Bioengineered Vessels Appear Safe for Use in Dialysis Patients
Off-the-shelf bioengineered vessels appear to be a safe substitute for synthetic or autologous grafts in providing vascular access for hemodialysis in end-stage renal disease patients, according to results of a small, first-in-man trial presented November 20, 2013, at the American Heart Association Scientific Sessions in Dallas, TX. The novel vessels also minimize the risk of rejection, clotting, and infection associated with use of synthetic or autologous vessels.
The pilot study, presented by Jeffrey H. Lawson, MD, PhD, of the Duke University Medical Center (Durham, NC), evaluated the safety and efficacy of the bioengineered vessels surgically implanted in the upper arms of 28 end-stage renal disease patients for arteriovenous access to hemodialysis at 3 Polish centers.
Using proprietary technology (Humacyte, Ressearch Triangle Park, NC), donated human vascular cells are isolated and grown in bioreactors on tubular scaffolds made of a biodegradable polymer. After secreting collagen and other molecules to form an extracellular matrix, the cells are removed with detergents, rendering the grafts nonimmunogenic and capable of storage.
In preclinical data, the bioengineered vessels proved mechanically similar to native vessels, with similar suture retention strength and burst pressure. They also showed evidence of cellular repopulation with endovascular cells, thereby reducing the risk of thrombosis, with little intimal hyperplasia.
The study cohort included 17 men and 11 women, with a mean age of 60 years and a mean BMI of 28. Comorbidities included hypertension (82%), diabetes (46%), and vascular disease (39%). Each patient had a mean 4.1 prior dialysis access procedures.
Vessels Patent at 6 Months
At 6 months, ultrasound showed that all bioengineered vessels were patent. Primary patency had been lost in 8 patients requiring 10 interventions (8 thrombectomies and 2 venous anastomosis angioplasties), for a 71% rate of unassisted primary patency. No infections, dilatations, or aneurysms were seen. In addition, there was no evidence of an immune response: At 3 months, the percent of patients with reactivity to Panel Reactive Antibody Class I antibodies declined slightly from pre-implant levels.
Flow rates suitable for dialysis (> 500 mL/min) were maintained for up to 1 year in 25 patients; 22 patients used the bioengineered vessels for dialysis 3 times per week, with more than 800 accesses in up to 9 months of experience per graft. Grafts proved easy to cannulate using standard techniques. Only 1 delayed hemostasis requiring intervention was seen.
Dr. Lawson observed that longer follow-up and additional clinical studies are required to confirm these preliminary observations.
Meanwhile, the U.S. Food and Drug Administration has approved an Investigational New Drug application to evaluate the bioengineered vessels in a multicenter U.S. trial of patients with end-stage renal disease undergoing dialysis.
Lawson JH. First-in-Man Evaluation of an Investigational Bioengineered Blood Vessel. Presented at: American Heart Association Scientific Sessions; November 20, 2013; Dallas, TX.
- Dr. Lawson reports serving as a consultant for Humacyte.