Stem cell therapy is the hot new solution for seemingly every physical problem, whether it's back pain, creaky knees, or blindness. But while everyone seems to be trying it, there's actually not much reliable research to back the efficacy, or even safety, of practicing many forms of the therapy. This wouldn't be an issue if an estimated 100,000 US patients weren't paying several hundred dollars per person for an under-researched method. To take one example: People are getting stem cell therapy on their arthritic knees, without any data to support such a thing. According to a study led by the Mayo Clinic's Shane Shapiro, an orthopedic and sports medicine physician, the recent use of bone marrow stem cells in painful, arthritic joints has dramatically increased, while exactly how well the treatment works—or how safe it is—has yet to be made clear. "So many of these therapies are going on without the science to back it up," he says. "We weren't comfortable offering this treatment to patients until we or someone else had studied it in a rigorous fashion."
So Shapiro set out to study the practice. He and his team found that it's safe, thankfully. They also turned up some curious results.
Each of the 25 patients involved in the study had two bad knees; in one knee, they received an injection of bone marrow stem cells. In the other, they received a saline (placebo) injection. The patients didn't know which knee received which injection.
The exciting but odd result was that after six months, both knees felt significantly better for most patients: 6 months after treatment, the average pain score was 1 out of 10 for both stem cell and saline-treated knees.
So, while that's pretty awesome news, the question remains: Why did both knees feel better when only one knee got the stem cells?
"There are scientific studies that show stem cells travel," Shapiro says. "It's certainly possible that we put the cells in one injured knee and they traveled to the other injured knee." It's also possible, he adds, that injecting anything inside the knee—the placebo saline solution included—has some sort of medicinal effect.
So what now? This kind of stem cell therapy to treat osteoarthritic pain has been deemed safe based on Shapiro's FDA-approved, well-designed clinical study. But we don't know how well it works compared to saline, or whether it works at all. It's possible, after all, that it was the placebo effect at play.
A stem cell has the unique ability to develop into all different sorts of cells. When a cluster of stem cells is injected into a diseased or damaged area like, in this case, an arthritic knee, it has the potential to naturally reproduce the needed healthy tissue. In theory, an excellent solution. But we'll need more research before many doctors are willing to recommend it. "The trial that we conducted is maybe the first piece in that puzzle," Shapiro says. "It's by no means a definitive tool; we're not routinely recommending patients get stem cell therapy, but we do present it to them as a reasonable alternative."