Recent Russian papers on stem cells

[Wise Young]

• (2003). [In Process Citation]. Izv Akad Nauk Ser Biol 371-4. Summary: We studied the behavior and differentiation of pluripotent embryonic stem cells of R1 mice in vivo. Undifferentiated embryonic stem cells and differentiating embryoid bodies grafted in abdominal cavity of the irradiated mice were shown to form tumors with derivatives of all germinal layers. Cells of the embryoid bodies form tumors two weeks after the grafting, while the undifferentiated embryonic stem cells form tumors only by week three. Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow, 119991 Russia. olgagordeeva@yandex.ru

[Wise Young]

• (2003). [In Process Citation]. Ontogenez 34:216-27. Summary: In the hybrid cells obtained by fusion of embryonic stem cells with adult differentiated cells, homologous chromosomes are in two ontogenetic configurations: pluripotent and differentiated. In order to assess the role of cis- and trans-regulation in the maintenance of these states, we studied a set of clones of hybrid cells of the type embryonic stem cells-splenocytes and used two approaches: segregation of parental chromosomes and comparison of pluripotency of the past hybrid cells and embryonic stem cells. The segregation test showed that the hybrid cells lost only the homologs of the somatic partner and this process was sharply accelerated when the cells were cultivated in nonselective conditions, thus suggesting the full or partial preservation of the initial differences in the organization of parental homologs. The descendants of the former hybrid cells, which had the karyotype similar to that of embryonic stem cells, demonstrated the level of pluripotency, comparable with that of embryonic stem cells despite the long-term effect of trans-acting factors from the somatic partner in the genome of hybrid cells. The data obtained are interpreted in the framework of the concept of "chromosome memory", in the maintenance of which the key role is played by cis-regulatory factors. Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, pr. Akad., Lavrent'eva 10, Novosibirsk, 630090 Russia. serov@bionet.nsc.ru

[Wise Young]

• (2003). [In Process Citation]. Ontogenez 34:211-5. Summary: Isolation and cultivation of stem and progenitor cells of human embryos and fetuses at the age of 7-12 weeks of gestation have been described. The embryonic cells of human brain formed neurospheres with heterogenous composition. Cell differentiation took place not only in the presence of serum or as a result of attachment of neurosphere to a sublayer, but also in floating neurospheres in the presence of mitogens. In most neurospheres, the nestin-immunopositive cells were located near the surface while the cells stained for beta-tubulin III and glial fibrillar acid protein, as compact groups inside the neurospheres. Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow, 119991 Russia. rim-poltavtseva@mail.ru

[Wise Young]

• (2003). [In Process Citation]. Ontogenez 34:204-10. Summary: Spontaneous formation of embryoid bodies and subsequent differentiation of some cells into cardiomyocytes were demonstrated on murine embryonic stem cells of R1 line. The lines of embryonic stem cells were obtained that had been transfected with genetic constructs carrying expressing regulatory genes of the human immunodeficiency virus tat and nef and "green protein" gene (GFP). The transfection of embryonic stem cells with the gene tat stimulated their proliferative activity, while this activity decreased in the cells transfected with the gene nef. The time necessary for the formation of embryoid bodies by all lines of transfected cells was similar to that in the control cells. In the cultures of cells transfected with nef and tat, the number of embryoid bodies and the percentage of embryoid bodies with contracting cardiomyocytes were higher and lower than in the control, respectively. Thus, an inverse correlation was observed between the effects of regulatory genes of the human immunodeficiency virus on proliferation and differentiation embryonic stem cells. Institute of Molecular Genetics, Russian Academy of Sciences, pl. Akad, Kurchatova 2, Moscow, 123182 Russia. esm@img.ras.ru

[Wise Young]

• (2003). [In Process Citation]. Ontogenez 34:193-203. Summary: Three and four independent cell lines with limited pluripotency were obtained from the inner cell mass cells of blastocysts and primordial germ cells of common voles, respectively. The results of cytogenetic analysis suggest that all these lines originated from the embryos of F1 Microtus rossiaemeridionalis x M. arvalis males and had a great number of near-triploid cells already during the early passages. The cells of these lines, like those of the inner cell mass, were characterized by the alkaline phosphatase activity. Nine independent cell lines were obtained as a result of hybridization of the mouse embryonic stem cells and vole splenocytes: eight lines and one line from hybridization with the M. kirgisorum and M. rossiaemeridionalis splenocytes, respectively. The cells of these lines expressed some properties of embryonic stem lines had a chromosome complement similar to the sum of two initial diploid sets of the mouse and vole. Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, pr. Akad. Lavrent'eva 10, Novosibirsk, 630090 Russia.

[Wise Young]

• (2003). [In Process Citation]. Ontogenez 34:174-82. Summary: The expression of regulatory genes of the POU, Pax, Prox, and Ptx gene families was studied at the initial stages of differentiation of murine embryonic stem cells of R1 line. mRNAs were isolated from undifferentiated embryonic stem cells and embryoid bodies formed at the early stages of in vitro differentiation and cDNA sequences were synthesized for comparative PCR analysis of the expression of studied genes. The levels of expression of the gene Oct-4 involved in maintenance of the pluripotent status of embryonic stem cells proved to be practically indistinguishable in undifferentiated cells and embryoid bodies, while the expression of Pax-6 markedly increased in the latter. The levels and patterns of expression of the homeobox transcription factors Prox-1 and Ptx-2 were compared on this cell model for the first time. A probable role of these genes in differentiation of the murine embryonic stem cells is discussed. Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow, 119991 Russia. olgagordeeva@yandex.ru