Getting the go ahead to begin a clinical trial by no means marks an end to a research team’s laboratory studies. A clinical trial is merely one experiment and is designed to answer a specific set of questions about a specific course of treatment. There will inevitably be more questions to pursue back in the lab in parallel with an ongoing clinical trial to potentially enhance the treatment.

That’s the scenario for Cedar-Sinai’s current CIRM-funded clinical trial testing a cell therapy for amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease. Animal studies published this week in Stem Cells suggests that an additional route of therapy delivery may have potential and should also be considered.

Microscopy image showing transplanted neural progenitor cells (green), the protein GDNF (red) and motor neurons (blue) together in brain tissue. Credit: Cedars-Sinai Board of Governors Regenerative Medicine Institute

ALS is an incurable disease that destroys motor neurons responsible for communicating muscle movement between the brain and the rest of the body via the spinal cord. ALS sufferers lose the use of their limbs and eventually the muscles that control breathing. They rarely live more than 3 to 5 years after diagnosis.

The CIRM-funded trial uses neural progenitor cells – which are similar to stem cells but can only specialize into different types of brain cells – that are genetically engineered to release a protein called GDNF that helps protect the motor neurons from destruction. These cells are being transplanted into the spinal cords of the clinical trial participants.

While earlier animal studies showed that the GDNF-producing progenitor cells can protect motor neurons in the spinal cord, the researchers also recognized that motor neurons within the brain are also involved in ALS. So, for the current study, the team tested the effects of implanting the GDNF-producing cells into the brains of rats with symptoms mimicking an inherited form of ALS.

The team first confirmed that the cells survived, specialized into the right type of brain cells and released GDNF into the brain. More importantly, they went on to show that the transplanted cells not only protected the motor neurons in the brain but also delayed the onset of the disease and extended the survival of the ALS rats.

These results suggest that future clinical trials should test transplantation of the cells into the brain in addition to the spinal cord. The team will first need to carry out more animal studies to determine the cell doses that would be most safe and effective. As first author Gretchen Thomsen, PhD, mentions in a press release, the eventual benefit to patients could be enormous:

Gretchen Thomsen

“If we are able in the future to reproduce our research results in humans, we could improve both the quality and length of life for patients diagnosed with this devastating disease.”