In this year we have made more induced pluripotent stem (iPSC) cell lines from Spinal Muscular Atrophy patients also using blood cells in addition to skin cells. Blood cells from patients are usually more readi;y accessible. As such, this technique can be used to make larger bank of similar cell lines. We have also rigorously tested all the iPSCs them for their quality. These lines are now available for distribution to other California researchers along with a certificate of analysis.
Motor neurons are a type of neuron that control muscle movement and are markedly destroyed in SMA patients. In order for these powerful iPS cells form patients to be useful for discovering new drugs for SMA it is very important that we can make motor neurons from iPSCs in large quantities of millions to billions in number. Only then will testing of thousands to millions of new drugs would be feasible in neurons from SMA patients. To this end, we have created a method for making a predecessor cell type to human motor neurons from human iPSCs in a petri dish. These predecessor cells, known as motor neuron precursor spheres (iMNPS), are grown as clumps of floating spherical balls, each containing thousands such cells that are grown in large numbers repeatedly for long periods of time. We have made these iMNPS now from many SMA patients as well as healthy humans. These spheres can be preserved for long period of time by freezing them at very low temperatures. They are then awoken at a later time making it convenient for testing large numbers of drugs.
Since iPSCs have the power to make any cell type in the human body, they can also be contaminated with other unwanted types of cells. Typically such a technique is very difficult to accomplish in pluripotent stem cells such as embryonic and iPSCs. Therefore, we have designed a more efficient scheme to generate iPSC lines from SMA patients that will become fluorescent color (green, red or blue) when then motor neurons are made from iPSCs. These types of cells are known as reporter cell lines. This will aid in picking out the desired cell type from patient iPSCs, in this case a motor neuron, and discard any unwanted cell types. This will enormously simplify testing of new drugs in SMA patient motor neurons.
Deficiency of an important protein in SMA patients is one of the key causes to the course of the disease. We have also designed an automated method for identifying new drugs in patient motor neurons that will test for correction of SMN protein levels in motor neurons.