Singapore scientists have made a breakthrough by identifying the stem cell that is key to understanding the regeneration of the lung tissue, a research promotion agency said on Friday. The scientists at the Genome Institute of Singapore and the Institute of Molecular Biology, both units of the Agency for Science, Technology and Research, found that a specific type of stem cells in the lungs known as the distal airway stem cells (DASCs) are involved in forming new alveoli to replace and repair damaged lung tissue. Alveoli are tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged in the blood. The research provides \"a firm foundation for understanding lung regeneration,\" the agency said. The team did the research by cloning adult stem cells taken from three different parts of the lungs, nasal epithelial stem cells, tracheal airway stem cells and distal airway stem cells. Despite the three types of cells being nearly 99 percent genetically identical, the team made the surprising observation that only DASCs formed alveoli when cloned in vitro. \"We are the first researchers to demonstrate that adult stem cells are intrinsically committed and will only differentiate into the specific cell type they originated from,\" said Wa Xian, principal investigator at the Institute of Molecular Biology. The research was jointly led by Wa and Frank McKeon from the Genome Institute of Singapore in collaboration with scientists at the National University of Singapore, and clinicians at the Harvard Medical School and the Brigham and Women\'s Hospital in Boston.