Nanoengineered Macrophages for in vivo Three-Dimensional Photoacoustic Imaging and Immunotherapy of Acute Lung Injury

Background: Acute lung injury (ALI) is a life-threatening condition lacking effective real-time monitoring and targeted therapeutic strategies. Cell-based drug delivery systems offer promise but are limited by the inability to track their in vivo distribution and therapeutic response. Methods: Macrophages were engineered to carry aluminum hydroxide-stabilized Tocilizumab (Alum/Toc) and labeled with indocyanine green (ICG) for photoacoustic (PA) imaging. The resulting platform (MΦ/ICG@Alum/Toc) was intravenously administered to Lipopolysaccharides (LPS)-induced ALI mice. Photoacoustic computed tomography (PACT) was used to monitor the dynamic recruitment, pulmonary accumulation, and clearance of the engineered cells over 48 h. Therapeutic efficacy was evaluated by histopathology and lung wet/dry ratio, and biosafety was assessed in major organs. Results: PACT enabled non-invasive, high-resolution tracking of nanoengineered macrophages, revealing rapid homing to inflamed lungs within 6 h, peak accumulation at 24 h, and subsequent hepatic clearance. Three-dimensional (3D) volumetric analysis confirmed targeted pulmonary delivery with minimal off-target distribution. The MΦ/ICG@Alum/Toc platform significantly reduced alveolar edema, inflammatory infiltration, and histopathological scores compared to free Toc, demonstrating superior therapeutic efficacy with excellent biocompatibility. Conclusion: This study establishes PACT as a powerful tool for guiding and monitoring cell-based therapies in real time. The nanoengineered macrophage platform offers a clinically translatable strategy for precision immunotherapy of ALI, with potential applications in other inflammatory diseases.