Generation of developmentally competent oocytes and fertile mice from parthenogenetic embryonic stem cells

Parthenogenetic embryos, created by activation and diploidization of oocytes, arrest at mid-gestation for defective paternal imprints, which impair placental development. Also, viable offspring has not been obtained without genetic manipulation from parthenogenetic embryonic stem cells (pESCs) derived from parthenogenetic embryos, presumably attributable to their aberrant imprinting. We show that an unlimited number of oocytes can be derived from pESCs and produce healthy offspring. Moreover, normal expression of imprinted genes is found in the germ cells and the mice. pESCs exhibited imprinting consistent with exclusively maternal lineage, and higher X-chromosome activation compared to female ESCs derived from the same mouse genetic background. pESCs differentiated into primordial germ cell-like cells (PGCLCs) and formed oocytes following in vivo transplantation into kidney capsule that produced fertile pups and reconstituted ovarian endocrine function. The transcriptome and methylation of imprinted and X-linked genes in pESC-PGCLCs closely resembled those of in vivo produced PGCs, consistent with efficient reprogramming of methylation and genomic imprinting. These results demonstrate that amplification of germ cells through parthenogenesis faithfully maintains maternal imprinting, offering a promising route for deriving functional oocytes and having potential in rebuilding ovarian endocrine function.

Nanos2 in the male reproductive system: Progress in studies / 中华男科学杂志

Nanos2, a member of the Nanos2 gene family, is a specific gene in male germ cells and encodes an evolutionarily conserved RNA binding protein expressed in male primordial germ cells (PGCs) during the embryonic period as well as in the spermatogonial stem cells (SSCs) of the testis. In the embryonic period, Nanos2 promotes the development of male PGCs and inhibits them from meiosis. In the process of spermatogenesis, Nanos2 suppresses the differentiation of SSCs in the testis and maintains the stability of the SSC pool. The knockout of Nanos2 may cause the disappearance of germ cells and sterility in male mice while its overexpression in the testis may lead to accumulation of SSCs in seminiferous tubules. Besides, Nanos2 is involved in the degradation of specific RNAs and possibly associated with some diseases of the male reproductive system. This review focuses on the recent progress in the studies of Nanos2 in the male reproductive system.

Artificial gametes from stem cells / 대한생식의학회지

The generation of artificial gametes is a real challenge for the scientific community today. In vitro development of human eggs and sperm will pave the way for the understanding of the complex process of human gametogenesis and will provide with human gametes for the study of infertility and the onset of some inherited disorders. However, the great promise of artificial gametes resides in their future application on reproductive treatments for all these people wishing to have genetically related children and for which gamete donation is now their unique option of parenthood. This is the case of infertile patients devoid of suitable gametes, same sex couples, singles and those fertile couples in a high risk of transmitting serious diseases to their progeny. In the search of the best method to obtain artificial gametes, many researchers have successfully obtained human germ cell-like cells from stem cells at different stages of differentiation. In the near future, this field will evolve to new methods providing not only viable but also functional and safe artificial germ cells. These artificial sperm and eggs should be able to recapitulate all the genetic and epigenetic processes needed for the correct gametogenesis, fertilization and embryogenesis leading to the birth of a healthy and fertile newborn.

A light- and electron microscopic study of primordial germ cells in the zebra fish (Danio rerio)

In sexually reproducing organisms, primordial germ cells (PGCs) give rise to the cells of the germ line, the gametes. In many animals, PGCs are set apart from somatic cells early during embryogenesis. This study explores the origin of primordial germ cells (PGCs) of the zebra fish and examines their morphology during early development (1st day-15th day). PGCs were selectively stained by the alkaline phosphatase histochemical reaction and viewed by light and electron microscopy from the time they are first detectable in the yolk sac endoderm. PGCs occurred in the subendodermal space on the syncytial periblast; differing from the surrounding endodermal cells. Later the PGCs moved to between the blastoderm and yolk sac and transferred to the dorsal mesentery where they formed gonadal anlage with mesoderm cells. PGCs were easily distinguished from somatic cells by their morphology and low electron density of their nuclei. Under light microscopy, PCGs were rounded with a distinct cytoplasmic membrane.

A new method of inducing mouse primordial germ cells into hepatocytes-like in vitro / 基础医学与临床

Objective To establish a new method for inducing the primordial germ cells to differentiate into hepatocyte-like in vitro.Methods The primordial germ cells(PGCs) from the gonadal ridges of the mouse embryos of 13 days postcoitum from Kunming pregnant mice were cultured in vitro.Then embryonic hepatocytes enclosed in microcapsule and liver tissue extract of newborn mice were added into medium to co-culture with PGCs for committed differentiation.Albumin(ALB) and ?-1-antitrypsin(AAT) were assayed by immunocytochemistry.Results The morphology of cells differentiated from PGCs likes star or ovum,the ALB and AAT immune positive expression were detected in those differentiated cells.The ratio of positive cells was above 70% in 2 weeks.Conclusion Microenvironment of embryonic hepatocyte microcapsules and liver tissue extract could effectively induce PGCs to differentiate into hepatocytes.

THE EFFECT OF TRANSPLANTATION OF MOUSE PRIMORDIAL GERM CELLS ON THE ACUTE DAMAGED LIVER / 解剖学报

Objective To investigate the milieu-dependent differentiation of primordial germ cells(PEGs) in the acute damaged liver microenviroment. Methods After PGCs were cultured and proliferated,these cells were labelled with 5-bromo-2-deoxyuridine(BrdU),then transplanted into the acute damaged liver by CCl_4 through tail vein.Two and four weeks later,the liver was extracted and 10?m-cryostat continuous sections were obtained.The existing and differentiation of the transplanted cells were identified by immunohistochemistry,immunofluorescence double staining and histochemistry for BrdU and hepatic-specific ALB,and the glycogen. Results Transplanted PGCs were found to be incorporated into the acute damaged liver and differentiated into hepatocytes,compensating for acute liver failure.Conclusion PGCs can be induced to differentiate into hepatocytes in the acute damaged liver microenvironment,and can be used for cellular hepatoplasty to treat severe liver disease.

THE RESEARCH ON THE PROLIFERATION AND DIFFERENTIATION OF MOUSE PRIMORDIAL GERM CELLS IN VITRO / 解剖学报

Objective To research on the proliferation and differentiation in vitro of primordial germ cells. Methods We got plenty of primordial germ cells(PGCs) by co-culture of PGCs with sertoli cells(SCs).The primary cells formed embryoid bodies(EBs) by suspension culture.furthermore,these EBs were plated on gelatin-coated culture plates for spontaneous differentiation. Results We got plenty of PGCs by coculture.Primary PGCs and passaged PGCs for histochemistry staining with AKP and immunohistochemistry staining for SSEA-1 display positive character.The EBs by suspension culture differentiated into epithelial-like,fibroblast-like and neuronal-like cells in vitro. Conclusion Primordial germ cells can proliferate and keep the character of stem cells by co-culture with SCs.PGCs can form EBs by suspension culture,most of these EBs can differentiate into neuronal-like cells,they also can differentiate into epithelial-like and fibroblast-like cells in vitro.