Xing Qin

Rosuvastatin enhances the therapeutic efficacy of adipose-derived mesenchymal stem cells for myocardial infarction via PI3K/Akt and MEK/ERK pathways

The poor viability of transplanted stem cells hampers their therapeutic efficacy for treatment of myocardial infarction. The aim of this study was to investigate whether rosuvastatin improved survival of adipose-derived mesenchymal stem cells (AD-MSCs) after transplantation into infarcted hearts. AD-MSCs isolated from Tg(Fluc-egfp) mice which constitutively express both firefly luciferase (Fluc) and enhanced green fluorescent protein were transplanted into infarcted hearts with or without rosuvastatin administration. Longitudinal in vivo bioluminescence imaging and histological staining revealed that rosuvastatin enhanced the survival of engrafted AD-MSCs. Furthermore, combined therapy of AD-MSC and rosuvastatin reduced fibrosis, decreased cardiomyocyte apoptosis, and preserved heart function. AD-MSCs were then subjected to hypoxia and serum deprivation injury in vitro to mimic the ischemic environment. Rosuvastatin (10−6 mmol/L) enhanced the viability and paracrine effect of AD-MSCs, and decreased their apoptotic rate. Western blotting revealed that rosuvastatin supplementation increased Akt and ERK phosphorylation, which resulted in FoxO3a phosphorylation and nuclear export. In addition, rosuvastatin administration decreased the pro-apoptotic proteins Bim and Bax, and increased the anti-apoptotic proteins Bcl-xL and Bcl-2. Furthermore, these effects were abolished by PI3K inhibitor LY294002 and MEK1/2 inhibitor U0126. This study demonstrates that rosuvastatin may improve the survival of engrafted AD-MSCs at least in part through the PI3K/Akt and MEK/ERK1/2 signaling pathways. Combination therapy with rosuvastatin and AD-MSCs has a synergetic effect on improving myocardial function after infarction.

Adipose Stromal Cells Amplify Angiogenic Signaling via the VEGF/mTOR/Akt Pathway in a Murine Hindlimb Ischemia Model: A 3D Multimodality Imaging Study

Although adipose-derived stromal cell (ADSC) transplantation has been demonstrated as a promising therapeutic strategy for peripheral arterial disease (PAD), the mechanism of action behind the observed therapeutic efficacy of ADSCs remains unclear. This study was designed to investigate the long-term outcome and therapeutic behavior of engrafted ADSCs in a murine hindlimb ischemia model using multimodality molecular imaging approaches. ADSCs (1.0×107) were isolated from Tg(Fluc-egfp) mice which constitutively express dual-reporter firefly luciferase and enhanced green fluorescent protein (Fluc+-eGFP+, mADSCsFluc+GFP+), then intramuscularly injected into the hindlimb of BALB/c-nu mice after unilateral femoral artery ligation and excision. Abbreviated survival (∼5 weeks) of post-transplant mADSCs within the ischemic hindlimb was longitudinally monitored using noninvasive bioluminescence imaging (BLI), fluorescence imaging (FRI), and bioluminescence tomography with micro-computed tomography (BLT/micro-CT). Use of the BLT/micro-CT system enabled quantitative 3-dimensional (3D) imaging of the cells’ distribution and kinetics in vivo. Engrafted mADSCs improved blood perfusion recovery, ambulatory performance and prognosis of the ischemic hindlimb, probably by inducing angiogenesis and formation of collateral vessels, which could be visualized using laser Doppler perfusion imaging (LDPI), micro-CT angiography, vascular-cast imaging, and immunofluorescence. mADSCs augmented activation of the pro-angiogenic VEGF/mTOR/Akt pathway in vivo, even though the cells failed to incorporate into the host microvasculature as functional components. Downregulation of VEGF/mTOR/Akt signaling using small molecule inhibitors counteracted mADSC-induced angiogenesis and perfusion restoration. This study demonstrates for the first time the spatiotemporal kinetics and functional survival of transplanted mADSCs in a PAD model using in vivo 3D multimodality imaging. Our study indicates that mADSCs potentiate pro-angiogenic signal amplification via a VEGF/mTOR/Akt-dependent pathway, and thereby promote recovery from hindlimb ischemia.

Oncostatin M (OSM) protects against cardiac ischaemia/reperfusion injury in diabetic mice by regulating apoptosis, mitochondrial biogenesis and insulin sensitivity

Oncostatin M (OSM) exhibits many unique biological activities by activating Oβ receptor. However, its role in myocardial I/R injury in diabetic mice remains unknown. The involvement of OSM was assessed in diabetic mice which underwent myocardial I/R injury by OSM treatment or genetic deficiency of OSM receptor Oβ. Its mechanism on cardiomyocyte apoptosis, mitochondrial biogenesis and insulin sensitivity were further studied. OSM alleviated cardiac I/R injury by inhibiting cardiomyocyte apoptosis through inhibition of inositol pyrophosphate 7 (IP7) production, thus activating PI3K/Akt/BAD pathway, decreasing Bax expression while up‐regulating Bcl‐2 expression and decreasing the ratio of Bax to Bcl‐2 in db/db mice. OSM enhanced mitochondrial biogenesis and mitochondrial function in db/db mice subjected to cardiac I/R injury. On the contrary, OSM receptor Oβ knockout exacerbated cardiac I/R injury, increased IP7 production, enhanced cardiomyocyte apoptosis, impaired mitochondrial biogenesis, glucose homoeostasis and insulin sensitivity in cardiac I/R injured diabetic mice. Inhibition of IP7 production by TNP (IP6K inhibitor) exerted similar effects of OSM. The mechanism of OSM on cardiac I/R injury in diabetic mice is partly associated with IP7/Akt and adenine mononucleotide protein kinase/PGC‐1α pathway. OSM protects against cardiac I/R Injury by regulating apoptosis, insulin sensitivity and mitochondrial biogenesis in diabetic mice through inhibition of IP7 production.

Inositol pyrophosphates mediate the effects of aging on bone marrow mesenchymal stem cells by inhibiting Akt signaling

IntroductionBone marrow-derived mesenchymal stem cells (BM-MSCs) have been proposed as an ideal autologous stem cell source for cell-based therapy for myocardial infarction (MI). However, decreased viability and impaired function of aged MSCs hampered the therapeutic efficacy of engrafted MSCs, and the underlying mechanisms remain unclarified. Here, we investigated the role of inositol phosphates 6 kinase (IP6Ks) inhibition on the therapeutic efficacy of BM-MSCs and its underlying mechanism.MethodsBM-MSCs isolated from young (8-week-old) or aged (18-month-old) donor male C57BL/6 mice, were subjected to hypoxia and serum deprivation (H/SD) injury with or without administration of inositol phosphates 6 kinase (IP6Ks) inhibitor TNP (10 μM). MSC apoptosis induced by H/SD was determined by flow cytometry and TUNEL assays. Protein expressions were evaluated by Western blot assay. Furthermore, the paracrine effects of MSCs were measured by reverse transcriptase–polymerized chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) analyses.ResultsAged BM-MSCs exhibited more Inositol pyrophosphate 7 (IP7) production, compared with young BM-MSCs. Meanwhile, the expression of phospho-Akt (Thr308) was significantly decreased in the aged MSCs, resulting in enhanced Bad activation and decreased Bax/Bcl-2 ratio. Moreover, the apoptosis in aged BM-MSCs was increased, compared with young BM-MSCs. Furthermore, TNP administration significantly inhibited IP7 production and increased the phosphorylation of Akt under both normoxic and hypoxic conditions. Meanwhile, IP6Ks inhibition reduced apoptotic index of aged MSCs, associated with decreased expressions of pro-apoptotic proteins Bax and Bad and increased anti-apoptotic protein Bcl-2. The expressions of angiogenic factors, including VEGF, bFGF, IGF-1 and HGF, were decreased in MSCs from aged mice. In addition, TNP administration enhanced the paracrine efficiency of aged BM-MSCs under normoxic and hypoxic conditions.ConclusionsThis study demonstrates for the first time that IP6Ks and IP7 play critical role in the aging related vulnerability to hypoxic injury and impaired paracrine efficiency of BM-MSCs, which is associated with impaired Akt activation.

Effects of hepatocyte growth factor overexpressed bone marrow‐derived mesenchymal stem cells on prevention from left ventricular remodelling and functional improvement in infarcted rat hearts

Bone marrow‐derived mesenchymal stem cells (BM‐MSCs ) transplantation has been reported to be a promising therapy for myocardial infarction (MI). However, low survival rate of BM‐MSCs in infarcted heart is one of the major limitations for the perspective clinical application. In this study, we aimed to investigate the effect of hepatocyte growth factor (HGF) on left ventricular function improvement of HGF gene‐modified BM‐MSCs (HGF‐MSCs) after its delivery into the infarcted rat hearts. BM‐MSCs were isolated with fibroblast‐like morphology and expressed CD44+CD29+CD90+/CD34‐CD45‐CD31‐CD11a. After 5‐azacytidine induction in vitro, 20%–30% of the cells were positively stained for desmin, cardiac‐specific cardiac troponin I and connexin‐43. Histological staining revealed that 2 weeks after MI is an optimal time point with decreased neutrophil infiltration and increased vascular number. Minimal infarct size and best haemodynamic analysis were also observed after cell injection at 2 weeks compared with that of 1 h, 1 week or 4 weeks. Echocardiogram confirmed that transplantation with HGF‐MSCs significantly improved left ventricular function compared with other groups in rat MI models. MSCs and HGF‐MSCslabelled with DAPI were detected 4 weeks after MI in the infarcted area. Decreased infarcted scar area and increased angiogenesis formation could be found in HGF‐MSCs group than in other groups as demonstrated by hematoxylin and eosin (H&E) staining and factor VIII staining. These results indicate that HGF‐MSCs transplantation could enhance the contractile function and attenuate left ventricular remodelling efficiently in rats with MI. Copyright

Myocardial Protective Effect of Extracellular Superoxide Dismutase Gene Modified Bone Marrow Mesenchymal Stromal Cells on Infarcted Mice Hearts

Aim: Extracellular superoxide dismutase (ecSOD) is a unique scavenger of superoxide anions and a promising target of gene therapy for ischemia/reperfusion injury (I/R). However, conventional gene therapies have limitation in effectiveness and efficiency. This study aimed to investigate the protective effects of ecSOD gene modified bone marrow mesenchymal stromal cells (BMSCs) on cardiac function improvement in mice infarcted heart. METHODS & RESULTS: BMSCs were isolated from Fluc+ transgenic mice (Tg FVB[Fluc+]) and transfected by adenovirus combined with human ecSOD gene. ELISA was performed to determine ecSOD protein level. Female syngeneic FVB mice were randomized into 5 groups: (1) Sham group (sham); (2) MI group (MI); (3) MI+BMSCs group (BMSC); (4) MI+BMSCs-vector group (BMSC-vector); (5) MI+ BMSCs-ecSOD group (BMSC-ecSOD). MI was accomplished by ligation of the left anterior descending artery. BMSCs (2x106) were injected into the border zone of infarction. In vivo bioluminescence imaging (BLI) was performed to monitor transplanted BMSCs viability. Echocardiography and histological staining revealed that BMSCs-ecSOD significantly reduced myocardial infarction size and improved cardiac function. Lucigenin chemiluminescence, DHE and TUNEL staining demonstrated that BMSCs-ecSOD delivery reduced ROS level and cell apoptosis both in vivo and in vitro. Western blot assay revealed that ecSOD supplementation increased FoxO3a phosphorylation in cardiomyocytes. Moreover, quantitative real-time PCR showed that pro-apoptotic factors (bim and bax) were decreased while the anti-apoptotic factor mir-21 expression was increased after ecSOD intervention. CONCLUSION: Intra-myocardial transplantation of adenovirus-ecSOD transfected BMSCs could exert potential cardiac protection against MI, which may be partly through reduction of oxidative stress and improvement of BMSCs survival.

Percutaneous intramyocardial delivery of mesenchymal stem cells induces superior improvement in regional left ventricular function compared with bone marrow mononuclear cells in porcine myocardial infarcted heart.

Aim: To investigate the efficacy and feasibility of percutaneous intramyocardial injection of bone marrow mesenchymal stem cells (MSC) and autologous bone marrow-derived mononuclear cells (BMMNC) on cardiac functional improvement in porcine myocardial infarcted hearts. Methods and Results: Acute myocardial infarction (AMI) was induced in 22 minipigs by temporary balloon occlusion of the left anterior descending coronary artery for 60min.Two weeks post AMI, BMMNC (n = 7, 245 ± 98×106), MSC (n = 8, 56 ± 17×106), or phosphate buffered saline (PBS; n = 7) were injected intramyocardially. Cardiac function and myocardial perfusion were analyzed by echocardiography and gated single-photon emission computed tomography/computed tomography (SPECT/CT) at 1 week before AMI and 2 and 10 weeks after AMI. Cell engraftment, proliferation, vascular density, and cardiac fibrosis were evaluated by histology analysis. In all groups, the echocardiography revealed no significant change in the left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV), or left ventricular end-diastolic volume (LVEDV) at 10 weeks after AMI compared with those at 2 weeks after AMI. However, the wall motion score index (WMSI) and left ventricular systolic wall thickening (WT%) were significantly improved at 10 weeks compared with those at 2 weeks after AMI in the MSC group (WMSI 1.55 ± 0.06 vs. 1.87 ± 0.10, WT 33.4 ± 2.3% vs.24.8 ± 2.7%,p < 0.05) but not in the BMMNC group. In addition, myocardial perfusion quantified by SPECT/CT was improved in both the MSC and BMMNC groups, whereas the MSC group showed a superior improvement in vascular density and collagen volume fraction (p < 0.05). Conclusion: This preclinically relevant study suggests that when delivered by percutaneous (transcatheter) intramyocardial injection, MSC might be more effective than BMMNC to improve ischemia and reperfusion after AMI.

Effects of cannabinoid receptor type 2 on endogenous myocardial regeneration by activating cardiac progenitor cells in mouse infarcted heart.

Cannabinoid receptor type 2 (CB2) activation is recently reported to promote proliferation of some types of resident stem cells (e.g., hematopoietic stem/progenitor cell or neural progenitor cell). Resident cardiac progenitor cell (CPC) activation and proliferation are crucial for endogenous cardiac regeneration and cardiac repair after myocardial infarction (MI). This study aims to explore the role and possible mechanisms of CB2 receptor activation in enhancing myocardial repair. Our results revealed that CB2 receptor agonist AM1241 can significantly increase CPCs by c-kit and Runx1 staining in ischemic myocardium as well as improve cardiomyocyte proliferation. AM1241 also decreased serum levels of MDA, TNF-α and IL-6 after MI. In addition, AM1241 can ameliorate left ventricular ejection fraction and fractional shortening, and reduce fibrosis. Moreover, AM1241 treatment markedly increased p-Akt and HO-1 expression, and promoted Nrf-2 nuclear translocation. However, PI3K inhibitor wortmannin eliminated these cardioprotective roles of AM1241. In conclusion, AM1241 could induce myocardial regeneration and improve cardiac function, which might be associated with PI3K/Akt/Nrf2 signaling pathway activation. Our findings may provide a promising strategy for cardiac endogenous regeneration after MI.

GW24-e3687 Electroacupuncture pretreatment ameliorates myocardial ischemia/reperfusion injury through regulation of cannabinoid receptor type 2

Objectives Electroacupuncture (EA) therapy has been widely accepted as a useful therapeutic technique with low or no risk in the clinical prevention from cardiac disease. However, the physiological mechanism underlying this protective effect remains unclear. The current study investigates the effects of EA pretreatment on myocardial ischaemia/reperfusion (MI/R) injury in mice and its possible signalling pathway. Methods Up to 100 C57BL/6 mice were randomly divided into Sham, MI/R, EA + MI/R, EA (-) + MI/R, and AM630 + EA + MI/R groups (n = 20, each group). The mice in EA + MI/R and AM630 + EA + MI/R groups received EA pretreatment for 30 min before MI/R. Five minutes before EA pretreatment, mice received intraperitoneal injection of the cannabinoid receptor type 2 (CB2) selective inhibitor AM630 (20 mg/kg) or vehicle. Left anterior descending coronary artery ligature in mice was performed for 30 min, and the myocardium was reperfused for 3 h after knot release (for apoptosis, oxidative stress, and CB2 expression) or 24 h (for cardiac function and infarct size determination). Results EA pretreatment significantly ameliorated MI/R-induced myocardial injury, evidenced by increased cardiac function, reduced infarct size, and decreased apoptosis in mice. This was associated with a reduction of oxidative stress in the infarcted myocardium, which was through CB2. Administration of AM630 before EA pretreatment didn’t improve cardiac function and inhibit oxidative stress. The expression of CB2 was up-regulated in hearts after EA pretreatment, as well as content of N-arach-idonoylethanolamine-anandamide (AEA) and 2-arachidonylglycerol (2-AG) in heart tissue. Furthermore, the expression of AMPK and PGC-1α in the left ventricular myocardial tissue was decreased in MI/R group, while increased in EA pretreatment group. Preinjection of CB2 inhibitor AM630 could partially decreased the EA pretreatment-mediated AMPK or PGC-1α expression. Conclusions Pretreatment with EA increases the production of endocannabinoid, which elicits protective effects against MI/R injury through CB2 activation. The mechanism of this effect is related to the activation of AMPK/PGC-1α pathways, followed by an inhibition of oxidative stress. These results suggest a novel mechanism of EA pretreatment-induced protective effects on MI/R.