Single-walled carbon nanotubes promote rat vascular adventitial fibroblasts to transform into myofibroblasts by SM22-α expression

The aim of this study was to explore whether single-wall carbon nanotubes (SWCNTs) can be used as artery tissue-engineering materials by promoting vascular adventitial fibroblasts (VAFs) to transform into myofibroblasts (MFs) and to find the signal pathway involved in this process. VAFs were primary cultured and incubated with various doses of SWCNTs suspension (0, 0.8, 3.2, 12.5, 50, and 200 μg/mL). In the present study, we used three methods (MTT, WST-1, and WST-8) at the same time to detect the cell viability and immunofluorescence probe technology to investigate the effects of oxidative injury after VAFs incubated with SWCNTs. Immunocytochemical staining was used to detect SM(22)-α expression to confirm whether VAFs transformed into MFs. The protein levels were detected by western blotting. The results of immunocytochemical staining showed that SM(22)-α was expressed after incubation with 50 μg/mL SWCNTs for 96 hours, but with oxidative damage. The mRNA and protein levels of SM(22)-α, C-Jun N-terminal kinase, TGF-β(1), and TGF-β receptor II in VAFs increased with the dose of SWCNTs. The expression of the p-Smad2/3 protein was upregulated while the Smad7 protein was significantly down-regulated. Smad4 was translocated to the nucleus to regulate SM(22)-α gene expression. In conclusion, SWCNTs promoted VAFs to transform into MFs with SM(22)-α expression by the C-Jun N-terminal kinase/Smads signal pathway at the early stage (48 hours) but weakened quickly. SWCNTs also promoted the transformation by the TGF-β(l)/Smads signal pathway at the advanced stage in a persistent manner. These results indicate that SWCNTs can possibly be used as artery tissue-engineering materials.