EUROMEDICA  Hanover 3-4  Juni 2010	Advanced methods of diagnosis, treatment and prophylactics
	European Academy of Natural Sciences, Hanover European Scientific Society, Hanover Berliner Medizinischen Gesellschaft, Berlin

Home

Abstracts

Contact

Disclaimer

There are lines of evidence indicating that hybrid cells generated by fusion of the ES cells with cells from adults retain their state of pluripotency comparable to that of the ES cells, with the consequential reprogramming of the differentiated cell genome. At the same time the detailed structural organization of hybrid nucleus and cytoplasm remains unclear. We have investigated the morphology of stable hybrid cells produced by fusion of embryonic stem (ES) cells with diploid embryonic mouse fibroblasts by transmission electron microscopy (TEM) and with morphometric analysis. TEM investigations have shown that ES cell and fibroblast differ in cell form, nuclear size, the density of organelles in the cytoplasm and form of endoplasmic reticulum. It was found that the mitochondria in these cells have also different morphology. Mitochondria shape in fibroblast is rod-like with dark matrix and narrow cristae directed perpendicular to the envelope. Two types of mitochondria of ellipse shape have been identified in ES cells. The first type mitochondria has light matrix and narrow cristae while the second type has dark matrix and vesicle-like cristae. The comparative TEM studies demonstrated the similarity of hybrid cells with ES cells but not with fibroblasts. In spite that the average sizes of hybrid cells and their nuclei are larger to that of the ES cells, their nuclear/cytoplasmic relations were completely identical. At the same time the nuclear envelope of hybrid cells forms numerous deep invaginations to the nucleoplasm which have never observed in the ES cells. We suggest that it is related with increasing of ploidy in hybrid cell because they contain the chromosomes of both fusion partners. However some fibroblast chromosomes have been eliminated. When hybrid cells are created, not only the nuclear genomes of parental cells unite but their cytoplasm as well. It is interesting that hybrid cells have lost the mitochondria derived from fibroblasts and contain two types of mitochondria with morphology identical to those observed in the ES cells. Hybrid cells contain narrow cisternae of endoplasmic reticulum and do not produce the collagen as fibroblasts. Thus data obtained support the conclusion about reprogramming of the differentiated cell genome in hybrid cells.

The work was supported by grant of the Russian Fund for Basic Research and the Program of the Russian Academy of Sciences: “Molecular and Cellular Biology”.