Dual-function hydrogels with sequential release of GSK3β inhibitor and VEGF inhibit inflammation and promote angiogenesis after stroke

Ischemic stroke is a devastating disease exhibiting a dismal prognosis due to overactive inflammation in the early stage and poor endogenous angiogenesis capacity in the late stage. To treat ischemic stroke, it is highly desirable to suppress the inflammatory response and combine it with sequential regulation of angiogenesis in the ischemic area. Here, we developed an engineered hyaluronic acid hydrogel for sequentially targeted dual drug delivery with different release kinetics to realize optimized combinatorial therapy. In this system, 6-bromoindirubin-3′-oxime (BIO), a glycogen synthase kinase 3 beta (GSK3β) inhibitor, was loaded in Pluronic F127 (PF127) nanoparticles for initial release to alleviate the inflammatory response and reduce cell apoptosis, while vascular endothelial growth factor (VEGF) was loaded in poly (lactic-co-glycolic acid) (PLGA) porous microspheres that enabled sustained release for continuous angiogenesis induction. As expected, hydrogels loaded with BIO/PF127 nanoparticles and VEGF/PLGA microspheres exerted a distinct therapeutic effect in two stages of ischemic stroke; they reduced the levels of early inflammatory factors IL-1β, IL-6 and TNF-α, promoted the polarization of microglia and astrocytes toward an anti-inflammatory phenotype, and improved late angiogenesis and behavioral performance. Hence, sequential delivery of anti-inflammatory and pro-angiogenic agents, corresponding to the spatiotemporal course of pathology development of ischemic stroke, provides a novel option to treat ischemic stroke via phased regulation of pathophysiological processes.