rhPro-UK in Acute Ischaemic Stroke Within 4.5 Hours of Stroke Onset Trial 2(PROST-2)

Inclusion Criteria: 1. Clinically diagnosed as acute ischemic stroke (according to the Chinese Guidelines for the Diagnosis and Treatment of Acute Ischemic Stroke 2018). 2. 18 years or older, male or female. 3. NIH Stroke Scale（NIHSS）scores of 4 to 25. 4. Treatment within 4.5 hours after stroke onset. 5. The symptoms of stroke last at least 30 minutes without significant improvement before treatment. 6. Informed consent by patient or by patient's guardians. Exclusion Criteria: 1. Prestroke modified rankin scale of ≥2. 2. Large areas of hypodense ischaemic changes on baseline CT（Infarction area\> 1/3 of the middle cerebral artery feeding area）. 3. Intracranial hemorrhage. 4. Previous history of intracranial hemorrhage. 5. Severe cerebral trauma or stroke history within 3 months. 6. Intracranial tumor or giant intracranial aneurysm. 7. Intracranial or intraspinal surgery within the past 3 months. 8. Gastrointestinal or urinary bleeding within the past 3 weeks. 9. History of major surgical procedures or severe trauma within the last 2 weeks (investigator evaluation). 10. Puncture in 1 week which can not be oppressed. 11. Active visceral hemorrhage. 12. Aortic arch dissection. 13. Bacterial endocarditis or pericarditis. 14. Planned for thrombectomy. 15. Patients with systolic blood pressure ≥ 185 mmHg or diastolic blood pressure ≥ 110 mmHg after anti-hypertension treatment. 16. High risk of acute hemorrhage include platelet count\<10\^9/L. 17. Received low molecular weight heparin or heparin within 24 hours. 18. Using of thrombin inhibitors or factor Xa inhibitor within the past 48 hours. 19. Using of oral anticoagulant drugs and PT \>15s or INR \>1.7. 20. Patients with epilepsy or other mental disorders that could not be adhered to at the beginning of stroke. 21. Blood glucose \< 2.8 mmol/L or \> 22.2 mmol/L. 22. Allergies to rhPro-UK or rt-PA active ingredients or other components. 23. Pregnant women or beastfeeding women. 24. Participants in other clinical trials within the past month. 25. The investigator believes that the patient is not suitable for the study.