|Planaria Image by Carolina Biological Supply Company|
The work, which was published in the February 20 issue of Nature, shows that a long-lived worm called a schistosome has a pool of stem cells that help re-grow organs and might contribute to it’s longevity. The World Health Organization considers infection by these worms to be the second most socioeconomically devastating parasitic disease, next only to malaria, with hundreds of millions infected worldwide (here’s more about schistosomes from Wikipedia).
Schistosomes aren’t well studied in the lab, so the researchers might have had a hard time finding the pool of stem cells if it weren’t for a relative called the planaria, which has long been a fixture in biology labs. These are the flat worms that some people might remember slicing in half during a high school biology lab, only to watch the worms regrow body parts.
Those body parts regrow thanks to a pool of flexible stem cells that can form any of the different organs in the planaria. This is in contrast to our own tissue-specific stem cells, which only form cells associated with that tissue—blood-forming stem cells only form cells of the blood and brain stem cells only form cells of the brain.
Because scientists knew so much about the planaria’s stem cells, they were able to quickly find similar cells in the schistosome. And, as it happens, schistosomes were also blessed in a supply of stem cells that can constantly repair the worm’s organs. They think these cells account for why the worms can live as a parasite for as long as decades.
Having found the key to the worm’s longevity, the goal is now to find a way of shutting them down, killing the worm and eliminating the infection.
In a press release from the Howard Hughes Medical Institute, the lead author on the paper Phillip Newmark, of the University of Illinois at Urbana-Champagne, says,
“People often wonder why we study the ‘lowly’ planarian, but this work provides an example of how basic biology can lead you. . . to findings that are directly relevant to important public health problems.”A.A.
Collins Iii JJ, Wang B, Lambrus BG, Tharp ME, Iyer H, & Newmark PA (2013). Adult somatic stem cells in the human parasite Schistosoma mansoni. Nature PMID: 23426263