The recently synthesized polyurea-nanoencapsulated surfactant-templated aerogels (X-aerogels) are porous materials with significantly improved mechanical strengths. Surface-wise they resemble polyurethane, a common biocompatible material, but their biocompatibility has never been investigated. As lightweight and strong materials, if X-aerogels also have acceptable biocompatibility, they may be used in many implantable devices. The goal of this study was to investigate their biocompatibility toward platelets, blood plasma, and vascular endothelial cells, in terms of cell activation and inflammatory responses. Platelets were incubated with X-aerogel and platelet activation was measured through CD62P and phosphatidylserine expression. Platelet aggregation was also measured. Contact with X-aerogel did not induce platelet activation or impair aggregation. To determine X-aerogel-induced inflammation, plasma anaphylatoxin C3a level was measured after incubation with X-aerogel. Results showed that X-aerogel induced no changes in plasma C3a levels. SEM and SDS-PAGE were used to examine cellular/protein deposition on X-aerogel samples after plasma incubation. No structural change or organic deposition was detected. Furthermore, X-aerogel samples did not induce any significant changes in vascular endothelial cell culture parameters after 5 days of incubation. These observations suggest that X-aerogels have a suitable biocompatibility toward platelets, plasma, and vascular endothelial cells, and they have potential for use in blood implantable devices.

Typically, tissue-engineered scaffolds mimic the topographical properties of the native extracellular matrix. However, other physical properties, such as the scaffold mechanical stiffness, are not imitated. The purpose of this study was to fabricate scaffolds with improved mechanical properties and investigate their biocompatibility towards endothelial cells and platelets. To enhance mechanical properties, an electrospinning apparatus was developed that fabricates fibers with sheath-core morphologies. Different combinations of cellulose acetate and chitosan were chosen to modulate the mechanical properties of the formed fibers. We hypothesized that mechanically stiffer scaffolds would improve endothelial cell growth and that all scaffolds would be compatible towards endothelial cells and platelets. Endothelial cell-culture conditions were quantified up to 5 days. Migration onto scaffolds was monitored for 10 days. Platelet aggregation, antagonized by thrombin receptor agonist peptide 6, was measured after scaffold incubation. A platelet activation time-course was assessed with the modified prothrombinase assay. As scaffold mechanical stiffness increased, endothelial cell growth within and adhesion to and migration throughout the scaffolds was promoted. Also, scaffolds did not induce platelet aggregation or activation. These results indicate that the mechanical stiffness of engineered scaffolds regulates endothelial cell-culture parameters and that these sheath-core electrospun scaffolds are compatible towards endothelial cells and platelets.