Bone marrow mesenchymal stem cells can differentiate into type II alveolar epithelial cells in vitro.

In this study, we demonstrate that BMSCs (bone marrow mesenchymal stem cells) can be successfully differentiated into type II alveolar epithelial cells in vitro under mimic pulmonary microenvironment. BMSCs were co-cultured with MRC-5 cells in modified SAGM (small airway growth medium). The BMSC-derived type II alveolar epithelial cells morphologically resemble human lung epithelial cells. They began to appear after 10 days in co-culture and became morphologically dominant after day 15. Correspondingly, SPC (surfactant protein C), a specific functional marker of human type II alveolar epithelial cells, was detected in differentiated cells by RT-PCR (reverse transcription-PCR) analysis after day 15. Immunostaining analysis revealed the present of scattered SPC-positive cells with a differentiation efficiency of 2.43-4.21%. Our study further showed that the SPC gene expression level in differentiated cells was related to the ratio of BMSCs to MRC-5 cells and the components of modified SAGM.