In vitro characteristics of a gelling PEGDA-QT polymer system with model drug release for cerebral aneurysm...

A liquid-to-solid gelling polymer system, such as the poly(ethylene glycol) diacrylate-pentaerythritol tetrakis (3-mercaptopropionate) (PEGDA-QT) system, can fill cerebral aneurysms more completely than current embolization materials, reducing the likelihood of aneurysm recurrence. PEGDA-QT gels were formulated using PEGDA of different molecular weights (PEGDA₅₇₅ and PEGDA₇₀₀ ), and their characteristics were examined in vitro. Experiments examined gel time, mass change, crosslink integrity, cytotoxicity, and protein release capabilities. In general, PEGDA₅₇₅ -QT gels were more hydrophobic, requiring an initiating solution with a higher pH (pH 9.5) to achieve a gel time comparable to PEGDA₇₀₀ -QT gels, which used an initiating solution at pH 9.19. The mass change and crosslink integrity of gels were analyzed over time after gels were submerged in 150 mM phosphate buffered saline. After 380 days, PEGDA₅₇₅ -QT gels achieved a maximum mass increase of 72% due to water uptake, while PEGDA₇₀₀ -QT gels doubled their initial mass (100% increase) by 165 days. Compression tests showed that PEGDA₇₀₀ -QT gels hydrolyzed more quickly than PEGDA₅₇₅ -QT gels. Cytotoxicity assays showed that in general, PEGDA₅₇₅ -QT negatively affected cell growth, while PEGDA₇₀₀ -QT gels promoted cell viability. Sustained, controlled release of lysozyme, a 14.3 kDa protein, was achieved over an 8-week period when loaded into PEGDA₇₀₀ -QT gels, but PEGDA₅₇₅ -QT gels did not show sustained release. These studies show that although they are similar in composition, these PEGDA-QT gel formulations behave considerably differently. Although PEGDA₇₀₀ -QT gels swell more and degrade faster than PEGDA₅₇₅ -QT gels, their cytocompatibility and protein release characteristics may prove to be more beneficial for in vivo aneurysm treatment. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.