Stem Cells: Helpful or Hurtful?

Stem cells are cells that seem to have the ability to divide perpetually, live indefinitely and, most important, possess the ability to reconstitute tissue or an entire organ.

The original stem cell is the fertilized egg, explains Aline Betancourt, PhD, research associate professor at the Tulane Center for Stem Cell Research and Regenerative Medicine in New Orleans. As it grows, internal cues cause it to “differentiate,” or to eventually become one thing or another, such as an eye or an ear. All this from one cell.

A current theory holds that cancers can develop from a rare type of cell that has the same infinite growth potential as a stem cell. Some see these not as true stem cells, but as a highly malignant and drug-resistant subpopulation of cancer cells. Others think they are, in fact, cancer stem cells, and that they are involved in metastasis as well.

Betancourt falls into the latter camp. She points to research where tumor cells that grow uncontrollably in a human don’t grow at all in a lab animal, evidence that only certain cells in a tumor can recreate that tumor.

There is a very intricate connection between cancer and our body’s immune response.

As adults, we have small pools of original stem cells remaining in specific organs. These stem cells respond to injury in that tissue. They also respond to injury signals from tumors, Betancourt says, which could make it possible to use stem cells to deliver anti-cancer agents directly to a tumor. This method could not only make treatment more effective, but also it would likely reduce side effects.

In some laboratory studies, normal stem cells have been shown to inhibit tumor growth and spread. In others, however, they seemed to encourage it. Clearly, employing these cells in treatment will require figuring out why that happens. Betancourt suspects the immune response plays a key role.

“There is a very intricate connection between cancer and our body’s immune response,” she says. “Yet the majority of studies we’re doing today are in immune-incompetent models, which miss half the picture, in my opinion. We’re working to model tumors in an immune-competent animal, so we can see if we get the same reaction as in its human counterpart.”