Increased insulin-like growth factor-1 protein in human left ventricular hypertrophy

Animal models of cardiac hypertrophy demonstrated increased expression of insulin-like-growth factor-1 (IGF-1) in the heart. To study protein expression of insulin-like-growth factor 1 in left ventricular hypertrophy (LVH) in humans 11 hearts of autopsy cases with LVH were compared to 11 controls using immunohistochemical staining with anti-human IGF-1. LVH was defined as thickening of the left ventricular wall which ranged from 1.6 to 2.5 cm with hearts weights from 400 to 900 g. Immunohistochemical staining for IGF-1 was increased in the presence of LVH. In cases of LVH 37.9 ± 3.5% of the cross-sectional myocardial area stained positively for IGF-1 compared to 6.8 ± 2.9% in controls (P < 0.001). The findings support the hypothesis that IGF-1 has a role in the pathogenesis of LVH in humans. The increase of IGF-1 protein with LVH suggests reactivation of the cardiac IGF-1 genes in the hypertrophied adult cardiomyocyte.