Human plasma α2‐macroglobulin promotes in vitro oxidative stress cracking of pellethane 2363‐80A: In vivo and in vitro correlations

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Abstract
It is hypothesized in this study that the phenomenon of environmental stress cracking (ESC) in polyetheruethane is caused by a synergistic action of biological components in the body fluids, oxidative agents, and stress. An in vitro system is designed to mimic the in vivo system; human plasma contains certain biological components that can act as a stress cracking promoter, while H2O2 (Co) solution provides an oxidative reaction comparable to that observed in the respiratory burst of adherent macrophages and foreign‐body giant cells. It is demonstrated that the phenomenon of in vivo stress cracking in Pellethane 2363‐80A is duplicated by an in vitro system that involves a pretreatment of prestressed specimens with human plasma at 37°C for 7 days followed by oxidation in 10% hydrogen peroxide with 0.10M cobalt chloride at 50°C for 10 days. The pretreatment with plasma has a synergistic effect with the oxidation by H2O2 (Co) treatment to produce ESC. A plasma component responsible for promoting stress cracking in Pellethane polyurethane is identified to be α2‐macroglobulin (α2M). © 1993 John Wiley & Sons, Inc.