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Ji Young Yhee,1 Hong Yeol Yoon,2 Hyunjoon Kim,3 Sangmin Jeon,2 Polla Hergert,1 Jintaek Im,1 Jayanth Panyam,3 Kwangmeyung Kim,2,4 Richard Seonghun Nho1 1Department of Medicine, University of Minnesota, Minneapolis, MN, USA; 2Center for Theragnosis, Biomedical Research Institute, Korea Institute of Science and Technology, Seoul, Republic of Korea; 3Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, USA; 4Korea University-Korea Institute of Science and Technology (KU-KIST) Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea Abstract: Recent progress in nanomedicine has shown a strong possibility of targeted therapy for obstinate chronic lung diseases including idiopathic pulmonary fibrosis (IPF). IPF is a fatal lung disease characterized by persistent fibrotic fibroblasts in response to type I collagen-rich extracellular matrix. As a pathological microenvironment is important in understanding the biological behavior of nanoparticles, in vitro cellular uptake of glycol chitosan nanoparticles (CNPs) in human lung fibroblasts was comparatively studied in the presence or absence of type I collagen matrix. Primary human lung fibroblasts from non-IPF and IPF patients (n=6/group) showed significantly increased cellular uptake of CNPs (>33.6–78.1 times) when they were cultured on collagen matrix. To elucidate the underlying mechanism of enhanced cellular delivery of CNPs in lung fibroblasts on collagen, cells were pretreated with chlorpromazine, genistein, and amiloride to inhibit clathrin-mediated endocytosis, caveolae-mediated endocytosis, and macropinocytosis, respectively. Amiloride pretreatment remarkably reduced the cellular uptake of CNPs, suggesting that lung fibroblasts mainly utilize the macropinocytosis-dependent mechanism when interacted with collagen. In addition, the internalization of CNPs was predominantly suppressed by a phosphoinositide 3-kinase (PI3K) inhibitor in IPF fibroblasts, indicating that enhanced PI3K activity associated with late-stage macropinocytosis can be particularly important for the enhanced cellular delivery of CNPs in IPF fibroblasts. Our study strongly supports the concept that a pathological microenvironment which surrounds lung fibroblasts has a significant impact on the intracellular delivery of nanoparticles. Based on the property of enhanced intracellular delivery of CNPs when fibroblasts are made to interact with a collagen-rich matrix, we suggest that CNPs may have great potential as a drug-carrier system for targeting fibrotic lung fibroblasts. Keywords: cellular uptake, glycol chitosan nanoparticles, idiopathic pulmonary fibrosis, macropinocytosis, type I collagen matrix

Keun Sang Oh,1 Ji Young Yhee,2 Dong-Eun Lee,3 Kwangmeyung Kim,2 Ick Chan Kwon,2 Jae Hong Seo,4 Sang Yoon Kim,5 Soon Hong Yuk1,4 1College of Pharmacy, Korea University, Sejong, 2Biomedical Research Center, Korea Institute of Science and Technology, Seoul, 3Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeonbuk, 4Biomedical Research Center, Korea University Guro Hospital, Seoul, 5Department of Otolaryngology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, Republic of Korea Abstract: Primary tumor and tumor-associated metastatic lymphatics have emerged as new targets for anticancer therapy, given that these are difficult to treat using traditional chemotherapy. In this study, docetaxel-loaded Pluronic nanoparticles with Flamma™ (FPR-675, fluorescence molecular imaging dye; DTX/FPR-675 Pluronic NPs) were prepared using a temperature-induced phase transition for accurate detection of metastatic lymphatics. Significant accumulation was seen at the primary tumor and in metastatic lymph nodes within a short time. Particle size, maximum drug loading capacity, and drug encapsulation efficiency of the docetaxel-loaded Pluronic NPs were approximately 10.34±4.28 nm, 3.84 wt%, and 94±2.67 wt%, respectively. Lymphatic tracking after local and systemic delivery showed that DTX/FPR-675 Pluronic NPs were more potent in tumor-bearing mice than in normal mice, and excised mouse lymphatics showed stronger near-infrared fluorescence intensity on the tumor-bearing side than on the non-tumor-bearing side at 60 minutes post-injection. In vivo cytotoxicity and efficacy data for the NPs demonstrated that the systemically administered NPs caused little tissue damage and had minimal side effects in terms of slow renal excretion and prolonged circulation in tumor-bearing mice, and rapid renal excretion in non-tumor-bearing mice using an in vivo real-time near-infrared fluorescence imaging system. These results clearly indicate that docetaxel-loaded Pluronic NPs could provide a strategy to achieve effective cancer therapy by simultaneous delivery to primary tumors, tumor lymphatics, and tumor-associated metastatic lymphatics. Keywords: metastatic lymphatics, primary tumor targeting, lymphatic tracking, temperature-induced phase transition, Pluronic nanoparticles