Design and Fabrication of Engineered Biomaterials for Tissue Engineering Applications such as Cardiovascular System

Khayat Norouzi, Sara | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50045 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Shamlou, Amir
  7. Abstract:
  8. Cardiovascular diseases are the leading cause of death all over the world, even more common than cancers. The first reason of mortality in Iran according to statistics is the occlusion of coronary arteries. Unfortunately almost one third of patients doesn’t have enough blood vessels to be used in the bypass surgery and need artificial vessels. These artificial blood vessels with small diameters (less than 6 mm) will fail quickly. As a result there is an increasing demand for tissue engineered blood vessels which are capable of enduring high blood pressures. An artificial blood vessel should mimic both structure and mechanical properties of the real one. Blood vessels have layered structures, so in this study a layered scaffold with electrospun fibers as inner layer and freeze-dried hydrogel as outer layer which can tolerate pulsatile blood flow was designed and fabricated. At the beginning polymers was chosen. To improve mechanical and biological properties PCL (synthetic polymer) and gelatin (natural polymer) was used. Anticoagulant drug, heparin, was loaded using different methods and drug release was monitored during a month. MTT tests indicate the positive effect of heparin on endothelial cell growth. Co-electrospun mats with 12 wt% emulsion electrospun PCL containing 1 w/w% heparin, and 15 wt% electrospun gelatin containing 32 w/w% heparin showed the highest endothelial cell attachment and growth. Beside adding heparin will result in up to 8 times less attached platelets that will reduce remarkably thrombosis danger. Using simple tensile test young modulus of bilayer scaffold was 1.5 MPa which is very close to coronary artery (0.8-1.8MPa). Compliance is an important parameter on graft failure. To measure this parameter FSI (Fluid Solid Interaction) simulation using ADINA software was done. The real 3D geometry of a patient was made using Mimmic software. Simulations showed the relation between compliance and scaffold thickness. Bilayered scaffold with 1 mm thickness showed the compliance (4.2) close to coronary artery (4.5), but even by decreasing electrospun thickness compliance (3) was far from coronary. In this study a bilayer scaffold with thickness (1mm), mechanical and biological properties close to coronary artery using simulation and tissue engineering was fabricated
  9. Keywords:
  10. Electrospinning ; Simulation ; Tissue Engineering ; Scaffold ; Coronary Arteries ; Coronary Artery Bypass ; Bypass Graft Surgery ; Biomaterials ; Cardiovascular System ; Vascular Grafts

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