Novel Biphasic Elastomeric Scaffold for Small-Diameter Blood Vessel Tissue Engineering

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Abstract
Compliance mismatch, thrombosis, and long culture times in vitro remain important challenges to the clinical implementation of a tissue-engineered small-diameter blood vessel (SDBV). To address these issues, we are developing an implantable elastomeric and biodegradable biphasic tubular scaffold. The scaffold design uses connected nonporous and porous phases as a basis to mimic, respectively, the intimal and medial layers of a blood vessel. Biphasic scaffolds were fabricated from poly(diol citrate), a novel class of biodegradable polyester elastomer. Scaffolds were characterized for tensile and compressive properties, burst pressure, compliance, foreign body reaction (via subcutaneous implantation in rats), and cell distribution and differentiation (via histology, scanning electron microscopy, and immunohistochemistry). Tensile tests, burst pressure, and compliance measurements confirm that the incorporation of a nonporous phase to create a "skin" connected to the porous phase of a scaffold can provide bulk mechanical properties that are similar to those of a native vessel. Compression tests confirm that the scaffolds are soft and recover from deformation. Subcutaneously implanted poly(diol citrate) porous scaffolds produce a thin fibrous capsule and allow for tissue ingrowth. In vitro culture of tubular biphasic scaffolds seeded with human aortic smooth muscle cells (HASMCs) and endothelial cells (HAECs) demonstrates the ability of this design to support cell compartmentalization, coculture, and cell differentiation. The newly formed HAEC monolayer stained positive for von Willebrand factor whereas collagen- and calponin-positive HASMCs were present in the porous phase.