Stem cell stories that caught our eye: Salamander limb regrowth, mass producing cells for kidneys and halting cancer stem cells

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

Fun with axolotls.  Axolotls, the albino aquatic critters that look like they have feathers growing out of the backs of their heads, have long been a favorite model for studying how they and their salamander cousins regrow limbs. But only recently, with refined methods for turning specific genes on and off, have we begun to really understand this amazing feat.

b115a-axolotl

Carl Zimmer, national correspondent for the online publication STAT, interviewed Jessica Whited of Harvard-affiliated Brigham and Women’s Hospital about her work trying to understand the genetics of limb regrowth and posted both a four-minute video and a short story about the research. Part of the video series Zimmer calls “Science Happens,” the interview lets Whited explain that when a limb is cut off, the animal summons cells called blastemas to the stump. Those cells have properties like stem cells in that they can make different tissues like the bone, skin and muscle needed to grow a limb, but they seem to do this by selectively turning genes on and off.

With a mix of cartoon drawings and real lab images, the video provides an easy to follow explanation of how the researchers turn off individual genes and then look for the effect. And I have to say I agree with Zimmer when talking about the axolotls he declares “I think they’re creepy.”

 

Advance for kidney disease.  Often in stem cell research you don’t want the starting stem cell and you don’t want the end desired tissue, you want the middleman called a progenitor that has already decided it wants to become the end tissue, but can still mass produce itself. Instead of being handed a roll of 10 dollar bills, you have a printing press with Hamilton’s face already set on the printing plate.

kidney progenitors Salk

Progenitor cells (bright red) growing in a kidney

In CIRM-funded research published this week in Cell Stem Cell a team at the Salk Institute has found a way to configure that printing press for nephron progenitor cells, the cells that yield the vital nephrons that allow your kidneys to cleanse your blood. While many have tried to mass produce these vital cells to repair damaged kidneys, they have not had much luck. These cells do not like to stay in the progenitor state. Once they are on the path toward the end tissue they like to keep on moving in that direction.

The Salk team, led by Juan Carlos Izpisua Belmonte, got around this by changing the progenitor cells’ environment. Instead of a flat lab dish, they grew them in 3D cultures and gave them a new mix of signaling molecules.

“We provide a proof-of-principle for how to make and maintain unlimited numbers of precursor kidney cells,” said Izpisua Belmonte in an institute press release posted by HealthMedicineNet. “Having a supply of these cells could be a starting point to grow functional organs in the laboratory as well as a way to begin applying cell therapy to kidneys with malfunctioning genes.”

Their system worked first in mouse cells and then in human cells. They predicted that the methods could be used to grow progenitor cells for many other tissues.

 

Halting cancer stem cells. The bad guys of the stem cell world, cancer stem cells (CSCs), are turning out to have a number of vulnerabilities, and many companies around the world have staked their fortunes on attacking one of those weak spots. While we have known for some time that CSCs require proteins in the Wnt family to grow, we haven’t had a good way of blocking that path. Now researchers at the Riken Center and National Cancer Center in Japan claim they have a candidate drug, at least for colon cancer.

They screened a library of compounds likely to inhibit the Wnt pathway and tested them in mice that had received transplants of human colon cancer. They found one, NCB-0846 that can be administered orally, that was able to suppress the cancer grafts.

 “We’re very encouraged by our promising preclinical data for NCB-0846, especially considering the difficulty in targeting this pathway to date, and shortly we hope to conduct a clinical trial at the NCC hospitals” said Dr. Tesshi Yamada of the National Cancer Center in a Riken release posted by ScienceCodex.

CIRM funds several team trying to halt CSCs, each team targeting a different vulnerability on the CSCs, including teams at Stanford, and at University of California campuses in San Diego and Los Angeles.

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