Stem Cell Niches and Bacteria

Stem Cell Niches and Bacteria

Yesterday I blogged briefly with some question about virus and stem cells. Today (well, late yesterday) an interesting article has come out about stem cell niches—the areas where stem cells develop—and bacteria. It’s a release from the Howard Hughes Medical Institute about a bacterium that infects a fruit fly and is passed on in the eggs to the progeny. The researchers studied the Wolbachia bacteria, which infect a wide range of insects, and found that the bacteria target the part of the ovary which contains stem cells. The researchers also found that when they transplanted uninfected cells into a fruit fly with an infection, the bacteria made their way to the new cells and infected them. An already infected organism, in other words, was still susceptible to further infection.

The study raised almost more questions than it answered—while it shows a mechanism by which bacterial infection can be spread throughout an insect species, there are now questions to be answered about how this adaptation occurred. One researcher suggested that perhaps there is even a as yet unknown helpful symbiotic relationship for the fly. Another question is how do the bacteria find the stem cell niche? Are there particular markers they respond to? And does this model occur in mammalian bacterial responses—in other words, are there bacteria that infect human stem cell niches? Further work can also be done to examine the transmission of diseases from insects to humans.

This obviously doesn’t have much to do directly with stem cell research, although finding a marker for a stem cell niche might be important, but I think it’s important to understanding disease vectors and the various biological interactions between bacteria and other organisms. I don’t know if cancer has ever been tied to a bacterium; cervical cancer is caused by a virus, but that’s very different. However, could bacteria infecting a stem cell niche cause a mutation—or alter the environment enough for a mutation to survive that otherwise would not—that eventually led to cancer? This question may be completely off the wall and a biological impossibility—the pros will know better than I—but it’s what I’m thinking about now.

By the way, one of my favorite fiction books about disease vectors is Connie Willis’s Doomsday Book, about the Black Plague. Well-written and very good. Check it out.