[The experimental study of suppressing silicosis fibrosis]

To compare the difference of effects on SiO(2)-induced alveolitis and early fibrosis between bone marrow-derived mesenchymal-like stem cells (BM-MSCs) and BM-MSCs transfected by pcDNA3.1-HGF and to explore the mechanism of this effects.

The Primary BM-MSCs from Wistar male young rats were cultured and labeled by 4, 6-diamidino-2-phenylindole (DAPI). Fifty Wistar rats were randomly divided into 3 groups:model group (10 rats),which was administered with SiO(2) by the trache, the next day,injected PBS via the tail vein; BM-MSCs group (20 rats),which was administered with SiO(2) by the trache, the next day,injected with 1 ml suspension of BM-MSCs via the tail vein; pcDNA3.1-HGF plus BM-MSC group (20 rats),which was administered with SiO(2) by the trache, the next day,injected with 1 ml suspension of BM-MSCs transfected by pcDNA3.1-HGF via the tail vein. On the 14th and 28th days after treatment, half of the animals were sacrificed, respectively, and the lungs were harvested for frozen section to observe the cell marked by DAPI. HE staining under a fluorescent microscope, and to observe the pulmonary alveolitis and fibrosis by HE and Masson staining under a light microscope. Western blot assay was used to detect the expression of HGF in rat lungs. The expression levels of tumor necrosis factor-α (TNF-α) in pulmonary tissues were analyzed quantitatively by ELISA. The contents of HYP in pulmonary tissues were analyzed quantitatively by sample hydrolysis method.

On the 14th and 28th days after treatment, the scores of pulmonary alveolitis and early fibrosis in pcDNA3.1-HGF plus BM-MSCs group were 2.36 ± 0.17, 2.8 ± 0.14 and 0.1 ± 0.11, 1.16 ± 0.13, which were significantly lower than those (1.68 ± 0.17, 1.58 ± 0.31 and 0.54 ± 0.15, 1.36 ± 0.13) in BM-MSCs group, also which were significantly lower those (2.36 ± 0.17, 2.80 ± 0.14 and 0.64 ± 0.09, 1.84 ± 0.17) in model group (P < 0.05); On the 14th and 28th days after treatment, the TNF-α contents of pulmonary tissues in pcDNA3.1-HGF plus BM-MSCs group were 280.4 ± 23.11 and 249.78 ± 22.33 pg/mg, which were significantly lower than those (341.58 ± 35.34, 442.29 ± 36.76 pg/mg and 319.51 ± 17.84, 348.53 ± 33.95 pg/mg) in BM-MSCs and model groups (P < 0.05); On the 14th and 28th days after treatment, the HYP contents of pulmonary tissues in pcDNA3.1-HGF plus BM-MSCs group were 0.46 ± 0.04 and 0.65 ± 0.05 µg/mg, which were significantly lower than those (0.63 ± 0.04, 1.04 ± 0.07 µg/mg and 0.72 ± 0.60, 1.39 ± 0.60 µg/mg) in BM-MSCs and model groups (P < 0.05).

The effects of BM-MSCs transfected by pcDNA3.1-HGF on suppressing pulmonary alveolitis and early fibrosis induced by SiO2 were better than those of BM-MSCs. The mechanism may be associated with the reduced pulmonary inflammation.