Jiang-Yong Min

Significant improvement of heart function by cotransplantation of human mesenchymal stem cells and fetal cardiomyocytes in postinfarcted pigs

BACKGROUND Viable cardiomyocytes after myocardial infarction (MI) are unable to repair the necrotic myocardium due to their limited capability of regeneration. The present study investigated whether intramyocardial transplantation of human mesenchymal stem cells (hMSCs) or cotransplantation of hMSCs plus human fetal cardiomyocytes (hFCs; 1:1) reconstituted impaired myocardium and improved cardiac function in MI pigs. METHODS AND RESULTS Cultured hMSCs were transfected with green fluorescent protein (GFP). Six weeks after MI induction and cell transplantation, cardiac function was significantly improved in MI pigs transplanted with hMSCs alone. However, the improvement was even markedly greater in MI pigs cotransplanted with hMSCs plus hFCs. Histological examination demonstrated that transplantation of hMSCs alone or hMSCs plus hFCs formed GFP-positive engrafts in infarcted myocardium. In addition, immunostaining for cardiac alpha-myosin heavy chain and troponin I showed positive stains in infarcted regions transplanted with hMSCs alone or hMSCs plus hFCs. CONCLUSIONS Our data demonstrate that transplantation of hMSCs alone improved cardiac function in MI pigs with a markedly greater improvement from cotransplantation of hMSCs plus hFCs. This improvement might result from myocardial regeneration and angiogenesis in injured hearts by engrafted cells.

Asiatic acid, a pentacyclic triterpene from Centella asiatica, is neuroprotective in a mouse model of focal cerebral ischemia

Asiatic acid, a triterpenoid derivative from Centella asiatica, has shown biological effects such as antioxidant, antiinflammatory, and protection against glutamate‐ or β‐amyloid‐induced neurotoxicity. We investigated the neuroprotective effect of asiatic acid in a mouse model of permanent cerebral ischemia. Various doses of asiatic acid (30, 75, or 165 mg/kg) were administered orally at 1 hr pre‐ and 3, 10, and 20 hr postischemia, and infarct volume and behavioral deficits were evaluated at day 1 or 7 postischemia. IgG (blood–brain barrier integrity) and cytochrome c (apoptosis) immunostaining was carried out at 24 hr postischemia. The effect of asiatic acid on stress‐induced cytochrome c release was examined in isolated mitochondrial fractions. Furthermore, its effects on cell viability and mitochondrial membrane potential were studied in HT‐22 cells exposed to oxygen‐glucose deprivation. Asiatic acid significantly reduced the infarct volume by 60% at day 1 and by 26% at day 7 postischemia and improved neurological outcome at 24 hr postischemia. Our studies also showed that the neuroprotective properties of asiatic acid might be mediated in part through decreased blood–brain barrier permeability and reduction in mitochondrial injury. The present study suggests that asiatic acid may be useful in the treatment of cerebral ischemia.

Neuroprotective effect of cyanidin-3-O-glucoside anthocyanin in mice with focal cerebral ischemia

The present study sought to determine the neuroprotective effect of anthocyanin cyanidin-3-O-glucoside (CG), isolated and purified from tart cherries, against permanent middle cerebral artery occlusion (pMCAO) in mice and its potential mechanisms of neuroprotection. C57BL/6 mice subjected to pMCAO were treated with CG orally. Twenty-four hours after pMCAO, neurological scoring was used to evaluate functional outcome. The brains were then excised for measuring infarct volume and brain superoxide levels were determined. In a separate set of experiments, the influence of CG on cytochrome c (cyt c) and apoptosis-inducing factor (AIF) release from mitochondria under oxidative stress were assessed in isolated cortical neurons from adult mouse brains. Infarction volume was attenuated by 27% in mice pre-treated with 2mg/kg of CG compared to vehicle-treated mice. Delayed treatment with 2mg/kg of CG also showed 25% reduction in infarct size. Neurological functional outcome was significantly improved in mice pre- or post-treated with CG. Compared to vehicle treated mice CG treated mice had lower levels of brain superoxide. CG also blocked the release of AIF from mitochondria under oxidative stress, but did not inhibit the release of cyt c. Our data show that CG is neuroprotective against pMCAO in mice, and this beneficial effect may be mediated by attenuation of brain superoxide levels after ischemia. CG may also exert its neuroprotective effect by blocking AIF release in mitochondria.

Differential Neuroprotective Effects of Carnosine, Anserine, and N-Acetyl Carnosine against Permanent Focal Ischemia

Carnosine (β‐alanyl‐L‐histidine) has been shown to exhibit neuroprotection in rodent models of cerebral ischemia. In the present study, we further characterized the effects of carnosine treatment in a mouse model of permanent focal cerebral ischemia and compared them with its related peptides anserine and N‐acetylated carnosine. We also evaluated the efficacy of bestatin, a carnosinase inhibitor, in ameliorating ischemic brain damage. Permanent focal cerebral ischemia was induced by occlusion of the middle cerebral artery (pMCAO). Mice were subsequently randomly assigned to receive an intraperitoneal injection of vehicle (0.9% saline), carnosine, N‐acetyl carnosine, anserine, bestatin alone, or bestatin with carnosine. Infarct size was examined using 2,3,5‐triphenyltetrazolium chloride staining 1, 3, and 7 days following pMCAO, and neurological function was evaluated using an 18‐point‐based scale. Brain levels of carnosine were measured in treated mice using high‐performance liquid chromatography 1 day following pMCAO. We demonstrated that treatment with carnosine, but not its analogues, was able to significantly reduce infarct volume and improve neurological function compared with those in vehicle‐treated mice. These beneficial effects were maintained for 7 days post‐pMCAO. In contrast, compared with the vehicle‐treated group, bestatin‐treated mice displayed an increase in the severity of ischemic lesion, which was prevented by the addition of carnosine. These new data further characterize the neuroprotective effects of carnosine and suggest that carnosine may be an attractive candidate for testing as a stroke therapy.

Cardiac Dysfunction After Left Permanent Cerebral Focal Ischemia The Brain and Heart Connection

Background and Purpose— Stroke can lead to cerebrogenic cardiac arrhythmias. We sought to investigate the effect of ischemic stroke on cardiac function in a mouse model of permanent middle cerebral artery occlusion (pMCAO). Methods— Twenty-four hours after the induction of focal ischemia, cardiac function was measured in mice by endovascular catheterization of the heart. Immediately after hemodynamic measurements, mice were euthanized and brains were excised and sectioned to measure infarct volume and the severity of insular cortex injury. Myocardial damage was evaluated by hematoxylin-eosin staining. Serum and heart levels of norepinephrine (NE) were also determined. Results— Cardiac dysfunction occurred in 9 out of 14 mice that underwent left pMCAO. In these 9 mice, the severity of left insular cortex lesion was greater than the mice with normal heart function. The serum and heart levels of NE were significantly higher in left pMCAO mice with heart dysfunction. Liner regression analysis indicates significant inverse correlation between the severity of left insular cortex damage and heart dysfunction. Mice that underwent right pMCAO did not exhibit cardiac dysfunction. Conclusions— This study shows that left focal cerebral ischemia can produce cardiac dysfunction, which is associated with the extent of left insular cortex damage. Furthermore, mice exhibiting cardiac dysfunction had elevated levels of NE in the serum and heart.

Clozapine-induced myocarditis: Role of catecholamines in a murine model

Clozapine, an atypical antipsychotic, is very effective in the treatment of resistant schizophrenia. However, cardiotoxicity of clozapine, particularly in young patients, has raised concerns about its safety. Increased catecholamines have been postulated to trigger an inflammatory response resulting in myocarditis, dilated cardiomyopathy, and death, although this has not yet been thoroughly studied. Here, we used the mouse to study whether clozapine administration could cause adverse myocarditis associated with an increase in catecholamines. Male Balb/C mice, age ~6 weeks, were administered 5, 10 or 25 mg/kg clozapine daily for 7 and 14 days; one group was administered 25 mg/kg clozapine plus 2 mg/kg propranolol for 14 days. Saline-treated mice served as controls. Heart sections were stained with hematoxylin and eosin for histopathological examination. Plasma catecholamines were measured with HPLC. Myocardial TNF-alpha concentrations were determined by ELISA. Histopathology of clozapine-treated mice showed a significant dose-related increase in myocardial inflammation that correlated with plasma catecholamine levels and release of TNF-alpha. Propranolol significantly attenuated these effects. A hypercatecholaminergic state induced by clozapine could explain the occurrence of myocarditis in some patients. Our data suggest that a beta-adrenergic blocking agent may be effective in reducing the incidence and severity of clozapine-induced myocarditis.

Induction of Cardiac Cytochrome P450 in Cocaine-Treated Mice

Cytochrome P450 (P450) is a ubiquitous family of enzymes responsible for the metabolism of a wide variety of drugs and their metabolites, including cocaine. To investigate the effects of cocaine on myocardial injuries and cardiac P450 expression, BALB/c mice were injected daily intraperitoneally with cocaine (30 mg/kg) or cocaine plus pretreatment of P450 inhibitors for 14 days. Tumor necrosis factor-α (TNF-α) content and creatine phosphokinase (CPK) activity in mice hearts and serums were significantly increased after long-term treatment with cocaine. Pretreatment with the P450 inhibitor, cimetidine (Cime, 50 mg/kg) or metyrapone (Mety, 40 mg/kg) abolished or significantly attenuated the effects of cocaine on TNF-α and CPK activity. Western blot analysis shows that mouse cardiac tissues express the P450 isoforms CYP1A1, CYP1A2, and CYP2J2. The protein levels normalized with cyclophilin A were 1.20 ± 0.07, 0.67 ± 0.03, and 1.48 ± 0.01 for CYP1A1, CYP1A2, and CYP 2J2, respectively. After cocaine administration, CYP2J2 increased by 43.6% and CYP1A1 increased by 108.5%, but CYP1A2 was not significantly altered. However, the cytochrome P450 inhibitors Cime and Mety suppressed the cocaine-induced increase in CYP1A1 and CYP2J2 expression. Moreover, application of Cime or Mety alone did not alter the level of cardiac TNF-α or the expression of P450. Our results demonstrate that long-term exposure to cocaine causes an increase in cardiac CYP1A1 and CYP2J2 concentration. We speculate that induction of P450 isoforms may cause cardiac injury due to cocaine metabolites locally catalyzed by P450 or the increase in P450 expression itself.

Embryonic stem cells attenuate viral myocarditis in murine model.

We used mice to test our hypothesis that in response to viral invasion, stem cells may migrate into the heart and attenuate the effect of viral myocarditis. Male BALB/c mice were divided into three groups: mouse embryonic stem (ES) cell control, encephalomyocarditis virus (EMCV), and EMCV + ES cells. After administration of ES cells via tail vein, mice were immediately inoculated with EMCV. Mice were sacrificed at different days after EMCV inoculation. Mortality was recorded. Inflammatory cell infiltration and necrosis (major pathological changes of viral myocarditis) were evaluated by hematoxylin-eosin staining. ES cell migration and differentiation were identified by immunofluorescence. The survival rate in the EMCV + ES cell group (80%) was significantly increased (p < 0.05) over the EMCV-alone group (64%). Also, the incidence of inflammatory cell infiltration and myocardial lesions was lower in the EMCV + ES cell mice. Furthermore, the result of green fluorescent protein (GFP) and a-actinin analysis indicated that ES cells migrated into the heart and differentiated into myocytes after virus inoculation. In conclusion, ES cells significantly increased the survival of viral myocarditis mice and also decreased the necrosis and infiltration of inflammatory cells. These results demonstrated the ability of stem cells to mitigate the effects of viral infection on the heart and illustrated their potential therapeutic application to other mammalian species, including humans.

Differential Patterns of Cocaine-Induced Organ Toxicity in Murine Heart versus Liver

To determine cocaines toxicity in different organs, BALB/c mice were intraperitoneally injected daily for 15 days with either saline or cocaine: 10 mg/kg, 30 mg/kg, or 60 mg/kg. Cardiac function, hepatic pathophysiology, heart and liver apoptosis, and tumor necrosis factor (TNF-α) levels were analyzed. After administration of cocaine, cardiac function decreased. Inflammatory cell infiltration and eosinophilic contraction bands were visible in the hearts of mice treated with 60mg/kg cocaine. Moreover, histopathology demonstrated that cocaine caused hepatic necrosis. TdT-mediated dUTP nick end-labeling (TUNEL) staining and DNA ladder analysis indicated that cocaine caused apoptosis in both the heart and liver. Moreover, immunoassay showed that TNF-α levels significantly increased in the heart and liver with cocaine administration. However, our RT-PCR study showed that there was no significant difference in either the heart or liver in the levels of mRNA for TNF-α between cocaine-treated and saline control mice. The present study demonstrated that cocaine is toxic to multiple organs, and at low dose can induce hepatic damage without gross pathological injury to the heart. The results suggest that the liver is more sensitive than the heart to cocaine toxicity, and induction of apoptosis or TNF-α elevation may be a common mechanism responsible for cocaines toxicity.

Pathophysiology and management of reperfusion injury and hyperperfusion syndrome after carotid endarterectomy and carotid artery stenting

Cerebral hyperperfusion is a relatively rare syndrome with significant and potentially preventable clinical consequences. The pathophysiology of cerebral hyperperfusion syndrome (CHS) may involve dysregulation of the cerebral vascular system and hypertension, in the setting of increase in cerebral blood flow. The early recognition of CHS is important to prevent complications such as intracerebral hemorrhage. This review will focus on CHS following carotid endarterectomy and carotid artery stenting. We will discuss the typical clinical features of CHS, risk factors, pathophysiology, diagnostic modalities for detection, identification of patients at risk, and prevention and treatment. Although currently there are no specific guidelines for the management of CHS, identification of patients at risk for CHS and aggressive treatment of hypertension are recommended.