| Clear images and colors | Post date: 2019/09/22 | |
 A team of researchers in AUT have utilized Polyurethane medical grids and carbon nanotubes to make artificial veins so lifelike that they can be used to replace clogged arteries.
As reported by AUT’s public relations office Dr. Rahim Fatoorechi the plans researcher said while pointing out the importance of artificial arteries: there haven’t been a lot of studies on the biomechanical aspects of artery replacements in humans and those done have mostly focused on the static qualities of these synthetics like their fracture strain and compliance.
He pointed out that if the mechanical qualities of the synthetic vein and a vein in the area of Anastomosis don’t comply with each other it could cause Intima hyperplasia (enlargement of an organ) he further stated: this incident would show that the graft was unsuccessful specially for veins smaller than 6mm in diameter.
Fatoorechi stated that although many grafts such as ePTFE and dacron are commonly used for vessels larger than 6mm in diameter which have a considerable blood flow and have sustainability between 80 and 90 percent in a 5 year period, smaller grafts closer to physiological sizes experience higher levels of stress compared to natural vessels where synthetic vessels are on average 10 times more elastic than natural human vessels which this in turn causes problems in the linkage.
He added: on this bases commercial grafts are not suitable for vessels smaller than 6mm in diameter and we urgently need a replacement with closer mechanical and biological similarities to natural human vessels.
This researcher pointed out the difficulties of open heart surgery and explained: In this type of surgery, the saphinus vessel is used to replace the blocked coronary artery, which in 50% of cases after 10 years, the arteries are clogged again and need another bypass surgery, where using the patient's own veins requires another surgery where where the artery is taken from one place and implanted in another.
Ha said the incompliance of biomechanical characteristics is the most important factor for the failure of artery transplants for veins smaller than 6mm in diameter and stated: in order to eradicate this problem a set of studies under the name of “designing, manufacturing and characterization of surrogate nanostructure vessels based on Polyurethane/ carbon nanotubes/ gelatin ” was conducted at AUT with the goal of designing and manufacturing synthetic vessels with biomechanical characteristics mimicking those of healthy human vessels.
Fatoorechi said the main substance used in manufacturing these artificial vessels are medical Polyurethane grids and noted: out of all the available biofriendly polymers which are used for artery grafts medical Polyurethane grids due to it having a hard section and a soft section which are controllable during the synthesis process has gained many researchers’ interest; because Polyurethane based grafts are much softer compared to commercially available grafts and have a higher conformity to natural vessels.
He stated that carbon nanotubes and gelatin polymers are among other materials used in producing these synthetic vessels, he continued: also the endothelial cells needed in this study were provided by the pastor institute and Polyurethane based nanostructures were used to make carbon nanotubes and gelatin polymers for the first time. The synthetic vessels made have very good qualities compared to natural human vessels also the base of these vessels provide an excellent environment for the growth, population and adhesion of the endothelial cells. According to this AUT alumni %70 of the material needed to make these vessels are available domestically and %30 are imported and all the matters relating to the synthesis and biological experiments were done within the country.
Fatoorechi stated the method used for synthesis in this project was electrospinning and pointed out: this method allowed us to manufacture the composite material in the shape of nanofibers where the veins themselves are a construct of nanofibers. Due to their high porosity and high area to volume ratio nanofibers have an unprecedented similarity to the outer cell matrices and provide a highly effective base for cell growth and adhesion.
Referencing the desired outcomes of the mechanical and biological experiments done outside the body (in vitro) he stated: based on these results we are preparing to replace an aorta in a sheep’s body. If all goes well we will start the commercialization of this product while also seeking a permit to do an implant in a human body, this process could take between 3 to 10 years.
The plans chief stated the importance of such discoveries saying: in %30 of cases the patient due to previous surgeries or old age is unable to provide a suitable replacement for their veins and this is where the importance of such synthetic arteries becomes more apparent, and in the case of this plan being successful and a permit to do this transplant on humans is given these patients will no longer face these problems.
He further stated the publishing of two articles in two accredited journals as other achievements of this study. This plan was made possible by the cooperation of the following: Dr. Rahim Fatoorechi AUT alumni, Dr. S. Attaollah Hashemi and Dr. Nabiollah Abolfathi directing the plan and the advising of Dr. Atefe Salook part of the AUT faculty and Dr. Alexander Seyfaliyan.
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