Annually, about 80,000 people die in the United Kingdom due to myocardial
infarction, congestive heart failure, stroke, or from other diseases related to
blood vessels. The current gold standard treatment for replacing the damaged
blood vessel is by autograft procedure, during which the internal mammary
artery (IMA) graft or saphenous vein graft (SVG) are usually employed.
However, some limitations are associated with this type of treatment, such as
lack of donor site and post-surgery problems that could negatively affect the
patient’s health. Therefore, this present work aims to fabricate a synthetic
blood vessel that mimics the natural arteries and to be used as an alternative
method for blood vessel replacement. Polymeric materials intended to be used
for this purpose must possess several characteristics including: (1) Polymers
must be biocompatible; (2) Biodegradable with adequate degradation rate; (3)
Must maintain its structural integrity throughout intended use; (4) Must have
ideal mechanical properties; and (5) Must encourage and enhance the
proliferation of the cells.
The feasibility of using synthetic biodegradable polymers such as poly (ε-
caprolactone) (PCL) and poly (lactide-co-glycolic acid) (PLGA) for fabricating
tubular vascular grafts was extensively investigated in this work. Many
fundamental experiments were performed to develop porous tissue-
engineered polymeric membranes for vascular graft purposes through
electrospinning technique to achieve the main aim. Electrospinning was
selected since the scaffolds produced by this method usually resemble
structural morphology similar to the extracellular matrix (ECM). Hence, four
6mm in diameter tubular shape vascular grafts PCL only, PLGA only, coaxial
(core-PCL and shell-PLGA), and bilayer (inner layer-PCL and outer layer-PLGA) was designed and fabricated successfully. The structure and properties
of each scaffold membrane were observed by scanning electron microscopy
(SEM), and these scaffolds were fully characterized by Fourier-transform
infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric
analysis (TGA), water contact angle measurements, mechanical tensile test,
as well as cell culture studies were carried out by seeding human umbilical
vein cells (HUVEC) and human vascular Fibroblast cells (HVF). Moreover, all
polymeric grafts underwent degradation process, and the change in their
morphological structure properties was studied over 12 weeks at room
temperature. All scaffolds were also exposed to a controlled temperature of
37°C for four weeks, in phosphate-buffered saline solution (pH, 7.3).
It was found that all scaffolds displayed exceptional fibre structure and
excellent degradability with adequate steady weight-loss confirming the
suitability of the fabricated scaffolds for tissue engineering applications. The
coaxial and bilayer scaffolds degraded at a much slower (and steadier) rate
than the singular PCL and PLGA tubular scaffolds. Coaxial grafts fabricated
via coaxial needle showed an increase in their fibre diameter and pore size
volume than other membranes, but also showed to have significant tensile
strength, elongation at fracture, and Young’s modulus. To conclude, all
scaffolds have demonstrated to be reliable to adhere and proliferate HUVEC,
and HVF cells, but these cells were attracted to the PLGA membrane more
than other fabricated membranes.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/19195 |
| Date | January 2021 |
| Creators | Bazgir, Morteza |
| Contributors | Sefat, Farshid, Youseffi, Mansour |
| Publisher | University of Bradford, Faculty of Engineering & Informatics, Department of Biomedical and Electronics Engineering |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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