Biopolymer/Suture Polymer Interaction: Is It a Key of Bioprosthetic Calcification?

The aim of this study was to evaluate the effect of suture material made of polyester (PET), polypropylene (PP), and polytetrafluoroethylene (PTFE) on the calcification of a bovine pericardium (BP) consisting of collagen biopolymer preserved with an epoxy compound. Non-porous film made of the synthetic reinforced polymer REPEREN^® was chosen as a control material. Samples of the material (sutured or non-sutured with each of the three types of surgical sutures) were implanted subcutaneously in 45 young rats for 30, 60, and 90 days. The calcium content of the explants was quantified using atomic absorption spectrometry, a histological examination was performed using hematoxylin and eosin and von Kossa staining, and the structure of the calcium phosphate deposits was studied using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) with color field mapping. The results demonstrated the absence of calcification in the non-sutured BP and in all the REPEREN^® groups. In the sutured BP samples, a dynamic increase in the Ca content and the Ca/P ratio to 1.67-1.7 (crystalline hydroxyapatite) was observed by the 90th day. The minimum Ca content among the sutured BP groups was detected in samples where the PET thread was used. The cellular reaction to BP was significantly more pronounced than the reaction to REPEREN^® throughout the entire observation period; collagen homogenization was noted near the sutures. It can be concluded that all the studied suture materials provoke BP calcification. PET has the minimal negative effect.