Transplanted Heart Cardiomyocytes Reveal Continous Expression of Antiapoptotic Bcl-2 Protein

BackgroundApoptotic mechanisms take place in cardiocyte death during acute heart graft rejection and remodeling by the mitochondrial pathway. This process is suppressed by Bcl-2 protein. Besides that, knowledge about cardiocyte antiapoptotic responses after heart transplantation is scanty. We sought to estimate Bcl-2 expression in the absence of rejection.MaterialThe study group included endomyocardial biopsies taken at 1 week, 1 month, 1 through to 10 years after heart transplant, which showed rejection grade “0”; the control group were donor heart fragments.MethodBcl-2 expression was determined immunohistochemically by NP030 antibody (DAKO) and Envision-DAB. The intensity of staining was assessed semiquantitatively.ResultsNo Bcl-2 expression was seen in the controls; in the posttransplant groups, the significantly strongest sarcoplasmic reaction was observed at 1 week after heart transplant. Thereafter, the reaction decreased, and was weakest in the 3- and 5-year groups. From this time, Bcl-2 expression increased albeit without statistical significance. The intensity of the reaction showed no correlation with the time elapsed from heart transplant (Spearman r = 0.05; P > .05).ConclusionThe expression of antiapoptotic Bcl-2 protein occurs during the entire posttransplant period, being probably a preservative and adaptative response.