[Atorvastatin protects swine bone marrow mesenchymal stem cells from apoptosis through AMPK but not PI3K/Akt pathway]

The effect of mesenchymal stem cells (MSCs) transplantation is poor because of the harsh environment post infarction. Our previous studies have proven that Statins could enhance the implanted bone marrow MSCs survival, but the exact mechanism remained to be clarified. We hypothesized that atorvastatin (Ator) could protect MSCs from hypoxia and serum-free (H/SF) induced apoptosis and investigated the potential mechanisms.

Chinese mini-swine's bone marrow derived MSCs were cultured in vitro and exposed to hypoxia and H/SF, Ator of various concentrations (0.001 - 10 µmol/L), AMPK inhibitor-compound C (CC), PI3K inhibitor-LY294002 (LY), Ator + CC and Ator + LY. Cell apoptosis was assessed using Annexin V/Prospidine Iodine kit by flow cytometry. Phosphorylation of AMPK, Akt, endothelial nitric oxide synthase (eNOS) level and phosphorylation were tested with Western blot. Real Time-PCR was performed to analyze the gene expression of AMPK, Akt and eNOS.

MSCs apoptosis in Ator (0.01 - 10 µmol/L) treated H/SF groups was significantly reduced compared with H/SF group (1.94% - 6.10% vs. 10.94%, P < 0.01 or 0.05). Apoptosis was higher in Ator + CC group than in 1 µmol/L Ator group (4.94% ± 0.98% vs. 2.59% ± 0.84%, P < 0.01) and similar between Ator + LY and 1 µmol/L Ator group (2.02% ± 0.45% vs. 2.59% ± 0.84%, P > 0.05). The gene expressions of AMPK, Akt and eNOS were significantly upregulated in atorvastatin treated groups. Meanwhile, phosphorylation of AMPK and eNOS increased in MSCs treated with atorvastatin (P < 0.01 or 0.05). Phosphorylation of eNOS significantly correlated with AMPK phosphorylation (r = 0.599, P = 0.004), but not with Akt phosphorylation (P = 0.263).

Atorvastatin can protect MSCs from H/SF induced apoptosis through AMPK pathway, which resulting in activation of eNOS.