May 12, 2011

Human Lung Stem Cell Discovered

Researchers looking to treat emphysema and other diseases believe they have discovered stem cells in the lung that can make a wide variety of the organ's tissues.

Stem cells can produce a wide variety of specialized cells and, if used correctly, can be harnessed to repair damage from diseases like Parkinson's and diabetes.

The study is reported in Thursday's issue of the New England Journal of Medicine by Drs. Piero Anversa and Joseph Loscalzo and colleagues at Brigham and Women's Hospital in Boston.

In a telephone interview with the Associated Press (AP) Anversa explained they were not 100 percent clear what the lung stem cell normally does but that he thinks it's involved in replacing other lung cells lost throughout life.

In contrast, the new lung cell would be an "adult" stem cell, like others found in the body. Adult stem cells maintain and repair the tissues where they're found. Bone marrow cells, for example, create various kinds of blood cells that have been used for years in transplants to treat leukemia and other blood diseases.

The cells were found in donated surgical samples of adult tissue and the same cells appeared in tissue donated from nine fetuses that had died, giving evidence that the cells are present before birth and perhaps participate in lung development.

To study the behavior of the cells, researchers injured lungs of mice and then injected six doses of about 20,000 cells apiece. The injected cells had formed airways, blood vessels and air sacs within 10 to 14 days. "We had a very large amount of regeneration" involving millions of new cells, Anversa said.

When these human lung stem cells were injected into mice, they surprised researchers by rebuilding airways, air sacs and blood vessels within two weeks. One expert called that "amazing."

Although it is still too early to tell what exact lung diseases might be treated in the future by using the cells. Loscalzo explains that researchers are focusing on emphysema and high blood pressure in the arteries of the lungs, called pulmonary hypertension. Emphysema is a progressive disease that destroys key parts of the lung, leaving large cavities that interfere with the lung's function.

Anversa said the cells may be used to build up lung tissue after lung cancer surgery. It's not clear whether they could be used in treating asthma, he said. The mouse experiments showed "the cells are smarter than we are," able to build normal lung structures in an injured lung.

Loscalzo said in a press release: "These are the critical first steps in developing clinical treatments for those with lung disease for which no therapies exist. Further research is needed, but we are excited about the impact this discovery could have on our ability to regenerate or recreate new lung tissues to replace damaged areas of the lungs."

Dr. Brigitte Gomperts at the Broad Stem Cell Research Center at the University of California, Los Angeles, told AP that scientists have been debating if a single stem cell type could create the more than 40 cell types in the lung. Each cell does a different job such as protecting the body from inhaled germs and exchanging oxygen for carbon dioxide.

It's a technically difficult question to study, said Gomperts, who was not involved in the new work. If the new results can be confirmed, "it's a significant advance" that will help in understanding normal lung repair and abnormal repair found in disease, she said.

The work was supported by the National Institutes of Health and a Swiss foundation.


On the Net: