New Tissue-Engineered Blood Vessel Replacements One Step Closer to Human Trials

Source: University of Minnesota

Summary: Researchers have created a new lab-grown blood vessel replacement, first-of-its-kind made up of biological materials which can be used in hemodialysis grafts, pediatric heart reconstruction, and adult bypass grafts.

According to the U.S. Renal Data System Annual Data Report, more than 100,000 people in the U.S. start hemodialysis (a process which removes waste products from blood in kidney failure cases) each year for the treatment of kidneys and more 400,000 people are being treated with life-saving hemodialysis. Currently, the preferred mode of blood vessel access for hemodialysis is arteriovenous fistula that connects an artery to a vein in the arm. As nearly 50% of the patients are experiencing complications (clotting, infections) with the current synthetic grafts. An artificial vessel like tubes (arteriovenous grafts) is required to overcome the complications. Researchers at the University of Minnesota have created a new lab-grown blood vessel replacement, first-of-its-kind made up of biological materials, decellularized graft that becomes repopulated with cells by the recipient’s own cells when implanted. The findings were published in the journal Science Translational Medicine.

Blood vessel-like tube grafts

Researchers have created a new lab-grown blood vessel replacement that is the first-of-its-kind nonsynthetic, decellularized graft that becomes repopulated with cells by the recipient’s own cells when implanted. Credit: University of Minnesota

Researchers have generated blood vessel-like tubes in the lab from post-natal human skin cells which are embedded in a gel-like material made of fibrin ( a protein involved in the clotting of blood). This cell-populated gel was placed in a bioreactor and grown for over 7 weeks and then the cells were washed away in the final week. The remnant was the collagen and other proteins secreted by the cells which make an all-natural but non-living tube for implantation. To test the vessels researchers implanted the 5 inch long lab-grown grafts into adult baboons. After 6 months, the grafts were shown to withstand nearly 30-time human blood pressure without bursting, resisted infection, showed no immune response and also withstood repeated needle punctures by self-healing.

The discovery could help many dialysis patients suffering from kidney failures each year. The grafts could also be adapted in the future for use as coronary and peripheral bypass blood vessels and tubular heart valves. With the success researchers are waiting to seek FDA approval for clinical trials in children with pediatric heart defects.

Professor Robert Tranquillo, “We harnessed the body’s normal wound-healing system in this process by starting with skin cells in a fibrin gel, which is Nature’s starting point for healing”, “Washing away the cells in the final step reduces the chance of rejection. This also means the vessels can be stored and implanted when they are needed because they are no longer a living material. In the future, thousands of the lab-grown vessels could be made from a small skin biopsy from one donor and then stored on the shelf for when they are needed by patients.

More Information: Z.H. Syedain et al. “A completely biological ‘off-the-shelf’ arteriovenous graft that recellularizes in baboons”, Science Translational Medicine (2017). … scitranslmed.aan4209

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