British team develops radical stem cell therapy to mend hearts and repair bones

A ground-breaking medical treatment that could dramatically enhance the body's ability to repair itself has been developed by a team of British researchers.

The therapy, which makes the body release a flood of stem cells into the bloodstream, is designed to heal serious tissue damage caused by heart attacks and even to repair broken bones. It is expected to enter animal trials this year and if successful will mark a big step towards the goal of using patients' own stem cells to regenerate damaged and diseased organs.

When the body is injured, bone marrow releases stem cells that home in on the damaged area. When they arrive, they start to grow into new tissues, such as heart cells, blood vessels, bone and cartilage. Scientists already know how to make bone marrow release a type of stem cell that can only make fresh blood cells. The technique is used to collect cells from bone marrow donors to treat people with the blood cancer leukaemia.

Now a team led by Sara Rankin at Imperial College London has discovered a way to stimulate bone marrow to release two other types of stem cell, which between them can repair bone, blood vessels and cartilage. Giving mice a drug called Mozobil and a naturally occurring growth factor called VEGF boosted stem cell counts in their bloodstream more than a hundredfold.

"This has huge and broad implications. It's an untapped process," said Rankin, whose study appears in the US journal Cell Stem Cell. "Suppose a person comes into hospital having had a heart attack. You give them these drugs and stem cells are quickly released into the blood. We know they will naturally home-in on areas of damage, so if you've got a broken bone, or you've had a heart attack, the stem cells will go there. In response to a heart attack, you'd accelerate the repair process."

Rankin likens the body's natural repair mechanism to a village with a single fire engine. When a fire breaks out the engine goes there and starts to hose it down. "What we're doing is sending signals to the fire station to release a hundred more fire engines, so the impact is much greater."

She added: "The body repairs itself all the time. We know that the skin heals over when we cut ourselves and, similarly, inside the body there are stem cells patrolling around and carrying out [a] repair where it's needed. However, when the damage is severe, there's a limit to what the body can do.

"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."

The group hopes to begin trials this year to investigate how effective the therapy is at repairing tissue damage in rodents. "All the evidence suggests these cells will make a significant difference to the natural repair process," Rankin said.

The therapy might also prove useful in treating patients with immune disorders, such as rheumatoid arthritis. One of the stem cell types released from bone marrow dampens down the immune system, and so could help to keep so-called autoimmune diseases under control.

A possible danger with some stem cell therapies in the pipeline is their use of embryonic stem cells. Because these can turn into any type of tissue there is a risk they could grow into cancer cells . The treatment uses stem cells that can only grow into blood vessels, bone and cartilage, so the cancer risk is removed.

Paul Fairchild, director of the Oxford Stem Cell Institute at the James Martin 21st Century School, University of Oxford, said: "This study brings closer to reality the prospect of tapping into the body's own resources of stem cells in order to repair diseased or injured tissues. Nevertheless, many questions remain to be answered, such as whether a procedure that releases stem cells from the bone marrow by interfering with their retention and migration will spare their ability to migrate to the very sites of injury or trauma where they are most needed."

Peter Weissberg, medical director at the British Heart Foundation, which jointly funded the research, added: "It has long been known that the bone marrow contains cells that can replace lost or aged blood cells. It now seems increasingly likely that the bone marrow also contains cells that have the capacity to repair damaged internal organs, such as the heart and blood vessels, but that too few of them are released to be effective.

"This research has identified some important molecular pathways involved in mobilising these cells. It may be possible to develop a drug that interacts with these pathways to encourage the right number and type of stem cells to enter the circulation and repair damage to the heart."

Boosting body's natural repair kit

Stem cells are a mainstay of the body's natural repair kit. When we damage ourselves, stem cells already circulating in the bloodstream rush to the affected area and start the healing process by growing into healthy new tissue.

The stem cells made in bone marrow are unique because they can form different types of tissue, such as bone or cartilage, depending on the repair job required.

Bone marrow contains three types of stem cell. One type can make blood cells, and is used to treat leukaemia, another can form bone and cartilage, while the third can make blood vessels.

The new therapy works by tricking bone marrow to release a surge of stem cells all at once. In the next two years, scientists behind the study hope to begin trials in mice to see how effective the therapy is at repairing bone fractures and damaged heart tissues caused by heart attacks. Only then will they know how well it can repair serious injuries and how quickly. If the trials are a success, they will be repeated in larger animals.

Along the way, scientists will work out the best drug doses to use and be on the lookout for side effects. The drugs used are already approved for use in patients, but trials in animals are still necessary and may take more than five years to complete.

You’ve read it. Now review it.

Back to top

Back to top