Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chromosomal Variations Found in Early Passage Female Human Embryonic Stem Cell Lines

28.06.2010
Human embryonic stem cells hold great promise for studying and treating disease and for the practice of regenerative medicine. However, more must be learned to ensure the cells that may one day be transplanted into humans are safe.

In one of many safety-related studies going on worldwide, scientists at the UCLA Broad Stem Cell Research Center have uncovered that variations in X chromosome inactivation take place in very early passages of female human embryonic stem cells lines, information that will play an important role in ensuring the safety of cells grown for therapeutic use and a discovery that also may have implications in the development of cancer.

Chromosomal and genetic variations found in human embryonic stem cells lines have been attributed, in large part, to the various culture conditions in which they’re grown, said Tamar Dvash, first author of the study and a postdoctoral fellow at UCLA.

However, the work by the Broad Stem Cell Research Center scientists reveals that very early in their growth, female human embryonic stem cells already show variation in the inactivation of the X chromosome.

“It suggests that culture conditions and methods in the derivation of human embryonic stem cells could be further improved to achieve a uniform pattern of X chromosome inactivation,” said Guoping Fan, an associate professor of human genetics and senior author of the study.

The study is published June 25, 2010 in the early online edition of the journal PLoS ONE, a publication of the Public Library of Science.

All female cells have two X chromosomes and in early development, one X chromosome is permanently inactivated. The X chromosome inactivation ensures that females, like males, have one functional copy of the X chromosome in each body cell and that the cells develop normally. If the second X chromosome is not inactivated, the result could be disease development, including some cancers in which two active X chromosomes can be found in the malignant cells, Dvash said.

Previously, what scientists knew about human embryonic development was gleaned from studying mouse embryos. However, the advent of human embryonic stem cell research has allowed researchers to closely study early human development. Dvash, Fan and other scientists, including collaborator Neta Lavon of Cedars-Sinai Medical Center, were examining the process of inactivation of the X chromosome when they made their observation.

The creation of a stem cell line includes many steps. The donated, frozen blastocysts are thawed and the inner cell mass – the 20 to 50 cells that are fully pluripotent in the blastocyst - is placed in culture with cells that support its growth. After a time, a small piece of the developing stem cell colony, or group of cells, is cut away and placed into a culture dish to further expand, a process called passaging.

The cells studied by Dvash and Fan were passaged only five to ten times instead of the usual more than 20 times, meaning the culture in which they were grown should have had less influence on any variation found in the cells. However, even at the first five passages, the resulting cells showed variations in X chromosome inactivation, meaning some cells had inactivated one X chromosome and some had not.

“People are looking at these cells as having great potential for transplantation and possible cures for diseases,” Dvash said. “What this study proves is that we need to monitor X chromosome inactivation closely in cells being considered for therapeutic use. We need to make sure they’re undergoing normal inactivation to ensure they will be stable when they begin to differentiate.”

Going forward, the scientists will also examine induced pluripotent stem cells, adult stem cells that have been reprogrammed to have all the qualities of embryonic stem cells, which can become any cell in the body. They will study skin cells taken from females, which would already have undergone inactivation of one X chromosome because they are already differentiated. The cells will be programmed into embryonic-like cells with two active X chromosomes so they can more closely study the process of inactivation.

“We want to know how does it happen and when,” Dvash said.

This study was funded by two grants from the California Institute of Regenerative Medicine, the state’s stem cell research agency.

The stem cell center was launched in 2005 with a UCLA commitment of $20 million over five years. A $20 million gift from the Eli and Edythe Broad Foundation in 2007 resulted in the renaming of the center. With more than 200 members, the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research is committed to a multi-disciplinary, integrated collaboration of scientific, academic and medical disciplines for the purpose of understanding adult and human embryonic stem cells. The center supports innovation, excellence and the highest ethical standards focused on stem cell research with the intent of facilitating basic scientific inquiry directed towards future clinical applications to treat disease. The center is a collaboration of the David Geffen School of Medicine, UCLA’s Jonsson Cancer Center, the Henry Samueli School of Engineering and Applied Science and the UCLA College of Letters and Science. To learn more about the center, visit our web site at http://www.stemcell.ucla.edu. To learn more about the center, visit our web site at http://www.stemcell.ucla.edu

Kim Irwin | Newswise Science News
Further information:
http://www.stemcell.ucla.edu

More articles from Life Sciences:

nachricht Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg

nachricht Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>