Human embryonic stem cells (hESC) have two important characteristics: first, they can be maintained in undifferentiated form indefinitely, and secondly, can be coaxed into differentiating in derivatives of all three germ layers such as muscle, neurons or insulin-producing cells. This is why they carry great hope for use in regenerative medicine and cell therapy. Moreover, these cell lines can be of great help to study molecular physiology linked to specific mutations, whether they are used in differentiation models, or to generate in-vitro models for gene therapy, drug screening and testing, thus reducing the need for animal models. During PGD, embryos from couples at risk to transmit a genetic disease are biopsied and the biopsied cell is analysed for the disease under consideration. Only healthy embryos are transferred to the mother, while affected embryos are available for research, such as derivation of hESC carrying monogenic diseases. We have thus been able to derive two hESC lines carrying fascio-scapulo-humeral disease (FSHD), and three carrying myotonic dystrophy (DM1). Moreover, we have already obtained in order to carry out this project, three additional lines carrying FSHD from Sydney IVF. The normal function of the gene responsible for FSHD, DUX4, is still unclear, but is probably related to early embryogenesis. This could explain why DUX4 has been found to be expressed in hESC (Snider et al, 2009). DUX4 expression was suppressed by differentiation of control iPS cells to embryoid bodies but this was not the case for FSHD iPS cells (Snider et al, 2009). It can thus be anticipated that in FSHD hESC, DUX4 persists to be expressed after the hESC have been differentiated. A comparison of the transcriptome of hESC with and without FSHD, and before and after differentiation would reveal key genes that are up- or down regulated by DUX4 expression.
In 2008, we showed that hESC are often subject to culture-induced chromosomal abnormalities, eg a dup(20)(q11.21) and an 18q deletion (Spits et al., 2008). As part of this project, we have analysed the transcriptome of 5 different cell lines with and without chromosome abnormality. These valuable data can serve as a control for the experiments we propose.
In order to highlight the gene expression disturbances expected from delayed DUX4 repression in FSHD hESC, we would like to compare the transcriptome of the FSHD-carrying hESC to healthy hESC as well as to cell lines carrying DM1 as additional specific control.