Exploratory Study of Intranasal Administration of Human Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles for the Treatment of Ischemic Stroke

Inclusion criteria: * Ischemic Stroke * Age 18-70 years, no gender restriction * Confirmed anterior circulation occlusion by CTA or MR angiography (MRA) * Pre-stroke mRS score of 0-1 * Post-stroke ASPECTS score \>= 6 * Pre-enrollment NIHSS score\>= 6 * Within 24 hours to 14 days of stroke onset * Patients who have not received thrombolysis or endovascular treatment * No significant liver or kidney dysfunction: ALT and AST\<= 2.5 times the upper limit of normal, serum creatinine and blood urea nitrogen \<= 1.25 times the upper limit of normal * No significant cardiac dysfunction * The subject or legal representative can sign the informed consent form and comply with the requirements of the study for administration and follow-up. Exclusion criteria: * Intracranial hemorrhagic conditions observed on cranial CT: hemorrhagic stroke, epidural hematoma, subdural hematoma, intraventricular hemorrhage, subarachnoid hemorrhage, or hemorrhagic transformation, etc. * Known severe allergy to contrast agents (excluding mild rash-type allergies) * Known bleeding tendencies (including but not limited to): platelet count \< 100×10\^9/L; received heparin treatment within 48 hours with aPTT \>= 35s; currently taking warfarin with INR \> 1.7 * Patients with brain tumors, or a history of epilepsy and severe head trauma * Patients with other systemic malignancies * Patients with other serious systemic diseases such as immunodeficiency, coagulation disorders, etc. * Patients with Alzheimer's dis…