| Abstract |
Pluripotent cells are unique due to their developmental potential and the
possibility to study them is the key step to understand human development.
These cells are characterized by their ability to originate all the
cellular lineages within an adult organism. Within embryonic milieu,
pluripotent cells represent a dynamic fraction of the total cell number.
Moreover, their physiological existence is constrained to early stages of
embryonic development. In vitro culture of the different types of
mammalian pluripotent cells, and singularly embryonic stem cells (ESC),
enables the characterization of the pluripotent state. In the four articles
included in this thesis we have addressed two different aspects of the
molecular characterization of mammalian pluripotent cells. First, we
investigated the establishment of the trophectoderm and the inner cell mass
in the embryo measuring transcript abundance and protein presence of the
transcription factors known to play a role in the earliest cellular
differentiation process. In addition we have evaluated of genomic stability
of human ESC lines during long-term culture, observing the accumulation of
subkaryotypic aberrations such as loss of heterozygosity that affect
loci comprising genes involved in genomic stability maintenance. We also
checked the genomic status of two human ESC lines derived from embryos that
had been diagnosed as abnormal after genetic preimplantation diagnosis
(PGD). The molecular analysis of these cells ruled out the
hypothesized self-correction of the aneuploidies between the PGD and the
establishment of the cell lines.
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