U.S. researchers have created the first human model in order to study a severe nerve disease. By using skin cells from a child suffering from spinal muscular atrophy (SMA) scientists can observe the disease develop, and possibly find a treatment for it.

SMA is a genetic disease which attacks motor neurons in the spine, and is caused by lack of a protein called survival motor neuron (SMN), without which motor neurons will die.

Researchers at the University of Wisconsin-Madison and the University of Missouri-Columbia grew batches of nerve cells with the genetic defects that cause SMA by turning the sample cells into stem cells by using a recently discovered cell called induced pluripotent stem cells (iPS), which act like embryonic stem cells, and inducing those to become motor neurons.

The same process was repeated for cells from the ailed child’s healthy mother. The child’s reproduced motor neurons started dying after two months while the mother’s developed normally. Clive Svendsen of the University of Wisconsin-Madison said the team encountered a split caused by the lack of the SMN protein. He added that the protein is important to motor neuron survival, as they are in essence the command cells that tell the muscles to move.

Svendsen told the journal Nature that iPS cells can grow for years in the lab and the experiment can be repeated with different batches of cells so researchers can replay the process. "Now you can replay the human disease over and over in the dish," he said, "and ask what are the very early steps that began the process."

Svendsen said that the find would help drug makers test potential treatments that prevent nerve death in SMA. His laboratory is one of many that have started using iPS cells as tools in studying diseases.