Featured Research

from universities, journals, and other organizations

Effects Of Aging In Stem Cells

Date:
July 30, 2007
Source:
PLoS Biology
Summary:
There is little disagreement that the body's maintenance and repair systems deteriorate with age, even as there is plenty of disagreement as to why. Stem cells combat the aging process by replenishing old or damaged cells--particularly in the skin, gut, and blood--with a fresh supply to maintain and repair tissue. Unfortunately, new evidence suggests that this regenerative capacity also declines with age as stem cells acquire functional defects. In highly purified hematopoietic stem cells from mice aged 2 to 21 months, gene expression analysis indicates a deficit in function, yet an increase in stem cell number with advancing age.

Aging HSCs exhibit a functional decline (yet an increase in cell number) and display a heightened stress and inflammatory response along with signs of epigenetic erosion.
Credit: S. M. Chambers, PLoS Biology, article authors

There is little disagreement that the body's maintenance and repair systems deteriorate with age, even as there is plenty of disagreement as to why. Stem cells combat the aging process by replenishing old or damaged cells--particularly in the skin, gut, and blood--with a fresh supply to maintain and repair tissue.

Unfortunately, new evidence published in the open-access journal PLoS Biology suggests that this regenerative capacity also declines with age as stem cells acquire functional defects.

Stuart Chambers, Margaret Goodell, and their colleagues investigated the molecular mechanisms underlying aging of stem cells by looking at the gene expression profiles of aging hematopoietic stem cells (HSCs), the precursors of blood cells. They found that genes involved in the inflammatory and stress response became more active with age, while genes important for regulating gene expression and genomic integrity became less active. These results lend strong support to the notion that HSCs succumb to the wear and tear of aging, just like other cells, and shed light on the mechanisms of aging.

To study HSCs' regenerative capacity over time, Chambers et al. isolated HSCs from young (aged 2 months) and old (aged 21 months) mice and then transplanted either young or old cells into mice whose bone marrow cells had been destroyed by radiation. The young and old HSCs gave rise to new marrow cells at roughly the same pace 4 weeks after transplantation. But at 8 and 16 weeks after transplantation, the old HSCs' contributions had dropped considerably, suggesting that aging HSCs lose their repopulating capacity. Yet, because HSCs increased in number, overall blood production from HSCs remained stable.

The finding that genes involved in the inflammatory response are expressed more (called up-regulation) as HSCs age fits with evidence linking inflammation and aging in the kidney, brain, and arteries. It may also help explain why HSCs lose function. One of the up-regulated genes, P-selectin, encodes a cell surface adhesion molecule. Because transplanted HSCs depend on cell adhesion to colonize bone marrow properly, the researchers explain, inappropriate up-regulation of genes encoding P-selectin may interfere with this process.

The markedly reduced expression (or down-regulation) of genes involved in chromatin remodeling, an "epigenetic" regulator of gene expression, suggested that transcriptional activity might be dysregulated across the genome.

Though the dominant model attributes the physical effects of aging to an accretion of isolated genetic insults, these results link age-related decline to global mechanisms operating across the genome. In the researchers' "epigenetic view of aging," chromatin dysregulation provides a logical explanation for the numerous and diverse age-related changes observed at the molecular, cellular, and organismal levels.

Over the normal course of aging, chromatin dysregulation leads to dysregulation of many genes, which in turn leads to a loss of normal cellular functions and a loss of growth regulation. These changes ultimately increase the risk of cancer, which, in many of its forms, increases dramatically with age. Future studies can investigate how epigenetic regulation, inflammation, and the stress response interact to better understand the molecular mechanisms of aging, and why so many of us face a high risk of cancer in our later years.

Reference: Chambers SM, Shaw CA, Gatza C, Fisk CJ, Donehower LA, et al. (2007) Aging hematopoietic stem cells decline in function and exhibit epigenetic dysregulation. PLoS Biol 5(8): e201. doi:10.1371/journal.pbio.0050201.


Story Source:

The above story is based on materials provided by PLoS Biology. Note: Materials may be edited for content and length.


Cite This Page:

PLoS Biology. "Effects Of Aging In Stem Cells." ScienceDaily. ScienceDaily, 30 July 2007. <www.sciencedaily.com/releases/2007/07/070724114053.htm>.
PLoS Biology. (2007, July 30). Effects Of Aging In Stem Cells. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2007/07/070724114053.htm
PLoS Biology. "Effects Of Aging In Stem Cells." ScienceDaily. www.sciencedaily.com/releases/2007/07/070724114053.htm (accessed October 20, 2014).

Share This



More Health & Medicine News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Another Study Suggests Viagra Is Good For The Heart

Another Study Suggests Viagra Is Good For The Heart

Newsy (Oct. 20, 2014) An ingredient in erectile-dysfunction medications such as Viagra could improve heart function. Perhaps not surprising, given Viagra's history. Video provided by Newsy
Powered by NewsLook.com
Ebola Worries End for Dozens on U.S. Watch Lists

Ebola Worries End for Dozens on U.S. Watch Lists

Reuters - US Online Video (Oct. 20, 2014) Forty-three people who had contact with Thomas Eric Duncan, the first person diagnosed with Ebola in the U.S., were cleared overnight of twice-daily monitoring after 21 days of showing no symptoms. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Beijing Marathon Runners Brave Hazardous Air Pollution

Beijing Marathon Runners Brave Hazardous Air Pollution

AFP (Oct. 19, 2014) Tens of thousands of runners battled thick smog at the Beijing Marathon on Sunday, with some donning masks as the levels of PM2.5 small pollutant particles soared to 16 times the maximum recommended level. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
Would A Travel Ban Even Work In Stopping Ebola Spread?

Would A Travel Ban Even Work In Stopping Ebola Spread?

Newsy (Oct. 19, 2014) The U.S. currently isn't banning travel from Ebola-stricken areas, but it's at least being considered. Some argue though it could be counterproductive. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins