Clinically available transcatheter aortic valve replacement (TAVR) technologies typically use chemically fixed bovine or equine tissues for the valve leaflets. While these fixed, xenogeneic materials have been used with success in devices placed by open surgical access, the tissue thickness (>500 microns) adds significantly to the overall crossing profile of the delivery device. Complications associated with device diameter are generally reported in at least 10-20% of clinical cases, making a reduced crossing profile one of the most critical targets for second generation TAVR devices. Another limitation associated with pericardium is fatigue induced delamination. Previously we have reported clinical results with a completely autologous tissue engineered vascular graft built using a process termed sheet-based tissue engineering. Using this approach, we were able to build small diameter blood vessels with supraphysiologic burst pressures, and demonstrated clinical durability with time points out to 3 years. Importantly, this tissue engineering approach requires no chemical fixation or exogenous biomaterials. More recently, we reported initial human use with an allogeneic version of the vessel. With time points out to 1 year, the allogeneic tissue engineered material demonstrated no evidence of immune reaction. This transition to an off-the shelf, allogeneic approach enables use the material in a variety of new clinical indications, including valve reconstruction. Valve leaflets built from a single sheet, demonstrated ultimate tensile strength in excess of that for bovine valve leaflets. Of note, the thickness of the sheet was less than 200 microns, roughly 30 percent that of bovine pericardium. The tissue can also be compressed, further reducing the thickness to approximately 75 microns. This thin, durable, single layered tissue can be assembled onto commercially available TAVR devices resulting in a reduction in crossing profile of approximately 2 Fr. The valve leaflets can be sutured easily, coapt normally, and can withstand arterial backpressure. Given the non-laminated structure of the tissue engineered leaflet, the lack of synthetic materials, and the durability demonstrated in other clinical indications, this approach may provide not only a reduced crossing profile, but also improved long term clinical results.


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  • Accepted: 05 June 2012
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