Washington: A new class of human stem cells that rapidly grow when implanted in the bone marrow of mice have been discovered.

The findings, by researchers with University Health Network (UHN), are a major advancement in human stem cell research with possible significant clinical implications for designing more effective cancer therapies.

"This is an exciting discovery because for the first time we have found human stem cells that rapidly rebuild a blood system. The potential is that it may allow transplant patients to quickly regain their blood cells, which are critical to their immune system", said lead author of the study Dr John Dick, senior scientist with UHN and a Professor at the University of Toronto.

The researchers identified the new stem cells after injecting a batch of stem cells directly into the bone of mice, instead of the traditional method of intravenous injection into the blood stream.

They observed this new subpopulation of stem cells rapidly repopulate the blood-producing system of the mice, produced high levels of blood cells within the first week or two after transplant, which is one-to two-weeks earlier than the normal rate.

This discovery builds on the Dr Dick's pioneering method of studying human stem cells by transplanting them into immunodeficient mice, which will not reject the human cells. The discovery could have far- reaching implications for cancer and transplant patients whose immune systems are weakened by their treatment.

These patients are very vulnerable to infections, usually for as long as three weeks after the treatment, until their blood system recovers enough to fight off infections.

ANI