Abstract
BackgroundPulmonary fibrosis (PF) is a growing clinical problem with limited therapeutic options. Human umbilical cord mesenchymal stromal cell (hucMSC) therapy is being investigated in clinical trials for the treatment of PF patients. However, little is known about the underlying molecular and cellular mechanisms of hucMSC therapy on PF. In this study, the molecular and cellular behavior of hucMSC was investigated in a bleomycin-induced mouse PF model.MethodsThe effect of hucMSCs on mouse lung regeneration was determined by detecting Ki67 expression and EdU incorporation in alveolar type 2 (AT2) and lung fibroblast cells. hucMSCs were transfected to express the membrane localized GFP before transplant into the mouse lung. The cellular behavior of hucMSCs in mouse lung was tracked by GFP staining. Single cell RNA sequencing was performed to investigate the effects of hucMSCs on gene expression profiles of macrophages after bleomycin treatment.ResultshucMSCs could alleviate collagen accumulation in lung and decrease the mortality of mouse induced by bleomycin. hucMSC transplantation promoted AT2 cell proliferation and inhibited lung fibroblast cell proliferation. By using single cell RNA sequencing, a subcluster of interferon-sensitive macrophages (IFNSMs) were identified after hucMSC infusion. These IFNSMs elevate the secretion of CXCL9 and CXCL10 following hucMSC infusion and recruit more Treg cells to the injured lung.ConclusionsOur study establishes a link between hucMSCs, macrophage, Treg, and PF. It provides new insights into how hucMSCs interact with macrophage during the repair process of bleomycin-induced PF and play its immunoregulation function.
Highlights
Pulmonary fibrosis (PF) is a chronic progressive disease that happens when lung damaged and scarred due to an aberrant wound-healing process [26]
We found that human umbilical cord mesenchymal stromal cells interact with macrophages and recruit regulatory T cells (Tregs) in damaged lungs
Human umbilical cord mesenchymal stromal cells can ameliorate bleomycin-induced PF To evaluate the role of human umbilical mesenchymal stromal cells on PF, mice were administered a single dose of bleomycin (2 U/kg) intratracheally on day 0 (Fig. 1A)
Summary
Pulmonary fibrosis (PF) is a chronic progressive disease that happens when lung damaged and scarred due to an aberrant wound-healing process [26]. Mouse genetic studies suggest that lung epithelial cells, especially alveolar type 2 cells, play a key role in initiating the pathogenic process and excessive pulmonary fibroblast proliferation and extracellular matrix (ECM) deposition leads to the destruction of alveolar structure [3, 38, 41]. Pulmonary macrophages contain two populations: alveolar macrophages (AMs) which reside in the alveolar lumen and interstitial macrophages (IMs) that are located in the lung parenchymal tissue [19, 37]. The molecular and cellular behavior of hucMSC was investigated in a bleomycininduced mouse PF model
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