Shanghai University researchers have developed composite artificial vessels consisting of three layers, the world’s first, promising better mechanical strength and cell growth properties.
Taking advantage of micro-imprinting and electro-spinning techniques, the team from the university’s Rapid Manufacturing Engineering Centre used two different materials to produce the artificial vein – the middle layer addressing the strength issue and the two outer coats offering cell-growth promoting properties. Overall, the graft offers better features than existing single or double-layer implants.
"The composite vascular grafts could be better candidates for blood vessel repair," said Yuanyuan Liu, an associate professor at the Rapid Manufacturing Engineering Centre, who led the team behind the invention described in the latest issue of the journal AIP Advances.
Offering a solution to obstructed or fragile blood vessels, grafts are used in medicine to divert blood flow to bypass affected areas in the human body.
Traditional grafts are taken from existing vessels in the patient’s body or from a suitable donor. However, these sources are often insufficient because of a limited supply in a patient’s body which may also be afflicted by the same underlying conditions that necessitate the graft in the first place.
Research has therefore focused on developing synthetic vessels mimicking the ability of the natural ones to grow cells around and degrade in time, creating a new replacement vessel in the process.
To allow the scaffolds to mimic the properties of natural vessels as much as possible, researches use a technique known as electro-spinning, which applies electrical charge to draw special liquid into the graft's extremely thin fibres.
Electro-spinning also allows for a high surface-to-volume ratio of nanofibres, providing ample space for host cells to grow and connect. These components all naturally degrade within six months to a year, leaving behind a new, intact blood vessel.
However, the existing grafts tend to be rather fragile, a major drawback preventing wider use of artificial veins.
Liu’s team has addressed the problem by electro-spinning the mixture onto the sides of a micro-imprinted biodegradable polymer commonly used in biomedical applications. The ends of this sheet were then folded and attached to make a tube-like vessel.
The scientists have then seeded the resulting scaffold with fast-growing rat fibroblast cells.
The team hopes to test the implants in an animal model soon to evaluate its efficiency.