Enzymatically cross-linkable sulfated bacterial polyglucuronic acid as an affinity-based carrier of FGF-2 for therapeutic angiogenesis

The fibroblast growth factor-2 (FGF-2) is a critical protein for biological processes such as angiogenesis and tissue regeneration. Recently, hydrogels based on semi-synthetic sulfated polysaccharides have been developed for the controlled delivery of FGF-2. These affinity-based FGF-2 carriers utilizing hydrogels based on sulfated polysaccharides enable sustained delivery of FGF-2, yet choice of materials is limited. Here, we demonstrate a novel synthetic sulfated polysaccharide-based hydrogel based on bacterial polyglucuronic acid (PGU). We synthesized phenol-grafted sulfated PGU (PGUS-Ph), an enzymatically cross-linkable PGU derivative that exhibited an enhanced affinity for FGF-2. The aqueous solution of PGUS-Ph, when combined with FGF-2, could be injected into affected sites and form a hydrogel in a minimally invasive manner. The FGF-2 released from the PGUS-Ph hydrogel induced blood vessel formation, as proven by a chick embryo-based angiogenesis assay. Our results indicate that the PGUS-Ph has the potential as an enzymatically cross-linkable and minimally invasively injectable affinity-based FGF-2 delivery system.