Progressive alterations in microstructural organization and biomechanical response in the ApoE mouse model of aneurysm

Abstract

AAA is a complex disease that leads to a localized dilation of the infrarenal aorta that develops over years. Longitudinal information in humans has been difficult to obtain for this disease, therefore mouse models have become increasingly used to study the development of AAAs. The objective of this study was to determine any changes that occur in the biomechanical response and fiber microstructure in the ApoE−/− AngII mouse model of aneurysm during disease progression. Adult ApoE−/− AngII infused mice along with wild-type controls were taken at 14 and 28 d. Aortas were excised and tested simultaneously for biaxial mechanical response and ECM organization. Data sets were fit to a Fung-type constitutive model to give peak strains and stiffness values. Images from two photon microscopy were quantified in order to assess the preferred fiber alignment and degree of fiber orientation. Biomechanical results found significant differences that were present at 14 d had returned to normal by 28 d along with significant changes in fiber orientation and dispersion indicating remodeling occurring within the aneurysmal wall. This return of some of the normal biomechanical function, in addition the continuing changes that occur in the microstructure suggest a restorative response that occurs in the ApoE−/− AngII infused model after the initial aneurysm formation.

Biomechanical Comparison of Glutaraldehyde-Crosslinked Gelatin Fibrinogen Electrospun Scaffolds to Porcine Coronary Arteries

“…There are a number researchers who have published studies that fit experimental biomechanical data of native vasculature to constitutive models [61,62], including our research group [52,53,60]. Some studies have used constitutive modeling to fit biomechanical data of developed synthetic TEVGs [64,65].…”

“…A custom-made MOD, shown in Fig. 3, has been used by our research group to conduct extensive studies on the mechanical behavior of porcine and mouse arteries [51][52][53][54][55][56]. This device has the capability of stretching the tubular samples axially, while recording axial load, pressure, and circumferential/axial strain information simultaneously.…”

“…This imaging process was performed for the constructs crosslinked for 2, 8, and 24 hrs. An in-house MATLAB image processing software (IAGUI) was used to determine fiber orientation data based off the MIP image for each experimental group [52,53]. The software detects fiber orientation and assigns intensity values for each angle value.…”

TGFβ2 differentially modulates smooth muscle cell proliferation and migration in electrospun gelatin-fibrinogen constructs

“…Furthermore, as part of the study of the tissue engineered scaffolds, our future work will also involve the biomechanical characterization of electrospun sheets seeded with SMCs and treated with exogenous TGFβ2 at different concentrations. The biomechanical response will be measured using a microbiaxial optomechanical device (MOD) designed in our laboratory to simultaneously measure the macroscopic and microstructural properties of planar and tubular vascular tissues [22, 59, 60]. …”

“…The Advanced Intravital Microscope (AIM) for multiphoton imaging at the University of Arizona's BIO5 institute was used to observe the total cell migration along the scaffold depth [21, 22]. The AIM is an Olympus BX51 upright laser-scanning microscope coupled to a Coherent 120-fs tunable pulsed Titanium-Sapphire laser (Santa Clara, CA).…”