Direct Detection of Pulmonary Fibrosis by Near-Infrared-Responsive Biomimetic Platelets

Background: Pulmonary fibrosis (PF) is a fatal lung disease and affects over 5 million patients worldwide. Precise and early detection of PF is of pivotal importance to slow the disease progression. However, there are currently no effective tools to detect PF directly. Purpose: This study aimed to develop an imaging modality to detect PF directly. Excessive collagen deposition is the hallmark of PF. Herein, we developed a novel PF diagnostic agent, namely PVD (platelets-derived nanovesicles labeled with dye), by utilizing near-infrared (NIR)-responsive biomimetic platelets that specifically recognize collagen. Methods: In brief, platelets membrane was extracted from purified platelets by freeze/thaw and formed to PVD nanovesicles via sonication and extrusion, when loaded with DiR dye. Red blood cells membrane loaded with DiR was prepared in the same way as PVD to form RVD as control. Collagen self-assembled on microplates was used as an in vitro collagen fibrils model and monocrotaline-induced rats were used as an in vivo PF model. Results: We demonstrated that PVD, but not RVD nor other controls, could bind collagen both in vitro and in vivo, and directly detect pulmonary fibrosis in vivo and ex vivo at the early PF stage. Conclusion: Collectively, PVD is a versatile NIR-responsive probe for the direct visualization of collagen, and can be particularly helpful in direct detecting PF. To the best of our knowledge, PVD is the first report of a NIR probe for the direct detection of pulmonary fibrosis.