Neurologists at Imperial College, London have conducted a small pilot study in stroke patients who received stem cell treatments after their strokes. To date, their patients have shown tentative signs of neurological recovery six months after receiving the stem cell treatment.
According to the physicians attending these patients, all five patients who participated in the study have improved after the therapy. Even though these results are hopeful, larger and better controlled trials are required to confirm if the implanted stem cells are responsible for the improvements in these patients. Brain scans of the patients showed that damage caused by the stroke had reduced over time. However, similar improvements are seen in stroke patients as part of the normal recovery process.
When assessed after their six-month check ups, all of the participating patients fared better on standard measures of disability and impairment that are normally caused by stroke. Once again, it is difficult to determine if these improvements result from the stem cell treatments or from standard hospital care.
This pilot study was designed to assess only the safety of the experimental therapy (phase I clinical trial) and with so few patients and no control group to compare them with, it is impossible to draw conclusions about the effectiveness of the treatment at this time.
Paul Bentley is a consultant neurologist at Imperial College London, and his group is presently applying for funding to run a more powerful randomized, controlled trial on this stem cell therapy, which, Bentley hopes, could include at least 50 patients by next year.
“The improvements we saw in these patients are very encouraging, but it’s too early to draw definitive conclusions about the effectiveness of the therapy,” said Soma Banerjee, a lead author and consultant in stroke medicine at Imperial College Healthcare National Health System (NHS) Trust. “We need to do more tests to work out the best dose and timescale for treatment before starting larger trials.”
All five patients who participated in this study were treated within seven days of suffering a severe stroke. Each patient had a bone marrow sample extracted from their hip bones, and these bone marrow cells were processed in the laboratory to isolated the stem cells that give rise to blood cells and blood vessel lining cells (so-called CD34+ cells). These stem cells were infused into one of the main arteries that supplies blood to the brain.
CD34+ cells do not grow into fresh brain tissue, but they might release pro-healing chemicals that suppress inflammation and recruit and stimulate other cells to grow within the damaged brain tissue. Some of the implanted CD34+ cells might also form new blood vessels, said Bentley.
Four out of five of the patients had the most serious type of stroke, and typically, only 4% of these patients survive and are able to live independently after six months. In the pilot study, published in Stem Cells Translational Medicine, all four were alive and three were independent six months later.
“Although they mention some improvement of some of the patients, this could be just chance, or wishful thinking, or due to the special care these patients may have received simply because they were in a trial,” said Robin Lovell-Badge, head of developmental genetics at the MRC’s National Institute for Medical Research in London.
Caution is certainly required in the interpretation of this pilot study, but I think that these results definitely merit a Phase II trial to determine if the improvements are stem cell-independent or stem cell-dependent.