Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists identify embryonic stem cells by appearance alone

28.08.2007
Some scientific results are hard to spot, especially in genetic research. Often scientists are unable to physically see if the gene they inserted into a cell has produced the desired trait. To overcome this problem researchers use various genetic markers that contain pieces of foreign DNA that cause cells to, for example, glow when exposed to ultraviolet light.

But scientists in the lab of Whitehead Member Rudolf Jaenisch didn’t have to resort to these genetic markers in their latest experiment because the results were easy to see. Building on their widely publicized June Nature paper, which demonstrated that it’s possible to convert specialized mouse skin cells into unspecialized stem cells, Whitehead postdoctoral researchers Alexander Meissner and Marius Wernig have now identified successfully reprogrammed cells by looks alone.

Their findings, which appear online in the journal Nature Biotechnology on Aug. 27, bring human stem cell therapies a step closer to reality. Before reprogramming can be applied to our own species to generate custom embryonic stem cells, scientists must be able to accomplish it without altering the DNA of the cells involved.

“This eliminates one of the major hurdles to reprogramming human cells,” says Jaenisch, who is also an MIT professor of biology. “If we overcome the other obstacles, this approach could one day provide custom human embryonic stem cells for use in therapy.”

Last spring, Wernig and Meissner relied on genetic markers to identify successfully reprogrammed cells. This required them to work with fibroblasts from a genetically modified mouse. The mouse was grown from embryonic stem cells that contained foreign DNA coding for antibiotic resistance. The scientists had strategically inserted these foreign DNA “markers” at particular points along the genome, next to genes expressed only in embryonic stem cells. All of the cells (including fibroblasts) in the resulting mouse contained the markers.

In the original experiment, the researchers took fibroblasts from the tail of this mouse and infected them with a special virus containing four genes (Oct4, Sox2, c-myc, and Klf4) capable of converting the cells to an embryonic state. Genes typically active in embryonic stem cells roared to life, triggering the adjacent foreign DNA to provide antibiotic resistance. Thus only fully reprogrammed cells survived exposure to an antibiotic, which allowed the scientists to isolate them.

“When we conducted the original experiment, we noticed that many of the infected cells had already started to change shape before the markers were activated,” says Wernig.

So they set up a new experiment to test if visual identification alone would work. Indeed, they were able to separate the reprogrammed cells from ordinary fibroblasts under a microscope, based on several physical differences. Fibroblasts are big and flat. Embryonic stem cells are small, round and form tight colonies.

“We’ve shown that there’s no need to use markers to isolate successfully reprogrammed cells,” says Meissner. “This significantly simplifies this approach in mice, as we can now work with ordinary fibroblasts.”

But another hurdle remains before the technique can be applied to human cells.

“We still used viruses containing foreign DNA to introduce the genes that induced the reprogramming,” explains Meissner.

The scientists are now working to eliminate the virus from the reprogramming process. Jaenisch believes they will eventually succeed and points out that the technique could eventually yield a bountiful supply of custom human embryonic stem cells for use in therapy.

Meissner and Wernig successfully reprogrammed about 0.5 percent of the fibroblasts. Given that there are millions of cells in a typical skin biopsy (researchers used skin from either the end of the tail or from the ear of the mouse), that translates into thousands of stem cells, each one capable of developing into any cell type of the body.

Ceal Capistrano | EurekAlert!
Further information:
http://www.wi.mit.edu

More articles from Life Sciences:

nachricht Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>