An orally deliverable ornithine-based self-assembling polymer nanomedicine ameliorates hyperammonemia in acetaminophen-induced acute liver injury

l-Ornithine (Orn) is a core amino acid responsible for ammonia detoxification in the body via the hepatic urea cycle. Clinical studies in Orn therapy have focused on interventions for hyperammonemia-associated diseases, such as hepatic encephalopathy (HE), a life-threatening neurological symptom affecting more than 80% of patients with liver cirrhosis. However, its low molecular weight (LMW) causes Orn to diffuse nonspecifically and be rapidly eliminated from the body after oral administration, resulting in unfavorable therapeutic efficacy. Hence, Orn is constantly supplied by intravenous infusion in many clinical settings; however, this treatment inevitably decreases patient compliance and limits its application in long-term management. To improve the performance of Orn, we designed self-assembling polyOrn-based nanoparticles for oral administration through ring-opening polymerization of Orn-N-carboxy anhydride initiated with amino-ended poly(ethylene glycol), followed by acylation of free amino groups in the main chain of the polyOrn segment. The obtained amphiphilic block copolymers, poly(ethylene glycol)-block-polyOrn(acyl) (PEG-block-POrn(acyl)), enabled the formation of stable nanoparticles (NanoOrn(acyl)) in aqueous media. We employed the isobutyryl (iBu) group for acyl derivatization in this study (NanoOrn(iBu)). In the healthy mice, daily oral administration of NanoOrn(iBu) for one week did not induce any abnormalities. In the mice exhibiting acetaminophen (APAP)-induced acute liver injury, oral pretreatment with NanoOrn(iBu) effectively reduced systemic ammonia and transaminases levels compared to the LMW Orn and untreated groups. The results suggest that the application of NanoOrn(iBu) is of significant clinical value with the feasibility of oral delivery and improvement in APAP-induced hepatic pathogenesis. STATEMENT OF SIGNIFICANCE: Liver injury is often accompanied by hyperammonemia, a life-threatening condition characterized by elevated blood ammonia levels. Current clinical treatments for reducing ammonia typically entail the invasive approach of intravenous infusion, involving the administration of l-ornithine (Orn) or a combination of Orn and L-aspartate. This method is employed due to the poor pharmacokinetics associated with these compounds. In our pursuit of enhancing therapy, we have developed an orally administrable nanomedicine based on Orn-based self-assembling nanoparticle (NanoOrn(iBu)), which provides sustained Orn supply to the injured liver. Oral administration of NanoOrn(iBu) to healthy mice did not cause any toxic effects. In a mouse model of acetaminophen-induced acute liver injury, oral administration of NanoOrn(iBu) surpassed Orn in reducing systemic ammonia levels and liver damage, thereby establishing NanoOrn(iBu) as a safe and effective therapeutic option.

Design of Antioxidant Nanoparticle, which Selectively Locates and Scavenges Reactive Oxygen Species in the Gastrointestinal Tract, Increasing The Running Time of Mice

Excess reactive oxygen species (ROS) produced during strong or unfamiliar exercise cause exercise-induced gastrointestinal syndrome (EIGS), leading to poor health and decreased exercise performance. The application of conventional antioxidants can neither ameliorate EIGS nor improve exercise performance because of their rapid elimination and severe side effects on the mitochondria. Hence, a self-assembling nanoparticle-type antioxidant (RNPO ) that is selectively located in the gastrointestinal (GI) tract for an extended time after oral administration is developed. Interestingly, orally administered RNPO significantly enhances the running time until exhaustion in mice with increasing dosage, whereas conventional antioxidants (TEMPOL) tends to reduce the running time with increasing dosage. The running (control) and TEMPOL groups show severe damage in the GI tract and increased plasma lipopolysaccharide (LPS) levels after 80 min of running, resulting in fewer red blood cells (RBCs) and severe damage to the skeletal muscles and liver. However, the RNPO group is protected against GI tract damage and elevation of plasma LPS levels, similar to the nonrunning (sedentary) group, which prevents damage to the whole body, unlike in the control and TEMPOL groups. Based on these results, it is concluded that continuous scavenging of excessive intestinal ROS protects against gut damage and further improves exercise performance.

Efficacy of redox nanoparticles for improving survival of transplanted cells in a mouse model of ischemic stroke

The success of cell transplantation therapy for ischemic stroke is hindered by the low cell survival rate in poststroke brain, due in part to high free radical production and ensuing oxidative stress. We have developed redox nanoparticles to eliminate reactive oxygen species. In this study, we tested the protective efficacy of these redox nanoparticles in cell culture and a mouse model of ischemic stroke. Induced human dental pulp stem cells were subjected to oxygen-glucose deprivation and reoxygenation to recapitulate ischemia and reperfusion in the penumbra surrounding a cerebral infarct. Cell viability using WST-8 assay, apoptosis using TUNEL, free radicals using MitoSOX, and inflammatory cytokines using ELISA kit were measured in the presence and absence of redox nanoparticles after oxygen-glucose deprivation and reoxygenation. The scavenging activity of redox nanoparticles against reactive oxygen species was detected by electron spin resonance. Moreover, induced cells were transplanted intracerebrally into to the distal middle cerebral artery occlusion model with and without redox nanoparticles, and the survival rate measured. Cell viability was enhanced, while apoptosis, free radical generation, and inflammatory cytokine expression levels were reduced in cultures with redox nanoparticles. Further, reduced redox nanoparticles were detected in the cytoplasm, indicating free radical scavenging. Addition of redox nanoparticles also improved the survival rate of transplanted cells after 6 weeks in vivo. These redox nanoparticles may increase the applicability and success of induced stem cell therapy for ischemic stroke patents by promoting long-term survival.

Designing poly(gamma-aminobutyric acid)-based nanoparticles for the treatment of major depressive disorders

Major depressive disorder (MDD) is a worldwide concern owing to its negative impact on the quality of life. Gamma-aminobutyric acid (GABA), an essential neurotransmitter in the brain, is important for regulating the enteric nervous system and gut-brain dual communication (gut-brain axis), thus providing gastrointestinal GABA and GABA-related pathways with possible targets for MDD treatment. However, the use of GABA for this disease remains limited due to its poor pharmacokinetic properties, including the low permeability through the blood-brain barrier, and the rapid clearance from the gastrointestinal tract. Since poly(amino acid)s are advantageous for improving the beneficial bioactivities of conventional amino acids, poly(gamma-aminobutyric acid) (poly(GABA)) is a potential candidate for MDD therapy. Nevertheless, the non-water-soluble and non-dispersible characteristics of poly(GABA) render difficulty in administering its conventional forms in vitro/in vivo, thereby hindering its therapeutic applications. Therefore, this study proposes a new design for poly(GABA) in nanoparticle form, which is composed of the amphiphilic diblock copolymers of poly(GABA) and poly(ethylene glycol), providing a suitable formulation for medication applications. Herein, we report on a new orally deliverable poly(GABA)-based nanoparticles (NanoGABA) in aqueous media and their efficacy on mouse depression models. NanoGABA treatment efficiently attenuated depression-like symptoms as evidenced by behavioral tests (forced swimming tests and tail suspension tests) and stress biomarkers (corticosterone). These findings suggest that the newly designed poly(GABA)-based nanoparticles are a promising candidate for the treatment of depression. STATEMENT OF SIGNIFICANCE: This research is the first to report the preparation of poly(GABA)-based nanoparticles in aqueous conditions with beneficial physical properties to open the gate for medical and pharmaceutical applications of poly (GABA). It is also a pioneer in using poly(GABA)-based materials for major depressive disorder therapeutics in vivo. Oral administration of NanoGABA attenuates depressive-like symptoms by targeting the enteric nervous system possibly through modulation of the gut-brain axis pathways with negligible toxicity, suggesting that NanoGABA is a promising therapeutic agent for major depressive disorders.

Newly Designed Cysteine-Based Self-Assembling Prodrugs for Sepsis Treatment

Reactive oxygen species (ROS) are essential signaling molecules that maintain intracellular redox balance; however, the overproduction of ROS often causes dysfunction in redox homeostasis and induces serious diseases. Antioxidants are crucial candidates for reducing overproduced ROS; however, most antioxidants are less effective than anticipated. Therefore, we designed new polymer-based antioxidants based on the natural amino acid, cysteine (Cys). Amphiphilic block copolymers, composed of a hydrophilic poly(ethylene glycol) (PEG) segment and a hydrophobic poly(cysteine) (PCys) segment, were synthesized. In the PCys segment, the free thiol groups in the side chain were protected by thioester moiety. The obtained block copolymers formed self-assembling nanoparticles (Nano^Cys(Bu)) in water, and the hydrodynamic diameter was 40-160 nm, as determined by dynamic light scattering (DLS) measurements. Nano^Cys(Bu) was stable from pH 2 to 8 under aqueous conditions, as confirmed by the hydrodynamic diameter of Nano^Cys(Bu). Finally, Nano^Cys(Bu) was applied to sepsis treatment to investigate the potential of Nano^Cys(Bu). Nano^Cys(Bu) was supplied to BALB/cA mice by free drinking for two days, and lipopolysaccharide (LPS) was intraperitoneally injected into the mice to prepare a sepsis shock model (LPS = 5 mg per kg body weight (BW)). Compared with the Cys and no-treatment groups, Nano^Cys(Bu) prolonged the half-life by five to six hours. Nano^Cys(Bu), designed in this study, shows promise as a candidate for enhancing antioxidative efficacy and mitigating the adverse effect of cysteine.

Self-assembling polymer-based short chain fatty acid prodrugs ameliorate non-alcoholic steatohepatitis and liver fibrosis

With the preponderance of a high-calorie diet and sedentary lifestyle, the prevalence of non-alcoholic steatohepatitis (NASH), a state of abnormally elevated lipid accumulation in the liver with chronic inflammation, is increasing at an alarming rate worldwide. Hence, cost-effective therapeutic interventions are required to manage this disease at an early stage. Numerous reports have suggested a link between gut microbial dysbiosis, particularly a decrease in the abundance of short-chain fatty acids (SCFA)-producing microbiota and NASH pathogenesis. Considering these low molecular weight (LMW) SCFAs such as acetic, propionic, and butyric acids have been used to inhibit hepatic steatosis in mouse models. However, the poor pharmacokinetic (PK) profile of SCFAs, caused due to their LMW, renders them therapeutically ineffective. Thus, to improve the PK characteristic-based therapeutic efficacy of LMW SCFAs, we designed SCFA-based prodrugs that possess self-assembling characteristics in aqueous media. The designed SCFA prodrugs consist of enzyme-metabolizable amphiphilic block copolymers, [poly(ethylene glycol)-b-poly(vinyl ester)s] conjugated to propionic acid (PA) or butyric acid (BA) by an ester linkage, which self-assemble into stable nanosized micelles several tens of nanometers in diameter (Nano^PA and Nano^BA). Via pharmacological analysis, we confirmed that, after oral administration, LMW BA decreased to a physiological level within 24 h in the liver, whereas BA liberated from Nano^BA was observed until 72 h post-administration, implying a sustained release profile. Here, we evaluated the therapeutic efficacy of Nano^SCFA in a choline-deficient, L-amino acid-defined high-fat diet (CDAHFD)-induced NASH and liver fibrosis mouse model by ad libitum drinking. Nano^SCFA, particularly Nano^BA, exhibited the remarkable potential to ameliorate the phenotypic features of fatty liver disease by reducing hepatic lipogenesis and fibrosis, with negligible adverse effects. In contrast, conventional LMW SCFAs failed to prevent the pathogenesis of fatty liver disease, which plausibly can be explained by their rapid clearance and discernible adverse effects. Mechanistic studies revealed that Nano^BA restored the nuclear expression of PPARα, a transcriptional factor regulating mitochondrial fatty acid oxidation, in the periportal hepatocytes and decreased the CPT1A expression level in the hepatic tissues, reflecting the therapeutic effects of Nano^BA. Taken together, we confirmed that our Nano^SCFA potentially improved the PK properties of SCFAs, and it consequently alleviated NASH symptoms and fibrotic liver compared to LMW SCFAs. Our study establishes Nano^SCFA as a suitable nano-assembled prodrug for NASH treatment.

Direct evidence for the involvement of intestinal reactive oxygen species in the progress of depression via the gut-brain axis

Depression is a serious global social problem. Various therapeutic drugs have been developed based on the monoamine hypothesis; however, treatment-resistant depression is a common clinical issue. Recently, the gut-brain axis, which is associated with the hypothesis that the intestinal environment affects the brain, has garnered significant interest, and several studies have attempted to treat brain disorders based on this axis. These attempts include fecal transplantation, probiotics and prebiotics. In this study, we focused on intestinal reactive oxygen species (ROS) because excessive ROS levels disturb the intestinal environment. To elucidate the impact of scavenging intestinal ROS on depression treatment via the gut-brain axis, a novel polymer-based antioxidant (siSMAPo^TN), which was distributed only in the intestine and did not diffuse into the whole body after oral administration, was used. siSMAPo^TN selectively scavenged intestinal ROS and protected the intestinal environment from damage caused by chronic restraint stress (CRS). In addition, siSMAPo^TN suppressed physiological and behavioral depression-related symptoms in the CRS mouse model.

Design of a new self-assembling antioxidant nanomedicine to ameliorate oxidative stress in zebrafish embryos

Oxidative stress, which is a persistent state of elevated reactive oxygen species (ROS), is implicated in the pathogeneses of several diseases, making antioxidant-based therapeutics the aptest intervention. Nevertheless, the clinical failure of conventional low-molecular-weight (LMW) antioxidants in oxidative stress-related diseases to yield favorable therapeutic outcomes and an increased mortality rate attributable to their poor pharmacokinetic characteristics, necessitates the development of alternative therapeutics. In light of this, we designed and synthesized a new amphiphilic polymer functionalized with a clinically safe base polymer of poly(styrene-co-maleic anhydride) copolymer conjugated with the LMW pleiotropic antioxidant TEMPO (a potent antioxidant) and biocompatible poly(ethylene glycol) (TEMPO-installed PSMA-g-PEG), which self-assembles into nano-sized micelles (SMAPo^TN) under physiological conditions. We investigated its safety and antioxidant ability using zebrafish models. Common LMW antioxidants, such as 4-hydroxy-TEMPO (TEMPOL), vitamin C, N-acetyl-L-cysteine, and edaravone exposure induced phenotypic distortions, a manifestation of developmental toxicity, and resulted in high lethality in zebrafish larvae. LMW TEMPOL also adversely affected embryo hatchability, induced arrhythmia and cardiac edema, and failed to protect against oxidative stress. In contrast, exposure of zebrafish embryos to SMAPo^TN increased the hatchability, protected embryos against various inducers of oxidative stress, and did not induce any phenotypic alterations or discernible toxicity. Taken together, we conclude that SMAPo^TN surpasses LMW TEMPOL in terms of the ability to protect zebrafish, attributable to efficient ROS scavenging without perturbing normal redox homeostasis. These results imply that SMAPo^TN can be used as a therapeutic intervention against various oxidative stress-induced diseases. STATEMENT OF SIGNIFICANCE: Failure of low molecular weight (LMW) antioxidants to improve therapeutic index in various oxidative stress-related pathogenesis, attributable to their poor pharmacokinetic characteristics, greatly limits their clinical translation. To overcome this limitation, we developed a self-assembling antioxidant nanoparticle (SMAPo^TN) comprised of amphiphilic polymer; poly(styrene-co-maleic anhydride) conjugated with TEMPO as an antioxidant and biocompatible poly(ethylene glycol). Preliminary studies carried out in the in vivo models of zebrafish embryos confirmed that exposure of LMW antioxidant resulted in acute developmental toxicity, high lethality, and failure to rescue embryos against oxidative stress inducers. In contrast, SMAPo^TN did not exert discernible toxicity and significantly improved their survival under oxidative stress. Our finding establishes antioxidant nanoparticles as more suitable therapeutic intervention for oxidative stress-induced diseases than LMW antioxidants.

Short-chain fatty acid-releasing nano-prodrugs for attenuating growth and metastasis of melanoma

Low-molecular-weight (LMW) short-chain fatty acids (SCFAs), such as propionic and butyric acids, have been reported to possess anti-neoplastic effects; however, rapid renal clearance and high dose-based side effects limit their clinical translation. Hence, in this study, we have designed a new self-assembling nano-prodrugs that can effectively supply SCFAs: endogenous enzyme-metabolizable block copolymer poly(ethylene glycol)block-poly(vinyl ester) possessing several units of SCFAs conjugated as side chains via ester linkages. These amphiphilic polymers spontaneously self-assemble into nanostructures under aqueous conditions to form orally administrable nano-prodrugs (butyric acid: Nano^BA and propionic acid: Nano^PA). Herein, we show the therapeutic efficacy of SCFA nanoparticles (Nano^SCFA) in a mouse model of metastasis (melanoma). Ad libitum intake of our Nano^SCFA markedly demonstrated a decrease in the metastatic tumor nodules in the lungs compared with the effect observed after LMW SCFA administration with no discernible toxicity to the GI tract. In contrast, LMW SCFAs, even at a lower concentration than that of the Nano^SCFA, facilitated villus atrophy. Taken together, our work suggests that the use of Nano^SCFA as a therapeutic intervention for metastatic cancer is preferable over typical LMW SCFAs. STATEMENT OF SIGNIFICANCE: Low-molecular-weight (LMW) short-chain fatty acids (SCFAs) have shown versatile therapeutic effects on various diseases, including anti-tumorigenesis effects. However, their clinical translation is limited due to their poor pharmacokinetic profile and adverse effects. To overcome these limitations, we have developed new amphiphilic block copolymer-based SCFA-prodrugs, which self-assemble into nanoparticles in aqueous media (Nano^SCFA). SCFAs are covalently conjugated to the hydrophobic polymer segment via ester linkage, which can be enzymatically metabolized after oral administration. In the present study, we confirmed that ad libitum intake of Nano^SCFAs retarded the growth and metastatic potential of B16-F10 tumors compared to the LMW SCFAs with negligible discernible toxicity, reflecting Nano^SCFA as a preferable therapeutic intervention to LMW SCFA counterparts.

Recent advances in self-assembling redox nanoparticles as a radiation protective agent

<abstract> <p>The search for potent radiation-protective drugs for clinical use continues. Studies have, so far, focused on targeting the neutralization of radiation-generated reactive oxygen species (ROS) to protect the cells against the deleterious effects of exposure to ionizing radiation. However, the development of efficacious radioprotective drugs, which are mostly low molecular weight (LMW) compounds, is mainly limited due to their inherent toxicity and rapid excretion from the body. Thus, researchers reformulated these LMW compounds into nano-based formulations. This review discusses recent advances in the use of self-assembling redox nanoparticles as a new group of radioprotective agents. The copolymer micelle (herein referred to as redox nanoparticles; RNP) contains an active part, amino-TEMPO, that effectively scavenges radiation-induced ROS in the body, as demonstrated <italic>in vivo</italic>. With the use of nanoparticle-based technologies, optimized formulations of these LMW ROS-neutralizers lead to the significant reduction of its toxicity, high bioavailability and longer blood circulation, which consequently resulted in its notable enhanced efficacy (for example, increased survival rate, reduced radiation-induced syndromes and organ damage) against the damaging effects of ionizing radiation. Consistent with the available data on the use of RNP and other nano-based radioprotective agents, it can be concluded that the inherent ROS-targeting activity of a drug intended for radiation protection is as vital as its bioavailability in the specific tissues and organs, where the short-lived ROS are produced during radiation exposure. In this review article, we summarized the current status of the development of radioprotective agents, including our self-assembling radioprotective agents.</p> </abstract>

Design of self-assembling anti-epileptic drug for long-acting drug delivery in vivo

Valproic acid (VPA) has been extensively used for the treatment of seizures in epilepsy. The recommended VPA concentration in the blood is in the range of 50-100 μg mL^-1 and its therapeutic efficiency is well recognized. Since its therapeutic range is relatively narrow, strict scheduling of daily self-medication is required to optimize therapeutic outcomes and avoid adverse effects. To facilitate patient convenience in long-term and chronic therapies, the development of a sustained drug delivery system for VPA is a promising strategy. In this study, an enzyme-metabolizable block copolymer possessing a valproate ester, poly(ethylene glycol)-b-poly(vinyl valproate), was synthesized. The synthesized block copolymers formed stable nanoparticles (denoted Nano^VPA) by self-assembly under physiological conditions and released VPA via enzymatic hydrolysis. Nano^VPA showed improved pharmacokinetics compared to sodium valproate in vivo, and therapeutic efficacy in a pentylenetetrazol (PTZ)-induced kindling mouse model after once-weekly administration.

A silica-based antioxidant nanoparticle for oral delivery of Camptothecin which reduces intestinal side effects while improving drug efficacy for colon cancer treatment

Camptothecin (CPT) is a potent anticancer agent for the treatment of colorectal cancer; however, it exhibits some limitations, including poor solubility, low stability, and low bioavailability via oral administration, which restrict its usability in clinical treatments. In addition, overproduction of reactive oxygen species (ROS) during chemotherapy induces drug resistance and severe intestinal side effects. In this study, silica-installed ROS scavenging nanoparticles (siRNP) with 50-60 nm in diameter were employed to overcome the aforementioned drawbacks of CPT. The solubility of CPT was significantly improved by incorporating it into the core of the nanoparticle, forming CPT-loaded siRNP (CPT@siRNP). The anticancer activity of CPT@siRNP against colorectal cancer cells (C-26) in vitro was significantly improved as compared to free CPT through higher efficiency of intracellular internalization and induction of apoptosis. Owing to its antioxidant properties, CPT@siRNP reduced cytotoxicity to normal endothelial cells, which was in sharp contrast to the high toxicity of free CPT. Oral administration of CPT and CPT@siRNP to the C-26 tumor-bearing mice exhibited antitumor activity, accompanied by effective suppression of tumor growth. Although CPT treatment suppressed tumor progression, it caused severe side effects, including intestinal damage and significant bodyweight loss. Interestingly, such noticeable side effects were not observed in the mice treated with CPT@siRNP, and the effect of tumor growth inhibition tended to be similar to or higher than that of CPT treatment. The results obtained in this study indicate that CPT@siRNP is a potential therapeutic nanomedicine for the treatment of colon cancer. STATEMENT OF SIGNIFICANCE: Here we employed silica-containing antioxidant nanoparticle (siRNP) as promising oral delivery nanocarrier of campothecin (CPT) to treat colon cancer. The design of siRNP via covalent conjugation of antioxidant nitroxide radicals and the silanol groups in the polymer backbone contributes to a significant increase in the absorption of hydrophobic drug molecules inside the core and enhances the stability of nanoparticles in the gastrointestinal environment for oral drug delivery. CPT-loaded siRNP (CPT@siRNP) significantly improved solubility of CPT. As compared to free CTP, the CPT@siRNP treatment showed a significantly higher toxicity to colon cancer cell, inhibition of cancer cell migration, and induction of apopotosis. With the antioxidant feature, siRNP also significantly suppressed the intestinal side effects caused by CPT treatment in tumor-bearing mouse model.

Sorafenib-loaded silica-containing redox nanoparticles for oral anti-liver fibrosis therapy

Liver fibrosis is a chronic disease resulting from repetitive or prolonged liver injury with limited treatment options. Sorafenib has been reported to be a potential antifibrotic agent; however, its therapeutic effect is restricted because of its low bioavailability and severe adverse effects in the gastrointestinal (GI) tract. In this study, we developed sorafenib-loaded silica-containing redox nanoparticles (sora@siRNP) as an oral nanomedicine to treat liver fibrosis. The designed siRNP were prepared by self-assembly of amphiphilic block copolymers, which possess antioxidant nitroxide radicals as a side chain of the hydrophobic segment and porous silica particles in the nanoparticle core. The silica moieties in the core formed a crosslink between the self-assembling block copolymers to afford stable drug absorption, which could be useful in harsh GI conditions after oral drug administration. Based on in vitro evaluation, sora@siRNP exerted antiproliferative and antifibrotic effects against hepatic stellate cells (HSCs) and low toxicity against normal endothelial cells. A pharmacokinetic study showed that siRNP significantly improved the bioavailability and distribution of sorafenib in the liver. In an in vivo study using a mouse model of CCl₄-induced liver fibrosis, oral administration of sora@siRNP significantly suppressed the fibrotic area in comparison to free sorafenib administration. In mice with CCl₄-induced fibrosis, free sorafenib administration did not suppress the expression of α-smooth muscle actin; however, mice treated with sora@siRNP showed significantly suppressed expression of α-smooth muscle actin, indicating the inhibition of HSC activation, which was confirmed by in vitro experiments. Moreover, oral administration of free sorafenib induced severe intestinal damage and increased leakage into the gut, which can be attributed to the generation of reactive oxygen species (ROS). Our antioxidant nanocarriers, siRNP, reduced the adverse effects of local ROS scavenging in the GI tract. Our results suggest that sora@siRNP could serve as a promising oral nanomedicine for liver fibrosis.

Retraction Note to: Coffee component hydroxyl hydroquinone (HHQ) as a putative ligand for PPAR gamma and implications in breast cancer

This article has been retracted. Please see the Retraction Notice for more detail:

Self-Assembling Antioxidants for Ischemia-Reperfusion Injuries

Significance: Ischemia-reperfusion (IR) injury is a major component of severe damage in vascular occlusion during stroke, myocardial infarction, surgery, and organ transplantation, and is exacerbated by the excessive generation of reactive oxygen species (ROS), which occurs particularly during reperfusion. With the aging of the population, IR injury is becoming a serious problem in various organs, such as the kidney, brain, and heart, as well as in the mesenteric capillaries. Recent Advances: To prevent reperfusion injuries, natural and synthetic low-molecular-weight (LMW) antioxidants have been well studied. Critical Issues: However, these LMW antioxidants have various problems, including adverse effects due to excessive cellular uptake and their rapid clearance by the kidney, and cannot fully exert their potent antioxidant capacity in vivo. Future Directions: To overcome these problems, we designed and developed redox polymers with antioxidants covalently conjugated with them. These polymers self-assemble into nanoparticles in aqueous media, referred to as redox nanoparticles (RNPs). RNPs suppress their uptake into normal cells, accumulate at inflammation sites, and effectively scavenge ROS in damaged tissues. We had developed two types of RNPs: RNP^N, which disintegrates in response to acidic pH; and RNP^O, which does not collapse, regardless of the environmental pH. Utilizing the pH-sensitive and -insensitive characteristics of RNP^N and RNP^O, respectively, RNPs were found to exhibit remarkable therapeutic effects on various oxidative stress disorders, including IR injuries. Thus, RNPs are promising nanomedicines for use as next-generation antioxidants. This review summarizes the therapeutic impacts of RNPs in the treatment of kidney, cerebral, myocardial, and intestinal IR injuries. Antioxid. Redox Signal. 36, 70-80.

Design of enzyme-responsive short-chain fatty acid-based self-assembling drug for alleviation of type 2 diabetes mellitus

Short-chain fatty acids (SCFAs), such as propionic and butyric acids have been touted as potential therapeutic interventions that can ameliorate diabetic pathogenesis. However, SCFAs are low-molecular-weight (LMW) compounds that have limited clinical use due to unfavorable pharmacokinetics, off-target effects, poor palatability and unpleasant odor. Hence, to improve the therapeutic utilization of SCFAs, the enzyme metabolizable block copolymers, [poly(ethylene glycol)-b-poly(vinyl ester)s], possessing propionate and butyrate esters were synthesized, which formed stable nanoparticles by self-assembling under physiological conditions. In this study, the therapeutic efficacy of propionic acid- and butyric acid-based self-assembling nanoparticles (PNP/BNP) was evaluated in a mouse model of type 2 diabetes mellitus through ad libitum drinking. The conventional antidiabetic drug, exenatide- and BNP-treated mice showed the highest glucose tolerance, whereas LMW SCFAs remained ineffective in normalizing glucose homeostasis. The better efficacy of BNP over the LMW SCFAs was attributable to (i) higher consumption of BNP than the LMW SCFAs by the mice (good palatability and odorless), (ii) prolonged residence time of BNP (48 h) in the gastro-intestinal tract (muco-adhesion) contributing to intestinal enzyme-mediated sustained release of butyric acid, and (iii) negligible off-target effects (no abrupt rise in the bloodstream). The aforementioned data suggest that SCFA-based nanoparticles are more potential therapeutic interventions than LMW SCFAs for metabolic diseases such as diabetes.

Antioxidant Nanomedicine Significantly Enhances the Survival Benefit of Radiation Cancer Therapy by Mitigating Oxidative Stress-Induced Side Effects

Oxidative stress-induced off-target effects limit the therapeutic window of radiation therapy. Although many antioxidants have been evaluated as radioprotective agents, none of them are in widespread clinical use, owing to the side effects of the antioxidants themselves and the lack of apparent benefit. Aiming for a truly effective radioprotective agent in radiation cancer therapy, the performance of a self-assembling antioxidant nanoparticle (herein denoted as redox nanoparticle; RNP) is evaluated in the local irradiation of a subcutaneous tumor-bearing mouse model. Since RNP is covered with a biocompatible shell layer and possesses a core-shell type structure of several tens of nanometers in size, its lifetime in the systemic circulation is prolonged. Moreover, since 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), one of the most potent antioxidants, is covalently encapsulated in the core of RNP, it exerts intense antioxidant activity and induces fewer adverse effects by avoiding leakage of the TEMPO molecules. Preadministration of RNP to the mouse model effectively mitigates side effects in normal tissues and significantly extends the survival benefit of radiation cancer therapy. Moreover, RNP pretreatment noticeably increases the apoptosis/necrosis ratio of radiation-induced cell death, a highly desirable property to reduce the chronic side effects of ionizing irradiation.

An Antioxidant Nanoparticle Enhances Exercise Performance in Rat High-intensity Running Models

Although the adverse effects of excessively generated reactive oxygen species (ROS) on the body during aerobic exercise have been debated, there are few reports on the remarkable effects of the application of conventional antioxidants on exercise performance. The conventional antioxidants could not enhance exercise performance due to their rapid excretion from the body and serious adverse effects on the cellular respiratory system. In this study, impact of the original antioxidant self-assembling nanoparticle, redox-active nanoparticle (RNP), is investigated on the exercise performance of rats during running experiments. With an increase in the dose of the administered RNP, the all-out time of the rat running extends in a dose-dependent manner. In contrast, with an increase in the dose of the low-molecular-weight (LMW) antioxidant, the all-out running time of the rats decreases. The control group and LMW antioxidant treated group decrease in the number of red blood cells (RBCs) and increase oxidative stress after running. However, the RNP group maintains a similar RBC level and oxidative stress as that of the sedentary group. The results suggest that RNP, which shows long-blood circulation without disturbance of mitohormesis, effectively removes ROS from the bloodstream to suppresses RBC oxidative stress and damage, thus improving exercise performance.

Newly Developed Self-Assembling Antioxidants as Potential Therapeutics for the Cancers

Elevated reactive oxygen species (ROS) have been implicated as significant for cancer survival by functioning as oncogene activators and secondary messengers. Hence, the attenuation of ROS-signaling pathways in cancer by antioxidants seems a suitable therapeutic regime for targeting cancers. Low molecular weight (LMW) antioxidants such as 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO), although they are catalytically effective in vitro, exerts off-target effects in vivo due to their size, thus, limiting their clinical use. Here, we discuss the superior impacts of our TEMPO radical-conjugated self-assembling antioxidant nanoparticle (RNP) compared to the LMW counterpart in terms of pharmacokinetics, therapeutic effect, and adverse effects in various cancer models.

Molecular design of a high-performance polymeric carrier for delivery of a variety of boronic acid-containing drugs

Because of their many useful and unique properties, boronic acids are well suited for biomedical applications such as antitumor chemotherapy and boron neutron capture therapy (BNCT). Bortezomib, a boronic acid derivative, has drawn a lot of attention as a potent proteasome inhibitor. Nevertheless, because of rapid excretion and off-target effects, the clinical translation of boronic acid-containing drugs is limited. To this end, we employed a polymeric carrier to stably encapsulate boronic acid-containing drugs and achieve superior pharmacokinetics with an on-target drug release capability. Accordingly, to construct a supramolecular polymeric nanoparticle, we took advantage of the facile, stable, and pH-sensitive conjugation between boronic acids and diethanolamine-installed polymeric carriers. We demonstrated the feasibility of our molecular design by generating and applying bortezomib-loaded nanoparticles to a subcutaneous tumor-bearing mouse model. Stable encapsulation and pH-sensitive release of bortezomib facilitated antitumor efficacy and alleviated hepatotoxicity. We also verified the versatility of our approach through biological evaluations of the nanoparticles encapsulating benzo(b)thiophene-2-boronic acid, phenylboronic acid, and p-phenylene-diboronic acid.

Non-isotope enriched phenylboronic acid-decorated dual-functional nano-assembles for an actively targeting BNCT drug

The feasibility of boron neutron capture therapy (BNCT) greatly depends on the selective accumulation of ¹⁰B in tumors. The p-boronophenylalanine-fructose (BPA-f) complex has been established as a conventional BNCT agent due to its preferential uptake into tumors, which is driven by amino acid transporters. However, the retention of BPA-f in tumors is highly limited because of an antiport mechanism, which is regulated by a gradient of amino acid concentration across the cancer cell membrane. Thus, to preserve a high ¹⁰B concentration in tumors, patients are inevitably subjected to a constant intravenous infusion. To this end, we employed a phenylboronic acid (PBA)-decorated polymeric nanoparticle (Nano^PBA) as a sialic acid-targeting BNCT agent. In this manner, the PBA can exhibit dual functionalities, i.e., exhibiting a neutron capture capacity and hypersialyated cancer cell targeting effect. Our developed Nano^PBA possesses a supramolecular structure composed of a core and shell comprised of poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) segments, respectively. The PBA moiety is installed at the PEG end, providing an unusually strong targeting effect, supposedly via multivalent binding onto the cancer cell membrane. As in BNCT, we verified the feasibility of Nano^PBA against a B16 melanoma-bearing mouse model. By virtue of efficient tumor targeting, even at a 100-fold lower dose than BPA-f, the Nano^PBA achieved a potent antitumor effect.

Improving silymarin oral bioavailability using silica-installed redox nanoparticle to suppress inflammatory bowel disease

Chronic inflammatory diseases such as inflammatory bowel diseases (IBD), which are strongly related to the overproduction of reactive oxygen species (ROS), have become more threatening to health. Silymarin is an active compound with the effect of expressing anti-inflammatory activity; however, it exhibits poor bioavailability due to the rapid metabolism and secretion, low permeability across the intestinal epithelial cells, and poor water solubility. In this study, we developed silica-containing redox nanoparticles (siRNP) with 50-60 nm in diameter to improve the bioavailability of silymarin by improving its uptake into the bloodstream and delivery to the targeted tissues of the colon. Silymarin-loaded siRNP (SM@siRNP) significantly increased the antioxidant capacity and anti-inflammatory efficacy in vitro by scavenging 2,2-diphenyl-1-picrylhydrazyl free radical and suppressing nitric oxide and pro-inflammatory cytokines as compared to the other treatments such as free silymarin, siRNP, and silymarin-loaded si-nRNP (the control nanoparticle without ROS scavenging property). Orally administered SM@siRNP significantly improved the bioavailability of silymarin and its retention in the colonic mucosa. The anti-inflammatory effects of SM@siRNP were also investigated in dextran sodium sulfate (DSS)-induced colitis in mice and it was observed that SM@siRNP treatment significantly improved the damage in the colonic mucosa of DSS colitis mice as compared to the other treatments. The results in this study indicate that SM@siRNP is a promising nanomedicine for enhancing the anti-inflammatory activity of silymarin and has a high potential for the treatment of IBD.

Nitric Oxide Nano-Delivery Systems for Cancer Therapeutics: Advances and Challenges

Nitric oxide (NO) plays important roles in various physiological and pathological functions and processes in the human body. Therapeutic application of NO molecules has been investigated in various diseases, including cardiovascular disease, cancer, and infections. However, the extremely short half-life of NO, which limits its clinical use considerably, along with non-specific distribution, has resulted in a low therapeutic index and undesired adverse effects. To overcome the drawbacks of using this gaseous signaling molecule, researchers in the last several decades have focused on innovative medical technologies, specifically nanoparticle-based drug delivery systems (DDSs), because these systems alter the biodistribution of the therapeutic agent through controlled release at the target tissues, resulting in a significant therapeutic drug effect. Thus, the application of nano-systems for NO delivery in the field of biomedicine, particularly in the development of new drugs for cancer treatment, has been increasing worldwide. In this review, we discuss NO delivery nanoparticle systems, with the aim of improving drug delivery development for conventional chemotherapies and controlling multidrug resistance in cancer treatments.

Fibrinolytic tissue plasminogen activator installed redox-active nanoparticles (t-PA@iRNP) for cancer therapy

Favorable blood flow within solid tumors has become the principal strategy for drug delivery. The use of thrombolytic drugs, such as tissue plasminogen activator (t-PA), in combination with other drugs or drug carriers may increase their therapeutic effect by increasing drug delivery near the solid tumor through fibrin degradation and blood flow restoration. We, therefore, designed t-PA-installed redox-active nanoparticles (t-PA@iRNP) to improve the perfusion of antioxidant nanoparticles in tumors, via fibrin degradation to decompress tumor vessels. Additionally, antioxidant iRNP was developed for tumor inhibition by reduction of critically elevated levels of reactive oxygen species (ROS) in tumors. The t-PA@iRNP, when administered to a colon cancer model, degraded the deposited fibrin and improved the iRNP and immune cells penetration in tumor tissues via the restored blood flow, thus more effectively inhibited tumor growth. The anti-tumor effect of iRNP was attributed to ROS-reduction mediated downregulation of crucial a transcriptional factor, NF-κB. Conclusively, this study provides a new strategy to enhance the delivery of nanotherapeutics into solid tumors.

Antioxidant nanomedicine with cytoplasmic distribution in neuronal cells shows superior neurovascular protection properties

This study investigated whether nitroxide radical (4-amino-TEMPOL)-containing nanoparticles (RNPs; antioxidant nanomedicine) can prevent neurovascular unit impairment caused by reactive oxygen species (ROS) after cerebral ischemia-reperfusion. C57BL/6J mice underwent transient middle cerebral artery occlusion (tMCAO). The mice were randomly divided and administered intra-arterial RNPs injection (9 mg/kg, 7 μM/kg), edaravone (3 mg/kg, 17 μM/kg), or phosphate-buffered saline (control group). Survival rate and neurological score were evaluated 24 h post-injection. RNPs distribution was determined using immunofluorescence staining and blood-brain barrier (BBB) disruption using Evans blue extravasation assay. Effect of RNPs and edaravone on microglia polarization into microglia M1 and M2 was evaluated. We also determined multiple ROS-scavenging activities in brain homogenates of RNPs- and edaravone-treated animals using an electron spin resonance-based spin-trapping method. Compared with edaravone, RNPs significantly improved the survival rate and neurological deficit, inhibited BBB disruption and supported polarization of microglia into M2 microglia. RNPs were localized in endothelial cells, the perivascular space, neuronal cell cytoplasm, astrocytes, and microglia. Scavenging capacities of hydroxyl, alkoxyl, and peroxyl radicals were significantly higher in the RNPs-treated group. RNPs show promising results as a future neuroprotective nanomedicine approach for cerebral ischemia-reperfusion injury.

Enhancing Boron Uptake in Brain Glioma by a Boron-Polymer/Microbubble Complex with Focused Ultrasound

Boron neutron capture therapy (BNCT) is a promising radiotherapy for treating glioblastoma multiforme (GBM). However, the penetration of drugs (e.g., sodium borocaptate and BSH) for BNCT into brain tumors is limited by cerebral vesicular protective structures, the blood-brain barrier, and the blood-brain tumor barrier (BTB). Although BSH has been reported to be selectively taken up by tumors, it is rapidly excreted from the body and cannot achieve a high tumor-to-normal brain ratio (T/N ratio) and tumor-to-blood ratio (T/B ratio). Despite the development of large-molecular weight boron compounds, such as polymers and nanoparticles, to enhance the permeation and retention effect, their effects remain insufficient for clinical use. To improve the efficiency of boron delivery to the tumor site, we propose combinations of self-assembled boron-containing polyanion [polyethylene glycol- b-poly(( closo-dodecaboranyl)thiomethylstyrene) (PEG- b-PMBSH)] nanoparticles (295 ± 2.3 nm in aqueous media) coupled with cationic microbubble (B-MB)-assisted focused ultrasound (FUS) treatment. Upon FUS sonication (frequency = 1 MHz, pressure = 0.3-0.7 MPa, duty cycle = 0.5%, sonication = 1 min), B-MBs can simultaneously achieve safe BTB opening and boron drug delivery into tumor tissue. Compared with the MBs of the PEG- b-PMBSH mixture group (B + MBs), B-MBs showed 3- and 2.3-fold improvements in the T/N (4.4 ± 1.4 vs 1.3 ± 0.1) and T/B ratios (1.4 ± 0.6 vs 0.1 ± 0.1), respectively, after 4 min of FUS sonication. The spatial distribution of PEG- b-PMBSH was also improved by the complex of PEG- b-PMBSH with MBs. The findings presented herein, in combination with the expanding clinical application of FUS, may improve BNCT and treatment of GBM.

[Design of New Cancer Nanotherapeutics Which Controls Active Gaseous Molecules in Vivo]

　Reactive oxygen species (ROS) are known to play a variety of roles in many important events in vivo. However, the overproduction of ROS causes serious adverse effects to living beings. Numerous drugs have been developed and applied to reduce overproduced ROS, but these have failed to be clinically approved. Since most of these antioxidants are low molecular weight (LMW) compounds, they not only eliminate ROS related to diseases, but also destroy the essential redox reactions necessary for basic energy production in living bodies. In the mitochondria of normal cells, ATP production by electron transport chain is carried out, and a large amount of ROS is thus generated; however, LMW antioxidants also nonspecifically enter normal cells and affect essential oxidation. To improve selective antioxidant properties without damage to these normal redox reactions, we designed new polymer antioxidants. These polymers have self-assembling properties and form nanoparticles (RNPs) in which nitroxide radicals covalently attach as a side chain of the hydrophobic segment in the amphiphilic block copolymers, which are then compartmentalized into the solid core of the nanoparticles. Unlike LMW antioxidants, RNPs have extremely poor in vivo toxicity, as they are less likely to be taken up by healthy cells. Since one of RNPs, RNP^N has pH-sensitive disintegration properties, it disintegrates at pH lower than 7.0 such as solid tumors and inflammation. It can therefore be used in pH responsive bioimaging and therapy. We have used RNPs experimentally in the treatment of several diseases and confirmed their effectiveness.

Protection of Coral Larvae from Thermally Induced Oxidative Stress by Redox Nanoparticles

Coral reefs are one of the most biologically diverse and economically important ecosystems on earth. However, the destruction of coral reefs has been reported worldwide owing to rising seawater temperature associated with global warming. In this study, we investigated the potential of a redox nanoparticle (RNP^O) to scavenge reactive oxygen species (ROS), which are overproduced under heat stress and play a crucial role in causing coral mortality. When reef-building coral (Acropora tenuis) larvae, without algal symbionts, were exposed to thermal stress at 33 °C, RNP^O treatment significantly increased the survival rate. Proteome analysis of coral larvae was performed using nano-liquid chromatography-tandem mass spectrometry for the first time. The results revealed that several proteins related to ROS-induced oxidative stress were specifically identified in A. tenuis larvae without RNP^O treatment, whereas these proteins were absent in RNP^O-treated larvae, which suggested that RNP^O effectively scavenged ROS from A. tenuis larvae. Results from this study indicate that RNP^O treatment can reduce ROS in aposymbiotic coral larvae and would be a promising approach for protecting corals from thermal stress.

Nitroxide radical-containing nanoparticles attenuate tumorigenic potential of triple negative breast cancer

The critical importance of reactive oxygen species (ROS) as oncogene activators and essential secondary messengers in cancer cell survival have been widely reported. Since oxidative stress has been implicated as being pivotal in various cancers, antioxidant therapy seems an apt strategy to abrogate ROS-mediated cellular processes to attenuate cancers. We therefore synthesized ROS scavenging nitroxide radical-containing nanoparticles (RNPs); pH insensitive RNP^O and pH sensitive RNP^N, to impede the proliferative and metastatic characteristics of the triple negative breast cancer cell line, MDA-MB-231, both in vitro and in vivo. RNPs significantly curtailed the proliferative and clonogenic potential of MDA-MB-231 and MCF-7 cell lines. Inhibition of ROS-mediated migratory and invasive characteristics of MDA-MB-231, via down regulation of NF-κB and MMP-2, was also confirmed. Furthermore, a significant anti-tumor and anti-metastatic potential of RNPs was observed in an MDA-MB-231 mouse xenograft model. Such tumoricidal effects of RNPs were attained with negligible adverse effects, compared to conventional low molecular weight antioxidants, TEMPOL. Thus, the tumoricidal effects of RNPs are suggestive of insights on precedence of nanoparticle-based therapeutics over current low molecular weight antioxidants to curtail ROS-induced tumorigenesis of various cancers.

Antioxidative biointerface: biocompatible materials scavenging reactive oxygen species

Oxidative stress caused by reactive oxygen species (ROS) occurs as events in which living tissues contact certain materials. These events include cell cultures and implantation of materials. Because of the high reactivity of ROS, they damage cells by oxidizing DNA, lipids, and proteins. Conversely, ROS also act as signaling molecules regulating cellular morphology. In particular, mitochondrial ROS are involved in the regulation of cellular physiology, including differentiation, autophagy, metabolic adaptation, apoptosis, and immunity. The balance between generation and elimination of ROS is essential for signaling pathways and proper cell function, and redox imbalance leads to cellular dysfunction and disturbs cellular homeostasis. To reduce oxidative stress, versatile antioxidants, including natural compounds, have been used; however, their poor bioavailability and pro-oxidant effects have limited the versatility of these antioxidants. Recent developments of antioxidative biointerfaces may represent a potent solution to this issue. Designed biointerfaces composed of polymer antioxidants eliminate excessive ROS at the interface between living tissues and materials, and do not disturb regulated redox balance inside cells, thus eliminating unexpected cell responses, such as inflammation and dysfunction.

Prevention of UV-Induced Melanin Production by Accumulation of Redox Nanoparticles in the Epidermal Layer via Iontophoresis

UV rays induce melanin production in the skin, which, from a cosmetic point of view, is problematic. Reactive oxygen species (ROS) generated in the skin upon UV irradiation are thought to be responsible for melanin production. Thus, effective antioxidants are recognized as useful tools for prevention of UV-induced melanin production. Redox nanoparticles (RNPs) containing nitroxide radicals as free radical scavengers were previously developed, and shown to be effective ROS scavengers in the body. RNPs are therefore expected to be useful for effective protection against UV-induced melanin production. However, as the sizes of RNPs are typically larger than the intercellular spaces of the skin, transdermal penetration is difficult. We recently demonstrated effective transdermal delivery and accumulation of nanoparticles in the epidermal layer via faint electric treatment, i.e., iontophoresis, suggesting that iontophoresis of RNPs may be a useful strategy for prevention of UV-induced melanin production in the skin. Herein, we performed iontophoresis of RNPs on the dorsal skin of hairless mice that produce melanin in response to light exposure. RNPs accumulated in the epidermal layer upon application of iontophoresis. Further, the combination of RNPs with iontophoresis decreased UV-induced melanin spots and melanin content in the skin. Taken together, we successfully demonstrated that iontophoresis-mediated accumulation of RNPs in the epidermis prevented melanin production.

Abstract WMP119: Neurovascular Unit Protection Using Nitroxide Radicals-containing Nanoparticles (TEMPO-RNP) for Cerebral Ischemia-reperfusion Injury in Mice

Purpose: Reperfusion injury after thrombolytic therapy or mechanical thrombectomy would adverse neurological outcome. Generation of reactive oxygen species (ROS) due to reperfusion is relevant for aggravation. The development of drug therapy for scavenging free radical is expected to lead to better neurological prognosis. We developed a new core-shell type nanoparticle, RNP (radical containing nanoparticle), which consists of micelle containing 4-amino-TEMPO. The purpose of this study is to evaluate an efficacy of intra-arterial injection of RNP after reperfusion using tMCAO mice model.

Methods: C57BL/6J mice underwent tMCAO for 60 minutes and received RNP by intra-arterial injection from common carotid artery. We evaluated infarction size, neurological scale, and Evans blue extravasation at 24h after reperfusion. RNP distribution was detected by rhodamine labeling. We further examined immunofluorescense of CD31, Occludin, TUNEL, dihydroethydium, and 8-hydroxy-deoxyguanosine (8-OHdG). Multiple free radical scavenging capacity of ischemic hemisphere was analyzed by Electron Paramagnetic Resonance (EPR).

Results: RNPs were detected in endothelial cells and around neuronal cells in the ischemic lesion. The infarction size, neurological scale, Evans blue extravasation of the mice treated by RNP were significantly lower than the mice treated by PBS , control group. Intra-arterial RNP treatment preserved endothelium and expression of occludin in the ischemic brain. Further, apoptosis of neuronal cells and production of superoxide anions and 8OHdG were suppressed. By using EPR, multiple ROS scavenging capacity (•OH, •ROO, •O 2 - ) of the ischemic brain treated by RNP were higher.

Conclusions: These results suggest that intra-arterial injection of RNP have efficacy of neurovascular unit protection and reduce infarction volume by improving multiple ROS scavenging capacity.

Newly Designed Silica-Containing Redox Nanoparticles for Oral Delivery of Novel TOP2 Catalytic Inhibitor for Treating Colon Cancer

Although oral drug delivery is the most common route of drug administration, the conventional polymeric nanocarriers exhibit a low drug loading capacity and low stability in the gastrointestinal (GI) environments. In this study, a newly designed silica-containing redox nanoparticle (siRNP) with reactive oxygen species (ROS) scavenging capacity is developed as an ideal oral nanocarrier for a novel hydrophobic anticancer compound BNS-22 to treat colitis-associated colon cancer in vivo. Crosslinking of silica moieties significantly enhances the stability under acidic conditions and improves BNS-22 loading capacity of siRNP compared to the conventional redox nanoparticle. After oral administration to mice, BNS-22-loaded siRNP (BNS-22@siRNP) remarkably improves bioavailability and colonic tumor distribution of BNS-22. As the result, BNS-22@siRNP significantly inhibits the tumor progression in colitis-associated colon cancer mice compared to other control treatments. It is noteworthy that no systemic absorption of siRNP carrier is observed after oral administration. Interestingly, orally administered BNS-22@siRNP significantly suppresses the adverse effects of BNS-22 owing to its ROS scavenging capacity, and no other noticeable toxicities are observed in mice treated with BNS-22@siRNP although siRNP is localized in the GI tract. Our results indicate that siRNP is a promising oral drug nanocarrier for cancer therapy.

Development of a local anesthetic lidocaine-loaded redox-active injectable gel for postoperative pain management

Although local anesthesia is commonly applied for pain relief, there are several issues such as its short duration of action and low effectiveness at the areas of inflammation due to the acidic pH. The presence of excessive amount of reactive oxygen species (ROS) is known to induce inflammation and aggravate pain. To resolve these issues, we developed a redox-active injectable gel (RIG) with ROS-scavenging activity. RIG was prepared by mixing polyamine-b-poly(ethylene glycol)-b-polyamine with nitroxide radical moieties as side chains on the polyamine segments (PMNT-b-PEG-b-PMNT) with a polyanion, which formed a flower-type micelle via electrostatic complexation. Lidocaine could be stably incorporated in its core. When the temperature of the solution was increased to 37°C, the PIC-type flower micelle transformed to gel. The continuous release of lidocaine from the gel was observed for more than three days, without remarkable initial burst, which is probably owing to the stable entrapment of lidocaine in the PIC core of the gel. We evaluated the analgesic effect of RIG in carrageenan-induced arthritis mouse model. Results showed that lidocaine-loaded RIG has stronger and longer analgesic effect when administered in inflamed areas. In contrast, while the use of non-complexed lidocaine did not show analgesic effect one day after its administration. Note that no effect was observed when PIC-type flower micelle without ROS-scavenging ability was used. These findings suggest that local anesthetic-loaded RIG can effectively reduce the number of injection times and limit the side effects associated with the use of anti-inflammatory drugs for postoperative pain management.

STATEMENT OF SIGNIFICANCE

1. We have been working on nanomaterials, which effectively eliminate ROS, avoiding dysfunction of mitochondria in healthy cells. 2. We designed redox injectable gel using polyion complexed flower type micelle, which can eliminates ROS locally. 3. We could prepare local anesthesia-loaded redox injectable gel (lido@RIG). 4. Drug release could be extended by local administration of lido@RIG. 5. Deprotonation of lidocaine improved anesthetic effect because ROS were eliminated locally by RIG. 6. Local inflammation could be also suppressed by lido@RIG.

Neurovascular Unit Protection From Cerebral Ischemia-Reperfusion Injury by Radical-Containing Nanoparticles in Mice

BACKGROUND AND PURPOSE

Reperfusion therapy by mechanical thrombectomy is used to treat acute ischemic stroke. However, reactive oxygen species generation after reperfusion therapy causes cerebral ischemia-reperfusion injury, which aggravates cerebral infarction. There is limited evidence for clinical efficacy in stroke for antioxidants. Here, we developed a novel core-shell type nanoparticle containing 4-amino-4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (nitroxide radical-containing nanoparticles [RNPs]) and investigated its ability to scavenge reactive oxygen species and confer neuroprotection.

METHODS

C57BL/6J mice underwent transient middle cerebral artery occlusion and then received RNPs (9 mg/kg) through the common carotid artery. Infarction size, neurological scale, and blood-brain barrier damage were visualized by Evans blue extravasation 24 hours after reperfusion. RNP distribution was detected by rhodamine labeling. Blood-brain barrier damage, neuronal apoptosis, and oxidative neuronal cell damage were evaluated in ischemic brains. Multiple free radical-scavenging capacities were analyzed by an electron paramagnetic resonance-based method.

RESULTS

RNPs were detected in endothelial cells and around neuronal cells in the ischemic lesion. Infarction size, neurological scale, and Evans blue extravasation were significantly lower after RNP treatment. RNP treatment preserved the endothelium and endothelial tight junctions in the ischemic brain; neuronal apoptosis, O₂^- production, and gene oxidation were significantly suppressed. Reactive oxygen species scavenging capacities against OH, ROO, and O₂^- improved by RNP treatment.

CONCLUSIONS

An intra-arterial RNP injection after cerebral ischemia-reperfusion injury reduced blood-brain barrier damage and infarction volume by improving multiple reactive oxygen species scavenging capacities. Therefore, RNPs can provide neurovascular unit protection.

Chronic treatment with a smart antioxidative nanoparticle for inhibition of amyloid plaque propagation in Tg2576 mouse model of Alzheimer's disease

The present study aimed to assess whether our newly developed redox nanoparticle (RNP^N) that has antioxidant potential decreases Aβ levels or prevents Aβ aggregation associated with oxidative stress. The transgenic Tg2576 Alzheimer’s disease (AD) mice were used to investigate the effect of chronic ad libitum drinking of RNP^N solution for 6 months, including memory and learning functions, antioxidant activity, and amyloid plaque aggregation. The results showed that RNP^N-treated mice had significantly attenuated cognitive deficits of both spatial and non-spatial memories, reduced oxidative stress of lipid peroxide, and DNA oxidation. RNP^N treatment increased the percent inhibition of superoxide anion and glutathione peroxidase activity, neuronal densities in the cortex and hippocampus, decreased Aβ(1-40), Aβ(1-42) and gamma (γ)-secretase levels, and reduced Aβ plaque observed using immunohistochemistry analysis and thioflavin S staining. Our results suggest that RNP^N may be a promising candidate for AD therapy because of its antioxidant properties and reduction in Aβ aggregation, thereby suppressing its adverse side effect.

Development of Gd3N@C80 encapsulated redox nanoparticles for high-performance magnetic resonance imaging

As novel magnetic resonance imaging (MRI) contrast agent, gadofullerene encapsulated redox nanoparticles (Gd₃NPs) were prepared by encapsulation of Gd₃N@C₈₀ in the core of core-shell-type polymer micelles composed of original polyamine with a reactive oxygen species (ROS)-scavenging ability. Because Gd₃NPs possess biocompatible PEG shell with a smaller size (ca. 50 nm), they had high colloidal stability in a physiological environment, and showed low cytotoxicity. Specific accumulation of Gd₃NPs in a tumor was confirmed in tumor-bearing mice after systemic administration. The tumor/muscle (T/M) ratio of the Gd ion reached five at 7.5 h after the administration. T₁-weighted MRI signal enhancement of the T/M ratio increased by 8% at 6 h postinjection of Gd₃NPs (Gd dose:14.35 μmol/kg). Although Gd₃NPs showed a tendency for extended blood circulation, they did not have severe adverse effects, probably due to the confinement of Gd in a hydrophobic fullerene in addition to the ROS-scavenging capacity of these nanoparticles. In sharp contrast, systemic administration of Gd-chelate nanoparticles (GdCNPs) to mice disrupts liver function, increases leukocyte counts, and destroys spleen and skin tissues. Leaking of Gd ions from GdCNPs may cause such adverse effects. Based on these results, we expect that Gd₃NPs is high-performance MRI contrast agents for tumor diagnosis.