Multipotent mesenchymal stem cells (MSCs) are located in the human adult lung and have an extended life span in vivo. Plumonary MSCs were derived from bronchoalveolar lavage (BAL) samples obtained from lung transplant recipients undergoing bronchoscopy.
BAL-derived mesenchymal cells exhibited typical characteristics of classical bone marrow–derived MSCs, such as: adherence to plastic surface in tissue culture; formation of distinct colony-forming units (CFU-Fs) in cell culture; expression of surface proteins typically associated with MSCs but not of hematopoietic stem cell markers (CD34, CD45 and CD14); multipotent differentiation capacity of individual colonies to give rise to adipocytes, chondrocytes, and osteocytes.
Bronchoalveolar lavage (BAL) samples (10–50 ml) obtained from lung transplant recipients undergoing bronchoscopy were processed for isolation of mesenchymal cells. Recovered BAL fluid was filtered through sterile gauze for noncellular particulate material and mucus removal. Cells were pelleted by centrifugation at 1,000 g for 5 minutes and seeded at a density of 2×106 mononuclear cells per 100 mm cell culture dish. The cells were cultured in medium consisting of high-glucose DMEM supplemented with fetal bovine serum (10%), penicillin/streptomycin (100 U/ml), and fungizone (0.5%). Medium was first replaced after 24 hours and then every 3 days thereafter. Single separated fibroblastoid colonies termed CFU-Fs were identified at a mean interval of 14 days (range, 7–21 days) from initial plating. To study mesenchymal cells obtained from each individual patient, all colonies growing in a 100-cc plate were trypsinized and passed into a T-75 flask. A homogeneous population of mesenchymal cells was obtained from individual patients by second passage.
EMBRYONIC DEVELOPMENT & STEM CELL COMPENDIUM
