Angiotensin converting enzyme inhibitors, among them captopril, improve survival following myocardial infarction (MI). The mechanisms of captopril action remain inadequately understood due to its diverse effects on multiple signalling pathways at different time periods following MI. Here we aimed to establish the role of captopril in late-stage post-MI remodelling. Left anterior descending artery (LAD) ligation or sham surgery was carried out in male C57BL/6J mice. Seven days post-surgery LAD ligated mice were allocated to daily vehicle or captopril treatment continued over four weeks. To provide comprehensive characterization of the changes in mouse heart following MI a 3D light sheet imaging method was established together with automated image analysis workflow. The combination of echocardiography and light sheet imaging enabled to assess cardiac function and the underlying morphological changes. We show that delayed captopril treatment does not affect infarct size but prevents left ventricle dilation and hypertrophy, resulting in improved ejection fraction. Quantification of lectin perfused blood vessels showed improved vascular density in the infarct border zone in captopril treated mice in comparison to vehicle dosed control mice. These results validate the applicability of combined echocardiographic and light sheet assessment of drug mode of action in preclinical cardiovascular research.

Fibrosis is the hallmark of hypertensive heart disease and heart failure with preserved ejection fraction. Perivascular fibrosis impairs vascular function while interstitial fibrosis leads to compromised cardiac contractility. How these fibrosis types are represented in mouse models of hypertensive heart disease and to what extent the transcriptional signatures of cardiac fibrosis are defined by their location is unknown. Mice were dosed over 4 weeks with angiotensin II (AngII) alone or together with α 1 -adrenergic agonist phenylephrine (PE) and were characterized by echocardiography, light sheet imaging and fibrosis histology. While both groups developed systolic and diastolic dysfunction, hypertrophy and perivascular fibrosis, co-administration of PE resulted in a more severe disease phenotype and prevalent interstitial fibrosis, highlighting the benefits of this model in preclinical research. High-precision spatial transcriptomics based on laser capture microdissected perivascular and interstitial fibrotic areas revealed activation of distinct pro-fibrotic as well as cardioprotective pathways in the AngII+PE infusion model. Perivascular and interstitial fibrosis showed remarkable differences in global gene expression signatures, as demonstrated by high expression of osteochondrogenic genes and markers of secretory fibroblasts in perivascular fibrosis. A limited number of upregulated genes is shared between the fibrosis locations. These data collectively show the suitability of mouse models of hypertensive heart disease to study cardiac fibrosis and demonstrate how progression of fibrosis in mice is closely coupled to deteriorating cardiac dysfunction associated with highly distinct molecular signatures of perivascular and interstitial fibrosis.

The pathogenesis of diabetic cardiomyopathy (DC) is poorly understood and new drugs targeting the myocardium are absent. This may be ascribed to the failure of available pre-clinical models to recapitulate essential clinical features of DC and heart failure. We hypothesized that the combination of experimental diabetes and pharmacologically induced cardiac stress might provide a novel rat model displaying a distinct profile of DC. Non-insulin dependent type 1 like diabetes mellitus was induced by partial (90%) pancreatectomy (Px). Pronounced hyperglycemia was established within two weeks (blood glucose levels of 23.3 ± 3.7 mM). Five weeks post Px or sham surgery, vehicle or the sympathomimetic agent, isoproterenol (Iso, 1 mg/kg, SC) was administered for 10 days. Ten weeks after surgery, the heart was isolated for detailed histological and molecular characterization. The relative weight of the left ventricle (LV) was significantly increased in Px-Iso rats compared to sham-vehicle treated control rats (0.22 ± 0.03 vs. 0.25 ± 0.02 mg/g BW, p<0.05), indicating Px-Iso-induced cardiac hypertrophy. Compared to sham-vehicle rats, cardiac muscle fibers of Px-vehicle rats had attenuated respiratory function and increased reliance upon oxidation of fatty acid substrates, measured by high-resolution respirometry. Interestingly, this aggravation was reversed in Px-Iso rats. Moreover, Iso induced cardiac fibrosis demonstrated by quantitative histology (area fraction; Px-vehicle vs. Px-Iso: 3.1 ± 0.2% vs. 6.3 ± 0.5%; Sham-vehicle vs. Sham-Iso: 3.7 ± 0.4% vs. 7.6 ± 0.5%, p<0.001). Echo- and electrocardiography as well as transcriptome analyses were applied to further assess LV remodeling and cardiac function. In conclusion, the Px-Iso rat model may provide a state-of-the-art model of DC displaying key features of the clinical condition. Hereby, this model may be useful in the evaluation of cardiovascular effects of novel compounds in the pre-clinical phase of drug development. Disclosure L. Thisted: Employee; Self; Gubra. R.T. Lindsay: None. K. Fosgerau: Stock/Shareholder; Self; Novo Nordisk A/S. Employee; Self; Gubra. Stock/Shareholder; Self; Gubra. T. Secher: Employee; Self; Gubra. Employee; Spouse/Partner; Novo Nordisk A/S. M.B. Thomsen: None. T. Jespersen: None. A.J. Murray: None. P.J. Pedersen: None. N. Vrang: Board Member; Self; Gubra. Employee; Self; Gubra. Stock/Shareholder; Self; Gubra. L.N. Fink: Employee; Self; Gubra. Stock/Shareholder; Self; Novo Nordisk A/S. T.X. Pedersen: Employee; Self; Gubra. N.E. Zois: Employee; Self; Gubra.

Cardiovascular and renal complications are the predominant causes of morbidity and mortality amongst patients with diabetes. Development of novel treatments have been hampered by the lack of available animal models recapitulating the human disease. We hypothesized that experimental diabetes in rats combined with a cardiac or renal stressor, would mimic diabetic cardiomyopathy and nephropathy, respectively. Diabetes was surgically induced in male Sprague Dawley rats by 90% pancreatectomy (Px). Isoprenaline (Iso, 1 mg/kg, sc., 10 days) was administered 5 weeks after Px with the aim of inducing cardiomyopathy, and cardiac function and remodeling was assessed by echocardiography 10 weeks after surgery. Left ventricular (LV) fibrosis was quantified by Picro Sirius Red and gene expression analysis. Nephropathy was induced by Px combined with uninephrectomy (Px-UNx). Kidney function was assessed by measurement of glomerular filtration rate (GFR) and urine albumin excretion, and kidney injury was evaluated by histopathology and gene expression analysis. Px resulted in stable hyperglycemia, hypoinsulinemia, decreased C-peptide, and increased glycated hemoglobin (HbA1c) compared with sham-operated controls. Moreover, Px increased heart and LV weights and dimensions and caused a shift from α-myosin heavy chain (MHC) to β-MHC gene expression. Isoprenaline treatment, but not Px, decreased ejection fraction and induced LV fibrosis. There was no apparent interaction between Px and Iso treatment. The superimposition of Px and UNx increased GFR, indicating hyperfiltration. Compared with sham-operated controls, Px-UNx induced albuminuria and increased urine markers of kidney injury, including neutrophil gelatinase-associated lipocalin (NGAL) and podocalyxin, concomitant with upregulated renal gene expression of NGAL and kidney injury molecule 1 (KIM-1). Whereas Px and isoprenaline separately produced clinical endpoints related to diabetic cardiomyopathy, the combination of the two did not accentuate disease development. Conversely, Px in combination with UNx resulted in several clinical hallmarks of diabetic nephropathy indicative of early disease development.