Clinicians at Massachusetts General Hospital are developing treatments for Parkinson's disease and other disorders by using the patient's own stem cells to create replacement neurons.

For the past three years, neurosurgeon Jeffrey S. Schweitzer, MD, PhD, and his colleagues have been conducting a pilot study to develop a cell-based therapy for the disease. In 2019, the team hopes to gain approval from the Food and Drug Administration (FDA) for a formal clinical trial, a research study that evaluates new treatments and determines whether they're safe and effective for humans.

 

What Is Parkinson's Disease?

Parkinson's disease is a disorder that affects the part of the brain that controls movement and muscle control. The neurons in this part of the brain, which produce dopamine, progressively degenerate and cause problems with motor coordination. Some treatments for Parkinson's increase the amount of dopamine in the brain and may reduce some of the symptoms. Symptoms include:

  • Tremors
  • Rigidity
  • Slow movement
  • Problems with balance and coordination

The symptoms of Parkinson's generally develop slowly over several years. The progression and severity can differ from one person to another. According to the Parkinson's Foundation, approximately 60,000 Americans are diagnosed with the disease each year, and there are more than 10 million people living with the disease worldwide. There is currently no cure for Parkinson's, but it can be treated.

 

How Can Stem Cells Help?

Stem cells can develop into many different cell types, which allows them to repair and replace damaged cells. Every time a stem cell divides, the new cells either remain stem cells or become specialized cells, according to the National Institutes of Health. This includes muscle, brain or red blood cells.

Currently, no government in the world has approved a cell-based therapy for Parkinson's treatment due to previous concerns about the ethics of using stem cells because they were commonly sourced from embryos. However, the treatment Dr. Schweitzer and his team are proposing uses adult stem cells that can develop into specialized cells. These cells come directly from the patient.

"We take a skin biopsy, and four specific chemical signals can be put into cells from that sample to turn them back into undifferentiated stem cells," Dr. Schweitzer explains. An undifferentiated cell is one that hasn't developed into a specialized cell type.

"Once you've got a cell back to its embryological condition," he says, "you can give it step-by-step instructions that fool the cell into thinking it's in a particular site or part of an embryo." An embryonic stem cell has the potential to become almost any cell type that makes up the body.

The goal is to persuade the embryonic cell to become more specialized as a certain type of cell. As a treatment for Parkinson's, the cell would be persuaded to become a dopamine neuron.

Dr. Schweitzer partnered with Mass General Neurologist Dr. Todd M. Herrington, and Dr. Kwang-Soo Kim's research team at McLean Hospital, to develop a safe method of maturing the stem cells to the type of cells that are lost in Parkinson's disease.

"The hope has always been that rather than offer symptomatic treatment, such as deep-brain stimulation, we could develop a cure," Schweitzer says. "There are many labs around the world that are working on this, and there have been very encouraging results."

If the cell-based therapy is successful in curing Parkinson's disease, it may be applied to other disorders such as Alzheimer's disease. Dr. Schweitzer explained that Mass General is right on the cutting edge with these developments. He says that in the next one to two years, we can expect to see a number of centers offering clinical trials.