The goal of this study is to evaluate the safety and efficacy of JX10 versus placebo in participants with Acute Ischemic Stroke (AIS) who present for care within 4.5 to 24 hours. The main question the study aims to answer are: 1. JX10 improves functional outcomes as measured by the modified Rankin Scale score when compared with placebo following AIS. 2. Risk of symptomatic intracranial hemorrhage of JX10 in participants with AIS. During Part 1, participants will be randomized to JX 10 (1mg/kg, 3 mg/kg) or placebo. During Part 2, participants will receive JX10 (optimal dose chosen from Part 1) or placebo.