Scientists at Imperial College, London, have found a way to boost the body's production of certain types of adult stem cells that are involved in repairing damaged tissues. The technique, described in the journal Cell Stem Cell, may eventually lead to therapies that enhance self-healing of broken bones and regeneration of cardiac tissue after a heart attack.
When the body is injured, adult stem cells produced in the bone marrow are released into the blood stream and migrate to the site of injury where they participate in the repair or replacement of the damaged tissue. In the new study, the research team used a combination of naturally-produced proteins called growth factors and a new drug, Mobozil, to promote the release of different stem cells from the bone marrow of adult mice. Adult stem cells, like embryonic stem cells (ES cells), can divide indefinitely and so provide a continuous source of cells. However, unlike ES cells, they cannot become all cell types but are specialised into sub-categories. Amongst the types of stem cell produced in the bone marrow there are haematopoietic stem cells (HSCs) that can become different types of blood cell; mesenchymal stem cells (MSCs) that can become fat, bone or cartilage cells; and endothelial progenitor cells (EPCs) that can make new blood vessels.
The researchers found that treating the mice with a growth factor called GCSF followed by administration of Mobozil a few days later resulted in a dramatic increase in the number of HSCs released into the blood. This technique is already used to boost HSC numbers during bone marrow transplants for the treatment of leukaemia. However, they also found that if they treated the mice with a different growth factor, VEGF, followed by Mobozil, then there was a 100-fold increase in the number of MSCs and EPCs released into the bloodstream. This could potentially be used to help heal damaged muscles and bones, or after a heart attack to repair the cardiac blood vessels. It may also have an application in the treatment of autoimmune diseases such as rheumatoid arthiritis, as MSCs are known to play a role in suppressing inflammation.
Dr Sara Rankin, who led the study, explained: 'the body repairs itself all the time... However, when the damage is severe, there are limits to what the body can do of its own accord. We hope that by releasing extra stem cells, as we were able to do in mice in our new study, we could potentially call up extra numbers of whichever stem cells the body needs, in order to boost its ability to mend itself and accelerate the repair process.' There is, however, still much research to be done - the next stage is to investigate whether the release of extra stem cells actually translates to better, faster healing.