الفهرس 
Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Over the years, most of vascular diseases like cardiovascular diseases continue to increase and affect human health or in many cases lead to death because blood cannot reach to desired tissues or organs so closed blood vessels must be changed by vascular scaffolds to substitute the original vessel. Over days, these scaffolds cannot do its work perfectly due their occlusion. Preventing this occlusion depend on two approaches, the first is the correct choice of a tissue engineered vascular scaffold with suitable properties and the second is the success of seeding endothelial cells onto the selected scaffold because endothelial cells can release factors that can prevent its occlusion.
Actually this study was designed to fabricate a tissue engineered vascular scaffold in nano scale to mimic the structure of the main component of blood vessel. This scaffold was prepared from a synthetic polymer called polycaprolactone (PCL) in a nanofiber form by using electrospinning technique by dissolving it in 1:1 chloroform and N, N dimethyl formamide (DMF) as a solvent system with a concentration 13%. Moreover, a polycaprolactone microfiber scaffold may be prepared by the same technique with the same concentration by dissolving the polymer in 2:1 chloroform and DMF. So this study succeeded in making an important and effective comparison between nano and micro fiber shapes for the same polymer (PCL) in their surface morphology and their interaction with cells transplanted on them, this comparison has been made through scanning electron microscope (SEM) images for the scaffolds.
To kill all bacteria on these fabricated scaffolds and to be suitable for cell transplantation, this study used ionizing radiation (gamma radiation) with a dose 25 to 30 KGy as a sterilization method for the scaffolds by using the Mega Gamma Irradiation Unit at the National Center for Radiation Research and Technology – Egyptian Atomic Energy Authority.
In biological part of our study, in vitro studies were carried out to differentiate amnion cells [purchased from Center for Vaccination and Sera (Vacsera) – Egypt] to endothelial cells by using a vascular endothelial growth factor, since inverted microscope was used to differentiate between amnion cells and endothelial cells.
Also this study was designed to enhance growth of endothelial cells on the fabricated scaffold so we used low doses of He- Ne laser to know their effect on cell growth. Cells grown on scaffolds were irradiated with He: Ne laser at power output of 15mW of a wavelength 632 nm with Irradiated doses of 1, 2.5 and 5 J/cm2 every 48 hours for a duration of 12 days.
Growth of endothelial cells was detected by scanning electron microscope images, inverted microscope, from viability tests which were performed to tissue culture media and the scaffold such as malondialdehyde (MDA) level, nitric oxide (NO) level and deoxyribonucleic acid (DNA) content.
It was concluded that nano and micro scaffolds of polycaprolactone may be prepared by using electrospinning technique, There was no a clear effect of gamma radiation on the scaffold shape or surface morphology (it just sterilized the scaffolds), Amnion cells could be differentiated into endothelial cells by using vascular endothelial growth factor, The biocompatibility of PCL nano and micro fiber scaffolds with the cells, Laser irradiation induced cell growth more than that without laser and complete endothelium layer was formed for microfiber before nanofiber scaffold because the number of pores in micro scaffold are less than those in nanofiber scaffold.