Tissue engineering of samll calibre vascular grafts using a novel fibrin-polylactic acid composite scaffold

Atherosclerosis is the most frequent cause of mortality in Western societies. In addition to autologous vascular grafts and synthetic vascular grafts, cardiovascular tissue engineering promises new sources for vessel transplants. The necessity of a short production time led to the development of the Vascular Composite Graft with the advantages of viable tissue, optimal mechanical properties and minimal use of foreign body material. The Vascular Composite Graft is based on a co-scaffold system using autologous fibrin gel as a cell carrier and a macroporous (pore size 1–2mm) textile polylactic acid (PLA) mesh for mechanical support. Seeded myofibroblasts were isolated from sheep carotid artery. Vascular structures with an inner diameter of 4.5mm were produced using an injection moulding technique. The tissue-engineered vessels were conditioned using a flow rate of up to 100ml/min at physiological pulsatile pressure (˜120/90/70mmHg) for 20 days. Routine histological staining demonstrated adequate growth and morphology of the cells within the fibrin gel surrounding the PLA fibres. Synthesis of types I and III collagen, as well as elastin, was also detected. Furthermore, alphaSMA expression was evident in the myofibroblasts of the vascular graft. The burst strength of the graft was determined to be >400mmHg, underscoring the mechanical stability of the developing tissue. The Vascular Composite Graft, based on a co-scaffold of a PLA mesh and a fibrin cell carrier material, has a mechanically stable structure with remarkable tissue development, and is a potentially implantable structure for the replacement of bypass of diseased or occluded vessels.