Engineered neural stem cell vesicles activating Wnt promote blood-brain barrier repair after cerebral haemorrhage

The blood-brain barrier (BBB), a highly specialized neurovascular structure indispensable for preserving cerebral homeostasis, exhibits significant impairment across diverse neurological pathologies; however, its therapeutic targeting persists as a formidable challenge due to the inherent complexity of its multicellular architecture and dynamic regulatory networks. Although the Wnt/β-catenin signalling pathway orchestrates the development and maintenance of the BBB, the clinical translation of Wnt-based interventions remains elusive. We fabricated functionalized extracellular vesicles derived from neural stem cells (EVs-WK) by loading them with an engineered BBB-tropic ligand, Wnt7a-K190A, using electroporation. The therapeutic benefits of EVs-WK for BBB protection and repair were subsequently interrogated through comprehensive in vitro and in vivo analyses. In vitro mechanistic studies demonstrated that EVs-WK had three main effects: they enhanced BBB integrity, promoted synaptogenesis through β-catenin-mediated reinforcement and significantly attenuated neurotoxic activation of astrocytes. Cross-species validation using humanized EVs (hEVs-WK) confirmed the conserved therapeutic efficacy of this approach, as shown by the mitigation of lipopolysaccharide-induced barrier dysfunction and downregulation of inflammatory pathways. In murine intracerebral haemorrhage models, administering EVs-WK significantly reduced haematoma expansion and accelerated motor recovery. This modular EV platform combines BBB restoration with neurovascular unit repair, thus overcoming critical translational barriers in neurological therapeutics through targeted-controlled activation of Wnt signalling.