Rapamycin-Loaded Biomimetic Nanoparticles Reverse Vascular Inflammation.

RATIONALE: Through localized delivery of rapamycin via a biomimetic drug delivery system, it is possible to reduce vascular inflammation and thus the progression of vascular disease. OBJECTIVE: Use biomimetic nanoparticles to deliver rapamycin to the vessel wall to reduce inflammation in an in vivo model of atherosclerosis after a short dosing schedule. METHODS AND RESULTS: Biomimetic nanoparticles (leukosomes) were synthesized using membrane proteins purified from activated J774 macrophages. Rapamycin-loaded nanoparticles were characterized using dynamic light scattering and were found to have a diameter of 108±2.3 nm, a surface charge of -15.4±14.4 mV, and a polydispersity index of 0.11 +/ 0.2. For in vivo studies, ApoE-/- mice were fed a high-fat diet for 12 weeks. Mice were injected with either PBS, free rapamycin (5 mg/kg), or rapamycin-loaded leukosomes (Leuko-Rapa; 5 mg/kg) once daily for 7 days. In mice treated with Leuko-Rapa, flow cytometry of disaggregated aortic tissue revealed fewer proliferating macrophages in the aorta (15.6±9.79 %) compared with untreated mice (30.2±13.34 %) and rapamycin alone (26.8±9.87 %). Decreased macrophage proliferation correlated with decreased levels of MCP (monocyte chemoattractant protein)-1 and IL (interleukin)-b1 in mice treated with Leuko-Rapa. Furthermore, Leuko-Rapa-treated mice also displayed significantly decreased MMP (matrix metalloproteinases) activity in the aorta (mean difference 2554±363.9, P=9.95122×10-6). No significant changes in metabolic or inflammation markers observed in liver metabolic assays. Histological analysis showed improvements in lung morphology, with no alterations in heart, spleen, lung, or liver in Leuko-Rapa-treated mice. CONCLUSIONS: We showed that our biomimetic nanoparticles showed a decrease in proliferating macrophage population that was accompanied by the reduction of key proinflammatory cytokines and changes in plaque morphology. This proof-of-concept showed that our platform was capable of suppressing macrophage proliferation within the aorta after a short dosing schedule (7 days) and with a favorable toxicity profile. This treatment could be a promising intervention for the acute stabilization of late-stage plaques.

The efficiency of lipid nanoparticles with an original cationic lipid as a siRNA delivery system for macrophages and dendritic cells.

Small interfering of RNA (siRNA) technology has the potential to be a next-generation therapy. However, naked siRNA does not have high transfection efficiency and is rapidly degraded after systemic injection, so an appropriate drug delivery system (DDS) is required for clinical use. Several potential systems have been assessed, clinically focusing on hepatocyte or cancer tissue using siRNA. However, targeting immune cells using siRNA is still challenging, and a new DDS is required. In this study, we prepared lipid nanoparticles (LNP) composed of original cationic lipid, neutral lipid of DOPE (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) and PEG2000-DMPE (N-(carbonyl-methoxypolyethyleneglycol 2000)-1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine, sodium salt). Our LNP encapsulating siRNA (LNP/siRNA) exerted a knock-down (KD) effect on mouse inflammatory peritoneal macrophages in vitro. In addition, an in vivo KD effect by systemic administration of LNP/siRNA was observed in macrophages and dendritic cells (DCs) in mice. Furthermore, our LNP/siRNA showed in vitro KD effects not only on murine cells but also on human cells like monocyte-derived macrophages (MDMs) and monocyte-derived DCs (MDDCs). These results indicate the potential utility of our LNP for siRNA-based therapy targeting macrophages and DCs. Because these cells are known to have a significant role in several kinds of diseases, and siRNA can specifically suppress target genes that are closely associated with disease states and are untreatable by small molecules or antibodies. Therefore, delivering siRNA by our LNP to macrophages and DCs could provide novel therapies.

Tumor growth suppression by the combination of nanobubbles and ultrasound.

We previously developed novel liposomal nanobubbles (Bubble liposomes [BL]) that oscillate and collapse in an ultrasound field, generating heat and shock waves. We aimed to investigate the feasibility of cancer therapy using the combination of BL and ultrasound. In addition, we investigated the anti-tumor mechanism of this cancer therapy. Colon-26 cells were inoculated into the flank of BALB/c mice to induce tumors. After 8 days, BL or saline was intratumorally injected, followed by transdermal ultrasound exposure of tumor tissue (1 MHz, 0-4 W/cm2 , 2 min). The anti-tumor effects were evaluated by histology (necrosis) and tumor growth. In vivo cell depletion assays were performed to identify the immune cells responsible for anti-tumor effects. Tumor temperatures were significantly higher when treated with BL + ultrasound than ultrasound alone. Intratumoral BL caused extensive tissue necrosis at 3-4 W/cm2 of ultrasound exposure. In addition, BL + ultrasound significantly suppressed tumor growth at 2-4 W/cm2 . In vivo depletion of CD8+ T cells (not NK or CD4+ T cells) completely blocked the effect of BL + ultrasound on tumor growth. These data suggest that CD8+ T cells play a critical role in tumor growth suppression. Finally, we concluded that BL + ultrasound, which can prime the anti-tumor cellular immune system, may be an effective hyperthermia strategy for cancer treatment.

Enhancing Inflammation Targeting Using Tunable Leukocyte-Based Biomimetic Nanoparticles.

Biomimetic nanoparticles aim to effectively emulate the behavior of either cells or exosomes. Leukocyte-based biomimetic nanoparticles, for instance, incorporate cell membrane proteins to transfer the natural tropism of leukocytes to the final delivery platform. However, tuning the protein integration can affect the in vivo behavior of these nanoparticles and alter their efficacy. Here we show that, while increasing the protein:lipid ratio to a maximum of 1:20 (w/w) maintained the nanoparticle's structural properties, increasing protein content resulted in improved targeting of inflamed endothelium in two different animal models. Our combined use of a microfluidic, bottom-up approach and tuning of a key synthesis parameter enabled the synthesis of reproducible, enhanced biomimetic nanoparticles that have the potential to improve the treatment of inflammatory-based conditions through targeted nanodelivery.

Humanized Biomimetic Nanovesicles for Neuron Targeting.

Nanovesicles (NVs) are emerging as innovative, theranostic tools for cargo delivery. Recently, surface engineering of NVs with membrane proteins from specific cell types has been shown to improve the biocompatibility of NVs and enable the integration of functional attributes. However, this type of biomimetic approach has not yet been explored using human neural cells for applications within the nervous system. Here, this paper optimizes and validates the scalable and reproducible production of two types of neuron-targeting NVs, each with a distinct lipid formulation backbone suited to potential therapeutic cargo, by integrating membrane proteins that are unbiasedly sourced from human pluripotent stem-cell-derived neurons. The results establish that both endogenous and genetically engineered cell-derived proteins effectively transfer to NVs without disruption of their physicochemical properties. NVs with neuron-derived membrane proteins exhibit enhanced neuronal association and uptake compared to bare NVs. Viability of 3D neural sphere cultures is not disrupted by treatment, which verifies the utility of organoid-based approaches as NV testing platforms. Finally, these results confirm cellular association and uptake of the biomimetic humanized NVs to neurons within rodent cranial nerves. In summary, the customizable NVs reported here enable next-generation functionalized theranostics aimed to promote neuroregeneration.

Reproducible and Characterized Method for Ponatinib Encapsulation into Biomimetic Lipid Nanoparticles as a Platform for Multi-Tyrosine Kinase-Targeted Therapy.

Ponatinib (Pon) is a multi-tyrosine kinase inhibitor that demonstrated high efficiency for treating cancer. However, severe side effects caused by Pon off-targeting effects prevent its extensive use. Using our understanding into the mechanisms by which Pon is transported by bovine serum albumin in the blood, we have successfully encapsulated Pon into a biomimetic nanoparticle (NP). This lipid NP (i.e., "leukosomes") incorporates membrane proteins purified from activated leukocytes that enable immune evasion, and enhanced targeting of inflamed endothelium NPs have been characterized for their size, charge, and encapsulation efficiency. Membrane proteins enriched on the NP surface enabled modulation of Pon release. These NP formulations showed promising dose-response results on two different murine osteosarcoma cell lines, F420 and RF379. Our results indicate that our fabrication method is reproducible, nonuser-dependent, efficient in loading Pon, and applicable toward repurposing numerous therapeutic agents previously shelved due to toxicity profiles.

In vivo activation of PEGylated long circulating lipid nanoparticle to achieve efficient siRNA delivery and target gene knock down in solid tumors.

We developed a lipid nanoparticle formulation (LNPK15) to deliver siRNA to a tumor for target gene knock down. LNPK15 is highly PEGylated with 3.3% 1,2-distearoyl-sn-glycero-3-phosphatidylethanolamine-N-(polyethylene glycol-2000) (PEG-DSPE) and shows a long duration: the half-lives of siRNA in LNPK15 were 15.2 and 27.0h in mice and monkeys, respectively. Although LNPK15 encapsulating KRAS-targeting siRNA (LNPK15/KRAS) had very weak KRAS gene knock down activity in MIA PaCa-2 cells in vitro, LNPK15/KRAS showed a strong anti-tumor efficacy in MIA PaCa-2 tumor xenograft mice after intravenous administration at 5mg/kg twice weekly. KRAS mRNA and protein knock down was observed in tumor tissue, suggesting on-target anti-tumor efficacy. In order to elucidate the in vitro-in vivo discrepancy, we performed ex vivo knock down assay using serum samples obtained after intravenous administration of LNPK15/KRAS to mice and monkeys. The collected samples were added to MIA PaCa-2 cells, and KRAS gene knock down was evaluated after a 24-h incubation period. The knock down efficacy was weak (≈20%) with serum samples at initial sampling point (2h), and it became much stronger (∼90%) with serum samples at later time points. Lipid composition of LNPK15 in the serum samples was also investigated. Among the five lipids incorporated in LNPK15, PEG-DSPE was degraded more rapidly than siRNA and the other lipids in both mice and monkeys. In vitro lipase treatment of LNPK15/KRAS also hydrolyzed PEG-DSPE and enhanced knock down activity. From these results, it was concluded that LNPK15 acquires increased knock down activity after undergoing PEG-DSPE hydrolysis in vivo, and that is the key mechanism to achieve both long circulation and potent knock down efficiency. We also proposed an in vitro assay system using lipase for quality control of LNP to ensure biological activity.

Simplifying the Chemical Structure of Cationic Lipids for siRNA-Lipid Nanoparticles.

We report a potent cationic lipid, SST-02 ((3-hydroxylpropyl)dilinoleylamine), which possesses a simple chemical structure and is synthesized just in one step. Cationic lipids are key components of siRNA-lipid nanoparticles (LNP), which may serve as potential therapeutic agents for various diseases. For a decade, chemists have given enhanced potency and new functions to cationic lipids along with structural complexity. In this study, we conducted a medicinal chemistry campaign pursuing chemical simplicity and found that even dilinoleylmethylamine (SST-01) and methylpalmitoleylamine could be used for the in vitro and in vivo siRNA delivery. Further optimization revealed that a hydroxyl group boosted potency, and SST-02 showed an ID50 of 0.02 mg/kg in the factor VII (FVII) model. Rats administered with 3 mg/kg of SST-02 LNP did not show changes in body weight, blood chemistry, or hematological parameters, while the AST level decreased at a dose of 5 mg/kg. The use of SST-02 avoids a lengthy synthetic route and may thus decrease the future cost of nucleic acid therapeutics.

Plasmid DNA uptake and subsequent cellular activation characteristics in human monocyte-derived cells in primary culture.

Plasmid DNA (pDNA) uptake and subsequent cellular activation characteristics were studied in three types of human monocyte-derived cells, that is, human monocytes, macrophages, and dendritic cells (DCs) in primary culture. Naked pDNA was bound to and taken up by the macrophages and DCs while only significant binding occurred in the monocytes. pDNA binding to these monocyte-derived cells was significantly inhibited by polyinosinic acid (poly[I]), dextran sulfate, maleylated bovine serum albumin (Mal-BSA) and to a lesser extent by polycytidylic acid (poly[C]), but not by dextran or galactosylated BSA (Gal-BSA), mannosylated BSA (Man-BSA), suggesting that a specific mechanism for polyanions is involved in the pDNA binding. In cellular activation studies, naked pDNA could not induce TNF-alpha production from any monocyte-derived cells, regardless of the abundant presence of CpG motifs in the pDNA. However, when complexed with cationic liposomes, pDNA produced a significant amount of TNF-alpha from the human macrophages. TNF-alpha induction was not observed in the monocytes or DCs. Moreover, calf thymus DNA (CT DNA) complexed with cationic liposomes also induced TNF-alpha production to a similar extent in the human macrophages. These results indicate that, among human monocyte-derived cells, macrophages are activated by DNA when complexed with cationic liposomes in a CpG motif-independent manner.

Simultaneous delivery of doxorubicin and immunostimulatory CpG motif to tumors using a plasmid DNA/doxorubicin complex in mice.

To achieve delivery of doxorubicin (DXR), a very commonly used anticancer agent, to tumor tissues, it was intercalated to plasmid DNA to obtain a plasmid DNA/DXR complex. The cytotoxic effects of DXR, DNA and their complex were examined in colon26/Luc cells, a murine adenocarcinoma clone stably expressing firefly luciferase, co-cultured with RAW264.7 murine macrophage-like cells. Both CpG motif-containing plasmid DNA (CpG plasmid DNA) and DXR significantly inhibited the proliferation of colon26/Luc cells, but their complex was the most effective among those examined. Non-CpG plasmid DNA was less effective than the CpG plasmid DNA. When injected into mice bearing hepatic metastases of colon26/Luc cells, the CpG plasmid DNA/DXR complex produced a significant level of IL-12 in the serum and liver. The amount of DXR delivered to tumor tissues in the liver was greater when DXR was injected as a CpG plasmid DNA/DXR complex than as free DXR. The CpG plasmid DNA/DXR complex effectively inhibited the proliferation of colon26/Luc cells in the liver compared with free DXR, CpG plasmid DNA, or non-CpG plasmid DNA/DXR complex. These results indicate that CpG plasmid DNA is an effective polymer that inhibits tumor growth by delivering both a proinflammatory signal and anticancer agent to tumor tissues.