Study of Heart Transplant Rejection

Cardiac transplantation has been successful in improving survival in end stage heart failure. But graft rejection has limited survival after transplantation. In the first year, acute cellular rejection and infection remain the most common causes of morbidity and mortality. Afterwards, cardiac allograft vasculopathy (CAV), as a result of chronic vascular rejection, is the major cause of morbidity and mortality. Within the first year post-transplantation, almost two-thirds of recipients will experience at least one rejection episode. At five years post-transplantation, nearly 50% of survivors will have CAV. Clinically, the symptoms of acute rejection are relatively nonspecific (fatigue, dyspnea, fever). Most CAV patients remain asymptomatic until they develop serious problems such as myocardial infarction, heart failure, ventricular dysrhythmias or sudden cardiac death. Presently, the gold standard for diagnosing acute cardiac allograft rejection is right ventricular endomyocardial biopsy. This is an invasive method of diagnosis subject to morbidity and random sampling and interpretation error. Likewise, the gold standard for diagnosing CAV is cardiac catheterization with intravascular ultrasound, an invasive procedure also subject to morbidity. Noninvasive methods such as electrocardiography, echocardiography, and nuclear studies all have been studied, but have been unsuccessful, thus far, for either condition. Peripheral blood evaluations of cytokines and cytoimmunologic markers have also been unsuccessful in either condition. This clinical trial studies the feasibility of using functional genomics and proteomics to identify genes and proteins respectively that can serve as reliable biomarkers of acute cardiac cellular rejection and CAV. We plan to recruit subjects who are on the transplant waiting list. We will analyze the blood of these patients pre-transplant and serially post-transplant over one year and then regularly on a yearly basis. By correlating putative biomarkers with clinical, histological, and imaging based evidence of allograft disease we hope to build a database comprised of functional genomics, cytokine, cytoimmunologic and proteomics data relevant to the immunologic relationship between the donor organ and recipient. With this database we hope to obtain a minimal subset of differentially expressed genes, cytokines, cytoimmunologic and protein change profiles that is most predictive of both acute allograft rejection and CAV. This will eventually serve as the basis for a diagnostic blood test. Thus, with the application of functional genomics, cytokine, and cytoimmunologic analysis and proteomics we hope to derive a noninvasive method to detect both acute cellular cardiac allograft rejection and CAV, thereby minimizing the need for invasive methods of diagnosis. Further better understanding the genetic programs triggered and protein changes induced during rejection may lead to the identification of target pathways for developing new therapeutic approaches aimed at prevention.

Recently, several published reports have established that detection of donor DNA in recipient s blood can serve as a diagnostic tool of graft injury. The level of donor DNA measured as percentage of circulating cell-free donor DNA (%ccfdDNA) accurately diagnoses acute rejection with a high sensitivity and specificity, at times several months before the diagnosis by examining endomyocardial biopsies. The ability of cell free DNA to diagnose graft injury early opens a new window to re-examine markers of rejection. These markers are traditionally evaluated using biopsy results, often positive late during rejection. %ccfdDNA offers an opportunity to better characterize our analyses.

• INCLUSION CRITERIA - for Transplant Patients:

• Adult heart transplant center generally accepts patients within the physiologic age range of 12 to 65 years old, however, for our study heart transplant patients must be 18 years of age or above.
• Indication for cardiac transplantation as outlined by the 24th Bethesda Conference on Cardiac Transplantation. These are as follows:
• Peak VO(2) less than 10 ml/kg per minute or less than 50% of maximal predicted VO(2) with achievement of anaerobic metabolism.
• Severe cardiac ischemia consistently limiting routine activity not amenable to surgical or percutaneous revascularization.
• Recurrent symptomatic ventricular arrhythmias refractory to all accepted therapeutic modalities.

Exclusion criteria

- for Transplant Patients:

Adult heart transplant centers exclude infants, toddlers, and children with a physiologic age less than 12, and adults with advanced physiologic age (less than 65), however, for our study we will exclude heart transplant patients less than 18 years of age.

The final decision to exclude a candidate from cardiac transplantation will be made by the hospital's heart transplant committee. The committee uses, as a guideline, the criteria outlined in the 24th Bethesda conference.

Inclusion criteria

- for Control Subjects:

Any healthy normal man or women who is the appropriate age and gender for matching to a transplant patient.

Exclusion criteria

- For Control Subjects:

• EKG with evidence of clinically relevant heart disease.
• Echocardiogram with evidence of clinically relevant heart disease.
• Any disease process that is not well controlled by medications.
• Total tobacco use for greater than one month over the last 5 years.
• Symptoms of coronary or cardiac insufficiency.
• More than one major risk factor for coronary artery disease excluding gender or age.
• Confirmed intrauterine pregnancy in women.