Finite Element Analysis of Microfabricated Poly(Glycerol Sebacate) Scaffolds for use in Heart Valve Tissue Engineering

Open Access
Author:
Chowdhury, Surjyanil
Area of Honors:
Bioengineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • William O Hancock, Thesis Supervisor
  • Peter J Butler, Honors Advisor
  • Keefe B Manning, Faculty Reader
Keywords:
  • Chowdhury
  • finite element
  • COMSOL
  • heart valve
  • tissue engineering
  • poly glycerol sebacate
  • PGS
  • microfabricate
  • scaffold
  • mesh
Abstract:
Heart valve tissue engineering has the potential to make artificial valves which can grow, self-repair, and produce a minimal immune response when implanted due to being constructed of the patients own cells. In this study, finite element analysis using COMSOL multiphysics was used to examine the capability of microfabricated poly(glycerol sebacate) (PGS) scaffolds to both mimic the anisotropic behavior of native valvular tissue and to support collagenous tissue formation. This approach of using finite element (FE) analysis to model and analyze PGS scaffolds which could then be optimized based on the model was a novel approach used to study the structural mechanics of a recently developed PGS scaffold. This scaffold was comprised of diamond pores prior to and after cell seeding the constructs. Specifically, 2-D FE models of PGS scaffolds and cell seeded scaffolds were generated to predict the effective stiffness of the scaffold and engineered tissue. Experimental data of stiffness (done by the lab and generated from uniaxial mechanical tester samples) was matched with the stiffness obtained from FE analysis of representative scaffolds for two orthogonal material directions (PD along the long axis of the diamond pore and XD along the short axis of the pore). The findings indicated that the microfabricated PGS scaffold had mechanical characteristics which follow a rule-of-mixtures (corrected for angle) behavior. Furthermore, FE analysis was used to develop a correlation between the scaffold’s pore geometry and strut width (within the fabrication design) and the scaffold’s stiffness to determine an appropriate design that mimics the native leaflet’s stiffness and anisotropy. Results showed that the scaffold increased in anisotropy as the angle of the diamond shaped pore diverged from 90o when the overall volume fraction of the scaffold was held constant as the angle changed. Finally, uniaxial mechanical testing data on cell seeded scaffolds (done by the lab) was used to model a cell seeded scaffold that was used to predict the stiffness of the tissue formed within the scaffold.