Objective:To explore the effects and the possible mechanism of bone marrow mesenchymal stem cell (BMMSC) transplantation on apoptosis in rats cerebral cortex after cardiac arrest/cardiopulmonary resuscitation (CA/CPR).Methods:The BMMSC of 2 Sprague-Dawley (SD) rats aged 4-5weeks was extracted, and the 3rd passage was used in experimental study. Eighteen Sprague-Dawley (SD) rats were divided into sham group, model group (CA/CPR group) and intervention group (BMMSC group) according to random number table method, with 6 rats in each group. CPR was performed 6 minutes after asphyxia induced CA. In sham group, CA was not induced except performing general surgical procedure. At 1 hour after return of spontaneous circulation (ROSC), 0.5 mL phosphate buffered saline (PBS) was injected through tail vein in CA/CPR group. 2×10 9/L green fluorescence protein (GFP)-labeled BMMSC was injected through tail vein 1 hour after ROSC in BMMSC group. Neurological deficit score (NDS) were assessed in every group at 72 hours after CPR. Serum S100 calcium binding protein B (S100B) levels were assayed by enzyme linked immunosorbent assay (ELISA). Distribution of BMMSC in brain was observed under a fluorescent microscope. Apoptosis rate in cerebral cortex was assayed by TdT-mediated dUTP nick-end labeling (TUNEL). Western blotting was performed to measure the expression levels of active aspartic acid specific cysteine proteinase (caspase-8 and caspase-9) in cerebral cortex. Results:At 3 days after CPR, compared with sham group, the apoptosis of cerebral cortex cells was increased and brain damage was obvious, NDS score was decreased significantly (56.6±5.5 vs. 80.0±0.0, P < 0.05), and serum S100B was increased markedly (ng/L: 45.1±4.7 vs. 19.1±1.4, P < 0.05), apoptosis rate of cerebral cortex cells increased significantly [(52.9±11.8)% vs. (10.1±1.5)%, P < 0.05], the level of active caspase-8 expression in cerebral cortex was significantly higher (caspase-8/GAPDH: 0.689±0.047 vs. 0.330±0.108, P < 0.05), and there was no significant difference in active caspase-9 protein expression (caspase-9/GAPDH: 0.428±0.014 vs. 0.426±0.021, P > 0.05) in CA/CPR group. After BMMSC transplantation, GFP-labeled BMMSC were primarily detected in cerebral cortex, compared with CA/CPR group, the apoptosis of cerebral cortex cells and brain injury were significantly improved in BMMSC group, NDS score increased significantly (70.6±2.1 vs. 56.6±5.5, P < 0.05), serum S100B levels in BMMSC group were lower (ng/L: 32.0±3.2 vs. 45.1±4.7, P < 0.05), apoptosis rate of cerebral cortex cells decreased significantly [(31.1±3.4)% vs. (52.9±11.8)%, P < 0.05], and the active caspase-8 expression in cerebral cortex in BMMSC group was significantly decreased (caspase-8/GAPDH: 0.427±0.067 vs. 0.689±0.047, P < 0.05). The active caspase-9 expression in cerebral cortex in BMMSC group and CA/CPR group were not significantly different (caspase-9/GAPDH: 0.431±0.022 vs. 0.428±0.014, P > 0.05). Conclusion:BMMSC transplantation can alleviate rat brain damage after CA/CPR possibly by inhibiting the death receptor mediated apoptotic pathway to inhibit the apoptosis of brain cells.

Objective:To explore the effects of calcium/calmodulin dependent protein kinase II (CaMKII) on myocardial ischemia-reperfusion injury in vitro, and apoptosis and autophagy of myocardial cells in isolated rats.Methods:Seventy female SD rats (250-280 g) with normal electrocardiogram were selected to establish the myocardial IR injury model by Langendorff perfusion system. These SD rats were randomly divided into five groups (n=14): cardiac ischemia reperfusion group (IR group), CaMKII phosphorylation activator group (IR+ isoproterenol group), CaMKII phosphorylation inhibitor analogue group (IR+KN92 group), CaMKII phosphorylation inhibitor group (IR+KN93 group), and control group. After reperfusion, the left ventricular function and myocardial morphology were measured to assess the myocardial injury, and TUNEL was performed to assess the apoptosis index. Western blot was used to determine the phosphorylation levels of CaMKII and PLN (p-CaMKII/CaMKII and p-PLN/PLN), and the expression levels of apoptosis-related proteins Bax, Bcl-2, cleaved caspase-3, and autophagy marker proteins LC3II/LC3I, Beclin-1 and P62.Results:Compared with the control group, the left ventricular function of the IR group was decreased, morphological arrangement of myocardial fibers was disordered, and the apoptosis index was increased. The levels of p-CaMKII/CaMKII, p-PLN/PLN, cleaved caspase-3, Bax/Bcl-2, LC3II/LC3I, and Beclin-1 were increased significantly, while the level of P62 was decreased significantly, and apoptosis and autophagy were increased significantly (all P<0.05). Compared with the IR group, the myocardial damage of rats in the IR+KN93 group was significantly improved, the apoptosis index was decreased, and the expression of p-CaMKII/CaMKII, p-PLN/PLN, Cleaved Caspase-3, Bax/Bcl-2, LC3II/LC3I and Beclin-1 were significantly decreased and the level of p62 was remarkable increased, and apoptosis and autophagy decreased significantly (all P< 0.05). Compared with the IR group, the left ventricular function was further decreased in the IR+ isoproterenol group, while the levels of apoptosis and autophagy were further increased ( P < 0.05), while there was no significant difference in myocardial indexes between the IR+ KN92 group and the IR group ( P > 0.05). Conclusions:Inhibition of CaMKII phosphorylation attenuates isolated myocardial ischemia-reperfusion injury by reducing apoptosis and autophagy.