Acute Cellular Graft Rejection clinical trials

Cardiac Mitochondrial Function After Heart Transplantation

Studies have shown that cardiac function is affected immediately after heart transplantation (HTx), but seems to recover to some extent over the first year. This immediate effect is associated with lack of oxygen in the tissue and reperfusion injury causing cellular energy depletion, mitochondrial failure and cellular damage. This condition may progress into full blown primary graft failure (PGF), characterized as deterioration of the transplanted heart, which is seen in 3-30 % of HTx patients. In addition to PGF, chronic rejection owing to cardiac allograft vasculopathy (CAV) may develop. PGF and CAV remain the major heart related mortality causes, and additional assessment and treatments are therefore needed. Acute cellular rejection (ACR) is diagnosed based on endomyocardial biopsies (EMB), which are routinely performed to ensure prober immunosuppression in HTx patients. ACR occur in approximately 25% of HTx patients, and is associated with PGF and CAV. However, mitochondrial function and integrity may prove to be a more sensitive marker of allograft rejection than endomyocardial biopsies. Therefore, assessment of mitochondrial function may allow for earlier detection of allograft rejection and dysfunction. This may be of particular importance as emerging treatments are targeting both energy substrate supply for adenosine-triphosphate generation produced by the mitochondria and mitochondrial function in the failing heart. Despite the association between graft rejection and mitochondrial function, it remains unsettled whether mitochondrial function associate with PGF, ACR and CAV. Such findings may be of prognostic importance and even elucidate new treatment targets. Hence, we evaluate the mitochondrial status in HTx patients through four studies designed to assess different aspects of the interplay between cardiac function and mitochondrial integrity and function. Hypotheses: Study 1: Primary graft pump function is correlated to mitochondrial function in the first myocardial biopsy taken from the donor heart during the operation. Study 2: Cardiac mitochondrial function improves over the first 3 months after a heart transplantation. Study 3: Heart transplant patients with moderate to severe coronary graft vasculopathy has impaired mitochondrial function. Study 4: Myocardial external energy efficiency by positron-emission tomography can be used as a marker of mitochondrial function and chronic rejection in HTx patients.