About Parkinson’s Disease

Are there stem cell therapies available for Parkinson’s?

To our knowledge, no stem cell therapy has received Health Canada or U.S. Food and Drug Administration approval for Parkinson’s treatment at this time. Patients who are researching their options may come across companies with Web sites or materials that say otherwise and offer fee-based stem cell treatments for curing this disease. Many of these claims are not supported by sound scientific evidence and patients considering these therapies are encouraged to review some of the links below before making crucial decisions about their treatment plan.

For more about stem cell clinical trials for Parkinson’s click here. (For printed version: http://goo.gl/FY4gG)

For our profile of Dr. Ivar Mendez and his work in Parkinson’s click here.

How close are we? What do we know about Parkinson’s?

  • Parkinson’s is a chronic, degenerative disease of the central nervous system in which dopamine-producing neurons in the brain are lost. Dopamine is a neurotransmitter. It conveys messages to neurons that control our movements.
  • The exact cause of Parkinson’s remains a mystery. Currently there is no cure.
  • Only 10-15% of cases are familial and linked to multiple genes that can be inherited among family members.
  • The telltale signs of Parkinson’s are tremors in the hands, feet or face, rigidity, slowness and difficulty in movement, and increasing problems with balance, gait and posture.
  • There are a number of non-motor symptoms including changes in cognition, hallucinations, and changes in ability to taste and smell.
  • Treatments focus on drugs that can replace dopamine, stimulate dopamine receptors, block dopamine breakdown, or try to prevent the death of neurons. Deep brain stimulation may also be used to control symptoms.
  • There are still no therapies that can slow the progression of Parkinson’s.

How can stem cells play a part?

Parkinson’s is a good candidate for a stem cell therapy because the disease is caused by the loss of one kind of cell – the dopamine neuron. Stem cells have regenerative capacity and can grow into different types of cells and can also make many different support factors. Researchers are looking at two main ways of using stem cells for treating Parkinson’s: as factories to churn out dopamine neurons or as a source of growth factors to protect neurons. One strategy is to transplant or mobilize stem cells or the cells they make (progeny) to achieve functional recovery in patients.

Are there lots of groups working on developing a stem cell therapy?

Research teams around the globe are working to develop stem cell therapies for Parkinson’s. Their common goals are to identify which stem cells are best suited for the job, pinpoint which signals will be able to coax them into becoming dopamine neurons, and find ways to ramp up the production of the required cells. One of the key contributions to international research on Parkinson’s is the Halifax Protocol for injecting cells safely into the human brain. Researchers across Canada collaborated to develop this protocol and it is now widely recognized by neurosurgeons as the international standard for safe and effective brain repair using cell implantation. New surgical instruments to implant stem cells safely into the human brain, such as the computerized Halifax Injector System, have also been developed in Canada.

What research is underway?

Before research can be translated into the clinic for patients, it must be rigorously tested and validated. For Parkinson’s, this involves transplanting stem cells or their progeny into animal models to see if dopamine neurons can be restored or protected. Preclinical studies have validated the use of fetal cells and hundreds of patients with Parkinson’s have been transplanted with fetal-derived neurons over the past 20 years. However, fetal tissue is generally not regarded as a suitable source of stem cells for potential therapies. Many researchers are turning to other types of stem cells such as neural stem cells, bone marrow stem cells and induced pluripotent stem cells. Researchers are also refining methods for delivering stem cells into the brain, learning how to track the transplanted cells, and investigating which cues in the brain promote survival, integration and function of the cells. The road to finding a stem cell therapy for Parkinson’s is paved with many challenges that will take time to overcome. Translating knowledge and success from animal models to human trials will require an international multi-disciplinary network of scientists, clinicians and laboratories working together to arrive at safe and effective protocols for transplanting stem cells into the brain. These types of collaborations are happening and researchers are hopeful that they will provide the basis for testing future stem cell-based therapies for patients with Parkinson’s.

Current research using neural stem cells

Scientists think a patient’s own stem cells could be mobilized to repair the damage caused by Parkinson’s. Many transplant studies with rodents have proven that adult neural stem cells can multiply and go to a site in the brain that is stripped of neurons. But they appear to be limited in their potential to make dopamine neurons unless first being genetically reprogrammed. Another direction might be to use neural stem cells as the starting source for growing transplantable dopamine neurons in the laboratory. To do this, scientists are trying to identify the cocktail of growth hormones and signaling molecules that help the cells survive and grow.

Current research using bone marrow stem cells

On the immediate horizon is an intriguing approach that involves harvesting a particular stem cell population found in a patient’s bone marrow and injecting the cells back into the patient to minimize the likelihood of rejection. Studies have shown that these bone marrow stem cells can also be turned into neurons, but their real power likely resides in their ability to produce growth factors that support damaged neurons.

Current research using pluripotent stem cells

In nature, the master stem cell is the embryonic stem cell because it can make an entire human being. Researchers have found a way to turn back the clock on adult cells and reprogram them to act like embryonic stem cells. These cells are called induced pluripotent stem cells or iPS cells and they can be made from skin or other tissue cells. As well as being able to make dopamine neurons, iPS cells can also be used to create patient-specific cells lines for testing existing drugs and developing new ones.

Further reading on Parkinson’s

National Parkinson Foundation (US) (www.parkinson.org) European Parkinson’s Disease Association (www.epda.eu.com) Parkinson’s UK (www.parkinsons.org.uk)
The Michael J Fox Foundation for Parkinson’s Research (www.michaeljfox.org)