P633Molecular imaging of cardiomyopathy in caveolin-1 knockout mice by infrared spectroscopy

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Mice lacking Caveolin-1 (cav1ko) develop a servere hypertrophic cardiomyopathy (HCM). This HCM development is due to an uncoupling of the endothelial NO-synthase leading to the enhanced production of radicals. The cardiomyopathy is characterised by a thickened ventricle due to remodelling of the extracellular matrix composition mainly mediated by collagen deposition. The aim of the present study was to characterize the deposition of the ventricle of cardiomyopathic cav1ko mice compared to wildtype C57BL6 mice (wt) by using Fourier Transformed Infrared (FT-IR) micro spectroscopic imaging. Thin cryosections were prepared from hearts of 15 weeks old wt and cav1ko mice For the spectral analysis sections were transferred onto infrared transparent CaF2-slides. Parallel sections were prepared on glass slides for hematoxylin-eosin staining. Furthermore, Collagene 1, 3 and 4 were visualized by immunostaining. FT-IR micro spectroscopy was performed using a Bruker Hyperion system. Spectra were collected in transmission mode using a resolution of 6 cm 1 in a spectral range of 950 – 3800 cm-1.For analysis approximately 25.000 individual spectra of each sample were acquired.? Dominating bands are the amide I (1650 cm-1) and amide II (1550 cm-1) modes. Additional significant bands were observed around 1400 cm-1 (vibrations of fatty acids), 1460 cm-1 (CH2 bending vibrations). Absorption bands of nucleic acids are located between 1000 cm-1 and 1200 cm-1. In a first step, the spectra were evaluated by fuzzy k-means clusters analysis. The cluster analysis reveals significant differences in the biochemical composition between cav1ko and wt hearts. Principal component analysis was performed to image different types of collagen across the cardiac muscel section. This analysis shows that cardiomyopathic cav1ko mice have a higher content of collagen within the ventricle. This enlightens the capability of FT-IR micro spectroscopy for the label free and objective identification of cardiomyopathic heart failure.? In conclusion the FT-IR imaging spectroscopy is a label-free and objectiv method to characterize the structural changes of the arterial wall of cardiomyopathic tissue. Different types of collagen may modulate functional parameters in the heart and may play an important role in different forms of heart failure such as diastolic heart failure.

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