Mesenchymal stem cells (MSC) are a well-characterized population of adult stem cells. MSC have the potential to develop into mature cells that produce fat, cartilage, bone, tendons, and muscle. These properties, in combination with their developmental plasticity, have generated tremendous interest because of the potential use of MSC in regenerative medicine. Fetal lung is a rich source of MSC and studies have shown that MSC can differentiate into neural cells. MSC also enhance the engraftment of human umbilical cord blood-derived CD34 hematopoietic cells in immunodeficient mice. Flow cytometric analysis showed that fetal lung MSC express CD13, CD29, CD44, CD90, CD105, CD166, and also HLA-ABC. Human Pulmonary Mesenchymal Stem Cells allow to stablish in vitro disease models for High Throughput and High Content Screening.