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Myocardial apoptosis and injury of donor hearts kept in completely beating status with normothermic blood perfusion for transplants.

OBJECTIVE
Normothermic blood perfusion is the developing trend of donor heart preservation. Theoretically, donor hearts preserved in a beating status may be the perfect method to reduce time-dependent ischemic injury, resuscitate marginal hearts expanding the donor pool and potentially improve the function of isolated hearts. In this study, to investigate the protective effect of normothermic blood perfusion, we maintained the donor hearts in a beating status and compared the changes of myocardial apoptosis and injury with standard hypothermic and static storage.


METHODS
Thirty rat hearts were preserved in static cold storage (Group A, n=10, stored in 4°C histidine-tryptophan-ketoglutarate solution), or in static normothermic blood perfusion (Group B, n=10, perfused with normothermic blood) or in beating status (Group C, n=10, perfused continuously with normothermic blood) for 9 hours. Myocardial injury markers including creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI), myocardial metabolic rate related indicators including Methane Dicarboxylic Aldehyde (MDA) and Adenosine Triphosphate (ATP) were investigated before and after preservation. And also TUNEL staining and mRNA and protein expression of apoptosis markers such as Bax, Bcl-2, Caspase-3 and Cleaved Caspase-3 were used to evaluated the degree of myocardial apoptosis.


RESULTS
It is found that the levels of CK-MB and cTnI in Group C were significantly lower than those of Group A and Group B (P<0.05). However, there was no significant statistical difference of ATP content among three groups. When compared with Group A and B, the quality of MDA in Group C was obviously lower. In addition, it showed that a remarkable reduction in TUNEL-positive nuclear staining in Group C but higher in other two groups. And inhibited apoptosis was also confirmed by the results of mRNA and protein expression of apoptosis markers including Bax and Bcl-2.


CONCLUSIONS
It is an effective and appropriate approach to preserve donor hearts with continuous and normothermic blood perfusion as to keep them in beating status in heart transplantation, which could reduce myocardial ischemic damage and cardiac apoptosis in long-term preservation.