An Open, Study to Assess the Safety of RGTA® (OTR4132) in Patients With Acute Ischemic Stroke (AIS)

Inclusion Criteria: Eligible patients for this study will be included if all of the following conditions are met: 1. Age between 45 and 80 years 2. Acute ischemic stroke in anterior circulation territory, identified by magnetic resonance imaging (MRI) 3. Occlusion of anterior circulation i.e. internal carotid artery (ICA) or proximal middle cerebral artery (MCA) (M1 and/or M2 segment) 4. Volume of the infarcted lesion estimated below two thirds of the MCA territory (diffusion MRI sequence) 5. Endovascular thrombectomy initiated within 6 hours of stroke onset with known stroke onset time or Endovascular thrombectomy initiated within 6 to 16 hours of symptoms onset (last know well in case of unwitnessed onset) with a mismatch on brain MRI defined in \*. 6. Recanalization confirmed by angiography after endovascular treatment: TICI grade 2b - 3 7. NIHSS at pre-screening (National Institute of Health Stroke Scale/Score), including hand testing: between 11 and 25 8. No significant pre-stroke disability (pre-stroke modified Rankin Score (mRS): 0-1 9. Able to follow neuro-rehabilitation programme 10. Patient\*\* or legally authorized representative (family member or trusted person if patient unable to give consent) or independent physician (if patient unable to give consent and if an authorized representative cannot be reached) has signed informed consent). * Perfusion core/penumbra mismatch: * Infarct core volume \<70 mL * and critically hypoperfused volume/infarct core volume \>1.8 * and mismatch volume \>15mL \*\* Patients unable to give consent at baseline will go through a deferred consent procedure to continue the study Exclusion Criteria: * Eligible patients for this study will not be included if any of the following conditions are present: 1. Previous symptomatic stroke 2. Pre-existing medical, neurological, or psychiatric disease that would confound the neurological evaluation 3. Contra-indication to MRI 4. Evidence of intracranial haemorrhage (ICH) 5. At the discretion of the investigator, patients with co-morbidities associated with a life expectancy of less than 3 months or co-morbidities that could influence the study results or would complicate assessment of outcomes (e.g. dementia, psychiatric disease) or would make clinical follow-up difficult 6. History of allergy or anaphylactic reactions to any of the ingredients of OTR4132-MD or heparinoids 7. History of Hypersensitivity or anaphylactic reactions to iodinated contrast media 8. Severe renal failure with glomerular filtration rate (GFR) \< 30 mL/min 9. Severe uncontrolled arterial hypertension e.g. systolic blood pressure \> 185 mmHg or diastolic blood pressure \> 110 mmHg, or intravenous medication necessary to reduce blood pressure 10. Increased risk of haemorrhage (such as medical history of significant bleeding disorders, major surgery or significant trauma in the past 3 months, any history of central nervous damage or suspected intracranial haemorrhage, symptoms suggestive of subarachnoid haemorrhage, even if the MRI is normal, international normalized ratio (INR)\>1.3 or activated partial thromboplastin time (aPTT)\>ULN (upper limit of normal) 11. Suspected cerebral vasculitis based on medical history and imaging 12. Occlusions in multiple vascular territories 13. Evidence of intracranial tumour 14. Evidence of any prior intracranial intervention (i.e. neurosurgery, endovascular intervention) 15. Worsening of medical or neurological conditions or per-procedures complications 16. Any other serious, advanced, or terminal illness (investigator judgment) 17. Pregnant or breastfeeding or women without an adequate contraceptive method 18. Current participation in another investigation drug or device study 19. The patient is not a member or beneficiary of the French social security system