The Rockville, Maryland–based company Neuralstem has received US Food and Drug Administration (FDA) permission to test its spinal cord stem cells in twelve patients with amyotrophic lateral sclerosis, or Lou Gehrig's disease. The approval comes a month after the FDA placed Geron's planned clinical trial on hold for a second time. Neuralstem's trial had also previously been placed on hold by the FDA in February before it received the go-ahead in September.

Though both trials involve placing cells into the spinal cord, Neuralstem's product is made of cultured neural stem cells derived from a single eight-week-old foetus, whereas Geron's product, intended to treat spinal cord injury, is derived from embryonic stem cells that have been differentiated into precursors of neuron-support cells.

"This is certainly the first stem cell approach for ALS [amyotrophic lateral sclerosis]," says Lucie Bruijn, a scientist at the ALS Association, a patient group that also funds relevant research. Most other approaches for treating ALS are small molecule drugs, she says, and she's not aware of other cell therapy or other invasive approaches entering human testing in the near future.

[Editor's note: Shortly after this piece appeared on the Niche, we learned of additional clinical work in ALS. This uses mesenchymal stem cells derived from the patients who receive them. Read more here.]

The ALS Association has not funded Neuralstem's work directly, Bruijn says, but has advised the company and funded academic scientists who've been involved with the company.

Neuralstem's chief scientific officer Karl Johe says tests of large animal models show that the transplanted cells exert a neuroprotective effect over motor neurons, but it's not entirely clear how. Earlier this year, Neuralstem and collaborators published results in a rat model of ALS showing that transplanted cells could develop into interneurons that formed synapses with rats' motor neurons.

However, Johe emphasizes that the upcoming trial will assess safety rather than efficacy. The first few patients selected for the procedure will be those who are no longer able to walk. Because the injected cells protect rather than replace motor neurons, these sicker patients are less likely to benefit from treatment, but they are also less able to lose function if something goes wrong. Cells will be injected only on one side of the spinal cord in order to minimize the number of injection sites. Only one patient will be treated each month so that researchers can monitor effects over a longer period of time. Eventually, Johe says, the goal is to be able to inject cells in both lower and upper regions of the spinal cord in healthier patients and see if the injections can help motor neurons survive.

The trial is expected to take place at Emory University in Atlanta, Georgia. Though the FDA is allowing the trial to go forward, the university's patient-safety board will also need to approve the trial before it can proceed. Johe declined to say when approval may be received, but he did say discussions with the university were well underway.

Other companies using neural cells include ReNeuron, which received permission from UK authorities this January to start clinical trials for stroke. Its cell product is made from genetically modified cultures of neural stem cells, also of foetal origin.

StemCells Inc. is conducting trials in Batten disease, a neurodegenerative disorder that strikes children, and recently received approval for a clinical trial in a similar disease. It also uses neural stem cells from material originally derived from foetuses and has recently published research showing that its cell product delayed some symptoms of the disease by about three weeks.

As with human embryonic stem cells, the patent situation for neural stem cells is contentious. In a pair of duelling press releases this May, Neuralstem and StemCells both claimed key intellectual property on the cells.

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