Study to Evaluate the Efficacy and Safety of HepaStem in Patients With Acute on Chronic Liver Failure (ACLF)

Inclusion Criteria: 1. Are adults aged between 18 and 75 years old. 2. Have an initial diagnosis of ACLF at the investigational site. 3. Have ACLF grade 1 or 2 according to the EASL-CLIF Consortium definition. 4. Have a total bilirubin ≥ 5 mg/dL. 5. Are able to read, understand and give written informed consent. Main Exclusion Criteria: 1. Have a MELD-Na score \> 35. 2. Have underlying cirrhosis due to biliary disease. 3. Have underlying cirrhosis due to autoimmune hepatitis. 4. Have active bleeding at a non-compressible site or at a compressible site that, in the opinion of the investigator, poses an unacceptable risk for the patient's participation in the study. 5. Have received treatment for bleeding complications during the current hospitalization and has a persistent high risk for re-bleeding that, in the opinion of the investigator, poses an unacceptable risk for the patient's participation in the study. 6. Have a complete portal vein thrombosis. 7. Have coagulation disturbances defined as: * fibrinogen \< 80 mg/dL * platelets \< 50 x 10³/mm³ 8. Are requiring chronic dialysis therapy. 9. Have had a cerebrovascular, myocardial, limb arterial thrombotic event, or history for both thrombotic and hemorrhagic cerebrovascular events within 12 months prior to the Screening and not considered stabilized by the investigator. 10. Have a previous history of myocardial infarction and/or cardiac failure, with an ejection fraction rate (EFR) ≤ 40%.