Purpose Targeting and noninvasive imaging of a specific alveolar macrophage subpopulation in the lung has revealed the importance for early and better diagnosis and therapy of chronic obstructive pulmonary disease (COPD). In this study, the in vivo effect of pulmonary administration of iron oxide nanoparticles on the polarization profile of macrophages was assessed, and a noninvasive free-breathing magnetic resonance imaging (MRI) protocol coupled with the use of biocompatible antibody-conjugated superparamagnetic iron oxide (SPIO) nanoparticles was developed to enable specific targeting and imaging of a particular macrophage subpopulation in lipopolysaccharide-induced COPD mice model. Materials and methods Enzyme-linked immunosorbent assay, Real-time polymerase chain reaction, and flow cytometry analysis were performed to assess the biocompatibility of PEGylated dextran-coated SPIO nanoparticles. Specific biomarkers for M1 and M2 macrophages subsets were selected for conjugation with magnetic nanoparticles. MRI protocol using ultra-short echo time sequence was optimized to enable simultaneous detection of inflammation progress in the lung and detection of macrophages subsets. Flow cytometry and immunohistochemistry analysis were finally performed to confirm MRI readouts and to characterize the polarization profile of targeted macrophages. Results The tested SPIO nanoparticles, under the current experimental conditions, were found to be biocompatible for lung administration in preclinical settings. Cluster of differentiation (CD)86- and CD206-conjugated magnetic nanoparticles enabled successful noninvasive detection of M1 and M2 macrophage subpopulations, respectively, and were found to co-localize with inflammatory regions induced by lipopolysaccharide challenge. No variation in the polarization profile of targeted macrophages was observed, even though a continuum switch in their polarization might occur. However, further confirmatory studies are required to conclusively establish this observation. Conclusion Coupling of magnetic iron oxide nanoparticles with a specific antibody targeted to a particular macrophage subpopulation could offer a promising strategy for an early and better diagnosis of pulmonary inflammatory diseases using noninvasive MRI.

Purpose Targeting doxorubicin (DOX) by means of single-walled carbon nanotube (SWCNT) nanocarriers may help improve the clinical utility of this highly active therapeutic agent. Active targeting of SWCNTs using tumor-specific antibody and magnetic attraction by tagging the nanotubes with iron oxide nanoparticles can potentially reduce the unnecessary side effects and provide enhanced theranostics. In the current study, the in vitro and in vivo efficacy of DOX-loaded SWCNTs as theranostic nanoprobes was evaluated in a murine breast cancer model. Methods Iron-tagged SWCNTs conjugated with Endoglin/CD105 antibody with or without DOX were synthetized and extensively characterized. Their biocompatibility was assessed in vitro in luciferase (Luc2)-expressing 4T1 (4T1-Luc2) murine breast cancer cells using TiterTACS™ Colorimetric Apoptosis Detection Kit (apoptosis induction), poly (ADP-ribose) polymerase (marker for DNA damage), and thiobarbituric acid-reactive substances (oxidative stress generation) assays, and the efficacy of DOX-loaded SWCNTs was evaluated by measuring the radiance efficiency using bioluminescence imaging (BLI). Tumor progression and growth were monitored after 4T1-Luc2 cells inoculation using noninvasive BLI and magnetic resonance imaging (MRI) before and after subsequent injection of SWCNT complexes actively and magnetically targeted to tumor sites. Results Significant increases in apoptosis, DNA damage, and oxidative stress were induced by DOX-loaded SWCNTs. In addition, a tremendous decrease in bioluminescence was observed in a dose- and time-dependent manner. Noninvasive BLI and MRI revealed successful tumor growth and subsequent attenuation along with metastasis inhibition following DOX-loaded SWCNTs injection. Magnetic tagging of SWCNTs was found to produce significant discrepancies in apparent diffusion coefficient values providing a higher contrast to detect treatment-induced variations as noninvasive imaging biomarker. In addition, it allowed their sensitive noninvasive diagnosis using susceptibility-weighted MRI and their magnetic targeting using an externally applied magnet. Conclusion Enhanced therapeutic efficacy of DOX delivered through antibody-conjugated magnetic SWCNTs was achieved. Further, the superiority of apparent diffusion coefficient measurements using diffusion-weighted MRI was found to be a sensitive imaging biomarker for assessment of treatment-induced changes.

Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted special attention as novel nanoprobes capable of improving both the therapy and diagnosis of lung diseases. For safe prospective clinical applications, their biocompatibility has to be assessed after intrapulmonary administration. This study was therefore conducted to understand the biological impact of SPIONs and their further surface-functionalization with polyethylene glycol (PEG) having either negative (i.e. carboxyl) or positive (i.e. amine) terminal in a 1-month longitudinal study following acute and sub-acute exposures. Noninvasive free-breathing MR imaging protocols were first optimized to validate SPIONs detection in the lung and investigate possible subsequent systemic translocation to abdominal organs. Pulmonary Magnetic Resonance Imaging (MRI) allowed successful in vivo detection of SPIONs in the lung using ultra-short echo time sequence. Following high-dose lung administration, MR imaging performed on abdominal organs detected transient accumulation of SPIONs in the liver. Iron quantification using Inductive coupled plasma - Mass mass spectroscopy (ICP-MS) confirmed MRI readouts. Oxidative stress induction and genotoxicity were then conducted to evaluate the biocompatibility of SPIONs with their different formulations in a mouse model. A significant increase in lipid peroxidation was observed in both acute and sub-acute sets and found to regress in a time-dependent manner. PEG functionalized SPIONs revealed a lower effect with no difference between both terminal modifications. Genotoxicity assessments revealed an increase in DNA damage and gene expression of CCL-17 and IL-10 biomarkers following SPIONs administration, which was significantly higher than surface-modified nanoparticles and decreased in a time-dependent manner. However, SPIONs with carboxyl terminal showed a slightly prominent effect compared to amine modification.

These results demonstrate the efficiency of magnetic targeting to specifically deliver higher load of iron-tagged SWCNTs as novel nanocarriers for cancer theranostics and allow their sensitive detection using noninvasive MRI.

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