LungsAfter a fastidious one year work scientists from Duke University Medical Center have discovered  that natural renewal and healing processes of lungs depend on more than one type of stem cells.

In the process of tracking repair work scientists counted genetically labeled cells in the mouse lung for over a year, under different conditions.   Now they believe that
this important information may shed light on what goes wrong in conditions like lung cancer, chronic bronchitis and asthma.

Brigid Hogan, Ph.D., chair of the Duke Department of Cell Biology and senior author of the study and her team tagged and tracked Clara cells which are responsible for secretions and found in trachea and bronchioles, they followed them during the amazing reparing process which usually required due to fluctuation of oxygen supply and other environmental stress.

Findings:

  • The team tried to find out bronchioalveolar stem cells which are theoretically present on the border between the bronchioles and the alveoli, but didn’t find any, instead they found that their pre leveled stem cell only repair the air ways not the alveolis.
  • The team observed that  the proportion of tagged Clara cells in the airways stayed the same for over a year. 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.
  • 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.
  • They also found new replacement cells which arrived after the tagged cells were lost by wear and tear, they believe that this cells are basal cells. This basal cell are like undifferentiated classical stem cells.

Scientists are looking forward to learn exactly what this stem cell like basal cells are doing in airways and bronchioles of human lungs.

According to Hogan:

  • Secretory cells can give rise to ciliated cells, but they don’t know what controls this switch so that the correct proportion is always made.
  • In the airways of people with asthma there are many goblet cells that make mucus, but they don’t know where these cells come from.
  • What are the roles of basal cells?
  • Further research  is required for the specialized stem cell that gives rise to alveolar cells.

This new study was published in the journal Cell Stem Cell, and supported by an NIH grant and a Parker B. Francis Fellowship.

Research team includes:
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.

Source: ScieceDaily