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Technical Brief

Computationally Optimizing the Compliance of a Biopolymer Based Tissue Engineered Vascular Graft

[+] Author and Article Information
Scott Harrison

Department of Aerospace and Mechanical Engineering,
The University of Arizona,
Tucson, AZ 85721
e-mail: scottharrison@email.arizona.edu

Ehab Tamimi

Biomedical Engineering,
The University of Arizona,
Tucson, AZ 85721
e-mail: ehab@email.arizona.edu

Josh Uhlorn

Department of Biomedical Engineering,
The University of Arizona,
Tucson, AZ 85721
e-mail: juhlorn@email.arizona.edu

Tim Leach

Department of Biomedical Engineering,
The University of Arizona,
Tucson, AZ 85721
e-mail: tsleach@email.arizona.edu

Jonathan P. Vande Geest

Department of Aerospace and Mechanical Engineering,
The University of Arizona,
Tucson, AZ 85721;
Department of Biomedical Engineering,
The University of Arizona,
Tucson, AZ 85721;
Biomedical Engineering,
The University of Arizona,
Tucson, AZ 85721;
BIO5 Institute for Biocollaborative Research,
The University of Arizona,
Tucson, AZ 85721;
Soft Tissue Biomechanics Laboratory,
The University of Arizona,
Tucson, AZ 85721
e-mail: jpv1@email.arizona.edu

1Corresponding author.

Manuscript received September 11, 2015; final manuscript received November 18, 2015; published online December 8, 2015. Assoc. Editor: Hai-Chao Han.

J Biomech Eng 138(1), 014505 (Dec 08, 2015) (5 pages) Paper No: BIO-15-1447; doi: 10.1115/1.4032060 History: Received September 11, 2015; Revised November 18, 2015

Abstract

Coronary heart disease is a leading cause of death among Americans for which coronary artery bypass graft (CABG) surgery is a standard surgical treatment. The success of CABG surgery is impaired by a compliance mismatch between vascular grafts and native vessels. Tissue engineered vascular grafts (TEVGs) have the potential to be compliance matched and thereby reduce the risk of graft failure. Glutaraldehyde (GLUT) vapor-crosslinked gelatin/fibrinogen constructs were fabricated and mechanically tested in a previous study by our research group at 2, 8, and 24 hrs of GLUT vapor exposure. The current study details a computational method that was developed to predict the material properties of our constructs for crosslinking times between 2 and 24 hrs by interpolating the 2, 8, and 24 hrs crosslinking time data. matlab and abaqus were used to determine the optimal combination of fabrication parameters to produce a compliance matched construct. The validity of the method was tested by creating a 16-hr crosslinked construct of 130 μm thickness and comparing its compliance to that predicted by the optimization algorithm. The predicted compliance of the 16-hr construct was 0.00059 mm Hg−1 while the experimentally determined compliance was 0.00065 mm Hg−1, a relative difference of 9.2%. Prior data in our laboratory has shown the compliance of the left anterior descending porcine coronary (LADC) artery to be 0.00071 $±$ 0.0003 mm Hg−1. Our optimization algorithm predicts that a 258-μm-thick construct that is GLUT vapor crosslinked for 8.1 hrs would match LADC compliance. This result is consistent with our previous work demonstrating that an 8-hr GLUT vapor crosslinked construct produces a compliance that is not significantly different from a porcine coronary LADC.

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Figures

Fig. 1

Electrospinning setup

Fig. 2

MOD being used to test a gelatin/fibrinogen tubular construct

Fig. 3

Time dependent response surfaces used to determine constants for constitutive model in order to predict material behavior for crosslinking times for which experimental data has not been collected

Fig. 4

Example of an axisymmetric tube with fixed boundary conditions at the top and bottom and an applied pressure, P, on the inner surface. The tube has inside diameter (ID) and thickness t. The dotted line is the line of axisymmetry.

Fig. 5

Optimization program schematic

Fig. 6

Response surface and experimental data comparison

Fig. 7

Objective function (current compliance–desired compliance) and simulation results. The desired compliance was 0.0007 mm Hg−1.

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