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The examination of a biodegradable nanocomposite polymer and decellularised blood vessels as scaffold materials for tissue engineered vascular grafts in the paediatric patient

Dee, Ryan Joseph; (2018) The examination of a biodegradable nanocomposite polymer and decellularised blood vessels as scaffold materials for tissue engineered vascular grafts in the paediatric patient. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

There is a need for TEVG for surgical use in paediatric cases of vascular and congenital heart defects. Two materials were tested for the suitability as the basis of a tissue engineered vascular graft: a synthetic biodegradable nanocomposite polymer developed at Royal Free Hospital, polyhedral oligmeric silsesquioxane poly(caprolactone-urea) urethane (POSS-PCLUU); and umbilical vessels and rat aorta decellularised by Detergent Enzymatic Treatment (DET). Phase inversion with NaHCO3 porogen leaching was employed to fabricate porous POSS-PCLUU foams. Changing the concentration of NaHCO3 porogen was examined for its effect on bulk and surface properties and a concentration of 45% NaHCO3 porogen was selected for the extrusion of porous grafts. The mechanical and structural properties of grafts extruded using different sized NaHCO3 porogen particles at a concentration of 45% were investigated and a particle size of 60 µm was considered to be most appropriate. The maximum burst pressure was 238 mmHg and aneurysm formation was observed before graft failure. DET decellularisation removed a significant amount of DNA from human umbilical cord artery and vein, as well as rat aorta. The structure and mechanical strength of the vessels was maintained after decellularisation. Decellularised umbilical artery had a burst pressure of 831 mmHg and no aneurysm formation was observed. There was a large reduction in the extracellular proteins elastin and glycosaminogylcans (GAG). Human Umbilical Vein Endothelial Cells (HUVEC), Amniotic Fluid Stem Cells (AFSC) were seeded on to aliphatic POSS-PCLUU fabricated with 45% 60 µm NaHCO3 porogen. AFSC performed poorly in comparison to HUVEC. HUVEC had a large coverage of cells in the first few days post seeding but this dropped significantly after 7 days. HUVEC and AFSC both formed large clusters of cells when seeded on decellularised rat aorta. In conclusion, the POSS-PCLUU, DET decellularised umbilical vessels and rat aorta would not be suitable as a material for TEVG due to poor mechanical properties and scaffold-cell interaction.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: The examination of a biodegradable nanocomposite polymer and decellularised blood vessels as scaffold materials for tissue engineered vascular grafts in the paediatric patient
Event: UCL (University College London)
Language: English
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science
URI: https://discovery.ucl.ac.uk/id/eprint/10042126
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