Fibrosis and Fibrotic Gene Expression in Pediatric and Adult Patients with Idiopathic Dilated Cardiomyopathy

Abstract Background While fibrosis seems to be prognostic for adverse outcomes in adults with idiopathic dilated cardiomyopathy (IDC), little is known about the prevalence and development of fibrosis in pediatric IDC hearts. We hypothesize there is less activation of fibrosis at a molecular level in pediatric IDC hearts than in the failing adult heart. Methods and Results Pediatric hearts were analyzed histologically to determine the prevalence of fibrosis. Left ventricular tissue from adult and pediatric IDC hearts and adult and pediatric non-failing (NF) hearts were subjected to qRT-PCR to study the expression of important mRNAs that affect fibrosis. We found age-specific differences between IDC and NF hearts in regulation of non-coding galectin 3, Corin, MMP-2, MMP-9, TIMP-2, and TIMP-3. We also found markers that were similarly altered in both adult and pediatric IDC (ST2L, TIMP-1, and TIMP-4). Finally, microRNAs 29a-c were significantly decreased in the pediatric IDC patients. Conclusion Pediatric IDC patients demonstrate age-specific differences in the molecular pathways implicated in fibrosis in the adult heart. At the ultrastructural level the unique gene expression pattern appears to limit fibrosis in the failing pediatric heart.