Inclusion Criteria1. Subject is >/= 18 years of age
2. Subject has been diagnosed with acute ischemic stroke with onset ≤ 24 hours from enrollment.
3. Subject has NIH stroke score (NIHSS) ≥ 6 and ≤ 25.
4. Subject or legally authorized representative is willing and able to sign written informed consent.
Exclusion Criteria1. Subject has improvement in the NIH stroke scale as reflected by a reduction in ≥ 4 points from baseline at any time prior to enrollment.
2. Subject is currently prescribed angiotensin-converting-enzyme inhibitors (ACEi) and is unable or unwilling to convert to another antihypertensive pharmacological treatment for the duration of the study.
3. Subject has a history of significant allergic diathesis such as urticaria, angioedema or anaphylaxis.
4. Subjects with current malignancy or active malignancy ≤ 5 years prior to enrollment except basal cell or squamous cell carcinoma of the skin or in situ cervical cancer that has undergone potentially curative therapy and at least six months have elapsed since the procedure.
5. Subject has a history of clinically significant acute bacterial, viral, or fungal systemic infections in the last four weeks prior to enrollment.
6. Subject has clinical or laboratory evidence of an active infection at the time of enrollment.
7. Subject has known alpha 1-antitrypsin deficiency (α1-antitrypsin deficiency).
8. Subject has a known diagnosis of human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), or anti-hepatitis C virus (Anti-HCV) at screening.
9. Subject is pregnant or nursing.
10. Subject is male or female of childbearing potential, is participating in heterosexual sexual activity that could lead to pregnancy, and is unable or unwilling to practice medically effective contraception during the study.
11. Subject is participating in any other drug study ≤ 4 weeks or 5 half-lives of the investigational product, whichever is longer.
12. Subject does not have sufficient venous access for infusion of study treatment or blood sampling.
13. In the opinion of the Investigator, subject is unlikely to be followed for the duration of t the study.
14. Subject is unable or unwilling to comply with protocol requirements, including assessments, tests, and follow-up visits.
15. Subject has any other medical condition which in the opinion of the Investigator will make participation medically unsafe or interfere with the study results.