Article
Development of implantable small caliber vascular grafts made from autologous peripheral blood samples
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Published: | May 20, 2011 |
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Introduction: At present no ideal bypass material that would be suitable for replacing of even small-diameter vessels with a diameter of ≤ 5 mm is clinically available. Therefore, the generation of bioartificial vascular grafts remains a major challenge for vascular tissue engineering. Herein, we present the generation of implantable bioartificial vascular segments made from fibrin and vascular cells isolated from individual peripheral porcine blood samples in an in vitro-study.
Materials and methods: A fibrinogen preparation and colony-forming vascular cells were isolated from peripheral blood samples by means of density gradient centrifugation and cryoprecipitation from the same blood sample (n=10, 100 mL each). Stable fibrin tubes were obtained using an injection molding technique. During the generation of tubular segments the isolated and in vitro expanded vascular cells were simultaneously incorporated into the fibrin matrix. Engineered seeded segments were cultivated under dynamic conditions with pulsatile perfusion in a bioreactor system. For comparison a segment of 3 cm length from each graft was retained and kept under static culture conditions. Characterization was done by means of laser microscopy, immunohistochemistry (sm-alpha-actin, smoothelin and CD31), biomechanically and nitric oxide (NO)-assay.
Results: Stable tubes with a length of in mean 14 cm were reproducibly obtained. Exposure to pressure and shear stress resulted in a hierarchical arrangement of incorporated cells in the perfused segments, as was shown by a luminal confluent layer of CD31-positive cells covering a multilayer arrangement of sm-alpha-actin-positive cells in the wall. Perfused segments revealed biomechanical properties suitable for implantation into the arterial system and a significantly higher basal secretion of NO. Segments cultivated under static conditions showed no structured cellular arrangement and poor mechanical properties.
Conclusion: By means of a simple injection molding technique with simultaneous generation and seeding of tubular fibrin segments followed by dynamic cultivation in a bioreactor system implantable bioartificial vascular conduits were obtained.