Stroke is the second largest cause of death globally after ischemic heart disease.Of the total number of prevalent strokes, 84.4% are ischemic. Reperfusion therapy is the most important treatment for acute ischemic stroke (AIS) ,including intravenous thrombolysis and/or endovascular treatment.However,the most serious and common complication with reperfusion therapy is hemorrhage transformation(HT),which significantly increases disability and mortality. The fundamental mechanism leading to post-stroke HT is the disruption of the blood brain barrier(BBB) and increase of permeability.Endocan plays a critical role in vascular inflammatory responses by enhances the production of pro-inflammatory cytokines by endothelial cells,the expression of adhesion molecules such as inter-cellular adhesion molecule-1(ICAM-1) and vascular cell adhesion molecule-1(VCAM-1),and the adhesion of leukocytes to endothelial cells. Endocan significantly decreases levels of zonula occludens（ZO-1) and occludin which are tight junction proteins that play major roles in the maintenance of vascular barriers. Endocan could induce vascular endothelial growth factor-A(VEGF-A) and facilitate the binding of VEGF-A to its receptor(VEGFR-2) to enhanced endothelial permeability.Therefore,endocan is a reliable biomarker of endothelial dysfunction, which may be associated with disruption of the BBB. In this context, the investigators hypothesized that elevated pretreatment serum endocan levels might be independently associated with HT after reperfusion therapy in the acute phase of ischemic stroke. Serum endocan,ICAM-1,VCAM-1 and matrix metalloproteinase-9(MMP-9) levels will be determined by enzyme-linked immunosorbent assay(ELISA) in blood samples obtained at baseline (pretreatment) and at 12,24 hours after reperfusion therapy in patients with acute stroke and in healthy subjects.In the present study,the investigators attempt to investigate whether high levels of endocan are associated with HT in patients who received reperfusion therapy.In addition,the investigators explore the association between serum endocan and early neurological deterioration and unfavourable short-term prognosis.

Inclusion Criteria:

• Clinical diagnosis of acute ischemic stroke and presentation at the hospital within 24h from symptom onset
• Eligibility for intravenous thrombolysis and/or endovascular treatment
• Age ≥18 years

Exclusion Criteria:

• Administration of intravenous thrombolysis at another hospital in patients who are candidates for endovascular treatment
• Contraindications to intravenous thrombolysis
• Contraindications to iodinated contrast agent
• A history of ischemic stroke in three months
• Clinical diagnosis of autoimmune,inflammatory, hematological, or infectious diseases
• Clinical diagnosis of cancer
• Clinical diagnosis of severe cardiac,pulmonary,renal or liver failure
• Clinical diagnosis of dementia or psychosis
• Pregnant and lactating women

The patients in Xijing Hospital,Yan 'an University Xianyang Hospital and Xianyang First People's Hospital