Editors' ChoiceLung Disease

Breathing Easier

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Science Translational Medicine  25 May 2011:
Vol. 3, Issue 84, pp. 84ec78
DOI: 10.1126/scitranslmed.3002659

Each year, more than 400,000 patients in the United States die of debilitating chronic lung disorders such as chronic obstructive lung disease and pulmonary fibrosis. Given the lack of effective treatments, lung transplantation is often the only option. However, the lack of donor lungs for transplantation leaves many patients with chronic lung disease suffering from severe shortness of breath or hooked up to a ventilator.

In a landmark study, Kajstura et al. now purify and characterize a population of rare multipotent lung stem cells from adult human lung tissue. They identified this stem cell population on the basis of expression of the c-kit stem cell surface antigen, a strategy used successfully to isolate human hematopoietic and cardiac stem cells. The investigators verified the identity of these lung stem cells in vitro by analyzing lineage- and developmental-specific patterns of gene expression. Then they transplanted these human stem cells into the injured lungs of immunosuppressed mice and showed that they are able to regenerate healthy lung tissue, including the distal bronchioles and pulmonary vasculature, within 2 weeks. Next, the researchers demonstrated the self-renewal capacity of their human lung stem cell population by isolating the transplanted lung stem cells and serially transplanting them into the injured lungs of another group of recipient mice.

The identification of multipotent stem cells in human lung tissue has far-reaching implications for respiratory medicine. But there are many hurdles to overcome and questions to answer before these cells can be used in the clinic. For example, these lung stem cells are very rare and are hard to isolate and grow in culture. Will these lung stem cells be beneficial for treating acute lung injury? Could they be used in combination with tissue-engineering strategies or partial lung transplantation to boost replacement of damaged lung tissue in human patients? And most importantly, it is not known whether lung tissues repopulated by these cells are fully functional in vivo. Nevertheless, the new findings will energize physicians and scientists in their pursuit of ways to repair injured lung tissue and help the many patients suffering from deadly respiratory disorders.

J. Kajstura et al., Evidence for human lung stem cells. N. Engl. J. Med. 364, 1795–1806 (2011). [Abstract]

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