Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Pluripotent Adult Stem Cells Power Planarian Regeneration

13.05.2011
FINDINGS: Whitehead Institute researchers have determined that the planarian flatworm regenerates missing tissues by using pluripotent adult stem cells. Until now, scientists could not determine whether the dividing cells in planarians, called neoblasts, are a mixture of specialized stem cells that each regenerates specific tissues, or if individual neoblasts are pluripotent and able to regenerate all tissues.

RELEVANCE: Planarians are animal models of regeneration, and for the scientists that study them, the developmental potential of individual neoblasts has long been a fundamental question. Further study of planarian biology will now inform scientists how these adult organisms harness the power of pluripotent stem cells to achieve remarkable regenerative feats.

Ever since animals, such as lizards and starfish, were observed regenerating missing body parts, people have wondered where the new tissues come from. In the case of the planarian flatworm, Whitehead Institute researchers have determined that the source of this animal’s extraordinary regenerative powers is a single, pluripotent cell type.

Most advanced animals, including mammals, have a system of specialized stem cells. In humans, we have blood stem cells in our bone marrow that make blood and immune cells, skin stem cells that produce new layers of skin, and intestinal stem cells that continually renew our gut linings, to name just a few. In humans, only embryonic stem cells and germ cells are pluripotent—with the ability to create all cell types in the body.

In the planarian flatworm Schmidtea mediterranea, certain dividing cells, called neoblasts, have long been identified as essential for the regeneration that repairs the worm’s tissues. Until now, however, scientists could not determine whether neoblasts represent a mixture of specialized stem cells that each regenerates specific tissues or are themselves pluripotent and able to regenerate all tissues.

“And that question is at the heart of understanding regeneration in these animals,” says Whitehead Member Peter Reddien, who is also an associate professor of biology at MIT and a Howard Hughes Medical Institute (HHMI) Early Career Scientist. “The reason it’s never been possible to address this question is because we needed assays that allow us to ask what the regenerative potential of single cells is.”

Using complementary methods, Dan Wagner, Irving Wang—two graduate students in the Reddien lab and co-first authors—and Reddien have demonstrated that adult planarians not only possess pluripotent stem cells—known as clonogenic neoblasts (cNeoblasts)—but that a single such cell is capable of regenerating an entire animal. Their results are published in the May 13 issue of Science.

In one method, Wagner gave planarians a dose of radiation that killed all of their dividing cells, except for rare, isolated cNeoblasts. By labeling cells for a gene expressed only in neoblasts, Wagner observed that these individual surviving cNeoblasts divided to form large colonies of cells. Wagner analyzed the colonies and found that they contained cells differentiating into neurons and intestinal cells, indicating broad developmental potential for the initiating cNeoblast. Furthermore, Wagner showed that small numbers of cNeoblasts were capable of restoring regenerative potential to entire animals.

Using another method, Wang and Reddien transplanted single cNeoblasts from one strain of planarian into lethally irradiated host planarians from a different strain, which lacked their own neoblasts and the ability to regenerate. Because the donor cells were distinguishable from the host, the researchers demonstrated that the transplanted cNeoblast multiplied, differentiated, and ultimately replaced all the host’s tissues. From a single transplanted cell, the host not only regained the ability to regenerate, but was also converted to the genetic identity of the donor strain.

Because this work showed that cNeoblasts can differentiate into diverse tissue types and even replace all of the tissues in a host planarian, the researchers were able to conclude that cNeoblasts are pluripotent stem cells.

Further study of cNeoblasts could help researchers understand how stem cells can act to promote regeneration.

“This is an animal that, through evolution, has already solved the regeneration problem,” says Wagner. “We’re studying planarians to see how their regeneration process works. And, one day, we’ll examine what are the key differences between what’s possible in this animal and what’s possible in a mouse or a person.”

In the near future, the research group is interested in exploring the new possibilities provided by their techniques.

“Single-cell transplants have opened up a lot more experiments that we can do,” says Wang. “Now that it is possible to identify and isolate single cNeoblasts, we can explore what makes these cells pluripotent.”

This research was supported by the National Institutes of Health (NIH) and the Keck Foundation.

Written by Nicole Giese

Peter Reddien’s primary affiliation is with Whitehead Institute for Biomedical Research, where his laboratory is located and all his research is conducted. He is also a Howard Hughes Medical Institute Early Career Scientist and an associate professor of biology at Massachusetts Institute of Technology.

Full Citation:

“Clonogenic neoblasts are pluripotent adult stem cells that underlie planarian regeneration”

Science, May 13, 2011.

Daniel E. Wagner (1, 3), Irving E. Wang (1, 3), and Peter W. Reddien (1, 2)

1. Howard Hughes Medical Institute, MIT Biology, Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
2. Associate member, Broad Institute
3. These authors contributed equally

Nicole Giese | Newswise Science News
Further information:
http://www.wi.mit.edu

More articles from Life Sciences:

nachricht When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short
23.03.2017 | Institut für Pflanzenbiochemie

nachricht WPI team grows heart tissue on spinach leaves
23.03.2017 | Worcester Polytechnic Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>