The two types of stem cells

A couple of years ago, I delved into a personal research project, in order to write my second novel, Glass Chimera. From a layman’s perspective, I was learning about genes, DNA, cloning, and other areas of scientific endeavor that pertain to the science of genetics. I learned a lot about the human genome, more than I can ever understand or explain.

One particular area of genetics that is often discussed in our era is the use of stem cells. My limited investigation into the subject has brought me to this observation about stem cells: there are basically two types of them.

Embryonic stem cells are those found in the fertilized egg, or the embryo, of a newly-conceived fetus in a female’s uterus. These are the controversial stem cells, because the harvesting of them for medical use will most likely alter or terminate the embryo’s fetal development. Embryonic stems cells are pluripotent, insofar as they have potential to differentiate into many types of cells that are necessary for a fully developed body to, after birth, sustain life. These cells can be directed by the DNA genetic code to become, for instance, blood cells, skin cells, muscle, nerve, or whatever cells. My limited studies have indicated that the main value of embryonic stem cells is found in their use for medical research.

In the novel that I wrote while studying this, I include a hypothetical conversation between two graduate students in microbiology. In chapter 24, Erik is explaining stem cells to his friend Sam:

“. . .these guys that are doing this type of work, they remove the stem cells from the ICM (inner cell mass) that has congregated inside the 5-or-6-day old blastocyst—“

“So they’re sacrificing the embryo?” Sam wondered.

“I guess you could call it that,”

“What do they do with the outer part?”

“Oh, the trophoblast, God only knows. I suppose they use it for something or other in the lab, or maybe they culture those cells for some other developmental purpose. I don’t know. Anyway, they place the totipotent stem cells into culture and propogate them.”

“That’s what we call a stem cell line,” observed Sam.

“Uhhuh, but it’s tricky. Those cells have a built-in tendency toward differentiation. If they’re kept alive unto themselves, without chemical restraints, they’ll start to organize themselves into an embryo again.”

This “differentiation” potential of stem cells is their most useful attribute. At the same time, it is the very thing that makes them somewhat dangerous.

I mentioned above that there is another type of stem cells: adult stem cell. Their differentiation potential is quite limited, as compared to the embryonic type, but they are much safer for medical applications, mainly because they are obtained from a patient’s body, and then injected back into that same patient. So there’s no conflict between the genetic info in the medically modified stem cells and the genetic data resident in that patient’s other billions of cells. This second type of stem cell, the “adult” type, exists in the body of every child and adult. They enable the growth of new bodily tissue, and they exist in every part of the body.

Yesterday, June 17 2011, I was fascinated as I listened to a very informative discussion on the radio about new medical treatments utilizing these adult stem cells to repair damaged tissue.

Ira Flatow was again demonstrating his customary excellence in science journalism. The depth and scope of his NPR reporting keeps his show, Science Friday, on the cutting edge of popular science education. I always obtain galactical levels of new information and insight when I can listen to his Friday program, or catch it later online.

The spot I heard yesterday was SciFri 061711 Hour 1: Black Holes, Untested Cell Therapies, Solar Update, which I had clicked on at

http://www.sciencefriday.com/about/listen.


Ira was speaking to two medical doctors about Bartolo Colon, the great NY Yankees pitcher whose injured pitching arm required medical treatment. Ira explained that since the pitcher was in the latter years of his baseball career, surgery to correct his elbow problem might be too risky. So Bartolo had elected to have this relatively untested therapy performed on his arm by doctors in Dominican Republic. And guess what, it worked! Bartholo has made an impressive comeback in his pitching career, at the age of 37.

Dr. Rick Lehman, an orthopedic surgeon at the US Center for Sports Medicine (in St. Louis), described how cells taken from Bartolo’s own body had been medically treated and then injected back into his injured shoulder and elbow. The immature stem cells, as the doc explained, act to recruit blood supply, enhance healing of ligaments, and improve the natural healing mechanics inside the patient’s body.

Dr. Scott Rodeo, orthopedic surgeon at the Hospital for Special Surgery (in New York City) contributed to their fleshing out of the subject with specific comments about Bartolo Colon’s surgery, but also with some interesting facts about the different kinds of stem cells. For instance, risk of cancer is far lower with the use of these adult stem cells than the risk from using more primitive stem cells, such as those pluripotent ones found in embryos.

As a writer whose research had skirted these areas pioneering medicine, I was fortunate to have heard their productive talk on NPR about the minimally surgical restoration of a great pitcher’s arm.

And congratulations to Bartolo Colon, whose baseball career has been renewed.

Glass Chimera