Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Neural Stem Cells Are Long-Lived

06.10.2005


New studies in mice have shown that immature stem cells that proliferate to form brain tissues can function for at least a year — most of the life span of a mouse — and give rise to multiple types of neural cells, not just neurons. The discovery may bode well for the use of these neural stem cells to regenerate brain tissue lost to injury or disease.



Alexandra L. Joyner, a Howard Hughes Medical Institute investigator at New York University School of Medicine, and her former postdoctoral fellow, Sohyun Ahn, who is now at the National Institute of Child Health and Human Development, published their findings in the October 6, 2005, issue of the journal Nature. They said the technique they used to trace the fate of stem cells could also be used to understand the roles of stem cells in tissue repair and cancer progression.

“In terms of using neural stem cells for therapeutic purposes and to regenerate tissue, it’s important that they can continue to proliferate, and that these stem cells can make different cell types.”
Alexandra L. Joyner



Joyner said that previous studies by her lab and others had shown that a regulatory protein called Sonic hedgehog (Shh) orchestrates the activity of an array of genes during development of the brain. Scientists also knew that Shh played a role in promoting the proliferation of neural stem cells. However, Joyner said the precise role of Shh in regulating stem cell self-renewal — the process whereby stem cells divide and maintain an immature state that enables them to continue to generate new cells — was unknown.

In the studies published in Nature, Joyner and Ahn developed genetic techniques that enabled them to label neural stem cells in adult mice that are responding to Shh signaling at any time point so they could study which stem cells respond to Shh.

Other researchers had shown that transient bursts of Shh signaling caused neural stem cells to proliferate and create new neurons. But a central question remained, said Joyner. At issue was whether resting, or quiescent, cells — which are important for long-term function — responded to Shh signaling. Or was the response limited to the actively dividing stem cells with a short life span involved in building new tissue? To test these options, the researchers used a chemical called AraC that selectively kills fast-dividing cells, leaving only quiescent cells.

“This was an important experiment, because by giving AraC, we could kill all the cells that were actively dividing for a week,” said Joyner. “And since the quiescent cells only divide every couple of weeks, they were spared.” The researchers’ observations revealed that the quiescent cells did, indeed, respond to Shh signaling, expanding to produce large numbers of neural cells. Even when the researchers gave the mice two doses of AraC separated by a year, the quiescent cells recovered — demonstrating that the cells could still respond to Shh signaling.

That the quiescent stem cells remained capable of self-renewal after a year in both normal and AraC-treated mice was a central finding of the study, said Joyner. “It has been assumed that these cells probably live for some time, but it has never really been known whether they keep dividing, or divide a few times and give out,” she said.

The researchers also found evidence that neural stem cells in vivo responded to Shh signals by giving rise to other neural cell types, including glial cells that support and guide neurons. “An important point is that earlier studies indicating that neural stem cells could give rise to multiple cell types had been done in vitro,” said Joyner. “Before our work, it had never been formally shown that they normally make those different cell types in vivo.” Joyner and Ahn also found that the neural stem cell “niches” — the microenvironments in tissue that support and regulate stem cells — were not formed until late embryonic stages.

Joyner said that the new findings have important clinical implications. “In terms of using neural stem cells for therapeutic purposes and to regenerate tissue, it’s important that they can continue to proliferate, and that these stem cells can make different cell types,” she said.

In further studies, the researchers plan to use their technique of marking stem cells and tracing their fate to explore their role in repairing injured brain tissue in animal models. Such studies, she said, could reveal whether growth factors that influence stem cell growth could be used to treat brain injuries. “If these stem cells do produce cells that contribute to injury repair, it is fairly easy to infuse growth factors to coax these stem cells to do more in repairing injury,” she said.

Joyner and her colleagues are already discussing how to apply their genetic fate-mapping techniques to stem cells in the spinal cord and other organs. They are hopeful that since Shh signaling has been implicated in spurring the metastatic progression of cancer, the technique might also be used to explore the role of Shh signaling in tumor progression.

Jim Keeley | EurekAlert!
Further information:
http://www.hhmi.org

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>