Combined mesenchymal stem cells and metformin therapy modulates key macromolecular pathways in pulmonary fibrosis based on evidence from untargeted metabolomics

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease with limited therapeutic options, highlighting the need for novel interventions. Mesenchymal stem cells (MSCs) possess immunomodulatory and regenerative capacities, while metformin, a widely used antidiabetic agent, has recently shown anti-fibrotic potential through metabolic reprogramming. Metabolomic profiling offers a comprehensive approach to elucidate disease-associated biochemical alterations and therapeutic mechanisms. In this pilot study, bleomycin-induced pulmonary fibrosis in rats was treated with MSCs, metformin, or their combination. Untargeted LC-MS-based metabolomics of plasma and lung tissue, alongside histopathological evaluation, revealed that combination therapy most effectively corrected metabolic disruptions and attenuated fibrotic remodeling. Histology confirmed marked reductions in alveolar wall thickening, collagen deposition, and fibroblastic foci in the combination group compared to monotherapies. Metabolite changes in lung tissue included sphingosine (lipid metabolism), 5-hydroxyindoleacetic acid (serotonin turnover), cyclic GMP (nitric oxide signaling), and 4-guanidinobutanoic acid (arginine/creatine metabolism). Plasma regulation involved corticosterone (steroid biosynthesis), PC (18:2/18:2) (phospholipid remodeling), methionine (methylation balance), galactose 1-phosphate (carbohydrate metabolism), and niacinamide (NAD⁺ biosynthesis). These findings provide preliminary evidence that combined MSCs–metformin therapy synergistically ameliorates fibrosis and metabolic dysregulation, while identifying metabolites that may serve as potential biomarkers for disease progression and therapeutic response.