Stem cell breakthrough could speed up blood system recovery in cancer patients

The discovery of a new class of stem cells could reduce the time it takes to rebuild cancer patients’ depleted blood systems following chemotherapy and radiation treatment.

Stem cells are powerful, highly versatile cells found within most organs that can develop into every type of tissue within that organ. In the case of the blood system, all of the immune cells, platelet-producing cells, red blood cells and other infection-fighting white cells are generated from blood stem cells.

In the weeks following high dose chemotherapy or radiation treatment, cancer patients are highly vulnerable to infections because the treatment can destroy their healthy blood cells as well as cancerous ones. Doctors currently administer stem cells to cancer patients whose blood system has been damaged in this manner. It sometimes takes 2 to 4 weeks before these stem cells generate enough new infection-fighting blood cells – a long time for patients to be without protection from infection.

When a team led by Canadian Cancer Society researcher Dr John Dick tried injecting human stem cells directly into the bone marrow of mice, they found that new blood cells were generated much more rapidly than with the conventional intravenous method. The new strategy resulted in the blood system getting back to normal an average of 1 to 2 weeks sooner. The research team published their results in the journal Nature Medicine in July 2003.

The researchers believe this speedy production of new blood cells is the result of a previously unknown type of stem cell acting on the bone marrow. This finding builds on Dr Dick’s pioneering method of investigating human stem cells by transplanting them into immune-deficient mice. Dr Dick has received more than $2 million in funding for cancer research from the Society over the last 15 years.

“Injecting the stem cells directly into the bone marrow instead of using the traditional intravenous method was the ingenious strategy that led to identifying the stem cells responsible for rapid growth,” says Dr Michael Wosnick, Vice-President, Research, Canadian Cancer Society and Scientific Director of the Canadian Cancer Society Research Institute..

“This discovery is very promising news for the thousands of cancer patients whose blood systems have been damaged or weakened by their treatment,” he adds.

The researchers’ next steps will be to find a way to isolate this new class of stem cell and refine the delivery method for use in humans, since implanting stem cells directly into bone is a more complex and difficult procedure than the intravenous method. Yet Dr Dick is hopeful that this research advance will improve clinical care in the future.

“We believe this discovery provides the foundation to explore improved stem cell treatments in humans,” he says. “While a great deal has been learned in the last 40 years about why stem cell transplants work, there has been limited improvement in how they are carried out.”

Dr Dick is a senior scientist with Toronto’s University Health Network and a professor in the University of Toronto’s Department of Molecular and Medical Genetics.

Last modified on: 09 December 2009