Researchers believe they have isolated human lung stem cells for the first time, according to a report in the May 12 issue of the New England Journal of Medicine.
Cells from normal human lung tissue obtained from 12 unused donor lungs were identified as stem cells using the stem-cell antigen c-kit, which has been used before to identify cardiac and hematopoietic stem cells.
These lung cells were then expanded and, in a series of in vitro and in vivo studies, the researchers demonstrated the three properties fundamental to stem cells: self-renewal, clonogenicity, and multipotentiality, said Jan Kajstura, Ph.D., of the departments of anesthesia and medicine at Brigham and Women’s Hospital and Harvard Medical School, Boston, and associates.
The undifferentiated cells were nested in niches within the distal airways in the lung samples. Other types of stem cells also typically are located in such anatomical niches, the researchers noted.
In addition to these cells from adult donor lungs, identical cells also were found in lung tissue specimens from nine cases of fetal death.
When the stem cells were transplanted into deliberately injured mouse lungs, they became structurally and functionally integrated into the damaged organs and created human bronchioles, alveoli, and pulmonary vessels within 14 days, Dr. Kajstura and colleagues said (N. Engl. J. Med. 2011 May 12;364:1795-806).
These findings indicate that the lung stem cells might play a crucial role in lung tissue regeneration after injury and in lung tissue homeostasis, they said.
This study was supported by the National Institutes of Health and Cardiocentro Ticino. A patent has been filed for this class of human lung stem cells on behalf of Partners HealthCare (which includes Brigham and Women’s Hospital). Dr. Kajstura reported no conflicts of interest; a coauthor reported ties to Autologous.