Enhanced therapeutic efficacy of repeated bone marrow-derived MSC administration in a murine model of pulmonary fibrosis.

Abstract

BACKGROUND: Silicosis is a progressive lung fibrosis lacking effective treatment. Mesenchymal stem cells (MSCs) show antifibrotic potential, but their survival is impaired by the early inflammatory microenvironment. The therapeutic value of repeated MSC administration remains unclear. METHODS: A murine silicosis model was analyzed by single-cell RNA sequencing, bronchoalveolar lavage fluid (BALF) cytokine assays, and human Bone Marrow-Derived Mesenchymal Stem Cells (hBMSCs) transcriptomics after BALF exposure. Mice received either single or repeated intratracheal hBMSCs doses. Cell retention, lung function, imaging, histology, and fibrosis markers were assessed. The role of ZC3H4 in macrophage activation was examined by in vivo expression profiling, in vitro knockdown, and functional assays. RESULTS: Early silica exposure triggered strong M1 inflammation, high BALF cytokines, and hBMSCs senescence signatures. Repeated hBMSCs dosing improved cell persistence, reduced fibrosis on imaging and histology, enhanced lung function, and decreased collagen deposition compared with a single dose. Mechanistically, MSC therapy suppressed macrophage ZC3H4 expression, while ZC3H4 knockdown reduced macrophage activation and fibroblast migration. CONCLUSIONS: Repeated hBMSCs administration enhances therapeutic efficacy in silicosis by improving cell persistence and attenuating fibrosis, partly through ZC3H4-mediated regulation of macrophages.