Huntington’s Disease (HD) is an inherited, fatal degenerative brain disease that affects movement, cognition, and behavior. HD results from a mutation in one gene—the Huntington gene—which produces a toxic protein that ultimately kills nerve cells.
Early symptoms of HD are often quite subtle mental and emotional changes, proceeding to issues with coordination and movement. A hallmark symptom of Huntington’s disease is chorea: uncontrollable and often painful involuntary movements. The cognitive and psychiatric symptoms of HD become increasingly debilitating over time. Symptoms of the disease can worsen between generations of individuals with HD, leading to earlier onset and increased severity.
Existing drugs can reduce the involuntary movements and some psychiatric symptoms, but do nothing to slow the inexorable progression of the disease.
Progress Towards A Cure
California’s stem cell agency, the California Institute for Regenerative Medicine (CIRM) has awarded more than $27 million in funding to researchers studying Huntington’s disease.
No existing drugs can slow the inexorable progression of the disease.
At the University of California, Irvine, Dr. Leslie Thompson is leading a network of teams throughout California and across the country to identify and test stem cell treatments for Huntington’s disease. Thompson’s group is testing the effectiveness of a modified neural stem cell line that could ameliorate symptoms of HD. These neural stem cells are derived from human embryonic stem cells and the researchers are conducting essential preclinical trials in mice with HD.
Their goal is to finalize work that will lead to a pre-Investigational New Drug (IND) meeting with the Food & Drug Administration (FDA) and a path forward for clinical trials with the neural stem cells.
Another CIRM funded research team, headed by Dr. Vicki Wheelock and Dr. Jan Nolta at UC Davis, hopes to treat Huntington’s Disease by implanting stem cells that deliver a growth factor—called Brain Derived Neurotrophic Factor, or BDNF—into the brain. Scientists are able to engineer mesenchymal stem cells (normally, a type of connective or support cell) to secrete BDNF. While this special type of mesenchymal stem cell will not repopulate the brain cells that are destroyed in HD, BDNF offers important support to the affected brain region.
In mouse models, this has been shown to stimulate development and growth of new brain cells and reduce some of the HD-associated behavioral deficits. The hope is that the results of these animal model studies will translate to human patients and these modified stem cells can be used as “delivery vehicles” to offset HD-caused brain degeneration.