Creating motor neurones for research is a lengthy and expensive process, so Prof Kevin Eggan from Harvard University Massachusetts, asked whether we can predict at an early stage which stem cell lines will be the most useful in generating the best quantities of motor neurones, saving time, effort and money. He has been developing a ‘scorecard’ which he believes will help work out which cell lines are most useful.
But if you make motor neurones from skin cells, are they really motor neurones? At the moment there is no consensus on what makes a neurone a motor neurone, so Prof Eggan outlined a series of tests used in his lab that “provide confidence that these have more than a passing resemblance to motor neurones”. Additional encouraging results suggest that motor neurones created from ‘adult’ iPS cells are “pretty indistinguishable from those obtained from embryonic stem cells”. There are some differences, so comparative work using both types will need to continue for the forseeable future.
Prof Siddharthan Chandran, MND Association funded researcher at Edinburgh University then posed the question: “Do they reflect the different types of motor neurone found in the human body? There is no such thing as a ‘generic’ motor neurone, each one has its own postcode.”
So, can stem cell-derived motor neurones reflect the diversity of subtypes found in the human body? For example, the motor neurones that control eye movement are much more resistant to the disease than other motor neurone types, and motor neurone controlling limb muscles can behave differently from those controlling the trunk muscles.
The answer is preliminary, but encouraging.
Prof Hynek Wichterle, from the Columbia University New York, presented research showing that embryonic stem cells can be turned into different subtypes of motor neurone and Prof Chandran has been working on the same issue using iPS cells.
There is a lot of work to do, but having human motor neurones in a dish that faithfully reflect the diversity of types found in the body will greatly assist understanding of MND and may also help in identifying potential drugs that might target highly vulnerable motor neurone populations in patients with different clinical patterns of disease.