460
K. malek et al.
revealed increasing intensity of the 1204 and 1240 cm
−1
bands in diseased tissue
[146]. two-dimensional maps for the band at 1204 cm
−1
correlated well with trichrome-stained collagen deposition. the data indicates heterogeneous distribution
of collagen with its moderate increase in cardiomyopathic hamsters. the collagen
depositions were mainly localised in the left ventricle [146].
Next, experimental cardiomyopathy induced by chronic At 1 receptor blockade
has been used to illustrate the spectroscopic differences among control, untreated
cardiomyopathic and losartan-treated cardiomyopathic hearts, particularly in an
area of micro-infarctions throughout both the ventricular tissues [147]. this animal model mimics the gradual progression of congestive heart failure in humans.
Synchrotron-based FtIR instrumentation was used to improve the spatial resolution of the collected maps. An examination of the amide I and III regions shows
the presence of the collagen bands listed above in most cardiomyopathic tissues
and in some losartan-treated tissues on the contrary to normal cardiac tissue (rarely
detected). In addition, the comparison of collagen and lipid distributions for the
three models shows a reduction of lipid content in losartan-treated cardiomyopathic tissue in 200 day-old animals. this is concomitant with the replacement
scar tissue of the infarction regions. Furthermore, crystalline deposits surrounded
by collagen are detected in the necrotic regions. Based on their Raman spectra,
crystals were readily identified as calcium hydroxyapatite responsible for mineralisation in the heart tissue. the collagen content was quantified by a number of
pixel spectra, which showed evidence of collagen bands. In the early stage (65day animals), about 2.5 % of the total mapped area exhibited the characteristics
of the necrotic tissue in the three groups, despite the fact that both the control and
losartan-treated cardiomyopathic tissues were completely free of visible fibrosis.
this was explained by a cardioprotective effect from the treatment. In the 200-day
tissue sections, collagen-containing spectra were found in 2, 27 and 12 % of the
total number of spectra from control, diseased, and treated hearts, respectively,
indicating reduction of fibrosis due to successful treatment in late-stage cardiomyopathic hamsters [147].
FtIR monitoring of the treatment of infarcted rat myocardium by targeted delivery of vascular endothelial growth factor (vEgF) has been reported by Cheheltani
et al. [148]. here, collagen deposition in the infarct zone of the left ventricles was
mapped using the integrated intensity of a band at 1338 cm
−1
, because only this IR
maximum was found to be specific for collagen in the investigated tissue sections
[148]. the maps were then compared with immunostaining for collagen I by Alexa
Fluor 594 donkey anti-mouse Igg and the two histological staining protocols by using trichrome and picrosirius red, which also illustrated the distribution of collagen
of type I. Correlation coefficient values of ca. 0.8–0.9 indicated a very good agreement between collagen distribution derived from the IR and staining images. this
approach was also employed for the comparison of the infarcted myocardium with
the vEgF-treated group. In this case, the size of collagen scarring decreased from
18.7 to 1.6 % as revealed by the FtIR technique and was comparable to the staining
results. these findings demonstrate that FtIR imaging can be a powerful labelfree tool in the evaluation of collagen deposition and remodelling after myocardial
K. malek et al.
revealed increasing intensity of the 1204 and 1240 cm
−1
bands in diseased tissue
[146]. two-dimensional maps for the band at 1204 cm
−1
correlated well with trichrome-stained collagen deposition. the data indicates heterogeneous distribution
of collagen with its moderate increase in cardiomyopathic hamsters. the collagen
depositions were mainly localised in the left ventricle [146].
Next, experimental cardiomyopathy induced by chronic At 1 receptor blockade
has been used to illustrate the spectroscopic differences among control, untreated
cardiomyopathic and losartan-treated cardiomyopathic hearts, particularly in an
area of micro-infarctions throughout both the ventricular tissues [147]. this animal model mimics the gradual progression of congestive heart failure in humans.
Synchrotron-based FtIR instrumentation was used to improve the spatial resolution of the collected maps. An examination of the amide I and III regions shows
the presence of the collagen bands listed above in most cardiomyopathic tissues
and in some losartan-treated tissues on the contrary to normal cardiac tissue (rarely
detected). In addition, the comparison of collagen and lipid distributions for the
three models shows a reduction of lipid content in losartan-treated cardiomyopathic tissue in 200 day-old animals. this is concomitant with the replacement
scar tissue of the infarction regions. Furthermore, crystalline deposits surrounded
by collagen are detected in the necrotic regions. Based on their Raman spectra,
crystals were readily identified as calcium hydroxyapatite responsible for mineralisation in the heart tissue. the collagen content was quantified by a number of
pixel spectra, which showed evidence of collagen bands. In the early stage (65day animals), about 2.5 % of the total mapped area exhibited the characteristics
of the necrotic tissue in the three groups, despite the fact that both the control and
losartan-treated cardiomyopathic tissues were completely free of visible fibrosis.
this was explained by a cardioprotective effect from the treatment. In the 200-day
tissue sections, collagen-containing spectra were found in 2, 27 and 12 % of the
total number of spectra from control, diseased, and treated hearts, respectively,
indicating reduction of fibrosis due to successful treatment in late-stage cardiomyopathic hamsters [147].
FtIR monitoring of the treatment of infarcted rat myocardium by targeted delivery of vascular endothelial growth factor (vEgF) has been reported by Cheheltani
et al. [148]. here, collagen deposition in the infarct zone of the left ventricles was
mapped using the integrated intensity of a band at 1338 cm
−1
, because only this IR
maximum was found to be specific for collagen in the investigated tissue sections
[148]. the maps were then compared with immunostaining for collagen I by Alexa
Fluor 594 donkey anti-mouse Igg and the two histological staining protocols by using trichrome and picrosirius red, which also illustrated the distribution of collagen
of type I. Correlation coefficient values of ca. 0.8–0.9 indicated a very good agreement between collagen distribution derived from the IR and staining images. this
approach was also employed for the comparison of the infarcted myocardium with
the vEgF-treated group. In this case, the size of collagen scarring decreased from
18.7 to 1.6 % as revealed by the FtIR technique and was comparable to the staining
results. these findings demonstrate that FtIR imaging can be a powerful labelfree tool in the evaluation of collagen deposition and remodelling after myocardial