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Background: Tumor necrosis factor a receptor 1 (TNFalphaR1) plays an important role in the signal pathway of apoptosis. The objective of this study was to investigate the effects of TNFalphaR1 knockout on the up-regulation of erythropoietin receptor (Epo-R) and the coordinated anti-apoptosis functions during myocardial ischemia-reperfusion injury in mice., Methods: The ischemia-reperfusion injury model for cardiomyocytes was performed by ligating the left circumflex branch artery of TNFalphaR1 knockout (P55(-/-)) C17 B6 mice, as well as wild-type (P55(+/+)) C17 B6 mice. Triphenyltetrazolium chloride (TTC) staining was performed to observe the damaged area of the heart. TUNEL staining and DNA fragmentation were used to identify apoptosis. Mitochondrial Bcl-2 and Bax as well as expression of Epo-R and its downstream genes (Jak-2, stat-5, Akt, IkB-alpha, HIF-1alpha) were measured by Western blotting. The gene knockout mice were assigned into those undergoing the apoptosis surgical model group (KO group), and those subjected to sham operation (KOs group). Similarly, wild-type mice were either exposed to the surgical model (WT group) or subject to a sham operation (WTs group)., Results: The myocardial damage ratio of the wild-type group after the operation was significantly higher than that of the knockout group, (50.5 +/- 6.4)% vs (36.9 +/- 6.9)%, P < 0.01. Similarly, TUNEL positive ratio of the wild-type group was significantly higher than that of the knockout group, (63.1 +/- 5.6)% vs (42.1 +/- 4.7)%, P < 0.01. The gray value ratios of Epo-R, Jak-2, stat-5, Akt, IkB-alpha, HIF-1 and mitochondrial Bcl-2 in the KO group were significantly higher than those of the WT group, P < 0.05; however, mitochondrial Bax was significantly lower than that of the WT group significantly (P < 0.05)., Conclusions: Using the ischemia-reperfusion injury model in mice, cardiomyocytes of TNFalphaR1 knockouts exhibited anti-apoptotic characteristics. This information could be used to coordinate the prevention of myocardial apoptosis by up-regulating and activating the Epo-R pathway.

Objective: The present study was designed to test whether transplantation of human bone marrow-derived mesenchymal stem cells (hMSCs) in New Zealand rabbits with myocardial infarction can improve heart function; and whether engrafted donor cells can survive and transdifferentiated into cardiomyocytes., Methods: Twenty milliliters bone marrow was obtained from healthy men by bone biopsy. A gradient centrifugation method was used to separate bone marrow cells (BMCs) and red blood cells. BMCs were incubated for 48 h and then washed with phosphate-buffered saline (PBS). The culture medium was changed twice a week for 28 d. Finally, hematopoietic cells were washed away to leave only MSCs. Human MSCs (hMSCs) were premarked by BrdU 72 h before the transplantation. Thirty-four New Zealand rabbits were randomly divided into myocardial infarction (MI) control group and cell treated group, which received hMSCs (MI+MSCs) through intramyocardial injection, while the control group received the same volume of PBS. Myocardial infarction was induced by ligation of the left coronary artery. Cell treated rabbits were treated with 5 x 10(6) MSCs transplanted into the infarcted region after ligation of the coronary artery for 1 h, and the control group received the same volume of PBS. Cyclosporin A (oral solution; 10 mg/kg) was provided alone, 24 h before surgery and once a day after MI for 4 weeks. Echocardiography was measured in each group before the surgery and 4 weeks after the surgery to test heart function change. The hearts were harvested for HE staining and immunohistochemical studies after MI and cell transplantation for 4 weeks., Results: Our data showed that cardiac function was significantly improved by hMSC transplantation in rabbit infarcted hearts 4 weeks after MI (ejection fraction: 0.695+/-0.038 in the cell treated group (n=12) versus 0.554+/-0.065 in the control group (n=13) (P<0.05). Surviving hMSCs were identified by BrdU positive spots in infarcted region and transdifferentiated into cardiomyocytes characterized with a positive cardiac phenotype: troponin I., Conclusion: Transplantation of hMSCs could transdifferentiate into cardiomyocytes and regenerate vascular structures, contributing to functional improvement.