Gene Expression Profiling for Monitoring Graft Rejection in Heart Transplant Recipients

Heart transplantation is a life-prolonging therapy for many patients with stage D heart failure and other forms of advanced heart disease. However, graft rejection and/or immunosuppression-related side effects are major causes of morbidity and death among heart transplant patients. Graft rejection monitoring remains a challenge. It would be desirable to be able to detect rejection early enough and specifically enough to prevent allograft dysfunction without unnecessary overimmunosuppression. Hitherto, the main technique employed in monitoring the rejection status of a transplanted heart has been endomyocardial biopsy (EMB), which allows rejection to be screened for and monitored on the basis of the extent and distribution of lymphocytic infiltrates and associated myocardial damage. However, EMB has significant limitations: it is invasive, its sensitivity is limited by sampling efficacy, and it suffers from considerable between-observer variability. Although many noninvasive techniques have been investigated, none so far has proved able to match the performance of EMB. Currently, a multiparametric approach is employed that comprises clinical examination for signs or symptoms of heart failure, EMBs, drug level monitoring, allograft function tests (mainly echocardiographic studies), and screening for allograft vasculopathy. Gene expression profiling may be a promising tool for this purpose.