Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Moving Toward Regeneration

03.09.2012
The skin, the blood, and the lining of the gut—adult stem cells replenish them daily. But stem cells really show off their healing powers in planarians, humble flatworms fabled for their ability to rebuild any missing body part. Just how adult stem cells build the right tissues at the right times and places has remained largely unanswered.

Now, in a study published in an upcoming issue of Development, researchers at the Stowers Institute for Medical Research describe a novel system that allowed them to track stem cells in the flatworm Schmidtea mediterranea. The team found that the worms’ stem cells, known as neoblasts, march out, multiply, and start rebuilding tissues lost to amputation.

“We were able to demonstrate that fully potent stem cells can mobilize when tissues undergo structural damage,” says Howard Hughes Medical Institute and Stowers Investigator Alejandro Sánchez Alvarado, Ph.D., who led the study. “And these processes are probably happening to both you and me as we speak, but are very difficult to visualize in organisms like us.”

Stem cells hold the potential to provide an unlimited source of specialized cells for regenerative therapy of a wide variety of diseases but delivering human stem cell therapies to the right location in the body remains a major challenge. The ability to follow individual neoblasts opens the door to uncovering the molecular cues that help planarian stem cells navigate to the site of injury and ultimately may allow scientists to provide therapeutic stem cells with guideposts to their correct destination.

“Human counterparts exist for most of the genes that we have found to regulate the activities of planarian stem cells,” says Sánchez Alvarado. “But human beings have these confounding levels of complexity. Planarians are much simpler making them ideal model systems to study regeneration.”

Scientists had first hypothesized in the late 1800s that planarian stem cells, which normally gather near the worms’ midlines, can travel toward wounds. The past century produced evidence both for and against the idea. Sánchez Alvarado, armed with modern tools, decided to revisit the question.

For the new study, first author Otto C. Guedelhoefer, IV, Ph.D., a former graduate student in Sánchez Alvarado’s lab, exposed S. mediterranea to radiation, which killed the worms’ neoblasts while leaving other types of cells unharmed. The irradiated worms would wither and die within weeks unless Guedelhoefer transplanted some stem cells from another worm. The graft’s stem cells sensed the presence of a wound—the transplant site—migrated out of the graft, reproduced and rescued their host. Unlike adult stem cells in humans and other mammals, planarian stem cells remain pluripotent in fully mature animals and remain so even as they migrate.

But when Guedelhoefer irradiated only a part of the worm’s body, the surviving stem cells could not sense the injury and did not mobilize to fix the damage, which showed that the stem cells normally stay in place. Only when a fair amount of irradiated tissue died did the stem cells migrate to the injured site and start to rebuild. Next, Guedelhoefer irradiated a worm’s body part and cut it with a blade. The surviving stem cells arrived at the scene within days.

To perform the experiments, Guedelhoefer adapted worm surgery and x-ray methods created sixty to ninety years ago. “Going back to the old literature was essential and saved me tons of time,” says Guedelhoefer, currently a postdoctoral fellow at the University of California, Santa Barbara. He was able to reproduce and quantify results obtained in 1949 by F. Dubois, a French scientist, who first developed the techniques for partially irradiating planarians with x-rays.

But Guedelhoefer went further. He pinpointed the locations of stem cells and studied how far they dispersed using RNA whole-mount in situ hybridization (WISH), specifically adapted to planarians in Sánchez Alvarado’s lab. Using WISH, he observed both original stem cells and their progeny by tagging specific pieces of mRNA . The technique allowed him to determine that pluripotent stem cells can travel and produce different types of progeny at the same time.

“In other systems, most migrating stem cell progeny are not pluripotent,” says Guedelhoefer. “For the most part, blood stem cells in humans stay in the bone marrow but their progeny leave and turn into a few other cell types.” But in planarians, it looks like those two things are completely separate. Stem cells can move and maintain the full potential to turn into other types of cells.”

Next, Sánchez Alvarado looks forward to implementing genetic screens and transplantation experiments to disrupt or enhance the cellular behaviors the team observed, to figure out the “rules of engagement” for stem cell migration, he says.

“Why can some animals regenerate whole body parts but you and I are not good at it?” says Sánchez Alvarado. “Can we write an extra rule or erase one? Is it possible, for instance, to get rid of cancer while gaining regenerative properties? These are questions we’d love to have answers to.”

The Stowers Institute for Medical Research, a National Institutes of Health Training Grant (5T32 HD0791), a National Institutes of Health Grant (GM057260), and Howard Hughes Medical Institute provided funding for this work.

About the Stowers Institute for Medical Research

The Stowers Institute for Medical Research is a non-profit, basic biomedical research organization dedicated to improving human health by studying the fundamental processes of life. Jim Stowers, founder of American Century Investments, and his wife, Virginia, opened the Institute in 2000. Since then, the Institute has spent over 900 million dollars in pursuit of its mission.

Currently, the Institute is home to nearly 550 researchers and support personnel; over 20 independent research programs; and more than a dozen technology-development and core facilities.

Kristin Kessler | Newswise Science News
Further information:
http://www.stowers.org

More articles from Life Sciences:

nachricht Not of Divided Mind
19.01.2017 | Hertie-Institut für klinische Hirnforschung (HIH)

nachricht CRISPR meets single-cell sequencing in new screening method
19.01.2017 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

New Study Will Help Find the Best Locations for Thermal Power Stations in Iceland

19.01.2017 | Earth Sciences

Not of Divided Mind

19.01.2017 | Life Sciences

Molecule flash mob

19.01.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>