Suzuki M et al. (2007) GDNF secreting human neural progenitor cells protect dying motor neurons, but not their projection to muscle, in a rat model of familial ALS. PLoS ONE 2: e689

Researchers have found a way to protect dying motor neurons in a rat model of familial amyotrophic lateral sclerosis (ALS) by transplanting human neural stem cells producing glial-cell-line-derived neurotrophic factor (GDNF) into the rodent's spinal cord.

ALS is a progressive neurodegenerative disease that leads to the death of motor neurons in the spinal cord and brainstem. GDNF has been shown to protect motor neurons from degeneration in vitro, but delivery of the protein in vivo has proved difficult.

Suzuki and colleagues genetically modified human neural progenitor cells to release GDNF, and transplanted these cells into the spinal cord of the rat model of familial ALS to act as long-term 'mini pumps'.

The researchers were able to show that the transplanted cells were migrating to the regions of motor neuron degeneration and that GDNF was being successfully delivered to these regions. At early stages of ALS, GDNF preserved nearly 100% of the motor neurons, and it preserved over 30% at end stages of the disease. Muscle innervation was not maintained, however, and there were no changes in ipsilateral limb function. Human neural progenitor cells that were not secreting GDNF had no effect on the survival of degenerating motor neurons.

The authors conclude that their findings point towards the possibility of new stem-cell treatment strategies for ALS, although further studies are needed to investigate loss of muscle innervation in this setting.