Stroke patients enrolled into a very small pilot study designed to investigate the safety and feasibility of a stem cell therapy are all showing promising signs of recovery six months after the treatment was administered. While further studies are warranted, the results are encouraging because the cells were well tolerated by all participants and no adverse effects were detected.
For the study, which has been published in Stem Cells and Translational Medicine, five patients with acute ischemic (where a blockage prevents blood flow to the brain) stroke were given the experimental treatment within 7 days of stroke onset. The stem cells used, called CD34+ hematopoietic cells, were extracted from the patients’ bone marrow and then infused via a catheter into an artery that supplies blood to the brain.
These stem cells give rise to both blood cells and cells that line blood vessels. While they had never before been trialed in humans, animal studies had shown that they can significantly improve recovery after stroke. It is thought that they aid the repair process by releasing molecules that both dampen inflammatory responses and stimulate the growth of new brain cells and blood vessels in the affected region.
The patients were followed up for 6 months after the trial and were assessed using clinical functional scores and brain scans. None of the patients presented any treatment-related adverse effects and all of the patients showed clinical improvements. Furthermore, the brain lesions were found to reduce in volume in all patients.
Four of the patients also had the most serious type of stroke; only 4% of patients that suffer this kind of stroke are expected to survive after 6 months. Remarkably, 3 of these patients were independent after 6 months.
While these results are certainly encouraging as they demonstrate that the therapy is well-tolerated and safe, since a control group was not included the researchers cannot be certain that it was the therapy that triggered recovery. It is therefore possible that the patients would have improved over time without intervention which is why larger, controlled trials are warranted. Furthermore, future studies are also required to determine the best dosage and timing.
According to lead author Dr Paul Bentley of Imperial College London, the researchers are now investigating new brain imaging techniques that will allow them to monitor the fate of the cells after they have been administered.
The team’s ultimate goal is to develop a drug based on the molecules secreted by these stem cells, says lead researcher Professor Nagy Habib. This could be kept in hospitals ready for quick administration after stroke victims are admitted, reducing the time to therapy which should hopefully result in a better prognosis.
[Header image "Neurons, confocal fluorescence microscopy," by Zeiss Microscopy, via Flickr, used in accordance with CC BY-NC-ND 2.0]