donor hepatocytes. Whereas different studies were able to correct hepatic defects in animal models, they focused on the most mature phenotype of hepatocyte-like cells (HLCs) derived from pluripotent stem cells and needed freshly prepared cells, which limits clinical applications of HLCs. Here, we report the production of hepatic stem cells (pHSCs) from human-induced pluripotent stem cells (hiPSCs) in xeno-free, feeder-free, and chemically defined conditions using as extracellular matrix a recombinant laminin instead of Matrigel, an undefined animal-derived matrix. Freshly prepared and frozen pHSCs were transplanted via splenic injection in Gunn rats, the animal model for Crigler-Najjar syndrome. Following cell transplantation and daily immunosuppression treatment, bilirubinemia was significantly decreased (around 30% decrease, P < .05) and remained stable throughout the 6-month study. The transplanted pHSCs underwent maturation in vivo to restore the deficient metabolic hepatic function (bilirubin glucuronidation by UGT1A1). In conclusion, we demonstrate for the first time the differentiation of hiPSCs into pHSCs that (a) are produced using a differentiation protocol compatible with Good Manufacturing Practices, (b) can be frozen, and (c) are sufficient to demonstrate in vivo therapeutic efficacy to significantly lower hyperbilirubinemia in a model of inherited liver disease, despite their immature phenotype. Thus, our approach provides major advances toward future clinical applications and would facilitate cell therapy manufacturing from human pluripotent stem cells.     

趋化素样因子超家族在小鼠睾丸中的基因发育表达调控和蛋白表达定位

目的研究CKLFSF2小鼠同源序列cklfsf26基因在睾丸组织发育中的表达和定位,为其功能研究做出提示。方法利用RT-PCR方法检测cklfsf26基因在不同周龄小鼠睾丸组织中的表达情况；制备cklfsf2b多克隆抗体,利用免疫组织化学方法,检测cklfsf2b蛋白在小鼠睾丸组织中的表达定位。结果cklfsf2bmRNA在出生后第2周内出现,表达量逐渐增加,在成年前即达高峰并持续表达。cklfsf2b蛋白特异性的表达于睾丸Leydig细胞和Sertoli细胞,阳性信号均位于胞质内。结论cklfsf2b基因存在发育的表达调控,随着睾丸发育的日趋成熟,表达量逐渐增加：在Leydig细胞和Sertoli细胞的特异性表达表明其在睾酮合成和精子发生中均可能发挥作用,但其具体功能还需深入研究。