Combinational Therapy of Mesenchymal Stem Cells and Metformin in Bleomycin-Induced Idiopathic Pulmonary Fibrosis in Rat Model

Idiopathic pulmonary fibrosis (IPF) is a progressive and severe lung disease characterized by the buildup of interstitial fibrosis, where excessive collagen accumulates, leading to airway obstruction. This condition is initiated by the abnormal proliferation of alveolar type II (AT2) cells. Metformin, an established antidiabetic drug, has gained attention for its repurposed use as an anti-fibrotic agent. Meanwhile, adipose-derived mesenchymal stem cells (ADMSCs) exhibit potent anti-inflammatory and regenerative properties, and they have been shown to reduce collagen deposition. In this study, we hypothesize that the combination of metformin and ADMSCs can synergistically alleviate IPF and promote healthy lung tissue regeneration in a rat model. The goal is to evaluate the safety and efficacy of this approach at multiple levels; biochemical, molecular, histopathological, and histochemical. To induce IPF, Wistar albino rats received a single intratracheal dose of bleomycin (5 mg/kg body weight). The therapeutic phase involved treatment with either metformin or ADMSCs or a combination of both. Metformin was administered intraperitoneally (65 mg/kg body weight) every other day, while ADMSCs were delivered intravenously (1 × 10⁶ cells/0.5 ml DMEM/rat) through the tail vein. Our results demonstrated the effectiveness of combinational therapy, especially in mitigating oxidative stress. This was evidenced by the restoration of oxidative stress biomarkers, malondialdehyde (MDA), and catalase (CAT), as well as the regulation of collagenase type IV (MMP9), bovine serum albumin (BSA), and total protein levels in lung tissues. Moreover, the therapy modulated the expression of key inflammatory and fibrotic genes, including the pro-fibrotic marker TGF-β1, proinflammatory cytokine IL-6, and anti-inflammatory cytokine IL-10. Histopathological and histochemical analyses further supported the therapeutic benefits, showing significant recovery from bleomycin-induced fibrosis in rats treated with either the single or combined therapy. The findings suggest that this combinational approach could be a promising strategy for IPF treatment by simultaneously reducing inflammation, oxidative stress, and fibrosis while promoting tissue regeneration.