Collagen remodeling in the extracellular matrix of the cardiomyopathic Syrian hamster heart as assessed by FTIR attenuated total reflectance spectroscopy

Collagen type I and III deposition in the cardiac extracellular matrix contributes significantly to myocardial dysfunction. Diffuse and focal fibrosis is believed to accompany human congestive cardiomyopathy (CCM) associated with congestive heart failure (CHF). The left ventricle collagen remodeling that occurs in the hamster model of CCM is marked by left ventricle fibrosis, hypertrophy and dilation, proceeded by CHF post 150 days of age. The objectives of our study were to (i) evaluate changes in collagen deposition in the right (RV) and left (LV) ventricular tissue of cardiomyopathic (CMP) and control (CON) myocardium using FTIR ATR spectroscopy, (ii) classify the normal and diseased heart tissue using linear discriminant analysis (LDA) aided by a genetic algorithm (GA) selection of spectroscopically diagnostic regions in the mid-IR region, (iii) rationalize the spectroscopic differences between left/right ventricle tissue as well as CON/CMP tissue according to the pathophysiology documented for the UM-X7.1 strain of CMP hamsters. The presence of collagen in the tissue was confirmed spectroscopically by observation of the collagen IR fingerprint in the 1000-1800 cm-1 region. Difference spectroscopy was utilized to substantiate which tissue under comparison exhibited pronounced collagen content. Multivariate analysis (LDA) was carried out on user-selected spectral subregions and compared to class separation based on spectral subregions chosen nonsubjectively by a GA. Our study confirmed that the animals experienced LV collagen remodeling denoted by focal rather than diffuse fibrosis. In addition, RV collagen remodeling, denoted by decreased RV collagen content, appeared to accompany the increased LV collagen deposition found for the CMP animals.Key words: FTIR spectroscopy, collagen, cardiomyopathy, genetic algorithm, linear discriminant analysis.