As someone with a long previous career in stem cell transplantation, I would like to provide some medical perspective on a recent series of “commentary” articles about stem cells in Current in Zionsville.
Broadly speaking, there are 2 types of stem cell transplantation, autologous and allogeneic. The first is a process by which patients receive their own stem cells back, perhaps after some manipulation to enrich or expand them, and the second is the process by which a patient receives someone else’s stem cells, which have been carefully determined to be a compatible “match” for the patient. Both processes have been rigorously studied for decades in what we call hematological malignancies (diseases of the bone marrow and lymphoma most commonly), and are used to “rescue” the patient after very high doses of chemotherapy have been administered to kill the malignant cells.
In the case of the allogeneic transplantation (someone else’s cells), some sort of medicine must also be given to suppress the patient’s immune system, sometimes permanently, otherwise the patient could reject these foreign cells, even if they have been carefully matched. Unfortunately, as readers are probably aware, many times a suitable tissue match cannot be found, and patients die during the search.
The last decade or so has seen some exciting discoveries in which scientists have found that our cells (even those that are committed to form a certain cell lineage like skin, muscle, etc) can be manipulated in the lab to switch back to a stem cell that could then be manipulated to turn back into another type of cell. Of course many challenges await these early studies, including how to grow up enough of these to replace millions of damaged cells, and how do we make sure they get to where we want them to go, and in the case of foreign cells, how do we prevent their being rejected by the body, or form a tumor in the recipient’s body?
With the explosion of online “information,” one is wise to keep one philosophical maxim in mind: extraordinary claims require extraordinary evidence.
So, before believing that stem cells have seemingly magical properties to cure a plethora of diseases, we must demand that very careful, controlled studies have been performed to prove this and that appropriate safety studies have been published.
For example, if stem cells can really replace portions of diseased organs, then let’s see the results of biopsies showing these brand new cells have taken up shop and have turned into the right cell. And while foreign stem cells, including umbilical stem cells, might not fully attract the attention of our immune system initially, once they “grow up” into a lung, cartilage, or other cell, the immune system will be very “interested” in rejecting them (a very important evolutionary process to ward off invaders); how do we prevent this?
And, keep in mind that anything infused into a vein in our body heads to the lungs, which is comprised of miles of tiny blood vessels (capillaries, just wide enough for a single blood cell to pass). We had better hope stem cells don’t exit, invade, and multiply there, because our lungs are pretty useful for breathing.
The science of stem cells is advancing at a rapid pace and holds exciting promise in the coming decades for advances at the bedside. Hopefully, this perspective will assist readers in assessing the scientific validity of stem cell stories they may encounter online or in print.
Robert Ilaria, Jr., MD