Featured Research

from universities, journals, and other organizations

Sleuths Follow Lung Stem Cells For Generations To Shed Light On Healing

Date:
June 5, 2009
Source:
Duke University Medical Center
Summary:
More than one kind of stem cell is required to support the upkeep and repair of the lungs, according to a new study. Scientists painstakingly followed and counted genetically labeled cells in the mouse lung for over a year, under differing conditions, to learn more about natural renewal and healing processes. This information may shed light on what goes wrong in conditions like lung cancer, chronic bronchitis and asthma.

More than one kind of stem cell is required to support the upkeep and repair of the lungs, according to a new study published in the journal Cell Stem Cell.

Scientists at Duke University Medical Center painstakingly followed and counted genetically labeled cells in the mouse lung for over a year, under differing conditions, to learn more about natural renewal and healing processes. This information may shed light on what goes wrong in conditions like lung cancer, chronic bronchitis and asthma.

"We are learning the exact processes that maintain the various regions of the lung in tip-top condition and what happens when things go wrong," said Brigid Hogan, Ph.D., chair of the Duke Department of Cell Biology and senior author of the study. "Normally, the lung is beautifully organized, with the exact proportion of secretory and ciliated cells lined up next to each other to get their jobs done." The secretory cells lubricate and protect, while the hair-like projections of the ciliated cells waft the secretions up and out of the lungs.

In humans, under conditions of heavy smoking, or infection or inflammation due to asthma or cystic fibrosis, repeated cycles of damage and repair lead to a messy arrangement, she said. "You can get patches of cells building up in a stacked, flattened formation like skin cells. Some cells multiply too fast; others may make too much mucus."

The team tagged secretory cells, called Clara cells, found in both the trachea and bronchioles, the airway branches inside the lung. They followed them in normal mice and during the amazingly efficient repairs after damage by too much oxygen or other environmental stresses.

They tested the theory that there are BASCs (bronchioalveolar stem cells). These purportedly are on the border between the bronchioles and alveoli, which are the small air sacs where gas exchange takes place. BASCs were thought to replenish both regions of the lung.

Instead, the cells they labeled and followed in the bronchioles only renewed the airways and not the alveoli; they found no evidence for a special BASC population.

The Duke team was also surprised to find that the proportion of tagged Clara cells in the airways stayed the same for over a year. What's more, the genetic tag slowly appeared in ciliated cells, which told them that the secretory cells both make more of themselves and give rise to ciliated cells - a switch that had been suspected but never shown directly. Since the tagged cells renew over a long time and give rise to ciliated cells, they behave like long-term stem cells even though they are differentiated.

When the scientists tagged secretory cells in the trachea and followed them for a year, they found that the labeled cells gradually were lost. They could multiply and make ciliated cells but didn't do this for long. As the tagged cells were lost by wear and tear they were replaced by the descendants of unlabeled cells. From other experiments, Hogan and her colleagues think these replenishing cells are basal cells.

"In the wider trachea, there is a population of basal cells that are more like classical stem cells in being undifferentiated," Hogan said. Cells like these basal stem cells are found in the airways and bronchioles of human lungs. "It is important to know what these stem cells are doing in the human lung," Hogan said.

Until now, the lineage labeling tools had not been available for lung Clara cells. Postdoctoral fellow Emma Rawlins' efforts to tag the cells and count the daughters for over a year were "heroic," Hogan said.

"You really need this particular genetic flag to know exactly what a cell's fate is," Hogan said. "If you just stain the cells, this tells you only what they look like. It doesn't say who the parents are, and who begets whom, if you will. You have to count and work out the family tree."

Many questions remain. "While we know secretory cells can give rise to ciliated cells, we don't know what controls this switch so that the correct proportion is always made," Hogan said. "In the airways of people with asthma there are many goblet cells that make mucus, but we don't know where these cells come from. We also need to search for the specialized stem cell that gives rise to alveolar cells."

The study was supported by an NIH grant and a Parker B. Francis Fellowship. Other authors included Yan Xue, Hiroshi Hasegawa and Fan Wang of the Duke Department of Cell Biology; David M. Brass and Richard L. Auten from the Duke Department of Pediatrics; and Tadashi Okubo, formerly of Duke Cell Biology, now with the Center for Integrative Bioscience at the National Institutes of Natural Sciences in Aichi, Japan.


Story Source:

The above story is based on materials provided by Duke University Medical Center. Note: Materials may be edited for content and length.


Journal Reference:

  1. Emma L. Rawlins, Tadashi Okubo, Yan Xue, David M. Brass, Richard L. Auten, Hiroshi Hasegawa, Fan Wang, Brigid L.M. Hogan. The Role of Scgb1a1 Clara Cells in the Long-Term Maintenance and Repair of Lung Airway, but Not Alveolar, Epithelium. Cell Stem Cell, 2009; DOI: 10.1016/j.stem.2009.04.002

Cite This Page:

Duke University Medical Center. "Sleuths Follow Lung Stem Cells For Generations To Shed Light On Healing." ScienceDaily. ScienceDaily, 5 June 2009. <www.sciencedaily.com/releases/2009/06/090604144336.htm>.
Duke University Medical Center. (2009, June 5). Sleuths Follow Lung Stem Cells For Generations To Shed Light On Healing. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2009/06/090604144336.htm
Duke University Medical Center. "Sleuths Follow Lung Stem Cells For Generations To Shed Light On Healing." ScienceDaily. www.sciencedaily.com/releases/2009/06/090604144336.htm (accessed October 21, 2014).

Share This



More Health & Medicine News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How Nigeria Beat Its Ebola Outbreak

How Nigeria Beat Its Ebola Outbreak

Newsy (Oct. 20, 2014) The World Health Organization has declared Nigeria free of Ebola. Health experts credit a bit of luck and the government's initial response. Video provided by Newsy
Powered by NewsLook.com
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
CDC Calls for New Ebola Safety Guidelines

CDC Calls for New Ebola Safety Guidelines

AP (Oct. 20, 2014) Centers for Disease Control and Prevention Director Dr. Tom Frieden laid out new guidelines for health care workers when dealing with the deadly Ebola virus including new precautions when taking off personal protective equipment. (Oct. 20) Video provided by AP
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