BACKGROUND: Lung fibroblasts are believed to play an important role in lung tissue repair and regenerative process. The differentiation potential of lung fibroblasts is not known very well.OBJECTIVE: To investigate the multi-differentiation capacity of human lung fibroblasts.DESIGN: An observational comparative experiment.SETTING: Department of Respiratory Medicine, Beijing Shijitan Hospital and Central Laboratory of the First Hospital of Tsinghua University.MATERIALS: This study was performed at the Central Laboratory of the First Hospital of Tsinghua University from March 2006 to October 2006. Human adult lung fibroblasts were isolated as primary cultures from resected lung of patients with lung cancer.The study was approved by hospital's Medical Ethics Committee, and informed consent was signed. Dulbecco's modified Eagle's medium (DMEM), fetal calf serum (FCS), trypsin- ethylenediamine tetraacetic acid (EDTA), naphthol AS-MX phosphate and Fast Red TR were purchased from Sigma, USA. Mouse anti-human osteopondn antibody was from R&D Systems China Co., Ltd,Polyvinyl difluoride (PVDF) membranes were from Bio-Rad Laboratories Inc, Hercules, CA.METHODS: Human adult lung fibroblasts were isolated as primary cultures. Human lung fibroblasts were cultured in an osteogenic medium (containing 109-10-5 mol/L dexamethasone, 50 mg/L vitamin C and 10 mmol/L β-glycerophospate) and adipogenic medium (containing 15% horseurm, 10-8 mol/L dexamethasone and 10 mg/L insulin), or control medium (10% FCS).Ostcoblasts were detected by alkaline phosphatese (ALP) and calcium salt staining. The expression of osteopontin was measured by Western blotting. Oil Red-O staining was used for identification of mature adipocytes.MAIN OUTCOME MEASURES: The differentiation of lung fibroblasts induced by osteogenie medium; The differentiation of lung fibroblasts induced by adipogenic medium.RESULTS: With the induction of ostcogenic medium for 2 weeks, the differentiation of lung fibroblasts was induced by osteogenic and adipogenic medium, respectively. The expression of ALP and osteopontin was increased and the deposition of calcium salt was detected. After lung fibroblasts were cultured in adipogenic medium for 14 days, part of the cells gradually experienced morphological change from original spindle into oval shape. Oil Red -O staining indicated lipid drops accumulation within cytoplasm.CONCLUSION: Under certain condition, human long fibroblasts could differentiate into osteoblasts or adipocytes that were characterized by bone marrow mesenchymal stem cells.

Objective To investigate the differentiation potential of human lung fibroblasts.Methods The study was performed in First Hospital of Tsinghua University from March 2006 to October 2006.Human lung fibroblasts were cultured for 2 weeks in an osteogenic medium[containing 10% fetal calf serum (FCS)and 50 g/mL Vitamin C and 10 mmol/L ?-glycerophospate],adipogenic medium(containing 15% horse serum,10-8 mol/L dexmethasone and 10 mg/L insulin),or control medium(10% FCS).Osteoblasts were detected by alkaline phosphatese and calcium salt staining.The expression of osteopontin was measured by Western blotting,Oil Red -O staining for identification of mature adipocytes.Results With the induction of osteogenic medium for 2 weeks,the expression of alkaline phosphatese and osteopontin was increased and the deposition of calcium salt was detected.Mature adipocytes formed after culture with adipogenic medium for 2 weeks.Conclusion Under certain condition,human lung fibroblasts can differentiate into osteoblasts or adipocytes,which were characterized by bone marrow mesenchymal stem cells.