A stroke kills brain cells by interrupting blood flow. The most common ‘ischemic stroke’ is due to blockage in blood flow from a clot or narrowing in an artery. Brain cells deprived of oxygen can die within minutes. The loss of physical and mental functions after stroke is often permanent and includes loss of movement, or motor, control. Stroke is the number one cause of disability, the second leading cause of dementia, and the third leading cause of death in adults. Lack of movement or motor control leads to job loss and withdrawal from pre-stroke community interactions in most patients and institutionalization in up to one-third of stroke victims. The most effective treatment for stroke, thrombolytics or ‘clot-busters’, can be administered only within 4.5 hours of the onset of stroke. This narrow time window severely limits the number of stroke victims that may benefit from this treatment. This proposal develops a new therapy for stroke based on embryonic stem cells. Because our (and others’) laboratory research has shown that stem cells can augment the brain’s natural repair processes after stroke, these cells widen the stroke treatment opportunity by targeting the restorative or recovery phase (weeks or months after stroke instead of several hours).
Embryonic stem cells can grow in a culture dish, but have the ability to produce any tissue in the body. We have developed a technique that allows us to restrict the potential of embryonic stem cells to producing cell types that are found in the brain, making them ‘neural stem cells’. These are more appropriate for treating stroke and may have lower potential for forming tumors. When these neural stem cells are transplanted into the brains of mice or rats one week after a stroke, the animals are able to regain strength in their limbs. Based on these findings this grant is supporting conduct of IND-enabling work to initiate a clinical development program for stroke in humans by the end of this grant period.
A multidisciplinary team is working to test the effectiveness of stem cell delivery in several models of stroke, while enabling precise manufacture, testing and regulatory clearance of a first in human clinical trial. Defined milestones are being achieved, providing measurable assessment of progress toward therapy development. Definitive manufacturing and pharmacology studies are underway and regulatory filings are in progress. The team consists of stroke physicians/scientists, pharmacologists, toxicologists, experts in FDA regulatory and key collaborations with a biotechnology manufacturer active in this area. This California-based team has a track record of close interactions and brings prior stroke clinical trial and basic science experience to the proposed translation of a stem cell therapy for stroke.