The purpose of this study is to investigate the safety and feasibility of intra-arterial albumin infusion for patients with acute ischemic stroke after successful thrombectomy and to further explore the optimal dose of albumin through the implementation of a 3 + 3 dose-escalation design. At the maximum safe dose determined in the 3+3 dose-escalation phase, an additional 15 to 20 patients will be enrolled in the study, and comparisons were made with external patients who received endovascular treatment alone.

Albumin, the predominant plasma protein synthesized primarily in the liver, possesses various biochemical properties that are expected to confer a neuroprotective effect following acute ischemic stroke. Despite being utilized as a neuroprotective agent for stroke patients, albumin has not demonstrated efficacy, partly due to the persistence of the occluded vessel responsible for the stroke, thereby hindering the albumin's ability to exert its therapeutic effects in the ischemic region. In light of the advent of thrombectomy and subsequent recanalization of occluded blood vessels, it is imperative to reassess the potential impact of albumin. In first phase of this study, we plan to conduct a 3 + 3 dose-escalation trial to determine the safety and feasibility of intra-arterial albumin infusion for stroke patients undergoing successful mechanical thrombectomy. Since this is a 3 + 3 dose-escalation study with 7 doses (0.25g/kg, 0.35g/kg, 0.40g/kg, 0.45g/kg, 0.5g/kg, 0.55g/kg,0.60g/kg), a minimum of 21 (7 groups × 3 patient/group) patients will be required, assuming no major response occurs at any dose level, and a maximum of 42 (7 groups × 6 patient/group) patients will be required, assuming one major response occurs at each dose level. In second phase, at the maximum safe dose determined in the first phase, an additional 15 to 20 patients will be enrolled for intra-arterial albumin infusion.

Inclusion Criteria:

• Age 18 to 80 years;
• Patients with acute ischemic stroke caused by large vessel occlusion in the intracranial anterior circulation (internal carotid artery, middle cerebral artery M1 and M2 segments) ;
• mTICI score ≥ 2b for the occlude vessel after mechanical thrombectomy;
• Baseline National Institutes of Health Stroke score (NIHSS) ≥ 6;
• Stroke onset to arterial puncture time within 24 hours.

Exclusion Criteria:

• Upon admission, the patient's medical history and physical examination revealed manifestations indicative of congestive heart failure (CHF), such as jugular venous distention, the presence of a third heart sound, resting tachycardia at a rate of 100 beats per minute attributable to heart failure, hepatomegaly, and/or lower extremity edema attributable to heart failure or of unknown etiology;
• History of acute myocardial infarction within the preceding 3 months;
• The patient's medical history, electrocardiogram findings upon admission, or physical examination indicated the presence of second- or third-degree heart block or any arrhythmia associated with hemodynamic instability, as determined by the investigator's assessment;
• Acute or chronic renal failure with serum creatinine levels exceeding 2.0 mg/dL;
• Severe anemia characterized by a hematocrit below 32%;
• Computed tomography findings upon admission indicating the presence of any form of hemorrhage;
• Pregnancy status;
• Previous history of allergic reactions to albumin administration;
• Elevated blood pressure exceeding 185/110 mmHg when investigating the use of albumin administration;
• Presence of other potentially life-threatening medical conditions;
• Individuals with current chronic lung diseases, such as chronic obstructive pulmonary disease, bronchiectasis, or any other lung disorder that significantly impairs daily activities; 12. Individuals with known allergies to albumin.