Down-regulation of the autophagy gene, ATG7, protects bone marrow-derived mesenchymal stem cells from stressful conditions

다국어 초록 (Multilingual Abstract)

Background Mesenchymal stem cells (MSCs) are valuable for cell-based therapy. However, their applicationis limited owing to their low survival rate when exposed to stressful conditions.
Autophagy, the process by which cells recycle the cytoplasm and dispose of defectiveorganelles, is activated by stress stimuli to adapt, tolerate adverse conditions, or triggerthe apoptotic machinery. This study aimed to determine whether regulation of autophagywould affect the survival of MSCs under stress conditions.
Methods Autophagy was induced in bone marrow-derived MSCs (BM-MSCs) by rapamycin, andwas inhibited via shRNA-mediated knockdown of the autophagy specific gene, ATG7.
ATG7 expression in BM-MSCs was evaluated by reverse transcription polymerase chainreaction (RT-PCR), western blot, and quantitative PCR (qPCR). Cells were then exposedto harsh microenvironments, and a water-soluble tetrazolium salt (WST)-1 assay was performedto determine the cytotoxic effects of the stressful conditions on cells.
Results Of 4 specific ATG7-inhibitor clones analyzed, only shRNA clone 3 decreased ATG7expression. Under normal conditions, the induction of autophagy slightly increased theviability of MSCs while autophagy inhibition decreased their viability. However, understressful conditions such as hypoxia, serum deprivation, and oxidative stress, the inductionof autophagy resulted in cell death, while its inhibition potentiated MSCs to withstandthe stress conditions. The viability of autophagy-suppressed MSCs was significantlyhigher than that of relevant controls (P＜0.05, P＜0.01 and P＜0.001).
Conclusion Autophagy modulation in MSCs can be proposed as a new strategy to improve their survivalrate in stressful microenvironments.

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