WEDNESDAY, May 11 (HealthDay News) -- Contrary to current scientific thinking, human lungs do harbor stem cells capable of forming different parts of the lung, including blood vessels, a new study says.

The findings, reported May 12 in the New England Journal of Medicine, may open the door to eventual bioengineered lung tissue repair and replacement.

"These cells are very smart. They know what to do," said study senior author Dr. Piero Anversa. "The clinical implications are significant."

The findings could potentially offer a new avenue of treatment for patients suffering from respiratory conditions, such as emphysema, chronic obstructive pulmonary disease or pulmonary hypertension, that currently have only limited treatment options.

"Now that we have identified these cells and have the potential of growing them, we know it's not science fiction," said Dr. Andrew Pecora, vice president of cancer services and a stem cell expert with Hackensack University Medical Center in New Jersey. "A single cell placed in the right environment allows for the development of adult cells that can live for 80 years. The implications are potentially limitless."

Stem cells are those that first exist without organ-specific features but are capable of dividing and morphing into every other type of cell in the human body.

Stem cells are scattered throughout the body, and a growing cadre of scientists is attempting to harness their innate abilities to regenerate and repair parts of the human body, such as the heart.

The new findings challenge conventional knowledge about lung cells. According to an accompanying journal editorial, scientists had been holding on to the belief that no single cell in the lung could differentiate into multiple different types of cells, even though some cells do grow into specific cells, such as endothelial cells and the cells of the upper and lower airways.

For this trial, researchers were able to identify stem cells from 21 samples of normal human lungs, then expand them in a test tube.

The researchers coaxed the cells into developing into different types of lung cells, such as epithelial or vascular cells.

They next injected undifferentiated cells into mice whose lungs had been damaged.

"Over a period of about two weeks, we were able to regenerate a significant portion [of the lung] and essentially recreate various tissues," said Anversa, director of the Center for Regenerative Medicine at Brigham & Women's Hospital and Harvard Medical School in Boston. "The human structure was perfectly integrated with the structure of the mouse lung," he noted.

"The cells have the fundamental properties of stem cells," Anversa added. That means they could divide into new cells, form into many other types of cells and function when introduced into other environments.

But there's still a lot of work to be done before these cells actually have any implications for humans, the editorial cautioned.

Anversa will study the cells in larger animals before initiating a phase I clinical trial.

"We're talking a few years from now," he said. "We're not talking about tomorrow morning."

More information

The U.S. National Institutes of Health has more on stem cells.