Fengyun Zhang1, Fei Gao2, Kun Wang3, Xiaohong Liu2, Zhuoqi Zhang4. 1. Department of Cardiology, the Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221000, People's Republic of China. 2. Department of Cardiology, Institute of Cardiovascular Research, Affiliated Hospital of Xuzhou Medical University, Xuzhou, People's Republic of China. 3. Department of Cardiology, First People's Hospital of Suqian, Suqian, People's Republic of China. 4. Department of Cardiology, the Affiliated Hospital of Xuzhou Medical University, 99 West Huaihai Road, Xuzhou, 221000, People's Republic of China. zhuoqizhang@sina.com.
Abstract
BACKGROUND: Mesenchymal stem cells (MSCs) are favourable treatments for ischaemic diseases; however, MSCs from diabetic patients are not useful for this purpose. Recent studies have shown that the expression of miR-34a is significantly increased in patients with hyperglycaemia; the precise role of miR-34a in MSCs in diabetes needs to be clarified. OBJECTIVE: The aim of this study is to determine the precise role of miR-34a in MSCs exposed to hyperglycaemia and in recovery heart function after myocardial infarction (MI) in diabetes mellitus (DM) rats. METHODS: DM rat models were established by high-fat diet combined with streptozotocin (STZ) injection. MSCs were isolated from the bone marrow of donor rats. Chronic culture of MSCs under high glucose was used to mimic the DM micro-environment. The role of miR-34a in regulating cell viability, senescence and paracrine effects were investigated using a cell counting kit-8 (CCK-8) assay, senescence-associated β-galactosidase (SA-β-gal) staining and vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) ELISA, respectively. The expression of autophagy- and senescence-associated proteins in MSCs and silent information regulator 1 (SIRT1) and forkhead box class O 3a (FoxO3a) were analysed by western blotting. Autophagic bodies were analysed by transmission electron microscopy (TEM). The MI model was established by left anterior descending coronary artery (LAD) ligation, and then, the rats were transplanted with differentially treated MSCs intramuscularly at sites around the border zone of the infarcted heart. Thereafter, cardiac function in rats in each group was detected via cardiac ultrasonography at 1 week and 3 weeks after surgery. The infarct size was determined through a 2,3,5-triphenyltetrazolium chloride (TTC) staining assay, while myocardial fibrosis was assessed by Masson staining. RESULTS: The results of the current study showed that miR-34a was significantly increased under chronic hyperglycaemia exposure. Overexpression of miR-34a was significantly associated with impaired cell viability, exacerbated senescence and disrupted cell paracrine capacity. Moreover, we found that the mechanism underlying miR-34a-mediated deterioration of MSCs exposed to high glucose involved the activation of the SIRT1/FoxO3a autophagy pathway. Further analysis showed that miR-34a inhibitor-treated MSC transplantation could improve cardiac function and decrease the scar area in DM rats. CONCLUSIONS: Our study demonstrates for the first time that miR-34a mediates the deterioration of MSCs' functions under hyperglycaemia. The underlying mechanism may involve the SIRT1/FoxO3a autophagy signalling pathway. Thus, inhibition of miR-34a might have important therapeutic implications in MSC-based therapies for myocardial infarction in DM patients.
BACKGROUND: Mesenchymal stem cells (MSCs) are favourable treatments for ischaemic diseases; however, MSCs from diabetic patients are not useful for this purpose. Recent studies have shown that the expression of miR-34a is significantly increased in patients with hyperglycaemia; the precise role of miR-34a in MSCs in diabetes needs to be clarified. OBJECTIVE: The aim of this study is to determine the precise role of miR-34a in MSCs exposed to hyperglycaemia and in recovery heart function after myocardial infarction (MI) in diabetes mellitus (DM) rats. METHODS: DM rat models were established by high-fat diet combined with streptozotocin (STZ) injection. MSCs were isolated from the bone marrow of donor rats. Chronic culture of MSCs under high glucose was used to mimic the DM micro-environment. The role of miR-34a in regulating cell viability, senescence and paracrine effects were investigated using a cell counting kit-8 (CCK-8) assay, senescence-associated β-galactosidase (SA-β-gal) staining and vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) ELISA, respectively. The expression of autophagy- and senescence-associated proteins in MSCs and silent information regulator 1 (SIRT1) and forkhead box class O 3a (FoxO3a) were analysed by western blotting. Autophagic bodies were analysed by transmission electron microscopy (TEM). The MI model was established by left anterior descending coronary artery (LAD) ligation, and then, the rats were transplanted with differentially treated MSCs intramuscularly at sites around the border zone of the infarcted heart. Thereafter, cardiac function in rats in each group was detected via cardiac ultrasonography at 1 week and 3 weeks after surgery. The infarct size was determined through a 2,3,5-triphenyltetrazolium chloride (TTC) staining assay, while myocardial fibrosis was assessed by Masson staining. RESULTS: The results of the current study showed that miR-34a was significantly increased under chronic hyperglycaemia exposure. Overexpression of miR-34a was significantly associated with impaired cell viability, exacerbated senescence and disrupted cell paracrine capacity. Moreover, we found that the mechanism underlying miR-34a-mediated deterioration of MSCs exposed to high glucose involved the activation of the SIRT1/FoxO3a autophagy pathway. Further analysis showed that miR-34a inhibitor-treated MSC transplantation could improve cardiac function and decrease the scar area in DM rats. CONCLUSIONS: Our study demonstrates for the first time that miR-34a mediates the deterioration of MSCs' functions under hyperglycaemia. The underlying mechanism may involve the SIRT1/FoxO3a autophagy signalling pathway. Thus, inhibition of miR-34a might have important therapeutic implications in MSC-based therapies for myocardial infarction in DM patients.
Authors: Johannes A Govaert; Rutger-Jan Swijnenburg; Sonja Schrepfer; Xiaoyan Xie; Koen E A van der Bogt; Grant Hoyt; William Stein; Katherine J Ransohoff; Robert C Robbins; Joseph C Wu Journal: J Heart Lung Transplant Date: 2009-09-26 Impact factor: 10.247
Authors: Vincenza Cifarelli; Laura M Lashinger; Kaylyn L Devlin; Sarah M Dunlap; Jennifer Huang; Rudolf Kaaks; Michael N Pollak; Stephen D Hursting Journal: Diabetes Date: 2015-01-09 Impact factor: 9.461