Dr Caron, a research scientist at Genea, has developed a novel method of maturing embryonic stem (ES) cells into muscle cells, to provide a tool to advance research in FSHD high throughput drug development. The lack of adequate in vitro systems for high throughput screening (HTS) of drugs to treat FSHD has slowed the development of treatments for people affected by the disease.
The ESC cells used in this project are called ‘pluripotent’, which means they can be matured to form any cell type of the human body, including muscle, the cell type mostly affected by FSHD. They can be indefinitely grown in the laboratory and thus can be used to supply a continuing source of cells for research around the world.
Four ESC cell lines carrying the genetic (DNA) deletions associated with FSHD have been generated at Genea, and more cell lines are currently being isolated and grown for researchers to use. For this research, Dr Caron worked on turning ESC cells into the skeletal muscles that allow us to move and breath. This technically challenging task was performed by screening hundreds of thousands of combinations of compounds and factors. All combinations were analysed for their ability to mature ESC cells into skeletal muscle by testing for the appearance of muscle cell markers.
After repeating this HTS screening several times, Genea Scientists identified cocktails of compounds from which stem cells were efficiently and rapidly matured into functional muscles. This research was a stepwise process : ESC cells were first induced to form muscle precursor cells, followed by maturation to primitive muscle cells (myoblasts), and then to mature muscle cells (myotubes), which can contract like muscles and have mature, muscle specific markers (sarcomeric MHC (MF20) and dystrophin). These conditions were then applied to FSHD affected stem cells to form diseased skeletal muscle cells. FSHD-affected cells were initially compared to control (non-affected) cells for their capacities to produce mature muscle and the appearance of muscle fibre shape or branching.
While researchers couldn’t initially observe any obvious FSHD muscle defects, the expression of the FSHD associated toxic protein DUX4 was detected exclusively in FSHD muscle,confirming the diseased status of the cells. The expression of another FSHD candidate, ANT1, was also significantly higher in FSHD muscles. Further investigation also revealed that FSHD-affected muscles are thinner and shorter than the unaffected muscles and have more dead cells. Matured muscle cells were tested further and a detailed characterization of the diseased cells was performed to determine the nature and the molecular causes of the defects observed. About 700 genes were found to be differently regulated in FSHD mature muscle cells. These genes are currently being identified and further experiments are being performed to confirm the results.
In conclusion, this completely new and extremely powerful HTS testing platform has been used to identify potential new drug targets for treatment of FSHD and has provided an HTS platform for researchers world-wide, to study abnormalities observed in the muscles of FSHD affected people and to rapidly screen, in the laboratory, large numbers of new drugs for this devastating muscle wasting disorder.