Bone Marrow Mesenchymal Stem Cell-Derived Extracellular Vesicle Infusion for the Treatment of Respiratory Failure From COVID-19: A Randomized, Placebo-Controlled Dosing Clinical Trial.

BACKGROUND: Bone marrow mesenchymal stem cell (BM-MSC)-derived extracellular vesicles (ExoFlo) convey the immunomodulatory and regenerative properties of intact BM-MSCs. This study aimed to determine the safety and efficacy of ExoFlo as treatment for moderate to severe ARDS in patients with severe COVID-19. RESEARCH QUESTION: Do two doses of ExoFlo safely reduce mortality in COVID-19-associated moderate to severe ARDS compared with placebo? STUDY DESIGN AND METHODS: A prospective phase 2 multicenter double-anonymized randomized placebo-controlled dosing trial was conducted at five sites across the United States with infusions of placebo, 10 mL of ExoFlo, or 15 mL of ExoFlo on days 1 and 4. Patients (N = 102) with COVID-19-associated moderate to severe ARDS were enrolled and randomized to treatment. Adverse events were documented throughout the study. The primary outcome measure was all-cause 60-day mortality rate. Secondary outcomes included time to death (overall mortality); the incidence of treatment-emergent serious adverse events; proportion of discharged patients at 7, 30, and 60 days; time to hospital discharge; and ventilation-free days. RESULTS: No treatment-related adverse events were reported. Mortality (60-day) in the intention-to-treat population was reduced with 15 mL ExoFlo mixed with 85 mL normal saline (ExoFlo-15) compared with placebo (not significant, χ2, P = .1343). For the post hoc subgroup analyses, 60-day mortality was decreased with ExoFlo-15 compared with placebo (relative risk, 0.385; 95% CI, 0.159-0.931; P = .0340; n = 50). With ExoFlo-15, a relative risk of 0.423 (95% CI, 0.173-1.032; P = .0588; n = 24) was determined for participants aged 18 to 65 years with moderate to severe ARDS. Ventilation-free days improved with ExoFlo-15 (P = .0455; n = 50) for all participants aged 18 to 65 years. INTERPRETATION: The 15 mL dose of ExoFlo was found to be safe in patients with severe or critical COVID-19-associated respiratory failure. In participants aged 18 to 65 years, the risk reduction in 60-day mortality was further improved from subjects of all ages in the intention-to-treat population after two doses of 15 mL of ExoFlo compared with placebo. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT04493242; URL: www. CLINICALTRIALS: gov.

Exosomes Derived from Bone Marrow Mesenchymal Stem Cells as Treatment for Severe COVID-19.

This prospective nonrandomized open-label cohort study addresses the safety and efficacy of exosomes (ExoFlo™) derived from allogeneic bone marrow mesenchymal stem cells as treatment for severe COVID-19. During April 2020, ExoFlo was provided to 24 SARS-CoV-2 polymerase chain reaction-positive patients at a single hospital center, all of whom met criteria for severe COVID-19 as well as moderate-to-severe acute respiratory distress syndrome. Patients received a single 15 mL intravenous dose of ExoFlo and were evaluated for both safety and efficacy from days 1 to 14 post-treatment. All safety endpoints were met with no adverse events observed within 72 h of ExoFlo administration. A survival rate of 83% was observed. In total, 17 of 24 (71%) patients recovered, 3 of 24 (13%) patients remained critically ill though stable, and 4 of 24 (16%) patients expired for reasons unrelated to the treatment. Overall, after one treatment, patients' clinical status and oxygenation improved with an average pressure of arterial oxygen to fraction of inspired oxygen ratio (PaO2/FiO2) increase of 192% (P < 0.001). Laboratory values revealed significant improvements in absolute neutrophil count [mean reduction 32% (P value <0.001)] and lymphopenia with average CD3+, CD4+, and CD8+ lymphocyte counts increasing by 46% (P < 0.05), 45% (P < 0.05), and 46% (P < 0.001), respectively. Likewise, acute phase reactants declined, with mean C-reactive protein, ferritin, and D-dimer reduction of 77% (P < 0.001), 43% (P < 0.001), and 42% (P < 0.05), respectively. In conclusion, owing to its safety profile, capacity to restore oxygenation, downregulate cytokine storm, and reconstitute immunity, ExoFlo is a promising therapeutic candidate for severe COVID-19. Future randomized controlled trials (RCTs) are needed to determine ExoFlo therapeutic potential.