Umbilical Cord-derived Mesenchymal Stem Cells with Surfactant Protein B Alleviates Inflammatory Response in Acute Respiratory Distress Syndrome by Regulating Macrophage Polarization

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a severe disorder that is related to a high mortality. Mesenchymal stem cells (MSCs) have shown strong effects in relieving lung injury. AIMS: To determine the role of umbilical cord-derived MSCs (UC-MSCs) together with surfactant protein B (SP-B) in ARDS. STUDY DESIGN: Animal experimentation. METHODS: Immunophenotypic characteristics of UC-MSCs were identified. BALB/c mice were intratracheally administrated with lipopolysaccharide (LPS) and received UC-MSCs or UC-MSCs transfected with SP-B (UC-MSCs-SP-B). Pathological changes and lung injury degrees after transplantation were assessed by histological and biochemical analyses. Inflammatory chemokine and cytokine production in the bronchoalveolar lavage fluid (BALF) was measured using enzyme-linked immunoassay. Flow cytometry was used to examine macrophage phenotypes and differentiation of T-helper 17 (Th17) and T-regulatory (Treg) in the BALF. RESULTS: Our results showed that isolated UC-MSCs possessed multilineage differentiation potential. SP-B transfection into UC-MSCs strengthened the effects of UC-MSCs on lung function repair in LPS-induced ARDS. UC-MSCs and UC-MSCs-SP-B attenuated cellular infiltration. Additionally, UC-MSCs and UC-MSCs-SP-B inhibited the inflammatory response by promoting M2-like polarization, as well as reduced Th17 differentiation and promoted Treg differentiation. CONCLUSION: UC-MSCs in combination with SP-B, alleviates inflammatory reaction in ARDS by regulating macrophage polarization.