Stanford medical trial found stem cells injected into the brain aid stroke recovery

The results of the trial could represent a treatment breakthrough for the seven million chronic stroke sufferers in the United States

Published today in Stroke, the 18 patients involved in the study were previously thought to be irreversibly damaged, however demonstrated significant recovery after being administered the stem cells. The study’s lead, Gary Steinberg, told us the next steps researchers are taking to bring this treatment into mainstream therapy.

RG: Can you tell me the main findings from the trial, including the main improvements patients experienced after being injected with stem cells?

Gary Steinberg: The trial was a small study that was designed primarily as a safety and feasibility study to see if transplanting these cells into the brain around a stroke was a safe technique. However, we also had efficacy as a primary end point. The first finding was that the technique is safe and easy to do, it is feasible, and there are no serious adverse effects that would be prohibitive – the cells were well-tolerated.

The surprising finding was that patients who had chronic stroke, meaning they were six months to three years out from their stroke, recovered after the cell transplant. Normally, patients recover from their stroke in six months, and after six months there is little improvement. However, in our study the patients as a group improved within one month of the cells being administered and continued to improve at three months. This improvement was sustained at 12 months and it appears the improvement is even being sustained up to two years in the patients we are continuing to follow. This was a big surprise. We thought that after you have a stroke, you make some initial recovery, but after that the circuits are dead – or irreversibly damaged. What is remarkable about this study is that we learned that these circuits are not dead, so they could be resurrected. This changes our whole notion of what happens after a stroke and what happens after any kind of injury to the brain and spinal cord.

Not only did these people recover statistically on many different stroke scales, but their recovery was meaningful. Patients who couldn’t walk were walking, patients who couldn’t use their arm could use their arm. Some people who had problems communicating were talking. These are clinically meaningful recovery signs.

RG: How do the stem cells actually work in the brains of stroke sufferers?

Steinberg: The initial notion was that cells turn into neurons and reconstitute circuits. But that is definitely not what happened, especially using these cells – the cells were bone marrow derived cells, which cannot turn into neurons. They pump out very powerful growth factors and angiogenesis factors, as well as other molecules, and proteins that promote native recovery, called plasticity. In a simplistic sense, they turn the adult brain into an infant or neonatal brain that recovers very well from a stroke.

RG: What are the risks of this surgery?

Steinberg: We only had a few serious adverse effects, and that is defined as people who had to be admitted to hospital afterwards. But none had long-term adverse effects, and none of the adverse effects were related to the cells. The more common and less serious effects were things like transient headaches related to the procedure, and three quarters of the patients had headaches, but these resolved quickly. If you look at the benefits of improving your neurologic function compared with these minor effects, you’d have to agree it still weighs in favor of the procedure. These people were very disabled prior to the transplant.

RG: Do you believe the sample size involved in the study is large enough to be representative?

Steinberg: We don’t want to oversell this – it was a small study. We hope it will be generalized, and we just initiated another study of 156 patients with the same inclusion criteria as the study we just completed. In order to move this into a mainstream therapy we will need to do an even larger Phase 3 study – that’s a requirement of the FDA.

RG: What are the next steps in this research?

Steinberg: We are very excited about the results and we believe they provide real hope for the future, but we have a lot of work to do and will be running further studies using control patients. We also need to pinpoint the precise mechanism of how the cells recover function.

Image courtesy of UCL News.