Total Synthesis of Bipenicilisorin and Assignment of the Absolute Configuration.

The first total synthesis of bipenicilisorin (1) isolated from Penicillium chrysogenum SCSIO 41001 via its monomer natural product, penicilisorin (2), was achieved. Penicilisorin was synthesized in four steps from a o-bromobenzaldehyde derivative via the Pd-catalyzed one-pot fluorocarbonylation/lactonization/ß-elimination cascade reaction. Iodination of penicilisorin gave 7-iodopenicilisorin which was dimerized by Pd-catalyzed homodimerization to provide (±)-bipenicilisorin. The unknown absolute configuration of naturally occurring (+)-bipenicilisorin was examined by optical resolution of the (±)-synthetic bipenicilisorin and a comparison of experimental and theoretical electronic circular dichroism (ECD) spectra. These results support the absolute configuration of the natural product to be Sa. A cytotoxic activity test of (+)-and (-)-bipenicilisorin using A549 cells revealed that (+)-1 has a lower IC50 value than (-)-1.

Neutrophils bearing adhesive polymer micropatches as a drug-free cancer immunotherapy.

Tumour-associated neutrophils can exert antitumour effects but can also assume a pro-tumoural phenotype in the immunosuppressive tumour microenvironment. Here we show that neutrophils can be polarized towards the antitumour phenotype by discoidal polymer micrometric 'patches' that adhere to the neutrophils' surfaces without being internalized. Intravenously administered micropatch-loaded neutrophils accumulated in the spleen and in tumour-draining lymph nodes, and activated splenic natural killer cells and T cells, increasing the accumulation of dendritic cells and natural killer cells. In mice bearing subcutaneous B16F10 tumours or orthotopic 4T1 tumours, intravenous injection of the micropatch-loaded neutrophils led to robust systemic immune responses, a reduction in tumour burden and improvements in survival rates. Micropatch-activated neutrophils combined with the checkpoint inhibitor anti-cytotoxic T-lymphocyte-associated protein 4 resulted in strong inhibition of the growth of B16F10 tumours, and in complete tumour regression in one-third of the treated mice. Micropatch-loaded neutrophils could provide a potent, scalable and drug-free approach for neutrophil-based cancer immunotherapy.

Acute Kidney Injury Caused by Rhabdomyolysis Is Ameliorated by Serum Albumin-Based Supersulfide Donors through Antioxidative Pathways.

Oxidative stress is responsible for the onset and progression of various kinds of diseases including rhabdomyolysis-induced acute kidney injury (AKI). Antioxidants are, therefore, thought to aid in the recovery of illnesses linked to oxidative stress. Supersulfide species have been shown to have substantial antioxidative activity; however, due to their limited bioavailability, few supersulfide donors have had their actions evaluated in vivo. In this study, human serum albumin (HSA) and N-acetyl-L-cysteine polysulfides (NACSn), which have polysulfides in an oxidized form, were conjugated to create a supersulfide donor. HSA is chosen to be a carrier of NACSn because of its extended blood circulation and high level of biocompatibility. In contrast to a supersulfide donor containing reduced polysulfide in HSA, the NACSn-conjugated HSAs exhibited stronger antioxidant activity than HSA and free NACSn without being uptaken by the cells in vitro. The supersulfide donor reduced the levels of blood urea nitrogen and serum creatinine significantly in a mouse model of rhabdomyolysis-induced AKI. Supersulfide donors significantly reduced the expression of oxidative stress markers in the kidney. These results indicate that the developed supersulfide donor has the therapeutic effect on rhabdomyolysis-induced AKI.

Development of Functional Chimeric Nanoparticles by Membrane Fusion of Small Extracellular Vesicles and Drug-Encapsulated Liposomes.

Since small extracellular vesicle (sEVs) are involved in cell-to-cell communication via transfer of certain bioactive molecules and have the capability to overcome biological barriers against drug transport, their use as a drug delivery system (DDS) has been demonstrated in treatment of a diverse range of diseases. However, some issues in drug encapsulation have been pointed out, including low encapsulation efficiency and poor reproducibility. It was previously reported that liposomes containing phosphatidylserine (PS) can fuse together in the presence of calcium ion, which allows for drug encapsulation into the resultant liposomes (i.e., calcium fusion method). On the other hand, PS is reportedly present in lipid membrane of sEVs as a distinct lipid composition. We therefore hypothesized that PS-mediated membrane fusion of sEVs with PS-liposomes encapsulating therapeutic agents via the calcium fusion method can be applied to convenient drug encapsulation into sEVs. Membrane fusion of PS-liposomes and sEVs derived from murine melanoma B16F1 cells (B16-sEVs) was firstly confirmed. The obtained nanoparticles, termed chimeric nanoparticles (CM-NP), showed comparable cellular uptake to B16-sEVs into B16F1 cells. Moreover, CM-NP encapsulating an anticancer drug doxorubicin (DOX) (CM-NP-DOX) could be prepared by membrane fusion of PS-liposomes encapsulating DOX (PS-Lipo-DOX) and B16-sEVs. CM-NP-DOX exhibited a superior anticancer effect on B16F1 cells in vitro compared with PS-Lipo-DOX. These findings suggest that the calcium fusion method could be applied for membrane fusion of sEVs and PS-liposomes, and that this approach would likely be useful for efficient drug encapsulation into sEVs, as well as increasing liposome functionality.

The Effect of Iontophoretic-Delivered Polyplex Vaccine on Melanoma Regression.

Although the strategy in cancer vaccination is to provide a therapeutic effect against an established tumor, there is an urgent need to develop prophylactic vaccines for non-viral cancers. In this study, we prepared polyplex nanoparticles through electrostatic interactions between a positively-charged modified tumor associated antigen, namely human derived melanoma gp10025-33 peptide (KVPRNQDWL-RRRR), and a negatively charged cytosine-phosphate-guanosine motif (CpG-ODN) adjuvant. We previously demonstrated successful transdermal delivery of various hydrophilic macromolecules by iontophoresis (IP) using weak electricity. Herein, we investigated the effectiveness of IP in the transdermal delivery of a prophylactic polyplex vaccine. IP was successful in establishing a homogenous distribution of the vaccine throughout skin. Efficacy of the vaccine was demonstrated against melanoma growth. A significant tumor regression effect was observed, which was confirmed by elevated mRNA expression levels of various cytokines, mainly interferon (IFN)-γ, as well as infiltration of cytotoxic CD8+ T cells. Additionally, we evaluated the therapeutic effect of the vaccine and we found a significant reduction in tumor burden. Stimulation of systemic immunity was confirmed by upregulation of IFN-γ. This is the first report to demonstrate the use of IP in the transdermal delivery of a prophylactic melanoma vaccine.

One-Step Pharmaceutical Preparation of PEG-Modified Exosomes Encapsulating Anti-Cancer Drugs by a High-Pressure Homogenization Technique.

The use of exosomes encapsulating therapeutic agents for the treatment of diseases is of increasing interest. However, some concerns such as limited efficiency and scalability of conventional drug encapsulation methods to exosomes have still remained; thus, a new approach that enables encapsulation of therapeutic agents with superior efficiency and scalability is required. Herein, we used RAW264 macrophage cell-derived exosomes (RAW-Exos) and demonstrated that high-pressure homogenization (HPH) using a microfluidizer decreased their particle size without changing their morphology, the amount of exosomal marker proteins, and cellular uptake efficiency into RAW264 and colon-26 cancer cells. Moreover, HPH allowed for modification of polyethylene glycol (PEG)-conjugated lipids onto RAW-Exos, as well as encapsulation of the anti-cancer agent doxorubicin. Importantly, the doxorubicin encapsulation efficiency became higher upon increasing the process pressure and simultaneous HPH with PEG-lipids. Moreover, treatment with PEG-modified RAW-Exos encapsulating doxorubicin significantly suppressed tumor growth in colon-26-bearing mice. Taken together, these results suggest that HPH using a microfluidizer could be useful to prepare PEG-modified Exos encapsulating anti-cancer drugs via a one-step pharmaceutical process, and that the prepared functional Exos could be applied for the treatment of cancer in vivo.

Biomimetic Nanoparticle Drug Delivery Systems to Overcome Biological Barriers for Therapeutic Applications.

Targeted drug delivery using nanoparticles has been applied for the treatment of diverse diseases, including cancer and inflammatory diseases. Nanoparticle-mediated delivery of therapeutic agents via the enhanced permeability and retention effect generally augments their therapeutic efficiency; however, limitations with passive entry of nanoparticles into diseased sites, due to the presence of biological barriers represented by the endothelial layer, remain to be addressed. To this end, development of nanoparticles with intrinsic characteristics similar to circulatory cells (e.g., leukocytes, platelets) for use as biomimetic drug delivery systems (DDS) has been focused as a means to overcome the issues of conventional DDS. In particular, synthetic biomimetic nanoparticles coated with cellular membranes were recently prepared and shown to actively overcome the inflamed vessels and tumor microenvironment as a result of the functionality of membrane proteins, which allowed secure drug delivery into diseased sites. We recently developed liposomes modified with leukocyte membrane proteins via intermembrane protein transfer, a simple method to reconstitute cellular membrane proteins onto lipid bilayers. The resultant liposomes demonstrated the ability to cross the inflamed endothelial layer and permeate into tumor tissue by mimicking the properties of leukocytes. Thus, biomimetic DDS offer promise as new therapeutic approaches for various diseases by overcoming biological barriers that typically inhibit drug delivery. Herein, we review recent approaches to develop biomimetic DDS using the cell membrane coating method, and highlight our recent findings on leukocyte-mimetic liposomes prepared via intermembrane protein transfer.

Effective Anticancer Therapy by Combination of Nanoparticles Encapsulating Chemotherapeutic Agents and Weak Electric Current.

Delivery of medicines using nanoparticles via the enhanced permeability and retention (EPR) effect is a common strategy for anticancer chemotherapy. However, the extensive heterogeneity of tumors affects the applicability of the EPR effect, which needs to overcome for effective anticancer therapy. Previously, we succeeded in the noninvasive transdermal delivery of nanoparticles by weak electric current (WEC) and confirmed that WEC regulates the intercellular junctions in the skin by activating cell signaling pathways (J. Biol. Chem., 289, 2014, Hama et al.). In this study, we applied WEC to tumors and investigated the EPR effect with polyethylene glycol (PEG)-modified doxorubicin (DOX) encapsulated nanoparticles (DOX-NP) administered via intravenous injection into melanoma-bearing mice. The application of WEC resulted in a 2.3-fold higher intratumor accumulation of nanoparticles. WEC decreased the amount of connexin 43 in tumors while increasing its phosphorylation; therefore, the enhancing of intratumor delivery of DOX-NP is likely due to the opening of gap junctions. Furthermore, WEC combined with DOX-NP induced a significant suppression of tumor growth, which was stronger than with DOX-NP alone. In addition, WEC alone showed tumor growth inhibition, although it was not significant compared with non-treated group. These results are the first to demonstrate that effective anticancer therapy by combination of nanoparticles encapsulating chemotherapeutic agents and WEC.

[Development of Biomembrane-mimetic Nanoparticles for the Treatment of Ischemic Stroke].

Increase in vascular permeability of the blood-brain barrier (BBB) is a distinct pathology following ischemic stroke. In previous studies, we demonstrated that liposomal drug delivery system (DDS)-based delivery of neuroprotectants is useful for treating cerebral ischemia/reperfusion injury. Additionally, our previous studies reported that combination therapy with liposomal fasudil plus tissue plasminogen activator (t-PA), a thrombolytic agent, brings about decrease in the risk of t-PA-derived cerebral hemorrhage and prolong the therapeutic time window of t-PA for treating acute ischemic stroke. However, accumulation of systemically administered liposomes into the brain parenchyma is still limited, and new technologies are needed that can overcome the BBB. The unique properties of leukocytes and exosomes, one of the extracellular vesicles, make them promising candidates for overcoming biological barriers (including the BBB) for drug delivery, as leukocytes and certain exosomes were reported to be able to permeate through the inflamed BBB in the ischemic stroke area. We prepared leukocyte-mimetic liposomes (LM-Lipo) via transfer of leukocyte membrane proteins by employing a phenomenon called intermembrane protein transfer, and demonstrated that LM-Lipo could pass through the layer of inflamed endothelial cells via regulation of intercellular junctions, like leukocytes. Additionally, we showed that LM-Lipo efficiently penetrated into spheroids of cancer cells, and inhibited their growth by entrapped doxorubicin. Taken together, it was suggested that imparting leukocyte-like characteristics to liposomes may be an effective approach to overcoming biological barriers. Herein, we summarize our findings regarding liposomal DDS for ischemic stroke therapy and recent approaches to develop biomembrane-mimetic DDS using leukocytes and exosomes.

A simple, fast, and orientation-controllable technology for preparing antibody-modified liposomes.

Modification with antibodies is a useful strategy for the delivery of nanoparticles to target cells. However, the complexity of the required chemical modifications makes them time-consuming and low efficiency, and the orientation of the antibody is challenging to control. To develop a simple, fast, effective, and orientation-controllable technology, we employed staphylococcal protein A, which can bind to the Fc region of antibodies, as a tool for conjugating antibodies to nanoparticles. Specifically, we modified the C-domain dimer of protein A to contain a lysine cluster to create a molecule, DPACK, that would electrostatically bind to anionic liposomes. Using this protein, antibody-modified liposomes can be prepared in 35 min with two steps: (1) interaction of DPACK with liposomes and (2) interaction of an antibody with DPACK-modified liposomes. Binding efficiencies of DPACK with liposomes and IgG with DPACK-modified liposomes were 75% and 72-84%, respectively. Uptake of liposomes modified with anti-epidermal growth factor receptor (EGFR) antibodies via DPACK by EGFR-expressing cancer cells was significantly higher than that of unmodified liposomes, and the liposomes accumulated in tumors and colocalized with EGFR. This simple, fast, effective and orientation-controllable technology for preparing antibody-modified liposomes will be useful for active targeting drug delivery.

Overcoming thickened pathological skin in psoriasis via iontophoresis combined with tight junction-opening peptide AT1002 for intradermal delivery of NF-κB decoy oligodeoxynucleotide.

Transdermal delivery of nucleic acid therapeutics has been demonstrated to be effective for psoriasis treatment. We previously reported the utility of iontophoresis (IP) using weak electric current (0.3-0.5 mA/cm2) for intradermal delivery of nucleic acid therapeutics via weak electricity-mediated intercellular junction cleavage, and subsequent exertion of nucleic acid function. However, the thickened pathological skin in psoriasis hampers permeation of IP-administered macromolecules. Thus, approaches are needed to more strongly cleave intercellular spaces and overcome the psoriatic skin barrier. Herein, we applied a combination of tight junction-opening peptide AT1002 with IP, as synergistic effects of weak electricity-mediated intercellular junction cleavage and the tight junction-opening ability of AT1002 may help overcome thickened psoriatic skin and facilitate macromolecule delivery. Pretreatment with IP of an AT1002 analog exhibiting positively-charged moieties before fluorescence-labeled oligodeoxynucleotide IP resulted in the oligodeoxynucleotide permeation into psoriatic skin, whereas IP of the oligodeoxynucleotide alone did not. Moreover, psoriasis-induced upregulation of inflammatory cytokine mRNA levels was significantly suppressed by NF-κB decoy oligodeoxynucleotide IP combined with the AT1002 analog, resulting in amelioration of epidermis hyperplasia. These results suggest that synergistic effects of IP and an AT1002 analog can overcome thickened psoriatic skin and enable intradermal delivery of NF-κB decoy oligodeoxynucleotide for psoriasis treatment.

Suppression of Lipid Accumulation in 3T3-L1 Adipocytes by α-Tocopheryl Succinate.

Obesity is a pathological state related to various lifestyle-related diseases, such as diabetes and dyslipidemia, that may be prevented through the development of anti-obesity treatments. Lipid accumulation in cells could be affected by vitamin E ester α-tocopheryl succinate (TS), which has various biological activities, such as anti-cancer effect, via activation of cell signaling pathways, although the antioxidative activity of TS is lost due to esterification of the phenolic OH group. In this study, we found for the first time that TS significantly suppressed lipid accumulation in mouse 3T3-L1 adipocytes. TS treatment reduced the amount of triglycerides in the culture medium, and inhibited activity of glycerol-3-phosphate dehydrogenase, a marker of lipid synthesis. Furthermore, TS accelerated lipolysis. Treatment of adipocytes with TS for 24 h induced no significant cytotoxicity. In TS-treated cells, phosphorylation of Akt, which is involved in fatty acid synthesis via sterol regulatory element-binding proteins (SREBP), was prevented, while levels of phosphorylated protein kinase A (PKA) did not change. Taken together, these results suggest that vitamin E ester TS can suppress lipid accumulation in adipocytes by regulating lipid metabolic cell signaling.

Leukocyte-Mimetic Liposomes Penetrate Into Tumor Spheroids and Suppress Spheroid Growth by Encapsulated Doxorubicin.

As leukocytes can penetrate into deep regions of a tumor mass, leukocyte-mimetic liposomes (LM-Lipo) containing leukocyte membrane proteins are also expected to penetrate into tumors by exerting properties of those membrane proteins. The aim of the present study was to examine whether LM-Lipo, which were recently demonstrated to actively pass through inflamed endothelial layers, can penetrate into tumor spheroids, and to investigate the potential of LM-Lipo for use as an anticancer drug carrier. We prepared LM-Lipo via intermembrane protein transfer from human leukemia cells; transfer of leukocyte membrane proteins onto the liposomes was determined by Western blotting. LM-Lipo demonstrated a significantly high association with human lung cancer A549 cells compared with plain liposomes, which contributed to effective anti-proliferative action by encapsulated doxorubicin hydrochloride (DOX). Confocal microscopic images showed that LM-Lipo, but not plain liposomes, could efficiently penetrate into A549 tumor spheroids. Moreover, DOX-encapsulated LM-Lipo significantly suppressed tumor spheroid growth. Thus, leukocyte membrane proteins transferred onto LM-Lipo retained their unique function, which allowed for efficient penetration of the liposomes into tumor spheroids, similar to leukocytes. In conclusion, these results suggest that LM-Lipo could be a useful tumor-penetrating drug delivery system for cancer treatment.

[Development of DDS Actively to Overcome the Blood-brain Barrier in the Region of Ischemic Stroke].

We previously showed that increased permeability of the blood-brain barrier (BBB) after ischemic stroke enables extravasation of nano-sized liposomes and accumulation in the ischemic region, and that delivery of neuroprotective agents using liposomal drug delivery systems (DDS) is applicable for treating cerebral ischemia/reperfusion (I/R) injury. However, entry of liposomes into the brain parenchyma was limited in the early stages after I/R possibly due to microvascular dysfunction induced by pathological progression. As such, new approaches to overcome the BBB are needed. Leukocytes can pass through inflamed BBB in I/R region due to membrane proteins displayed on their surface. We thus hypothesized that incorporation of leukocyte membrane proteins onto liposomal membranes would impart leukocyte-mimicking functions to liposomes and that leukocyte-mimetic liposomes (LM-Lipo) may pass through inflamed endothelial cells and BBB, similar to leukocytes. LM-Lipo prepared using intermembrane protein transfer from human leukemia cells showed significantly increased association to inflamed human umbilical vein endothelial cells relative to plain liposomes. Moreover, LM-Lipo passed through inflamed endothelial cell layer by regulating intercellular junctions. These results suggest that imparting leukocyte-like properties to liposomes via intermembrane protein transfer would be an effective strategy to overcome inflamed endothelial barriers. In this review, we describe our findings on ischemic stroke treatment using liposomal DDS and the potential of LM-Lipo to overcome inflamed endothelial barriers.

Non-invasive delivery of biological macromolecular drugs into the skin by iontophoresis and its application to psoriasis treatment.

Biological macromolecular drugs, such as antibodies and fusion protein drugs, have been widely employed for the treatment of various diseases. Administration routes are typically via invasive intravenous or subcutaneous injection with needles; the latter is challenging for applications involving inflamed skin (e.g., psoriasis) due to concerns of expansion of inflammation. As a method of non-invasive transdermal drug delivery, we previously demonstrated that iontophoresis (IP) using weak electric current (0.3-0.5 mA/cm2) enables transdermal permeation of hydrophilic macromolecules, such as small interfering RNA and nanoparticles into the skin, and subsequent exertion of their functions. The underlying mechanism was revealed to be via intercellular junction cleavage by cellular signaling activation initiated by Ca2+ influx. Based on these findings, in the present study, we hypothesized that non-invasive intradermal delivery of biological macromolecular drugs could be efficiently achieved via IP. Fluorescence of FITC-labeled IgG antibody was broadly observed in the skin after IP administration (0.4 mA/cm2 for 1 h) and extended from the epidermis to the dermis layer of hairless rats; passive antibody diffusion was not observed. In imiquimod-induced psoriasis model rats, antibodies were also delivered via IP into inflamed skin tissue. Additionally, upregulation of interleukin-6 mRNA levels, which is related to pathological progression of psoriasis, was significantly inhibited by IP of the anti-tumor necrosis factor-α drug etanercept, but not by its subcutaneous injection. Importantly, IP administration of etanercept significantly ameliorated epidermis hyperplasia, a symptom of psoriasis. Taken together, the present study is the first to demonstrate that IP can be applied as a non-invasive and efficient intradermal drug delivery technology for biological macromolecular drugs.

Characteristics of unique endocytosis induced by weak current for cytoplasmic drug delivery.

We previously reported that a weak current (WC, 0.3-0.5 mA/cm2) applied to cells can induce endocytosis to promote cytoplasmic delivery of hydrophilic macromolecules (MW: <70,000), such as dextran and siRNA, which leak from WC-induced endosomes into the cytoplasm (Hasan et al., 2016). In this study, we evaluated the characteristics of WC-mediated endocytosis for application of the technology to cytoplasmic delivery of macromolecular medicines. WC induced significantly higher cellular uptake of exogenous DNA fragments compared to untreated cells; the amount increased in a time-dependent manner, indicating that endocytosis was induced after WC. Moreover, following WC treatment of cells in the presence of an antibody (MW: 150,000) with the lysosomotropic agent chloroquine, the antibody was able to bind to its intracellular target. Thus, high molecular weight protein medicines delivered by WC-mediated endocytosis were functional in the cytoplasm. Transmission electron microscopy of cells treated by WC in the presence of gold nanoparticles covered with polyethylene glycol showed that the WC-induced endosomes exhibited an elliptical shape. In the WC-induced endosomes, ceramide, which makes pore structures in the membrane, was localized. Together, these results suggest that WC can induce unique endocytosis and that macromolecular medicines leak from endosomes through a ceramide pore.

Low level electricity increases the secretion of extracellular vesicles from cultured cells.

Exosomes, a type of extracellular vesicles, can be collected from the conditioned medium of cultured cells, and are expected to be used in disease therapy and drug delivery systems. However, since the yield of exosomes from conditioned medium is generally low, investigations to develop new methods to increase exosome secretion and to elucidate the secretion mechanism have been performed. Our previous studies demonstrated that activation of intracellular signaling including Rho GTPase and subsequent endocytosis of extraneous molecules in cells could be induced by low level electricity (0.3-0.5 mA/cm2). Since exosomes are produced in the process of endocytosis and secreted by exocytosis via certain signaling pathways, we hypothesized that low level electric treatment (ET) would increase exosome secretion from cultured cells via intracellular signaling activation. In the present study, the influence of ET (0.34 mA/cm2) on extracellular vesicle (EV) secretion from cultured cells was examined by using murine melanoma and murine fibroblast cells. The results showed that the number of EV particles collected by ultracentrifugation was remarkably increased by ET in both cell lines without cellular toxicity or changes in the particle distribution. Also, protein amounts of the collected EVs were significantly increased in both cells by ET without alteration of expression of representative exosome marker proteins. Moreover, in both cells, the ratio of particle numbers to protein amount was not significantly changed by ET. Rho GTPase inhibition significantly suppressed ET-mediated increase of EV secretion in murine melanoma, indicating that Rho GTPase activation could be involved in ET-mediated EV secretion in the cell. Additionally, there were almost no differences in uptake of each EV into each donor cell regardless of whether the cells had been exposed to ET for EV collection. Taken together, these results suggest that ET could increase EV secretion from both cancer and normal cells without apparent changes in EV quality.

Biological Functions of α-Tocopheryl Succinate.

α-Tocopheryl succinate (TS) is a succinic acid ester of a well-known natural antioxidant α-tocopherol (α-T). Physicochemical characteristics of TS are entirely different from the original compound α-T. TS becomes vesicles via forming a lamella structure. Furthermore, although the antioxidative activity of α-T is lacked by esterification of phenolic hydroxyl (OH) moiety with succinate, TS has versatile biological functions, such as inhibition of cholinesterase activity, inhibition of nuclear factor-kappa B (NF-κB) activation, enhancement of lipopolysaccharide-induced nitric oxide production, and anticancer effect. Especially, we expect TS as a novel anticancer agent. TS nanovesicle shows significant anticancer activity in vitro and in vivo. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase produces superoxide which mediates the anticancer activity of TS. Moreover, it suggests that TS activates protein kinase C via direct interaction. Based on the analysis of structure and activity relationship, it ensures that succinate moiety of TS plays a vital role in anticancer activity. This review introduces the detail and mechanism of versatile biological functions of TS.

Engineering the Binding Kinetics of Synthetic Polymer Nanoparticles for siRNA Delivery.

The affinity of a synthetic polymer nanoparticle (NP) to a target biomacromolecule is determined by the association and dissociation rate constants (kon, koff) of the interaction. The individual rates and their sensitivity to local environmental influences are important factors for the on-demand capture and release a target biomacromolecule. Positively charged NPs for small interfering RNA (siRNA) delivery is a case in point. The knockdown efficacy of siRNA can be strongly influenced by the binding kinetics to the NP. Here, we show that kon and koff of siRNA to NPs can be individually engineered by tuning the chemical structure and composition of the NP. N-Isopropylacrylamide-based NPs functionalized with hydrophobic and amine monomers were used. koff decreased by increasing the amount of amine groups in the NP, whereas kon did not change. Importantly, NPs showing a low koff at pH 5.5 together with a high koff at pH 7.4 showed high knockdown efficiency when NP/siRNA complexes were packaged in lipid nanoparticles. These results provide direct evidence for the premise that the efficacy of an siRNA delivery vector is linked with the strong affinity to the siRNA in the endosome and low affinity in the cytoplasm.

Leukocyte-mimetic liposomes possessing leukocyte membrane proteins pass through inflamed endothelial cell layer by regulating intercellular junctions.

Nanoparticles such as liposomes have been applied for the treatment of various diseases such as cancer and inflammatory diseases by utilizing the enhanced permeability and retention effect. However, their entry into inflammation sites is still limited since passive delivery of nanoparticles is often hampered by the presence of endothelial barriers. As leukocytes can pass through the inflamed endothelium via utilizing membrane protein functions, we hypothesized that incorporating leukocyte membrane proteins onto liposomal membranes may impart leukocyte-mimicking functions to liposomes, allowing for their adherence to and active passage through the inflamed endothelium. Herein, we developed leukocyte-mimetic liposomes (LM-Lipo) by leukocyte membrane protein transfer and evaluated their function in vitro. Transfer of membrane proteins from human leukemia cells onto liposomal membranes allowed for significant association of the liposomes with inflamed human endothelial cells, and subsequent passage through inflamed endothelial cell layer. The confocal images showed that LM-Lipo significantly induced vascular endothelial-cadherin displacement. These results indicate that LM-Lipo adhered to and regulated intercellular junctions of inflamed endothelial cell layer, resulting in passage through the layer, by mimicking the function of leukocytes. Furthermore, it is suggested that liposomes possessing leukocyte-like functions could be useful for drug delivery to inflammation sites by overcoming endothelial barriers.