Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stem-cell powers challenged

14.03.2002


Transfer of green dye suggests adult stem cells and ES cells fuse.
© Nature


Fused cells become nerve cells and other cell types.
© Nature


Fusion may explain adult stem-cell morphing.

The hyped ability of adult stem cells to sprout replacement tissue types is being called into question. They may instead be fusing with existing cells, say two new reports, creating genetically mixed-up tissues with unknown health effects.

Recent studies have shown that adult stem cells transplanted from one tissue, such as blood, can spawn the cell types of another, such as nerves. The findings have stirred intense interest in stem cells’ medical potential to repair damaged or diseased tissues.



Now researchers have evidence that, rather than switching fates, adult stem cells may be fusing with those in existing tissues1,2. The resulting cells carry double the normal amount of DNA, and may be sickly.

The findings are a reality check for those hoping to use adult stem cells for clinical purposes. "The fusion issue is an important one," agrees stem-cell researcher Diane Krause of Yale University. She and others must now investigate whether fusion can explain their results, she says, and these experiments are under way.

Fate or fusion

When certain adult stem cells are injected into mice, their descendants have been found in muscle, liver, brain and heart. Like stem cells from embryos (ES cells), adult stem cells are thought to be able to give rise to many other cell types in the body.

Some researchers remain sceptical about this, as it challenges a long-held notion that adult stem cells are committed to producing only one class of cell. "There’s something unprecedented going on," says Austin Smith of the University of Edinburgh, UK.

Smith and Naohiro Terada of the University of Florida in Gainesville, looked for an alternative explanation. They grew adult stem cells from bone marrow and brain in the same dishes as ES cells. Both types fused spontaneously into hybrid cells. These acquired the properties of ES cells and produced muscle, nerve and other cell types.

Fusion occurs rarely - only once for every 10,000-100,000 cells. But the researchers think that transplanted stem cells fusing with cells around the body could explain some of the previous results. "It is quite possible that such fusion events have been previously misinterpreted," agrees Fred Gage, who works on nerve stem cells at the Salk Insitute in La Jolla, California.

However, Smith and Terada have only demonstrated fusion under very specific culture conditions; their results may not prove relevant to other situations, Krause warns.

Cell safety checks

How stem cells produce new tissue is important. Offspring formed by fusion may carry twice the normal number of chromosomes. This could make the cells genetically abnormal, precluding their medical use. Researchers agree that more rigorous criteria are needed to establish how new cells form from stem cells, and whether they function normally.

Previous transplantation experiments have not made these checks. Generally, researchers identify new cells using a fluorescent protein carried only by the original donor cell and inherited by its offspring. If cells fuse, this marker is still carried into the resulting hybrid. Only by checking for genes from the recipient animal can fusion be ruled out.

Terada and Smith concede that some stem cells may genuinely revert to an earlier stage of development or switch fates. "I’m not saying it never occurs," says Smith. Ultimately, they hope to direct transplanted stem cells to a damaged site and turn them into the tissue that is needed. Again, the mechanism by which this occurs must first be worked out.

References

  1. Terada, N. et al. Bone marrow cells adopt phenotype of other cells by spontaneous cell fusion. Nature, Advanced online publication DOI: nature730 , (2002).
  2. Ying, Q-L., Nichols, J., Evans, E. & Smith, A.G. Changing potency by spontaneous fusion. Nature, Advanced online publication DOI: nature729, (2002).

HELEN PEARSON | Nature News Service

More articles from Life Sciences:

nachricht Microscope measures muscle weakness
16.11.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

nachricht Good preparation is half the digestion
16.11.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>