Improving the 3D microenvironment of mesenchymal stromal cells for lung tissue repair in COPD

<bold>Background:</bold> In COPD, the extracellular matrix (ECM) is disrupted, impacting the mechanical properties of lung tissue. Lung-resident mesenchymal stromal cells (LMSCs) secrete crucial growth factors to support alveolar epithelial repair, e.g. hepatocyte growth factor (HGF), which is impaired in COPD. We hypothesized that LMSC-ECM interactions are disturbed in COPD, and that this disbalance can be restored by altering the ECM mechanical cues from the microenvironment. <bold>Methods:</bold> Collagen-derived gelatin methacrylate (GelMA) hydrogel (160 kDa; degree of modification 60%) was prepared by crosslinking with 0.5 mg/ml or 1 mg/ml lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), providing 2 mechanical environments. LMSCs from COPD patients or controls (n=4/group) were cultured on plastic or 2 mm-thick GelMA hydrogels. HGF gene and protein expression was assessed and an organoid transwell model was used to co-culture human alveolar epithelial H441 cells (upper chamber) and LMSCs with/without hydrogel (lower chamber). After 14 days, organoid size was quantified. <bold>Results:</bold> HGF gene and protein levels were lower in COPD compared to control-derived LMSCs. Culture on 0.5 mg/ml LAP GelMA hydrogel increased HGF levels in both COPD and control LMSCs. COPD-derived LMSCs induced aberrant organoid formation, with larger organoids than those supported by control-derived LMSCs. This effect was reversed when LMSCs were grown on 0.5 mg/ml LAP GelMA. <bold>Conclusion:</bold> This study indicates that altering the ECM mechanical microenvironment has the potential to restore the reparative properties of LMSCs in COPD. This highlights a potential strategy for improving alveolar epithelial repair by normalizing LMSC function.