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Christine Schill has osteoarthritis in both hips. “Seven years ago I noticed aching in my lower leg when I was sleeping. My doctor sent me for an ultrasound where they noticed some narrowing of space in my hip joint,” says Schill. “About three years ago it really became painful to walk.” An active person, she didn’t want the pain of arthritis to curtail her activities. She started seeing a naturopath who suggested a procedure called PRP (platelet rich plasma), which provided some pain relief for about 6-12 months. But now that the pain is returning, she is considering other options.

“I was hearing that stem cell therapy was a healing procedure. But once I started looking into it, nothing really supported those claims,” she said. “It doesn’t feel like it is a real, verified procedure, so I’ve decided to stay away from it.”

According to Health Canada, Alberta Health Services and McCaig Institute researcher Dr. Roman Krawetz, PhD, that decision is likely the correct one.

WHAT IS A STEM CELL?

Stem cells are rare cell types found in many tissues within the body. Some stem cell types give rise to our immune and blood cells, while the exact function of other stem cells remains obscure. One of the most common stem cell types being examined in clinical trials are mesenchymal stem cells (MSCs), which are found in bone marrow, fat and the tissue that lines the inside of our joints.

Stem cell therapy is a form of treatment where stem cells, typically MSCs, are isolated from the patient or another donor, expanded under strict regulations and then delivered back to the patient. However, most ‘stem cell therapies’ currently offered for a fee in private clinics are actually using techniques which do not isolate stem cells specifically, but instead isolate and re-inject a mixed bag of many cell types back into the patient. Furthermore, it is essential to note that currently in Canada (and the United States), there are no federally (Health Canada and/or FDA) approved stem cell therapies for the treatment of osteoarthritis.

THE HYPE

Private clinics around the world advertise astonishing healing results from stem cell therapy, many promising complete tissue regeneration. But, in fact, these treatments are unproven. “Currently, no evidence has been provided from placebo-controlled clinical trials that stem cell therapy provides any long term benefits to patients with osteoarthritis or cartilage injury,” says Krawetz. “At best, these current types of cell therapies being offered may provide some short term benefits in terms of reducing inflammation and/or pain. At worst, it could be dangerous, leading to increased inflammation or infection, with rare cases of disability and even death being reported.”

According to Krawetz, the often used term of ‘stem cell therapy’ is actually incorrect. “It should be called ‘cell therapy’ because really the current procedure just extracts cells from one part of the body, and after going into a machine that separates the cells from the components of tissues, those cells go back into your body,” he says. “There is no purification or isolation of stem cells, because currently there isn’t a reliable way of identifying the relevant stem cell populations from other cell types that may have little to no effect." That’s where Krawetz’s research comes in.

THE HOPE

Krawetz’s team focuses on characterizing the different types of cells present in a joint. In our bodies, and in specific tissues like joints, there are different types of stem cells, and each appears to have its own type of function. Some regulate inflammation, some regulate tissue homeostasis, and some have unknown functions. Some actually make inflammation worse. “There appears to be a very rare population of stem cells that actually has the ability to become new tissue and may contribute to regeneration. Our lab is trying to reliably identify those stem cells, as we believe they may have capacity to form new cartilage and bone tissue,” says Krawetz. “If we can find a marker to isolate only the stem cells we want, then we can purify them and flush away the rest.” Ultimately they hope to contribute to developing effective patient-derived cell-based therapies to restore cartilage damaged by injury or osteoarthritis.

PLACEBO EFFECT OR SOMETHING MORE?

While there is no definitive evidence that current ‘cell therapy’ procedures repair or regenerate tissue, there are studies that link these types of therapies for osteoarthritis with temporary pain relief. There have been small clinical trials where half the people received cell injections, the other half received injections of saline. Both groups reported the same results – a decrease in pain. “Some would argue that just the word ‘stem cell’ has a lot of power, and just the term might carry a placebo effect. However, it’s hard to actually test that hypothesis.”

There is also some science to suggest that stem cells may play a role as regulators of inflammation. “When somebody gets a stem cell injection, most of what is injected is regular cells, with maybe one to five percent being actual stem cells,” says Krawetz. “There are studies that show those one to five percent might be enough 
to change the inflammatory levels within the tissue.” One thought is that these stem cells coax a body’s own immune system to repair itself, in effect acting as a cellular type of anti-inflammatory. It is a promising area of research, and Krawetz’s lab is now focusing on new ways to harness and direct stem cells’ anti-inflammatory capacities, perhaps leading to the development of new pharmaceuticals for pain relief.

Randomized controlled trials are critical to moving this science forward - something Krawetz and the team at the McCaig Institute are uniquely positioned to do. The institute is currently seeking funding to undertake these projects.

Roman Krawetz is an associate professor in the department of Cell Biology and Anatomy, the Grace Glaum Professor in Arthritis Research and he holds a Canada Research Chair in Bone and Joint Stem Cell Biology.