The Protective Function And Mechanism Of Exendin-4in Conjunction With ADSCs For Myocardial Infarction

Aims:Acute myocardial infarction (AMI), which is accompanied with irreversible loss of functional cardiomyocytes, adverse cardiac remodeling response and progressive deteriorative heart function, is still a leading cause of morbidity and mortality worldwide. Though clinical methods are available for MI, none of them is so satisfactory. Due to the limited regenerative capacity of adult heart, stem cell therapy has been emerging as a novel and prospective therapy for myocardial repair. Animal experiments and clinical studies show ed that stem cell-based therapy could treat MI and improve cardiac function.Adipose tissue derived stem cells (ADSCs) have recently been considered as a promising candidate for myocardial repair due to their abundant autologous source, ease to harvest, cardiomyogenic potential and definite therapeutic effects, as well as similar to bone marrow mesenchymal stem cells (BMSCs). However, the poor cells viability after transplantation due to the hostile engraftment environment largely attenuated the therapeutic effect, including oxidative stress, inflammation, low vascularization, et al.Exendin-4has been exhibited potent antidiabetic activities through glucagon-like peptide-1(GLP-1) receptor (GLP-1R), and exerts cardioprotective effects beyond glucose control, such as potential anti-inflammatory, anti-oxidant and anti-apoptotic effects. In particular, GLP-1has been shown to be able to promote the proliferation and significantly reduce apoptosis of mesenchymal stem cells. These effects hint that exendin-4may be a good adjuvant agent for stem cell therapy for myocardial repair. In this study, we investigated the feasibility and efficiency of exendin-4as an adjuvant drug for ADSC transplantation for MI, and explored the possible mechanisms that may be involved.Methods:1) We successfully performed the lentiviral transduction in ADSCs, assessed phenotype and differentiation of ADSCs.2) ADSCs were exposed to hydrogen peroxide/serum deprivation (H2O2/SD) to mimic the ischemic microenvironment in vitro. MI was induced by the left anterior descending artery ligation in adult male Sprague-Dawley rats. ADSCs carrying double-fusion reporter gene (firefly luciferase and monomeric red fluorescent protein (Fluc-mRFP)) were quickly injected into border zone of myocardial infarction in rats treated with or without Exendin-4. Multi-techniques were used to assess the function and mechanism of ADSCs adjuvant with Exendin-4through improving ischemic microenvironment.3) Adhesion, ROS and necrosis were analyzed for ADSCs pretreated with or without Exendin4. Cardiac function, histology, immunohistochemistry were evaluatied in the SD rats MI model.Results:1) ADSCs labeled by lentiviral carrying Fluc-mRFP were successfully constructed.2) Longitudinal in vivo bioluminescence imaging indicated that Exendin-4enhanced the survival of transplanted ADSCs. Moreover, ADSCs adjuvant with Exendin-4decreased oxidative stress, apoptosis and fibrosis. They also improved myocardial viability and cardiac function as well as increased the differentiation rates of ADSCs into cardiomyocytes and vascular smooth muscle cells in vivo. In vitro, Exendin-4decreased the apoptosis and enhanced the paracrine effect of ADSCs. Western blotting demonstrated that Exendin-4activated STAT3through the phosphorylation of Akt and ERK1/2. Furthermore, Exendin-4increased expression of the anti-apoptotic protein Bcl-2and decreased the pro-apoptotic protein Bax in ADSCs.3) In vitro, Exendin-4pretreatment decreased the ROS level, necrosis and LDH release in ADSCs. Excessive ROS in ADSCs attenuated the adhesion-related integrins expression, which were restored by Exendin-4pretreatment. Meanwhile, Exendin-4could promote the adhesive property of ADSCs through activated Fak-Src complex. In vivo, Bioluminescence imaging showed that Exendin-4could promote ADSCs retention and survival in ischemic microenvironment. ADSCs pretreated with Exendin-4could significantly improve the cardiac function, decrease fibrosis, enhance vascular density.CONCLUSIONS:1) Real-time tracking in vivo on ADSCs platform was successfully constructed.2) Exendin-4could improve the survival and therapeutic efficacy of transplanted ADSCs through STAT3activation via the phosphorylation of Akt and ERK1/2.3) Pretreatment of ADSCs with Exendin-4could improve therapeutic efficiency following myocardial infarction via enhanced adhesion.4) This study suggests the potential of Exendin-4for stem cell based heart regeneration.