Synthetic polymer coatings diminish chronic inflammation risk in large ECM-based materials

Degradable materials that can support cell infiltration and remodeling are the basis of tissue engineered approaches to vascular repair. In addition, to replace or close a large area of the vasculature, a patch material or scaffold must also withstand high pressure over time. Extracellular matrix-based (ECM-based) scaffolds offer a biological substrate with environmental cues that can support the formation of appropriate vascular tissue. However, scaffolds made from pure natural materials can degrade rapidly, resulting in reduced mechanical integrity of the implant and possible chronic inflammation in the site. A hybrid biomaterial, combining the matrix-dense tissue pericardium with a layer of the degradable polymer poly(propylene fumarate) (PPF), is suited to withstand rapid enzymatic degradation and control the presentation of an unaltered natural tissue matrix for remodeling activity. In this study, we show that the polymer reinforced hybrid supports cellular infiltration, but has fewer macrophages in the vicinity of the implant after 6 weeks in vivo than an untreated tissue control in both athymic and immunocompetent rat models. This result is supported by changes seen in other inflammatory cell populations. Based on significant differences in the inflammatory response to untreated pericardium and PPF-reinforced pericardium, we conclude that the polymer reinforcement layer can be used as a tool to leverage presentation of the ECM molecules in ECM-based scaffolds. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 494-504, 2019.