Mesenchymal stem cell therapy on top of triple therapy with remdesivir, dexamethasone, and tocilizumab improves PaO2/FiO2 in severe COVID-19 pneumonia

Abstract

Background: Despite patients with severe coronavirus disease (COVID-19) receiving standard triple therapy, including steroids, antiviral agents, and anticytokine therapy, health condition of certain patients continue to deteriorate. In Taiwan, the COVID-19 mortality has been high since the emergence of previous variants of this disease (such as alpha, beta, or delta). We aimed to evaluate whether adjunctive infusion of human umbilical cord mesenchymal stem cells (MSCs) (hUC-MSCs) on top of dexamethasone, remdesivir, and tocilizumab improves pulmonary oxygenation and suppresses inflammatory cytokines in patients with severe COVID-19.

Methods: Hospitalized patients with severe or critical COVID-19 pneumonia under standard triple therapy were separated into adjuvant hUC-MSC and non-hUC-MSC groups to compare the changes in the arterial partial pressure of oxygen (PaO₂)/fraction of inspired oxygen (FiO₂) ratio and biological variables.

Results: Four out of eight patients with severe or critical COVID-19 received either one (n = 2) or two (n = 2) doses of intravenous infusions of hUC-MSCs using a uniform cell dose of 1.0 × 10⁸. Both high-sensitivity C-reactive protein (hs-CRP) level and monocyte distribution width (MDW) were significantly reduced, with a reduction in the levels of interleukin (IL)-6, IL-13, IL-12p70 and vascular endothelial growth factor following hUC-MSC transplantation. The PaO₂/FiO₂ ratio increased from 83.68 (64.34-126.75) to 227.50 (185.25-237.50) and then 349.56 (293.03-367.92) within 7 days after hUC-MSC infusion (P < 0.001), while the change of PaO₂/FiO₂ ratio was insignificant in non-hUC-MSC patients (admission day: 165.00 [102.50-237.61]; day 3: 100.00 [72.00-232.68]; day 7: 250.00 [71.00-251.43], P = 0.923).

Conclusion: Transplantation of hUC-MSCs as adjunctive therapy improves pulmonary oxygenation in patients with severe or critical COVID-19. The beneficial effects of hUC-MSCs were presumably mediated by the mitigation of inflammatory cytokines, characterized by the reduction in both hs-CRP and MDW.

Keywords: COVID-19; arterial partial pressure of oxygen vs. fraction of inspired oxygen; human umbilical cord mesenchymal stem cells; inflammatory cytokines; monocyte distribution width.

FIGURE 1

Surface markers of allogenic human umbilical cord mesenchymal stem cell (hUC-MSC). Flow cytometry analysis of hUC-MSC showing the positive surface markers CD73, CD90, CD105 (> 95%), and the negative markers CD11b, CD19, CD34, CD45, and HLA-DR (0.33%, 0.91%, 0.40%, 0.35%, and 0.6%, respectively). CD, cluster of differentiation; HLA-DR, major histocompatibility complex (MHC) II cell surface receptor of human leukocyte antigen.

FIGURE 2

The flow diaphragm of the study. Hospitalized patients who were diagnosed with 2019 novel coronavirus disease (COVID-19) by a positive real-time polymerase chain reaction (RT-PCR) for SARS-CoV-2 from nasal swab specimens were enrolled in this retrospective case control study between May 15, 2021, and June 15, 2021. The disease severity of COVID-19 affected patients was classified as mild, moderate, severe and critical conditions according to the National Institutes of Health treatment guidelines. A total of 21 patients with RT-PCR-confirmed SARS-CoV-2 infection were enrolled, of whom 13 patients were classified as having a mild/moderate disease and 8 as a severe/critical disease. Patients with severe/critical disease were separated into hUC-MSC and non-hUC-MSC groups. SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; PCR, polymerase chain reaction; SpO₂, oxyhemoglobin saturation by pulse oximetry; RR, respiratory rate; PaO₂/FiO₂ ratio, arterial partial pressure of oxygen to fraction of inspired oxygen ratio; MOHW, Ministry of Health and Welfare; hUC-MSC, human umbilical cord mesenchymal stem cell.

FIGURE 3

PaO₂/FiO₂ ratio trends on hUC-MSC and non-hUC-MSC patients. (A) PaO₂/FiO₂ ratio trend on hUC-MSC patients. In hUC-MSC group, data on the day of admission, post-hUC-MSC day 3, and day 7 were recorded. (B) PaO₂/FiO₂ ratio trend on non-hUC-MSC patients. In the non-hUC-MSC group, the PaO₂/FiO₂ ratio on the day of admission, day 3, and day 7 of hospitalization are listed. In non-hUC-MSC case 1, no further arterial gas examination needed on day 7 was judged by the primary care physician because of obvious clinical improvements in this patient. Abbreviations as in Figure 2.

FIGURE 4

Delta PaO₂/FiO₂ ratio difference on hUC-MSC and non-hUC-MSC patients. The delta PaO₂/FiO₂ ratio which was the difference of PaO₂/FiO₂ ratio between the admission day and day 7 of hospitalization also showed a larger increment in the hUC-MSC treated patients than in non-hUC-MSC patients (250.06 [188.78–296.90] vs. 15.76 [–40.12–42.32], P = 0.029). Abbreviations as in Figure 2.

FIGURE 5

Chest image records of hUC-MSC patients. Serial chest X-ray films obtained on admission day, post-hUC-MSC day 3, and post-hUC-MSC day 7 showed progressive improvements on pulmonary infiltrations in all patients receiving hUC-MSC infusions. Abbreviations as in Figure 2.

FIGURE 6

Changes of plasma levels of cytokines and chemokines in patients receiving hUC-MSC intervention. The plasma levels of 4 out of the 14 inflammatory cytokines including IL-6, IL-12p70, IL-13 and VEGF had a significant decrease in trend after receiving the hUC-MSC transplantation. GM-CSF, granulocyte-macrophage colony-stimulating factor; IFN, interferon; IL, interleukin; IP, interferon-gamma-inducible protein; MCP, monocyte chemoattractant protein; MIP, macrophage inflammatory protein; TNF, tumor necrosis factor; VEGF, vascular endothelial growth factor.