According to the results featured Online First in The Lancet, this pioneering technique may provide a new alternative for patients with unhealthy veins who require dialysis or heart bypass surgery without having to encounter the problems of synthetic grafts, which are prone to clots and blockages, or needing lifelong immunosuppressive treatment.
Martin Birchall and George Hamilton from the UK's University College London explain in an associated comment:
"The young girl in this report was spared the trauma of having veins harvested from the deep neck or leg with the associated risk of lower limb disorders, and avoided the need for a liver or multivisceral transplantation."
The hepatic portal vein is a large vein, through which all venous blood from the gastrointestinal system is carried to the inferior surface of the liver. A blockage of the hepatic portal vein can lead to serious complications, including lethal variceal bleeding, enlarged spleen, developmental retardation, and even death. Until now, clinicians only managed to achieve mixed success in attempting to restore portal blood flow by using umbilical veins and artificial grafts to build a bridge around the blockage (meso Rex bypass).
The researchers from the University of Gothenburg surgically removed a 9cm segment of iliac (groin) vein from a living human donor. After removing all living cells, they were left with a tube that consisting of just the protein scaffolding, which they injected with stem cells they took from the girl's own bone marrow. The graft was reimplanted in a meso Rex bypass procedure two weeks after seeding.
The girl developed no post-operative complications and the blood flow was immediately restored to normal function. A year after the operation the girl's height had increased from 137 to 143 cm and her weight increased from 30 to 35kg.
At the one-year follow up, the team observed a decreased portal blood flow, which required a second stem cell-based graft. The patient is doing well since the second graft and is capable of walking increasing long distances of 2 to 3 km in addition to doing light gymnastics.
Significantly, despite the fact that she is not taking any immunosuppressive drugs, she has not developed anti-donor antibodies.
The researchers declare in a concluding statement:
"The new stem-cells derived graft resulted not only in good blood flow rates and normal laboratory test values but also, in strikingly improved quality of life for the patient. The work also establishes the feasibility and safety of a novel paradigm for treatment, in cases of venous insufficiency, obstructed veins or inadequate autologous veins. Furthermore our work opens interesting new areas of research, including trying to reproduce arteries for surgical use in patients with arteriovenous fistulas for dialysis [a type of vascular access for dialysis] or coronary bypass surgery."
Birchall and Hamilton add:
"Olaussen and colleagues' report suggests that tissue-engineered vascular grafts are promising, but one-off experiences such as the procedure they describe need to be converted into full clinical trials in key target populations, and delivered via straightforward, quality-controlled production processes if regenerative medicine solutions are to become widely used and accepted."
Written By Petra Rattue