Tissue‐engineered Vascular Grafts for Congenital Heart Surgery

Abstract

ObjectiveWe developed a tissue engineered vascular graft (TEVG) formed by seeding autologous bone marrow‐derived mononuclear cells onto a biodegradable tubular scaffold fabricated from a knitted polyglycolic acid core and coated with a 50:50 copolymer of poly lactic acid and polycaprolactone. Once implanted, the scaffold degrades and neotissue forms giving rise to neovessel which is structurally and functionally similar to the native vessel into which it was implanted. Herein we will describe the natural history of the evolution of the mechanical properties of the TEVG after implantation and evaluate the impact of the mechanical properties of the TEVG on graft performance.MethodsWe utilized an ovine intrathoracic inferior vena cava model in order to evaluate the evolving mechanical properties of the TEVG and determine their impact on graft performance. We implanted TEVG into 24 juvenile lambs and serially assessed graft morphometry and function using serial angiography and intravascular ultrasound (IVUS) over a 6 ‐month to 1‐year period. We serially measured changes in graft size using both angiography and IVUS. We also assessed the graft hemodynamics at angiography. We measured graft displacement over both the cardiac and respiratory cycle. Finally, a subset of TEVGs were harvested and underwent biaxial mechanical testing.ResultsThe TEVG undergoes significant remodeling when after implantation. As the scaffold degrades, the TEVG transforms from a relatively stiff conduit to a highly compliant neovessel with growth capacity.ConclusionsThe transformation of the TEVG from a relatively stiff vascular conduit to a more compliant neovessel enables the graft to function as a capacitance vessel improving its performance when used in the venous circulation.Support or Funding InformationNIH R01HL139796