Washington: US scientists have discovered a brand-new type of cell hiding inside the delicate, branching passageways of human lungs.
The newfound cells play a vital role in keeping the respiratory system functioning properly and could even inspire new treatments to reverse the effects of certain smoking-related diseases such as chronic obstructive pulmonary disease (COPD), which is the result of inflammation of the air passages inside the lungs.
The experiments conducted by scientists during the study at the University of Pennsylvania analyzed healthy human lung tissue to identify the new cells, which they call respiratory airway secretory cells (RASCs). Unknown previously, the cells line tiny airway branches, deep in the lungs, near the alveoli structures where oxygen is exchanged for carbon dioxide.
The scientists showed that RASCs have stem-cell-like properties enabling them to regenerate other cells that are essential for the normal functioning of alveoli. RAS cells serve two main functions in the lungs. First, they secrete molecules that maintain the fluid lining along bronchioles, helping to prevent the tiny airways from collapsing and maximizing the efficiency of the lungs. Second, they can act as progenitor cells for alveolar type 2 (AT2) cells, a special type of alveoli that secrete a chemical that is used in part to repair other damaged alveoli. (A progenitor cell is a cell that has the capacity to differentiate into another type of cell, similar to how stem cells differentiate into other cells.)
Study lead author and professor at the Perelman School of Medicine at the University of Pennsylvania Edward Morrisey, who also specializes in respiratory systems, said that "RAS cells are what we have termed facultative progenitors, which means they act as both progenitor cells and also have important functional roles in maintaining airway health," adding that this means RAS cells play a vital role in maintaining healthy lungs.
This is a new discovery that helps medical fields start thinking about new treatment methods that could lead to better treatments in the future if researchers can properly harness the regenerative properties of these cells, he added.
COPD is the result of inflammation of airway passages inside the lungs. The inflammation of the airways makes it harder for the lungs to properly take in enough oxygen; as a result, COPD has similar symptoms to asthma. COPD can also lead to emphysema, in which alveoli are permanently destroyed, and chronic bronchitis, a long-lasting and intense cough usually accompanied by excess phlegm. Every year, more than 3 million people around the world die from COPD, according to the World Health Organization.
