The real, but oft-ignored risks of adult stem cell treatments

What’s the real story on adult stem cells? Do they really have little to no risk?

As a self-proclaimed fan of stem cells, including adult stem cells, I often find myself writing and talking about them to a large, diverse audience.

I’ve become a stem cell ambassador of sorts.

However, I am also a realist and a scientist who has studied cancer cells as well as the molecular basis of tumorigenesis for about half of my life. As such, I find myself increasingly fighting a strong current of misinformation, heck I’d even call it propaganda, when it comes to one particular area: adult stem cells.

Who are the folks proselytizing the misleading gospel about adult stem cells? Mostly, these people are the ones who are trying to make money from adult stem cells. They also tend to hate the FDA and diss’ embryonic stem (ES) cells. Somehow they think that any “bad news” for ES cells is automatically good news for adult stem cells and for their own bank accounts.

In stark contrast, most of the internationally recognized adult stem cell researchers, who regularly publish and are rightly excited about the field, do not want to have anything to do with the circus of adult stem cell clinics pushing non-FDA approved treatments. They are doing great science and advancing toward future regenerative medicine therapies. They recognize the value of studying stem cells of a variety of types too.

What’s the scoop on adult stem cells without any phony baloney?

Adult stem cells have great potential for a number of human diseases, but some folks are portraying adult stem cells in ways that reflect either (A) a dangerous lack of sophistication on their parts or (B) an intentional effort to mislead.

One of the most troubling myths often presented as concrete truth is the following: adult stem cells do not cause tumors.

The danger in this kind of absolute statement is that it lulls people, including potential patients, into a false sense of safety.

The reality is that, yes, adult stem cells are much safer relatively speaking than say undifferentiated ES cells, but this is a complex reality that does not reflect the simplistic black and white situation that some adult stem cell boosters would have you believe. These adult stem cell propagandists, who have inherent conflicts of interest due to their hope of garnering 10s of thousands of dollars from potential patients, make blanket statements such as “embryonic stem cells cause cancer” or “adult stem cells are safe”.

The complex, unfortunate reality is that any cell when given as a transplant has a potential risk to form a tumor and an additional risk to cause other side effects. Period. The risk is not zero.

Several factors influence the relative risk of any transplant to cause a tumor or other side effects. An admittedly clunky, but largely accurate reality is that these risks roughly go up proportionately in parallel as the number of stem cells transplanted increases. Conversely, the less differentiated nature possessed by the stem cells, the higher their relative risk when transplanted. Thus, mesenchymal stem cells (MSCs), with their limited multipotency are indeed relatively much safer than undifferentiated ES cells or induced pluripotent stem cells with their pluripotency.

But MSCs and adult stem cells more generally are not by definition inherently safe. That is absolutely false. In addition, most people imagine transplanting differentiated progeny of ES cells, which have low tumorigenic potential.

Tumors are not the only risks from transplants, even autologous adult stem cell transplants. Other risks include infection or catastrophic autoimmune response, which both can and have been fatal in real patients. Adult stem cell fans most often like to ignore these realities.

This failure to educate patients makes many of us in the stem cell field concerned that patients at dubious stem cell clinics are not giving true informed consent for the procedures that are being done to them because they are presented with false estimations of risk and reward.

It is ironic that one of the most common assertions made against ES cells (and those of us who study them too) is that the potential of ES cells has been hyped, when in reality today it is adult stem cells that are to a far greater extent being hyped as cures for everything ranging from aging to cancer to baldness.

Let’s keep it real as we pursue stem cell-based therapies regardless of the type of stem cell involved.

Our primary goal should be helping people and protecting patients. When the primary goal is instead to make money, as is the case for so many adult stem cell proponents and clinics out there today, there is significant danger as the priorities and safety of patients automatically take a back seat to turning a profit.

Greed can often become the driver in that “stem cell” car, pressing the accelerator and ignoring the brakes.