['The aim of this study was to test the hypothesis that angiotensin (Ang)-converting enzyme-2 (ACE2) overexpression may inhibit myocardial collagen accumulation and improve left ventricular (LV) remodeling and function in diabetic cardiomyopathy.', 'Hyperglycemia activates the renin-Ang system, which promotes the accumulation of extracellular matrix and progression of cardiac remodeling and dysfunction.', 'Ninety male Wistar rats were divided randomly into treatment (n = 80) and control (n = 10) groups. Diabetes was induced in the treatment group by a single intraperitoneal injection of streptozotocin. Twelve weeks after streptozotocin injection, rats in the treatment group were further divided into adenovirus-ACE2, adenovirus-enhanced green fluorescent protein, losartan, and mock groups (n = 20 each). LV volume; LV systolic and diastolic function; extent of myocardial fibrosis; protein expression levels of ACE2, Ang-converting enzyme, and Ang-(1-7); and matrix metalloproteinase-2 activity were evaluated. Cardiac myocyte and fibroblast culture was performed to assess Ang-II and collagen protein expression before and after ACE2 gene transfection.', 'Four weeks after ACE2 gene transfer, the adenovirus-ACE2 group showed increased ACE2 expression, matrix metalloproteinase-2 activity, and LV ejection fractions and decreased LV volumes, myocardial fibrosis, and ACE, Ang-II, and collagen expression in comparison with the adenovirus-enhanced green fluorescent protein and control groups. ACE2 was superior to losartan in improving LV remodeling and function and reducing collagen expression. The putative mechanisms may involve a shift in balance toward an inhibited fibroblast-myocyte cross-talk for collagen and transforming growth factor-beta production and enhanced collagen degradation by matrix metalloproteinase-2.'] Does angiotensin-converting enzyme-2 overexpression improve left ventricular remodeling and function in a rat model of diabetic cardiomyopathy?