Grafts Remodel into Growing Veins

Researchers tested whether a temporary blood-vessel graft could become a growing replacement vein in lambs. In 53 lambs, they placed 2-centimetre biodegradable grafts seeded with each animal’s own bone-marrow cells into the inferior vena cava, the large vein returning blood to the heart. The seeded cells disappeared soon after surgery, while cells from the neighbouring vein wall rebuilt the graft as its scaffold degraded. After early narrowing resolved, grafts lengthened from 21.0 ± 4.1 to 28.3 ± 2.3 millimetres alongside vertebral growth. By 52 weeks, their flexibility had normalized.