AFM Characterization of the Internal Mammary Artery as a Novel Target for Arterial Stiffening

Figures

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  Figure 1. The approach for localized nanomechanical mapping of the tunica media in human IMA. (a) The human internal mammary artery (IMA) was cryo-sectioned to 5 μm thickness tissue sections. Optical images captured with the microscope integrated with the AFM for the (b) dehydrated and (c) hydrated tissue sections. The IEL and EEL distinctly separate the tunica intima, tunica media, and tunica adventitia in the IMA. (d) Schematic diagram of AFM imaging and the IMA histology.

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  Figure 2. Examples of AFM force-indentation curves obtained from (a) PS1 and (b) PDMS reference samples in ambient and fluid conditions, respectively.

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  Figure 3. Nanomechanical properties of the dehydrated media in both groups in ambient condition. (a) Bar graph showing a significant difference in elastic modulus of patients as mean ± SEM (n = 8 patients in low PWV group; n = 9 patients in high PWV group). (b) Distribution of measured elastic modulus for both groups; significant differences were found between modulus distributions of two groups overall in the dehydrated media (Kolmogorov–Smirnov test, p < 0.0001).

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  Figure 4. Nanomechanical properties of the hydrated media in the fluid condition in all available patients. (a) The elastic modulus of hydrated media in each patient (n = 7 patients per group, Mann–Whitney test, p = 0.005). (b) Modulus distribution of the medial layer in low and high PWV groups (n = 42 measurements per group, Kolmogorov–Smirnov test, p < 0.0001).

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  Figure 5. Example images showing the hydrated media (a) topography, (b) DMT modulus map, (c) histogram showing the elastic modulus distribution and for the dehydrated media, (d) topography, (e) DMT modulus map, and (f) histogram showing the elastic modulus distribution and for the dehydrated media mapping of topography. All images are for patient 627.

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  Figure 6. PCA of patient proteomics, quantitative metadata, and nanomechanical variables. (a) Score plot of the two first components. Each dot represents a patient. Patients colored by group (red - high PWV, green - low PWV). (b) Loading plot of (a) showing the variables that contribute the most of the structured observed in (a); PWV and elastic modulus of hydrated media (E-Hy), dehydrated media (E-Me), adventitia (E-Ad), and combined dehydrated media and adventitia (E-Me+Ad) are four of the most contributing variables to the separation between both groups. (c) Score plot of the two principal components of patient data without the PWV variable. Similar separation between both groups can be observed. (d) Loading plot of (c) shows that E-Hy, E-Me, E-Ad, and E-Me+Ad are four of the most contributing variables to the separation observed. E-Me and E-Ad were highly correlated. Of the SLRPs, mimecan presents the most contribution to the separation between groups observed.