This is a Phase II multi-center, double-blind, placebo-controlled, randomized study in Patients with moderate to severe lung injury due to COVID-19 or other potential viral and bacterial pathogens.

This is a Phase II multi-center, double-blind, placebo-controlled, randomized study in Patients with moderate to severe lung injury due to COVID-19 or other potential viral and bacterial pathogens. The study will enroll up to 40 Patients into two cohorts, randomized 1:1 to receive active study drug plus standard treatment or placebo (LRS) plus standard treatment. On the treatment (Day 0) Cohort 1 will receive a single IV dose of hMSCs Cohort 2 will receive Lactated Ringer's Solution. A second dose of MSCs or LRS will be given to Cohort 1 or Cohort 2, respectively on Day 3 after the first dose. Patients who discontinue the study before Month 1 for reasons other than adverse events will be replaced.

Inclusion Criteria:

• Laboratory-confirmed diagnosis of COVID-19 <= 14 days prior to randomization

• The presence of moderate to severe Acute Respiratory Distress Syndrome (ARDS) as defined by the Berlin Definition:

  1. Bilateral chest radiograph infiltrates.
  2. PaO2:FiO2 ratio of less than 200.
  3. Absence of other clinical conditions that could present in a similar manner (non-infectious pneumonitis, cardiogenic pulmonary edema)

• Absence of moribund state that would indicate imminent demise and poor chance of survival.

Exclusion Criteria:

• Females of childbearing potential who are pregnant or unwilling to undergo pregnancy testing; females with a positive pregnancy test on screening day will be excluded.
• Breastfeeding mothers
• Patients on ECMO
• Receiving concurrent treatment with an investigational agent in a clinical trial.
• Exception: Use of COVID-19 convalescent plasma is permitted.
• More than 72hrs on mechanical ventilation before randomization
• Receiving concurrent investigational vaccine

This is double-blind study