[Effects of bone marrow mesenchymal stem cells on bleomycin induced pulmonary fibrosis in rats].

Objective: To study the effects of bone marrow mesenchymal stem cells (MSC) on pulmonary fibrosis.

Methods: Bone marrow MSC were harvested from 6 week old male SD rats. Forty-eight female SD rats were randomly divided into six groups. The pulmonary fibrosis models were made by intratracheal instillation of bleomycin (5 mg/kg in 0.3 ml normal saline). The normal controls received intratracheal instillation of NS instead of bleomycin. On the 1st and 7th day after bleomycin administration, the rats received MSC infusion or a same amount of phosphate buffer solution (PBS) as controls via the tail vein, respectively. The rats were sacrificed by the 28 day of experiment, and the pathologic changes and hydroxyproline contents of the lung tissues were investigated. The sry gene of Y chromosome was detected by polymerase chain reaction (PCR).

Results: For rats receiving MSC on the 1st and 7th day after bleomycin administration, the lung fibrotic scores were 1.0 +/- 0.2 and 1.6 +/- 0.5, respectively, significantly decreased as compared with rats receiving no MSC (2.5 +/- 0.5 & 2.3 +/- 0.8, respectively). The hydroxyproline contents of lung tissue were (83 +/- 17) microg/mg and (96 +/- 20) microg/mg, also significantly decreased as compared with rats receiving no MSCs [(123 +/- 32) microg/mg & (127 +/- 34) microg/mg, respectively]. Earlier administration of MSCs resulted in more significant improvement of lung injury. The sry gene (322 bp) was detected in lungs of female rats receiving MSC on the first day of bleomycin induced lung injury.

Conclusions: MSC may be involved in the repair of lung injury, especially in the early stage. MSCs are effective in preventing bleomycin induced lung injury and fibrosis.