Development of implantable autologous small-calibre vascular grafts from peripheral blood samples

At present the generation of a small-calibre (≤5 mm) vascular replacement for artificial bypasses remains a challenge for tissue engineering. The biocompatibility of bioartificial vessel replacements is of decisive significance for function and depends on the materials used. A completely autologous vessel substitute must exhibit high biocompatibility and functionality. For this purpose we developed and optimised a technique for the engineering of an autologous bypass material from a fibrin scaffold and vascular cells isolated from the same sample of peripheral blood in a porcine model.

Fibrinogen, late outgrowth endothelial and smooth muscle cells were isolated from peripheral blood samples (n=14, 100 mL each). Fibroblasts were isolated from porcine aortic adventitial tissue (n=4). Tubular seeded fibrin segments were obtained using an injection moulding technique with the simultaneous incorporation of the in vitro expanded cells into the fibrin matrix. The segments were cultivated under dynamic conditions with pulsatile perfusion in a bioreactor. Morphological and functional characterization was done.

Artificial vascular segments with a length of 150 mm were reproducibly obtained with a hierarchical arrangement of incorporated cells similar to the structure of the vascular wall. By additional seeding of fibroblasts, suturable segments with biomechanical properties suitable for implantation into the arterial system were obtained.

Implantable bioartificial vascular grafts can be generated from blood. After cultivation under dynamic conditions the vascular segments possess a structure similar to that of the vascular wall and exhibit biomechanical properties sufficient for implantation as arterial substitutes.