Background: 3,5,3'-Levo-triiodothyronine (L-T3) replacement elicits postischaemic recovery of the heart limiting cell death, but it is unknown whether this effect depends on preservation of resident stem cells pool. Signals of ischemic cell death are mainly generated from mitochondria following the hydrogen peroxide (H2O2) release. The mitochondrial turnover promotes cell survival by removing damaged mitochondria. We hypothesize that L-T3 prevents ischemic-induced death of human mesenchymal stem cells (hMSCs) by enhancing the mitochondrial turnover. Methods: hMSCs were exposed for 24h to H2O2 (100?M) and treated with L-T3 at physiological dose (3nM for 24h, T3-SCs) or vehicle (SCs). We measured cell caspase-3 activation, as a marker of apoptosis, in each experimental condition. The mitochondrial turnover was investigated by measuring the number of mitochondria, the cell level of parkin, a mediator of mitophagy, and mitochondrial transcription factor A (TFAM), a mediator of mitochondrial biogenesis. The experiments were repeated in hMSCs after parkin or TFAM downregulation using selective short interfering-RNA (siRNA). Results: Significant two-fold increase of caspase 3-activation was observed in stressed SCs, but not in T3-SCs. TFAM expression was significantly reduced by 71.4% in SCs compared to unstressed cells, but the parkin expression was unchanged. L-T3 treatment of stressed hMSCs increased the expression of TFAM (2.2?0.2 vs. 1?0.1 a.u., p<0.05) and parkin (2.7?0.1 vs. 1.6?0.1 a.u., p<0.05) compared to SCs, without affecting cell differentiation. Parkin or TFAM downregulation completely abolished the prosurvival effects of L-T3 in hMSCs exposed to H2O2. Conclusions: L-T3 treatment at physiological dose increases survival of hMSCs in presence of oxidative stress by enhancing mitochondrial turnover without promoting cell differentiation.
L-triiodothyronine rescues mesenchymal stem cells from H2O2-induced cell death by eliciting mitochondrial turnover.
Forini F;Di Primio C;Nicolini G;Iervasi G;
2011
Abstract
Background: 3,5,3'-Levo-triiodothyronine (L-T3) replacement elicits postischaemic recovery of the heart limiting cell death, but it is unknown whether this effect depends on preservation of resident stem cells pool. Signals of ischemic cell death are mainly generated from mitochondria following the hydrogen peroxide (H2O2) release. The mitochondrial turnover promotes cell survival by removing damaged mitochondria. We hypothesize that L-T3 prevents ischemic-induced death of human mesenchymal stem cells (hMSCs) by enhancing the mitochondrial turnover. Methods: hMSCs were exposed for 24h to H2O2 (100?M) and treated with L-T3 at physiological dose (3nM for 24h, T3-SCs) or vehicle (SCs). We measured cell caspase-3 activation, as a marker of apoptosis, in each experimental condition. The mitochondrial turnover was investigated by measuring the number of mitochondria, the cell level of parkin, a mediator of mitophagy, and mitochondrial transcription factor A (TFAM), a mediator of mitochondrial biogenesis. The experiments were repeated in hMSCs after parkin or TFAM downregulation using selective short interfering-RNA (siRNA). Results: Significant two-fold increase of caspase 3-activation was observed in stressed SCs, but not in T3-SCs. TFAM expression was significantly reduced by 71.4% in SCs compared to unstressed cells, but the parkin expression was unchanged. L-T3 treatment of stressed hMSCs increased the expression of TFAM (2.2?0.2 vs. 1?0.1 a.u., p<0.05) and parkin (2.7?0.1 vs. 1.6?0.1 a.u., p<0.05) compared to SCs, without affecting cell differentiation. Parkin or TFAM downregulation completely abolished the prosurvival effects of L-T3 in hMSCs exposed to H2O2. Conclusions: L-T3 treatment at physiological dose increases survival of hMSCs in presence of oxidative stress by enhancing mitochondrial turnover without promoting cell differentiation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
