Engineered SIRPα-Enriched Extracellular Vesicles Enable Targeted Clearance of CD47+Pathological Fibroblasts in Fibrotic Disease

Abstract

The persistence of pathological fibroblasts driven by CD47-mediated "don't eat me" immune evasion has shown acritical challenge in addressing fibrotic diseases. Here, we present an innovative therapeutic approach usingengineered extracellular vesicles (EVs) enriched with Signal Regulatory Protein Alpha (SIRPα) to block the CD47signal and promote clearance of diseased fibroblasts through professional phagocytes.We have stably transduced human bone marrow-derived mesenchymal stem cells (MSCs) using lentiviral vectors toexpress SIRPα. Furthermore, we have developed a novel three-dimensional large-scale manufacturing process forEV production that achieved over 90% purity and a tenfold increase in yield compared to conventional methods.The therapeutic potential of SIRPα-EVs was evaluated in a bleomycin-induced idiopathic pulmonary fibrosis (IPF)mouse model, supported by single-cell transcriptomic analysis of human IPF samples that confirmed significantCD47 upregulation in disease-associated fibroblasts and macrophages. Biodistribution studies using fluorescentlylabeled SIRPα-EVs demonstrated preferential accumulation in fibrotic lung tissue. Flow cytometry revealedapproximately fivefold higher uptake in pathological fibroblasts compared to normal fibroblasts. In vivo dataindicated that SIRPα-EVs exhibited superior therapeutic efficacy compared to conventional treatments(dexamethasone, nintedanib, pirfenidone) at lower doses, evidenced by restored alveolar architecture, reducedfibrotic lesions, and decreased Ashcroft scores. Molecular analyses confirmed the downregulation of key fibroticmarkers, including α-SMA, CD47, inflammatory cytokines, and TIMP1.These findings highlight the transformative potential of SIRPα-EVs as a targeted therapy for fibrotic diseases andestablish a foundation for clinical translation in conditions that currently lack effective treatment options.