At Duke University, scientists used a single basal cell to grow hollow spheres of differentiated ciliary and secretory lung cells. This type of research should help investigators to learn more about lung health and to develop new treatments using a standalone test platform that resembles real lungs.
The scientists isolated basal cells, set each separately in a gel suspension, and observed the cells growing into a hollow sphere as they divided. Analysis shows that the basal cells remain on the outside of the sphere, while inside the hollow was lined in an equal arrangement of cilial and secretory cells, as in nature.
“This basal cell is making daughters, which are polarized and retain their orientation so that they will form a structure with luminal (airway lining) cells on the inside,” Hogan [Brigid Hogan, chair of the Duke Department of Cell Biology] said.
“Only about 5 percent of the basal cells we isolated and put into gel formed these spheres; perhaps these are the ones that are normally ready to leap into action when they are challenged.”
After painstakingly sorting individual green fluorescent mouse basal cells from the other lung tissue cells, the scientists studied the genes expressed in these mouse cells using microarray technology. They found more than 600 genes preferentially expressed in the basal cells compared with the other cells.
“We found that many of these genes are similar to genes expressed in stem cells in other tissues,” Hogan said. “We think these genes are helping these cells to stay â€˜quiet’ and keep them from dividing until they get the right signal.”
The researchers also found that one gene expressed in the basal cells encodes a surface receptor, also found on human lung basal cells.
“This meant we were able to use a labeled antibody against this receptor to efficiently extract human lung basal cells to create the human bronchospheres for study,” Hogan said.
Press release: Duke Scientists Create Model to Study Lung Diseases…
Image: Ciliary and secretory cells (green) form inside the basal stem cell (red)
Abstract in PNAS: Basal cells as stem cells of the mouse trachea and human airway epithelium