Mechanochemically-reprogrammed stem cell exosomes reconcile the biogenesis internalization trade-off for pulmonary fibrosis therapy

Abstract

Matrix stiffness serves as a pivotal biophysical cue of extracellular vesicle (EV) function and cellular uptake, yet the mechanical cues that enhance EV function may not simultaneously favour cellular uptake. Through comparative analyses across pulmonary cell populations, we identified macrophages as the predominant EV recipients in our experimental system and as a functionally relevant effector population in pulmonary fibrosis. Herein, we developed a mechanochemical reprogramming strategy to coordinate the immunomodulatory function of mesenchymal stem cell (MSC)-derived EVs with their uptake by macrophages. We found that soft-matrix conditioning of MSC-derived EVs enhanced immunomodulatory activity and promoted an anti-inflammatory macrophage phenotype. By contrast, increasing matrix stiffness upregulated ATP-binding cassette transporter A1 (ABCA1), increased EV membrane cholesterol, and enhanced macrophage uptake. Guided by these complementary mechanical responses, we combined soft-matrix conditioning with ABCA1 modulation to generate mechanochemically programmed MSC-EVs. This strategy preserved the immunomodulatory advantages associated with the soft matrix while enhancing macrophage uptake and increasing EV production. In a murine model of pulmonary fibrosis, mechanochemically reprogrammed EVs produced higher and more persistent EV-associated signals in lung tissue and were preferentially associated with pulmonary macrophages. Treatment promoted anti-inflammatory and reparative macrophage responses and was accompanied by reduced pulmonary inflammation and fibrotic remodelling. Together, these findings establish a mechanochemically reprogrammed strategy that coordinates MSC-EV immunomodulatory function with macrophage uptake while increasing EV production, providing a framework for engineering EV-based therapies for pulmonary fibrosis.