Exosome Evidence Index

Studies / COVID-19 lung disease and inhaled use

Bone marrow stem cell vesicles (ExoFlo) for respiratory failure from COVID-19

Lightner AL et al., CHEST, 2023

Mixed or short-lived resultStrength of design, level 3 of 5: Controlled trial

Mixed or short-lived result: Some benefit, but only on some measures, in a subgroup, or for a short time.

Level 3 of 5: Treated patients were compared with a control: placebo, another treatment, or the untreated side of the face. Most exosome trials at this level are small and short.

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Design
Phase 2, randomized, double-blind, placebo-controlled
People
102 people
Made from
Bone marrow
How it was given
IV infusion, two doses

What they found

No treatment-related adverse events. Lower 60-day mortality was seen in the higher-dose group and in a subgroup of patients aged 18 to 65.

What limits it

The trial was too small to prove benefit, and subgroup findings need confirmation. The maker launched a phase 3 trial in 2023; check NCT04493242 and the phase 3 registry entry for status.

Read the study

Reviewed by Tomaz Mesar, MD. Last reviewed October 2026. No exosome product is FDA-approved for any use. Before you book a treatment

Other studies of covid-19 lung disease and inhaled use

  1. No benefit over controlStrength of design, level 3 of 5: Controlled trial

    Stem cells with or without added vesicles for COVID-19 ARDS

    Zarrabi M et al., Stem Cell Research & Therapy, 2023. 43 analyzed (8 got cells plus vesicles). Made from: umbilical cord.

    Both treated groups had lower inflammatory markers than the control group, with no serious adverse events. A 2025 review of the trial reports no significant difference between cells alone and cells plus vesicles.

  2. Safety onlyStrength of design, level 2 of 5: Study without a control group

    Inhaled adipose stem cell vesicles in healthy volunteers

    Shi M et al., Journal of Extracellular Vesicles, 2021. 24 healthy volunteers. Made from: fat (adipose) stem cells.

    All doses were well tolerated. Two people had a brief, mild slowing of heart rate that was not linked to dose.

  3. Improvement reported, no control groupStrength of design, level 2 of 5: Study without a control group

    Bone marrow stem cell exosomes (ExoFlo) for severe COVID-19

    Sengupta V et al., Stem Cells and Development, 2020. 24 people. Made from: bone marrow.

    Oxygen levels, clinical status, and lab markers improved, survival was 83%, and no adverse events were seen within 72 hours.

  4. Improvement reported, no control groupStrength of design, level 2 of 5: Study without a control group

    Inhaled adipose stem cell exosomes for severe COVID-19

    Zhu Y et al., Stem Cell Research & Therapy, 2022. 7 people. Made from: fat (adipose) stem cells.

    All patients tolerated treatment. Lymphocyte counts rose slightly, and lung lesions on CT regressed to varying degrees.