In vivo label-free optical monitoring of structural and metabolic remodeling of myocardium following infarction

Figures

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  Fig. 1. Diagram of the heart illustrating the regions of interest (ROI) studied. RV – Right ventricle; LVP – left ventricle posterior wall; LVA – left ventricle anterior wall. The region highlighted in red corresponds to the region of infarction.

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  Fig. 2. Representative histology images of AMC (A - D) and MI hearts (E - H) stained with PSR at weeks 1 (A, E), 2 (B, F), 4 (C, G) and 16 (D, H). Arrows on the bottom row indicate region of infarction (LVA) where scar tissue was formed, and deposition of collagen is more pronounced.

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  Fig. 3. Autofluorescence lifetime parameters (see section on Data Analysis) measured in RV at 1, 2, 4 and 16 weeks.

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  Fig. 4. Autofluorescence lifetime parameters measured in LVP at 1, 2, 4 and 16 weeks. Differences in AMC and MI hearts are more pronounced compared to those observed for RV in all channels. In channel 4, we observe a general decrease in τ1 (all time points) and an increase in τ2 (weeks 2, 4 & 16) in MI relative to AMC hearts.

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  Fig. 5. Autofluorescence lifetime parameters measured in LVA at 1, 2, 4 and 16 weeks. We observe a gradual increase in autofluorescence lifetime of MI hearts from week 1 to week 16, which suggests that collagen proliferation in the scar region starts immediately after MI induction. As in other regions, the lifetime component τ1 of channel 4 is shorter in MI than in AMC hearts at earlier time points. At week 16, extensive collagen proliferation leads to an increase in the fluorescence lifetime that possibly masks alterations in the fluorescence lifetime parameters caused by metabolic changes.

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  Fig. 6. Normalized autofluorescence intensities in the RV, LVP and LVA under 372 nm excitation. Standard deviation bars are not included to avoid overcrowding the plots. Markers in each channel identify time point studied, from left (week 1) to right (week 16), as indicated in channel 1 of the right ventricle plot (left panel).

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  Fig. 7. Normalized absorbance spectra in the RV between 500 and 600 nm for AMC (blue) and MI (red) hearts for different time points (left to right). Solid lines show average and dimmed lines show corresponding standard deviation curves.

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  Fig. 8. Normalized absorbance spectra in the LVP between 500 and 600 nm for AMC (blue) and MI (red) hearts for different time points (left to right). Solid lines show average and dimmed lines show corresponding standard deviation curves.

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  Fig. 9. Normalized absorbance spectra in LVP between 500 and 600 nm for AMC (blue) and MI (red) hearts for different time points (left to right). Solid lines show average and dimmed lines show corresponding standard deviation curves.