Preclinical In Vivo Evaluation and Screening of Zinc-Based Degradable Metals for Endovascular Stents

Zinc alloy development and characterization for vascular stent application have been facilitated by many standardized and inexpensive methods. In contrast, overly simplistic in vitro approaches dominate the preliminary biological testing of materials. In 2012, our group introduced a metal wire implantation model in rats as a cost-effective and realistic approach to evaluate the biocompatibility of degradable materials in the vascular environment.In this work, we adapted metrics routinely used for evaluating stents to quantitatively characterize the long-term progression of the neointima that forms around zinc-based wire implants. Histological cross-sections were used to measure the length of neointimal protrusion from the wire into the lumen (denoted wire to lumen thickness), the base neointimal length (describing the breadth of neointimal activation), and the neointimal area. These metrics were used to provide in-depth characterization details for neointimal responses to Zn-Mg and Zn-Li alloys and may be used to compare different materials.