Xiangshao Fang

Mesenchymal stem cells transplantation suppresses inflammatory responses in global cerebral ischemia: contribution of TNF-α-induced protein 6

Aim:To investigate the effects of mesenchymal stem cells (MSCs) transplantation on rat global cerebral ischemia and the underlying mechanisms.Methods:Adult male SD rats underwent asphxial cardiac arrest to induce global cerebral ischemia, then received intravenous injection of 5×106 cultured MSCs of SD rats at 2 h after resuscitation. In another group of cardiac arrest rats, tumor necrosis factor-α-induced protein 6 (TSG-6, 6 μg) was injected into the right lateral ventricle. Functional outcome was assessed at 1, 3, and 7 d after resuscitation. Donor MSCs in the brains were detected at 3 d after resuscitation. The level of serum S-100B and proinflammatory cytokines in cerebral cortex were assayed using ELISA. The expression of TSG-6 and proinflammatory cytokines in cerebral cortex was assayed using RT-PCR. Western blot was performed to determine the levels of TSG-6 and neutrophil elastase in cerebral cortex.Results:MSCs transplantation significantly reduced serum S-100B level, and improved neurological function after global cerebral ischemia compared to the PBS-treated group. The MSCs injected migrated into the ischemic brains, and were observed mainly in the cerebral cortex. Furthermore, MSCs transplantation significantly increased the expression of TSG-6, and reduced the expression of neutrophil elastase and proinflammatory cytokines in the cerebral cortex. Intracerebroventricular injection of TSG-6 reproduced the beneficial effects of MSCs transplantation in rats with global cerebral ischemia.Conclusion:MSCs transplantation improves functional recovery and reduces inflammatory responses in rats with global cerebral ischemia, maybe via upregulation of TSG-6 expression.

Impaired Cerebral Mitochondrial Oxidative Phosphorylation Function in a Rat Model of Ventricular Fibrillation and Cardiopulmonary Resuscitation

Postcardiac arrest brain injury significantly contributes to mortality and morbidity in patients suffering from cardiac arrest (CA). Evidence that shows that mitochondrial dysfunction appears to be a key factor in tissue damage after ischemia/reperfusion is accumulating. However, limited data are available regarding the cerebral mitochondrial dysfunction during CA and cardiopulmonary resuscitation (CPR) and its relationship to the alterations of high-energy phosphate. Here, we sought to identify alterations of mitochondrial morphology and oxidative phosphorylation function as well as high-energy phosphates during CA and CPR in a rat model of ventricular fibrillation (VF). We found that impairment of mitochondrial respiration and partial depletion of adenosine triphosphate (ATP) and phosphocreatine (PCr) developed in the cerebral cortex and hippocampus following a prolonged cardiac arrest. Optimal CPR might ameliorate the deranged phosphorus metabolism and preserve mitochondrial function. No obvious ultrastructural abnormalities of mitochondria have been found during CA. We conclude that CA causes cerebral mitochondrial dysfunction along with decay of high-energy phosphates, which would be mitigated with CPR. This study may broaden our understanding of the pathogenic processes underlying global cerebral ischemic injury and provide a potential therapeutic strategy that aimed at preserving cerebral mitochondrial function during CA.

Ultrastructural evidence of mitochondrial abnormalities in postresuscitation myocardial dysfunction

OBJECTIVES Though there is evidence to implicate that the mitochondrion may play an important role in the development of postresuscitation myocardial dysfunction, limited data are available regarding the ultrastructural alterations of the mitochondria, mitochondrial energy-producing ability, and their relationship to postresuscitation myocardial dysfunction. This study was designed to determine whether mitochondrial abnormalities contribute to the development of postresuscitation myocardial dysfunction. METHODS Fifteen anesthetized male Sprague-Dawley rats were randomized to: (1) global myocardial ischemia/reperfusion, in which 8 min of ventricular fibrillation was induced and successful defibrillation was achieved after 6 min of cardiopulmonary resuscitation (CPR); (2) global myocardial ischemia, in which ventricular fibrillation and CPR were performed without defibrillation attempt; and (3) sham control. RESULTS Myocardial function was significantly impaired after resuscitation. Mitochondria were massively swollen in global ischemic hearts and mildly swollen in the resuscitated hearts. Concomitantly, ATP levels abruptly declined during global ischemia and partially recovered after resuscitation. Furthermore, mitochondrial abnormalities were supported by the incapability of utilizing energy substrates manifested by the accumulations of intramyocellular lipid droplets and glycogen deposits. CONCLUSIONS In this model of cardiac arrest and CPR, the presence of ultrastructural mitochondrial abnormalities, further evidenced by the incapability of utilizing energy substrates and impairment of energy-production, might, in part, contribute to the development of postresuscitation myocardial dysfunction.

Carbon monoxide releasing molecule‑2 attenuated ischemia/reperfusion‑induced apoptosis in cardiomyocytes via a mitochondrial pathway.

Carbon monoxide (CO) is an endogenous gaseous transmitter that exerts multi-protection in ischemia/reperfusion (I/R) injury, but few experimental studies regarding CO on myocardial I/R-induced apoptosis, as well as its underlying mechanism have been conducted. The present study was designed to investigate whether CO released from CO-releasing molecule-2 (CORM-2) is capable of ameliorating myocardial I/R-induced apoptosis via a mitochondrial apoptotic pathway. Primary cultures of neonatal rat cardiomyocytes were randomly distributed into four groups: Control, I/R (cultured cardiomyocytes were subjected to 2 h simulated ischemia followed by 4 h reperfusion), CORM-2 and inactive CORM-2 (iCORM-2) groups (20 µM CORM-2 and 20 µM iCORM-2 were administered at the beginning of reperfusion following ischemia, respectively). Flow cytometric analysis showed that CORM-2 treatment significantly decreased apoptosis of cardiomyocytes triggered by simulated I/R. CORM-2 partially recovered mitochondrial respiration and ultrastructure alteration, and lowered caspase-3 expression and the release of cytochrome c. Furthermore, CORM-2 partly reduced BAK/BAX expression in mitochondria, as well as the BAX level in the cytoplasm. Cardioprotection is lost when CORM-2 is replaced by iCORM-2. CORM-2 treatment, at the time of reperfusion, was concluded to attenuate myocardial I/R-induced apoptosis. The protection mechanisms may be targeted to the mitochondria and involved in the inhibition of the BAK/BAX‑mediated intrinsic pathway.

Activation of Pyruvate Dehydrogenase Activity Bydichloroacetate Improves Survival and Neurologic Outcomes After Cardiac Arrest in Rats

ABSTRACT No pharmacological interventions are currently available to provide neuroprotection for patients suffering from cardiac arrest. Dichloroacetate (DCA) is a pyruvate dehydrogenase kinase inhibitor, which activates pyruvate dehydrogenase (PDH), and increases cell adenosine triphosphate (ATP) production by promoting influx of pyruvate into the Krebs cycle. In this study, we investigated the effects of DCA on post-resuscitation neurological injury in an asphyxial cardiac arrest rat model. Asphyxial cardiac arrest was established by endotracheal tube clamping. A total of 111 rats were randomized into three groups: Sham group, Control group, and DCA intervention group. Animals in DCA intervention group were intraperitoneally administered DCA with a loading dose of 80 mg/kg at 15 min after return of spontaneous circulation (ROSC), whereas rats in the Control group received equivalent volume of saline. DCA treatment increased 3-day survival time, and reduced neurologic deficit scores at 24, 48, and 72 h after ROSC. It also attenuated cellular apoptosis and neuronal damage in the hippocampal cornuammonis one region by hematoxylin-eosin staining and TdT-mediated dUTP nick-end labeling assay. In addition, DCA reduced the messenger RNA expression of tumor necrosis factor &agr; and interleukin 1&bgr; in brain hippocampus and cortex after ROSC. Furthermore, DCA treatment significantly increased ATP production, PDH activity, and decreased blood glucose, lactate, and brain pyruvate levels after ROSC. Our results suggested that DCA has neuroprotective effects on brain injury after cardiac arrest, and its salutary effects were associated with an increase of mitochondrial energy metabolism in the brain through activation of PDH activity.

Inhibition of dynamin-related protein 1 has neuroprotective effect comparable with therapeutic hypothermia in a rat model of cardiac arrest

&NA; Dynamin‐related protein 1 (Drp1) regulates mitochondrial fission, it has been proven that inhibition of Drp1 by mdivi‐1 improves survival and attenuates cerebral ischemic injury after cardiac arrest. In this study, we compared the effects of Drp1 inhibition with therapeutic hypothermia on post‐resuscitation neurologic injury in a rat model of cardiac arrest. Rats were randomized into 4 groups: mdivi‐1 treatment group (n = 39), hypothermic group (n = 38), normothermic group (n = 41), and sham group (n = 12). The rats in the mdivi‐1 treatment group were received intravenously 1.2 mg/kg of mdivi‐1 at 1 minute after the return of spontaneous circulation (ROSC). In rats in hypothermia group, rapid cooling was initiated at 5 minutes after resuscitation, and the core temperature was maintained to 33 ± 0.5°C for 2 hours. The results showed that both Drp1 inhibition and therapeutic hypothermia increased 3‐day survival time (all P < 0.05) and improved neurologic function up to 72 hours post cardiac arrest. In addition, both Drp1 inhibition and therapeutic hypothermia decreased cell injury, apoptosis in hippocampal cornu ammonis 1 region and brain mitochondrial dysfunction including adenosine triphosphate production, reactive oxygen species and mitochondrial membrane potential after cardiac arrest. Moreover, therapeutic hypothermia decreased mitochondrial Drp1 expression and mitochondrial fission after cardiac arrest. In conclusion, inhibition of Drp1 has a similar effect to therapeutic hypothermia on neurologic outcome after resuscitation in this cardiac arrest rat model, and the neuroprotective effects of therapeutic hypothermia are associated with inhibition of mitochondrial fission.