Frontier: Stem cells protect neurons in ALS


by Elizabeth Norton Lasley

September, 2007

The immature but versatile precursors to human cells known as stem cells are widely hailed for their ability to develop into many kinds of tissue. But they can do more than just take over for dying cells: Researchers have now used stem cells to deliver a powerful protective substance to injured motor neurons in an animal model of amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease).

Clive Svendsen of the University of Wisconsin, Madison, and colleagues engineered a line of embryonic stem cells to secrete a compound called glial cell line-derived neurotrophic factor (GDNF), which nourishes and protects neurons. Previous studies had pointed to GDNF’s usefulness in treating ALS, but getting it to the injured cells was a hurdle—among other things, GDNF does not get through the defense of cells and tissue known as the blood-brain barrier.

As they reported July 31 in PloS ONE, the online journal of the Public Library of Sciences, the investigators implanted GDNF-secreting stem cells directly into the spinal cords of rats with ALS. The transplants took hold and, in rats with early-stage disease, protected virtually all injured neurons.

More striking, the engineered cells showed a high affinity for damaged neurons. “They moved straight to the injured areas and acted as mini-pumps producing GDNF,” Svendsen says.

The treatment did not restore communication between motor neurons and muscles or improve the rats’ ability to use their limbs. But Svendsen comments that, in a deadly disease with no effective treatment, keeping the neurons alive is an important first step.