Fig. 3

PS-NP via inhalation targets pulmonary antigen-presenting cells in lung metastases. a Representative ex vivo fluorescence imaging of major organs dissected from 4T1-luc lung metastases-bearing mice at 1, 24, and 48 h post inhalation of DiR-labeled PS-coated NPs. Light signals were exclusively from both lungs and b the lung signals were quantified (n = 3 biologically independent mice/time; **p < 0.01, Student’s t test). c HPLC measurements of concentrations of PS-coated NPs labeled with RhoB in various tissues of the 4T1-luc lung metastasis mice post inhalation (n = 3/time) were consistent with the IVIS imaging data. With the lung concentrations decreasing over time, NP increased in TDLNs. d Metastases-bearing lung tissues obtained 24 and 48 h post inhalation were subjected to immunofluorescent staining. The merged images clearly showed that DiR-labeled NPs (red) co-localized predominantly with CD11c+ APCs (green). Co-staining of 4T1 tumor cells with anti-luciferase (purple) indicated that the PS-NPs were distributed well into individual metastases and captured by intratumoral APCs. DAPI (blue), scale bar 20 μm. e Representative FACS characterization of pulmonary APC subsets in 4T1 lung metastasis-bearing lungs: alveolar macrophages (AMs; CD11c+F4/80+), interstitial macrophages (IMs; CD11c−F4/80+) and DCs (CD11c+F4/80−). f The percentage of DiR+ AMs, IMs, and DCs within their respective subpopulations was determined at 1, 24, 48, and 96 h after inhalation of NP-DiR. g The percentage of DiR+ migratory mAM, mDC103+, mCD11b + DCs in the total of APCs migrated to TDLNs was determined at different times post inhalation. Data are shown as mean ± SD of n = 3 biologically independent mice. Source data are provided as a Source Data file