The goal of this clinical trial is to explore the safety, tolerability, and efficacy in study intervention, MatriPlax, in subjects with Acute Respiratory Distress Syndrome (ARDS). MatriPlax contains placenta choriodecidual membrane-derived Mesenchymal Stem Cells (pcMSCs). Participants will receive two doses of MatriPlax on Day 1 and Day 4 and conduct efficacy and safety evaluations until 12 months after treatment or withdrawal from the study.

This open-label, dose-escalation Phase I study plans to evaluate the safety, tolerability, and efficacy of MatriPlax.

This is a conventional 3+3 dose-escalation study in which subjects with moderate or severe ARDS will receive intravenous MatriPlax infusion.

Participants will be assigned to one of three dose cohorts (low, middle and high doses of MatriPlax), depending on the time of their enrollment. Each participant will receive two doses of MatriPlax on Day 1 and Day 4. Each dose cohort will have three to six subjects enrolled sequentially with at least 1 week in between. All participants will be followed until 12 months after receiving MatriPlax or withdrawal from the study.

A Data Safety and Monitoring Board (DSMB) meeting will be held when all participants of each cohort complete their 28-day of treatment and evaluation period. The DSMB will determine if the study is safe to proceed to the next dose level or it requires to recruit more subjects to the concurrent dose level for safety evaluation.

Inclusion Criteria:

1. Clinical diagnosis of moderate or severe ARDS according to the Berlin definition

   • Acute onset of respiratory failure within 1 week of identified insult

   • Respiratory failure associated with known ARDS risk factors and not fully explained by either cardiac failure or fluid overload

   • Radiological abnormalities on chest X-ray or computerized tomography (CT) scan, i.e., bilateral infiltrates that are not fully explained by effusions, lobar/lung collapse, or nodules

   • Hypoxic respiratory failure

     • Moderate ARDS: PaO2/ FiO2 ratio > 100 mmHg (13.3 kPa) to ≤ 200 mmHg (26.6 kPa) with positive end expiratory pressure (PEEP) ≥ 5 cmH2O
     • Severe ARDS: PaO2/ FiO2 ratio ≤ 100 mmHg (13.3 kPa) with PEEP ≥ 5 cmH2O

2. Administration of study drug must be planned to take place within 72 hours since moderate or severe ARDS diagnosis

3. Either gender, 20 ~ 80 years old (inclusive)

4. Dated and signed informed consent

5. A subject has been admitted to an ICU or RCC and is already on or candidates for mechanical ventilation

6. A subject with the primary disease of ARDS caused by documented virus infection (including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2))

7. With normal vital sign parameters:

   1. Systolic blood pressure ≥ 90 mmHg and ≤ 160 mmHg
   2. Diastolic blood pressure ≥ 50 mmHg and ≤ 95 mmHg
   3. Pulse rate ≥ 60 beats per minute (bpm) and ≤ 100 bpm
   4. Body temperature ≥ 35.5°C and ≤ 37.7°C

Exclusion Criteria:

1. No intent/unwillingness to follow lung-protective ventilation strategy or fluid management manual

2. On extracorporeal membrane oxygenation (ECMO) support

3. Severe chronic respiratory disease with a PaCO2 > 50 mm Hg or with any oxygen support

4. A subject who is extremely unlikely to survive more than 24 hours in the opinion of the investigator

5. World Health Organization (WHO) Class III or IV pulmonary hypertension

6. Clinical evidence of left ventricular failure

7. With acute diseases or serious medical conditions include cardiovascular (such as cardiac arrhythmia, QT prolongation), pulmonary (except ARDS), hepatic, neurologic, metabolic, renal, psychiatric condition, autoimmune disease, medical history, physical findings, or laboratory abnormality that in the investigators' opinion are not in stable condition and participating in the study could adversely affect the safety of the subject

8. Severe liver disease (Childs-Pugh Score > 10)

9. Acute or chronic kidney disease (Stage-3B, 4 or 5 renal impair; estimated glomerular filtration rate (eGFR) ˂ 60 mL/min/1.73 m^2 or dialysis)

   Note: eGFR (mL/min/1.73 m^2) = 186.3 × (serum creatinine in mg/dL)^-1.154 × (age)^-0.203× (0.742 if female) × (1.212 if African American/black)

10. History of pulmonary embolism

11. Previous solid organ transplant

12. With major surgery within 14 days prior to Screening visit Note: Major surgery is defined as an invasive operative procedure where one or more of the following occurred: 1) A body cavity was entered; 2) A mesenchymal barrier was crossed; 3) A fascial plane was opened; 4) An organ was removed; 5) Normal anatomy was operatively altered. All other invasive operative procedures are minor surgeries.

13. Presence of any active malignancy within 2 years prior to Screening visit

14. History of the human immunodeficiency virus (HIV) infection

15. History of severe allergic or anaphylactic reactions

16. Known or suspected hypersensitivity or previous adverse reaction to any ingredients of study product

17. Participation in a clinical trial of an interventional medicinal product within 12 weeks prior to Screening visit

18. With any other uncontrolled illness judged by the principal investigator that entering the trial may be detrimental to the subject

19. Pregnant or lactating or premenopausal with childbearing potential but not taking reliable contraceptive method(s) during the study period. At least one form of birth control must be adopted. Acceptable forms include:

    • Placement of an intrauterine device (IUD) or intrauterine system (IUS).
    • Barrier methods of contraception: condom or occlusive cap (diaphragm or cervical/vault caps)

20. Female subject with childbearing potential who has positive serum or urine pregnancy test at Screening Visit

21. Unable to return for follow-up visits for clinical evaluation or laboratory studies

22. Inappropriate to participate in this clinical study because of psychiatric disorders or any condition as judged by the principal investigator

23. Hypersensitive to penicillin, streptomycin and amphotericin B antibiotics

24. With specific known risk factors for thrombotic events, including obesity (Body mass index (BMI) >35), diabetes mellitus Type I, history of deep vein thrombosis (DVT) or thrombotic episodes, acquired or inherited thrombophilic disorders, hypercoagulable conditions, and other cardiovascular risk factors judged by the investigator

25. Use of estrogens/oral contraceptives within 6 weeks prior to Screening visit

26. Current smoker or has smoked within 3 months prior to Screening visit.