Mesenchymal stromal cell therapy for COVID-19 acute respiratory distress syndrome: a double-blind randomised controlled trial

From pandemic onset to present: five years of insights into ARDS caused by COVID-19

INTRODUCTION

COVID-19-associated acute respiratory distress syndrome (ARDS) has challenged healthcare systems, initially resembling classical ARDS but later recognized as distinct. Unique features such as endothelial injury, microthrombosis, and dysregulated inflammation influenced treatment efficacy. Understanding its evolution is key to optimizing therapy and improving outcomes.

AREAS COVERED

This review synthesizes current evidence on COVID-19-associated ARDS, covering epidemiology, pathophysiology, clinical phenotypes, and treatments. It explores the shift from L and H phenotypes to a refined disease model and highlights key therapies, including corticosteroids, immunomodulators, prone positioning, ECMO, and vaccination's impact on severity and ARDS incidence.

EXPERT OPINION

At the onset of the COVID-19 pandemic in December 2019, uncertainty was overwhelming. Early clinical guidelines relied on case reports and small case series, offering only preliminary insights into disease progression and management. Despite the initial chaos, the scientific community launched an unprecedented research effort, with over 11,000 clinical trials registered on ClinicalTrials.gov investigating COVID-19 treatments. Several evidence-based strategies emerged as gold standards for managing COVID-19-associated acute respiratory distress syndrome, surpassing prior approaches. The pandemic exposed vulnerabilities in global healthcare, reshaped modern medicine, accelerated innovation, and reinforced the essential role of evidence-based practice in critical care and public health policy.

Impact of mesenchymal stromal/stem cell infusions on circulating inflammatory biomarkers in COVID-19 patients: analysis of a phase I-IIa trial

BACKGROUND AIMS

SARS-CoV-2 infection triggers respiratory inflammation with potentially fatal systemic effects. Mesenchymal stromal/stem cells (MSCs) are promising for treating severe COVID-19 due to their anti-inflammatory and regenerative capacities. This study investigates the effects of allogeneic MSCs in severe COVID-19 pneumonia.

METHODS

In the phase I/IIa RESCAT trial (May 2021-Feb 2022), patients with severe COVID-19 pneumonia received two intravenous MSC infusions and were compared to a control group (CTRL). To assess cytokine and biomarker responses, the MSC group was matched 1:2 with standard care patients (mCTRL) by age, gender, BMI, and PaO2/FiO2 (Nov 2020-Feb 2021). Random-effects linear regression evaluated cytokine and biomarker trends over time between MSC and control groups.

RESULTS

Seventeen patients (MSC = 5, CTRL = 2, mCTRL = 10) were analyzed. Two MSC infusions were feasible and safe, with all patients discharged on average 15 ± 3.7 days postsecond infusion. While IL1RA and IL18 levels significantly increased in CTRL-mCTRL patients (P = 0.044 and P = 0.032), MSC treatment averted these rises, showing a distinct trajectory, particularly for IL1RA. MSC treatment also reduced IL6 levels compared to CTRL-mCTRL, while both groups showed similar reductions in Long pentraxin. Furthermore, MSC infusions prevented the neurofilament light chain surge observed in CTRL patients.

CONCLUSIONS

MSC in COVID-19 patients resulted safe and feasible, effectively modulating inflammatory cytokines, in particular mitigating brain damage related biomarker, suggesting both reduced inflammation and a potential neurological protection.

STING-deficiency in lung resident mesenchymal stromal cells contributes to the alleviation of LPS-induced lung injury

Acute respiratory distress syndrome (ARDS) is characterized by acute diffuse inflammatory lung injury with a high mortality rate. Mesenchymal stromal cells (MSC) are pluripotent adult cells that can be extracted from a variety of tissues, including the lung. Lung-resident MSC (LR-MSC) located around vascular vessels and act as important regulators of lung homeostasis, regulating the balance between lung injury and repair processes. LR-MSC support the integrity of lung tissue by modulating immune responses and releasing trophic factors. Studies have reported that the STING pathway is involved in the progression of lung injury inflammation, but the specific mechanism is unclear. In this study, we found that STING deficiency could ameliorate lipopolysaccharides (LPS)-induced acute lung injury, STING knockout (STING KO) LR-MSC had an enhanced treatment effect on acute lung injury. STING depletion protected LR-MSC from LPS-induced apoptosis. RNA-sequencing and Western blot results showed that STING KO LR-MSC expressed higher levels of MSC immunoregulatory molecules, such as Igfbp4, Icam1, Hgf and Cox2, than WT LR-MSC. This study highlights that LR-MSC have a therapeutic role in acute lung injury, and we demonstrate that STING deficiency can enhance the immunomodulatory function of LR-MSC in controlling lung inflammation. Thus, STING can be used as an intervention target to enhance the therapeutic effect of MSC.