PH-sensitive,cerebral Vasculature-targeting Hydroxyethyl Starch Functionalized Nanoparticles For Treatment In Ischemic Stroke

Purpose:Angiogenesis,a critical restorative process after ischemia,is a promising therapeutic approach for improving neurological deficits.However,conventional drug delivery methods have bottlenecks in crossing the blood-brain barrier（BBB）.In this study,a dual-targeted therapeutic strategy was reported to enable p H-sensitive drug release and allow cerebral ischemia targeting to improve stroke therapeutic efficacy.Methods:Carboxylated hydroxyethyl starch（HES）was combined with Pro-His-Ser-Arg-Asn（PHSRN）peptide through amide reaction,and the small molecule agonist SAG of Smo receptor was electrostatically adsorbed to form SAG@PHSRN-HES nanodrugs.Several assays were used to identify and characterize the nanodrugs.Calculate the nanodrug loading and encapsulation rate.In vitro release,cellular drug delivery,and in vivo imaging were used to investigate the drug release behavior and the characteristics of targeting brain ischemia of nanodrugs.A cerebral ischemia-reperfusion model of C57BL/6 mice was established and treated by tail vein injection of nanodrugs for 5 consecutive days.The behavioral functions of mice were judged by neurological function symptom score and foot-failure test.The cerebral protection effect was evaluated by brain MRI and Nissl staining methods for infarct volume and brain leakage measurement.Immunofluorescence staining of vascular density,tight junctions,and synaptophysin at the ischemic penumbra of brain tissue was used to confirm the effect of nanomedicine treatment.Cytotoxicity assay,hemolysis test,blood and biochemical analysis,and tissue sectioning were used to evaluate the safety of nanomedicines.Results:SAG@PHSRN-HES was synthesized by a two-step method with a spherical particle size around 31.52 nm.¹H MRI and FTIR confirmed the successful synthesis.The rates of drug loading and encapsulation were 6.9 and 62.1 wt.%.Experiments with in vitro drug release revealed that the release of nanodrug increased with decreasing p H.In vivo imaging experiments showed that SAG@PHSRN-HES could target the integrinα₅β₁,which was expressed in cerebral ischemia,and the enrichment of nanomedicines in cerebral ischemia was 11 times that of free drugs.After nanodrug administration,the animal model of cerebral ischemia revealed decreased infarct size,leakage,neurological impairments,and mortality.Immunofluorescence staining revealed more angiogenesis and tight junctions in the nanodrugs group,with correspondingly higher expression of the angiogenic factor Ang-1.In vitro and in vivo safety assessment showed that the nanomedicine did not produce significant toxic side effects on cells and tissues within a certain dose range.Conclusion:The nanodrugs developed in this work can be released sensitively in a low p H environment while targeting the region of cerebral ischemia.SAG@PHSRN-HES utilizes the synergistic mechanism of PHSRN and SAG to promote angiogenesis and blood-brain barrier integrity,consequently boosting neuroplasticity and neurofunctional recovery.Nanomedicines provide in vivo safety while improving efficacy.Dual-targeted has a good therapeutic potential to treat cerebral ischemia.