Health Canada researchers leading the way to safer stem cell treatments

The existence of stem cells in the human body is among the most interesting scientific discoveries of our time. In the earliest beginnings of the fertilized egg, stem cells are capable of developing all the different types of cells, tissues and organs within our bodies. As we develop in the womb, stem cells become specialists, taking on the job of repairing and replenishing the tissues where they reside—some replenish skin or muscle tissue, while others repair heart, liver and even brain tissue, and continue to do so throughout our lifetimes.

These unique properties have made stem cells the object of extensive research to determine their usefulness in medicine. In fact, bone marrow transplants, which have been used for several decades in the treatment of leukemia and some other forms of cancer, are actually stem cell transplants—the stem cells found in bone marrow are responsible for making all the different types of blood cells in our bodies.

Researchers believe the power of stem cells could be harnessed much more in the future by providing a mechanism of treatment for almost any type of ailment, from heart disease and stroke to any of the several immune disorders that affect millions of people each year.

Tapping into the potential of stem cells

While there are many types of specialized stem cells in the human body, one type is especially promising as a potential treatment for multiple diseases. These are mesenchymal stem cells or MSCs.

They are found mostly in our bone marrow and seem to support blood formation but, as Dr. Michael Rosu-Myles of the Biologics and Genetic Therapies Directorate at Health Canada in Ottawa explains, MCSs do a lot more than that. "These particular stem cells do all kinds of repair work in our bodies," says Dr. Rosu-Myles. "On their own, they form fat, cartilage and bone tissue, and they help other specialized stem cells make repairs to other types of tissue—heart muscle, pancreatic islets, blood vessels, skin cells and even nerve cells. They can also alter how our immune system works, potentially preventing unwanted immune reactions such as those responsible for diabetes or organ rejection following transplantation."

Good news and bad news

This versatility has made MSCs among the most-studied of all types of stem cells. An MSC-based treatment has already been approved for use in children who are rejecting a bone marrow transplant, and MSC-based treatments for diseases ranging from diabetes to sepsis are currently being tested in humans.

MSCs do have one very important drawback—like all stem cells, MSCs have the potential to mutate and become cancerous. "MSCs can mutate and cause sarcoma, a fairly rare form of cancer," says Dr. Rosu-Myles. "And, just as they can help other types of stem cells make repairs, if another type of stem cell becomes cancerous, MSCs can help those cancerous stem cells grow more cancer. Obviously, if you're treating someone with MSCs, you don't want to inject them with cells that will increase their risk of cancer."

Reducing the risk

Dr. Rosu-Myles and his research team at Health Canada—with support from collaborators at other labs in Canada and in Spain—have developed a way to tell tumourigenic MSCs—that is, potentially cancerous—from normal versions of the cell.

"By altering the DNA of MSCs, in much the same way that would occur in cancer, we were able to determine the number of steps that take place on the way to the cell becoming cancerous," says Dr. Rosu-Myles. "We then looked at what was happening in the cell at each of those different steps in order to see if there was a genetic means to track the process."

With that information, Dr. Rosu-Myles and the team identified a list of protein and gene changes that indicate a particular MSC cell has a high probability of becoming cancerous—a discovery with significant potential to help ensure the safety of MSC-based treatments in the future. "The next step is to use the genetic technologies we have available to determine which markers will be the most effective for developing a rapid and dependable test platform to screen MSCs about to be used for treatment," says Dr. Rosu-Myles. "Clinicians could eliminate the possibility of administering potentially dangerous stem cells to patients. MSC-based therapies would be much safer."

GRDI support a key factor

The research that led to the identification of tumourigenic markers in mesenchymal stem cells has been a hugely collaborative effort funded for several years by the Government of Canada's Genomics Research and Development Initiative (GRDI). "Without the network of researchers we were able to put together here in Canada and internationally, this would not have happened," says Dr. Rosu-Myles. "And without the funding from the GRDI, we would not have been able to assemble this great team. It's as simple as that."