Abstract Number ‐ 127: Poly(vinyl alcohol) grafts of brain aneurysms with patient‐specific morphologies

Abstract

Introduction Current animal models of brain aneurysms used for testing neuro‐interventional devices have highly simplistic vascular anatomy in comparison with human aneurysm‐parent vessel complexes. Poly(vinyl alcohol) (PVA) is a leading biomaterial for manufacture of artificial vascular grafts because of its biocompatibility, hemocompatibility, availability, low cost, moldability/castability, and tunable mechanical properties to match arterial compliance [1,2]. However, PVA is non‐cell adhesive and requires modification with additives to promote endothelialization of the luminal surface to maintain long‐term graft patency [1,3]. We have previously studied the biocompatibility of resorcinol bis(diphenyl phosphate) (RDP) coated clays blended with polymers and have found excellent cell adhesion and proliferation with human dermal fibroblasts as well as dental pulp stem cells [4]. Our overall goal is to develop a new in vivo model of brain aneurysms by manufacturing patient‐specific aneurysm anatomies with a blend of PVA and RDP clay and grafting them into animals. Here, we evaluate the casting of PVA in the shape of patient‐specific aneurysms. Methods 10% PVA (w/w) (99% hydrolyzed, 85–124K molecular weight, Sigma Aldrich) was dissolved in deionized water, to which 1% RDP clay (ICL Industrial Products, Be’er Sheva, Israel) was added. The PVA was crosslinked using 15% (w/w) of sodium trimetaphosphate and 30% (w/w) of sodium hydroxide, after which rheological studies (stress sweeps using a Bohlin Gemini rheometer) were conducted. In the casting procedure, negative molds of both simple tubes and complex aneurysm geometries were designed using Rhinoceros 3D software (Robert McNeel & Associates, Seattle, WA) and 3D printed in ABS plastic. The negative mold was then filled with beeswax, resulting in a positive wax mold that was dip‐coated 8 times in PVA solution, and spun on a two‐axis spinner in between each dip to ensure even coverage. After overnight drying in a fume hood, the model was placed in heated water, allowing the wax to melt out and leaving behind the luminal PVA cast. Results Rheology on the crosslinked polymers showed that the PVA/RDP blend exhibited over twice the elastic modulus of unblended PVA (Figure A). Such enhanced mechanical properties are consistent with previous studies [5]. Both simple tubular geometries and patient‐specific anatomies were able to be successfully cast using the methodology developed here (Figure B). Conclusions This proposed casting methodology demonstrates a realistic, efficient way to replicate complex aneurysm geometries with comparatively inexpensive materials and short time frame. Future endeavors will include further exploration of the PVA/RDP biocompatibility as well as completing the casting procedure with a PVA/RDP blend.