OBJECTIVE: To explore a feasibility of engraftment of systemically transplanted bone marrow stromal cells (BMSCs) and differentiation into lung epithelial cells in lipopolysaccharides (LPS)-injured lungs. METHODS: BMSCs were isolated from bone marrow of transgenic green fluorescent protein (GFP) C57BL/6J mice and systemically administered to bone marrow-suppressed wild-type C57BL/6J mice. A mouse model of lung injury was prepared by intratracheal instillation of LPS. Recipients were assigned to four groups: intratracheal PBS + BMSCs transplantation (CM), intratracheal LPS + BMSCs transplantation (LM), intratracheal PBS + irradiation + BMSCs transplantation (CIM) and intratracheal LPS+ irradiation + BMSCs transplantation (LIM). BMSCs engraftment in recipient lungs was determined by immunofluorescent staining 14 days after BMSCs administration. Alveolar epithelial type II cells were isolated from recipient lungs and the rate of GFP positive cells was measured by flow cytometry. Expression of surfactant protein (SP)-A, SP-C and aquaporin (AQP)-5 mRNA in the lungs was evaluated by real-time PCR. RESULTS: GFP and cytokeratin positive cells were observed in lung parenchyma of the CIM and the LIM groups, but not in the CM and the LM groups. The LIM group had more positive cells than the CIM group. The rates of GFP positive cells were higher in the CIM (11.10+/- 3.19%) and the LIM groups (14.40+/- 2.40%) than those in the CM and the LM groups (2.82+/- 1.03% and 3.81+/- 0.93%, respectively; P< 0.05). The LIM group had higher mRNA expression of SP-C than the CM group (2.09+/- 0.18 vs 1.38+/- 0.30; P< 0.05). CONCLUSIONS: Donor derived BMSCs can engraft in LPS-injured lungs and differentiate into lung epithelial cells, suggesting BMSCs transplantation might contribute to lung repair.