Inhibition of autophagy protects against PAMAM dendrimers-induced hepatotoxicity

Advances in Polymeric Nanomaterial-mediated Autophagy for Cancer Therapy

Autophagy is an important biological mechanism for eukaryotic cells to regulate growth, death, and energy metabolism, and plays an important role in removing damaged organelles, misfolded or aggregated proteins, and clearing pathogens. It has been found that autophagy is closely related to cell survival and death, and is of great significance in cancerigenesis and development, playing a bidirectional role in cancer inhibition and cancer promotion. Therefore, treating cancers by regulating autophagy has attracted much attention. A large amount of research evidence indicates that polymeric nanomaterials are able to regulate cellular autophagy, and their good biocompatibility, degradability, and functionalizable modification open up a broad application prospect for improving the therapeutic effect of cancers. This review provides an overview of the research progress of polymeric nanomaterials for modulating autophagy in the treatment of cancers.

All Roads Lead to Rome: Comparing Nanoparticle- and Small Molecule-Driven Cell Autophagy

Autophagy, vital for removing cellular waste, is triggered differently by small molecules and nanoparticles. Small molecules, like rapamycin, non-selectively activate autophagy by inhibiting the mTOR pathway, which is essential for cell regulation. This can clear damaged components but may cause cytotoxicity with prolonged use. Nanoparticles, however, induce autophagy, often causing oxidative stress, through broader cellular interactions and can lead to a targeted form known as "xenophagy." Their impact varies with their properties but can be harnessed therapeutically. In this review, the autophagy induced by nanoparticles is explored and small molecules across four dimensions: the mechanisms behind autophagy induction, the outcomes of such induction, the toxicological effects on cellular autophagy, and the therapeutic potential of employing autophagy triggered by nanoparticles or small molecules. Although small molecules and nanoparticles each induce autophagy through different pathways and lead to diverse effects, both represent invaluable tools in cell biology, nanomedicine, and drug discovery, offering unique insights and therapeutic opportunities.

DNA-Based Nonviral Gene Therapy─Challenging but Promising

Over the past decades, significant progress has been made in utilizing nucleic acids, including DNA and RNA molecules, for therapeutic purposes. For DNA molecules, although various DNA delivery systems have been established, viral vector systems are the go-to choice for large-scale commercial applications. However, viral systems have certain disadvantages such as immune response, limited payload capacity, insertional mutagenesis and pre-existing immunity. In contrast, nonviral systems are less immunogenic, not size limited, safer, and easier for manufacturing compared with viral systems. What's more, nonviral DNA vectors have demonstrated their capacity to mediate specific protein expression in vivo for diverse therapeutic objectives containing a wide range of diseases such as cancer, rare diseases, neurodegenerative diseases, and infectious diseases, yielding promising therapeutic outcomes. However, exogenous plasmid DNA is prone to degrade and has poor immunogenicity in vivo. Thus, various strategies have been developed: (i) designing novel plasmids with special structures, (ii) optimizing plasmid sequences for higher expression, and (iii) developing more efficient nonviral DNA delivery systems. Based on these strategies, many interesting clinical results have been reported. This Review discusses the development of DNA-based nonviral gene therapy, including novel plasmids, nonviral delivery systems, clinical advances, and prospects. These developments hold great potential for enhancing the efficacy and safety of nonviral gene therapy and expanding its applications in the treatment of various diseases.

Autophagy regulation by inorganic, organic, and organic/inorganic hybrid nanoparticles: Organelle damage, regulation factors, and potential pathways

The rapid development of nanotechnology requires a more thorough understanding of the potential health effects caused by nanoparticles (NPs). As a programmed cell death, autophagy is one of the biological effects induced by NPs, which maintain intracellular homeostasis by degrading damaged organelles and removing aggregates of defective proteins through lysosomes. Currently, autophagy has been shown to be associated with the development of several diseases. A significant number of research have demonstrated that most NPs can regulate autophagy, and their regulation of autophagy is divided into induction and blockade. Studying the autophagy regulation by NPs will facilitate a more comprehensive understanding of the toxicity of NPs. In this review, we will illustrate the effects of different types of NPs on autophagy, including inorganic NPs, organic NPs, and organic/inorganic hybrid NPs. The potential mechanisms by which NPs regulate autophagy are highlighted, including organelle damage, oxidative stress, inducible factors, and multiple signaling pathways. In addition, we list the factors influencing NPs-regulated autophagy. This review may provide basic information for the safety assessment of NPs.

Lysosomal nanotoxicity: Impact of nanomedicines on lysosomal function

Although several nanomedicines got clinical approval over the past two decades, the clinical translation rate is relatively small so far. There are many post-surveillance withdrawals of nanomedicines caused by various safety issues. For successful clinical advancement of nanotechnology, it is of unmet need to realize cellular and molecular foundation of nanotoxicity. Current data suggest that lysosomal dysfunction caused by nanoparticles is emerging as the most common intracellular trigger of nanotoxicity. This review analyzes prospect mechanisms of lysosomal dysfunction-mediated toxicity induced by nanoparticles. We summarized and critically assessed adverse drug reactions of current clinically approved nanomedicines. Importantly, we show that physicochemical properties have great impact on nanoparticles interaction with cells, excretion route and kinetics, and subsequently on toxicity. We analyzed literature on adverse reactions of current nanomedicines and hypothesized that adverse reactions might be linked with lysosomal dysfunction caused by nanomedicines. Finally, from our analysis it becomes clear that it is unjustifiable to generalize safety and toxicity of nanoparticles, since different particles possess distinct toxicological properties. We propose that the biological mechanism of the disease progression and treatment should be central in the optimization of nanoparticle design.

Dendrimers and Derivatives as Multifunctional Nanotherapeutics for Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent form of dementia. It affects more than 30 million people worldwide and costs over US$ 1.3 trillion annually. AD is characterized by the brain accumulation of amyloid β peptide in fibrillar structures and the accumulation of hyperphosphorylated tau aggregates in neurons, both leading to toxicity and neuronal death. At present, there are only seven drugs approved for the treatment of AD, of which only two can slow down cognitive decline. Moreover, their use is only recommended for the early stages of AD, meaning that the major portion of AD patients still have no disease-modifying treatment options. Therefore, there is an urgent need to develop efficient therapies for AD. In this context, nanobiomaterials, and dendrimers in particular, offer the possibility of developing multifunctional and multitargeted therapies. Due to their intrinsic characteristics, dendrimers are first-in-class macromolecules for drug delivery. They have a globular, well-defined, and hyperbranched structure, controllable nanosize and multivalency, which allows them to act as efficient and versatile nanocarriers of different therapeutic molecules. In addition, different types of dendrimers display antioxidant, anti-inflammatory, anti-bacterial, anti-viral, anti-prion, and most importantly for the AD field, anti-amyloidogenic properties. Therefore, dendrimers can not only be excellent nanocarriers, but also be used as drugs per se. Here, the outstanding properties of dendrimers and derivatives that make them excellent AD nanotherapeutics are reviewed and critically discussed. The biological properties of several dendritic structures (dendrimers, derivatives, and dendrimer-like polymers) that enable them to be used as drugs for AD treatment will be pointed out and the chemical and structural characteristics behind those properties will be analysed. The reported use of these nanomaterials as nanocarriers in AD preclinical research is also presented. Finally, future perspectives and challenges that need to be overcome to make their use in the clinic a reality are discussed.

Recent advances of nanotechnology in COVID 19: A critical review and future perspective

The global anxiety and economic crisis causes the deadly pandemic coronavirus disease of 2019 (COVID 19) affect millions of people right now. Subsequently, this life threatened viral disease is caused due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, morbidity and mortality of infected patients are due to cytokines storm syndrome associated with lung injury and multiorgan failure caused by COVID 19. Thereafter, several methodological advances have been approved by WHO and US-FDA for the detection, diagnosis and control of this wide spreadable communicable disease but still facing multi-challenges to control. Herein, we majorly emphasize the current trends and future perspectives of nano-medicinal based approaches for the delivery of anti-COVID 19 therapeutic moieties. Interestingly, Nanoparticles (NPs) loaded with drug molecules or vaccines resemble morphological features of SARS-CoV-2 in their size (60–140 nm) and shape (circular or spherical) that particularly mimics the virus facilitating strong interaction between them. Indeed, the delivery of anti-COVID 19 cargos via a nanoparticle such as Lipidic nanoparticles, Polymeric nanoparticles, Metallic nanoparticles, and Multi-functionalized nanoparticles to overcome the drawbacks of conventional approaches, specifying the site-specific targeting with reduced drug loading and toxicities, exhibit their immense potential. Additionally, nano-technological based drug delivery with their peculiar characteristics of having low immunogenicity, tunable drug release, multidrug delivery, higher selectivity and specificity, higher efficacy and tolerability switch on the novel pathway for the prevention and treatment of COVID 19.

Nano-drug delivery system for pancreatic cancer: A visualization and bibliometric analysis

Background: Nano drug delivery system (NDDS) can significantly improve the delivery and efficacy of drugs against pancreatic cancer (PC) in many ways. The purpose of this study is to explore the related research fields of NDDS for PC from the perspective of bibliometrics.

Methods: Articles and reviews on NDDS for PC published between 2003 and 2022 were obtained from the Web of Science Core Collection. CiteSpace, VOSviewer, R-bibliometrix, and Microsoft Excel were comprehensively used for bibliometric and visual analysis.

Results: A total of 1329 papers on NDDS for PC were included. The number of papers showed an upward trend over the past 20 years. The United States contributed the most papers, followed by China, and India. Also, the United States had the highest number of total citations and H-index. The institution with the most papers was Chinese Acad Sci, which was also the most important in international institutional cooperation. Professors Couvreur P and Kazuoka K made great achievements in this field. JOURNAL OF CONTROLLED RELEASE published the most papers and was cited the most. The topics related to the tumor microenvironment such as “tumor microenvironment”, “tumor penetration”, “hypoxia”, “exosome”, and “autophagy”, PC treatment-related topics such as “immunotherapy”, “combination therapy”, “alternating magnetic field/magnetic hyperthermia”, and “ultrasound”, and gene therapy dominated by “siRNA” and “miRNA” were the research hotspots in the field of NDDS for PC.

Conclusion: This study systematically uncovered a holistic picture of the performance of NDDS for PC-related literature over the past 20 years. We provided scholars to understand key information in this field with the perspective of bibliometrics, which we believe may greatly facilitate future research in this field.

Impact of Degree of Ionization and PEGylation on the Stability of Nanoparticles of Chitosan Derivatives at Physiological Conditions

Nowadays, the therapeutic efficiency of small interfering RNAs (siRNA) is still limited by the efficiency of gene therapy vectors capable of carrying them inside the target cells. In this study, siRNA nanocarriers based on low molecular weight chitosan grafted with increasing proportions (5 to 55%) of diisopropylethylamine (DIPEA) groups were developed, which allowed precise control of the degree of ionization of the polycations at pH 7.4. This approach made obtaining siRNA nanocarriers with small sizes (100–200 nm), positive surface charge and enhanced colloidal stability (up to 24 h) at physiological conditions of pH (7.4) and ionic strength (150 mmol L⁻¹) possible. Moreover, the PEGylation improved the stability of the nanoparticles, which maintained their colloidal stability and nanometric sizes even in an albumin-containing medium. The chitosan-derivatives displayed non-cytotoxic effects in both fibroblasts (NIH/3T3) and macrophages (RAW 264.7) at high N/P ratios and polymer concentrations (up to 0.5 g L⁻¹). Confocal microscopy showed a successful uptake of nanocarriers by RAW 264.7 macrophages and a promising ability to silence green fluorescent protein (GFP) in HeLa cells. These results were confirmed by a high level of tumor necrosis factor-α (TNFα) knockdown (higher than 60%) in LPS-stimulated macrophages treated with the siRNA-loaded nanoparticles even in the FBS-containing medium, findings that reveal a good correlation between the degree of ionization of the polycations and the physicochemical properties of nanocarriers. Overall, this study provides an approach to enhance siRNA condensation by chitosan-based carriers and highlights the potential of these nanocarriers for in vivo studies.

Safety Challenges and Application Strategies for the Use of Dendrimers in Medicine

Dendrimers are used for a variety of applications in medicine but, due to their host–guest and entrapment characteristics, are particularly used for the delivery of genes and drugs. However, dendrimers are intrinsically toxic, thus creating a major limitation for their use in biological systems. To reduce such toxicity, biocompatible dendrimers have been designed and synthesized, and surface engineering has been used to create advantageous changes at the periphery of dendrimers. Although dendrimers have been reviewed previously in the literature, there has yet to be a systematic and comprehensive review of the harmful effects of dendrimers. In this review, we describe the routes of dendrimer exposure and their distribution in vivo. Then, we discuss the toxicity of dendrimers at the organ, cellular, and sub-cellular levels. In this review, we also describe how technology can be used to reduce dendrimer toxicity, by changing their size and surface functionalization, how dendrimers can be combined with other materials to generate a composite formulation, and how dendrimers can be used for the diagnosis of disease. Finally, we discuss future challenges, developments, and research directions in developing biocompatible and safe dendrimers for medical purposes.

Emerging innate biological properties of nano-drug delivery systems: A focus on PAMAM dendrimers and their clinical potential

Drug delivery systems or vectors are usually needed to improve the bioavailability and effectiveness of a drug through improving its pharmacokinetics/pharmacodynamics at an organ, tissue or cellular level. However, emerging technologies with sensitive readouts as well as a greater understanding of physiological/biological systems have revealed that polymeric drug delivery systems are not biologically inert but can have innate or intrinsic biological actions. In this article, we review the emerging multiple innate biological/toxicological properties of naked polyamidoamine (PAMAM) dendrimer delivery systems in the absence of any drug cargo and discuss their correlation with the defined physicochemical properties of PAMAMs in terms of molecular size (generation), architecture, surface charge and chemistry. Further, we assess whether any of the reported intrinsic biological actions of PAMAMs such as their antimicrobial activity or their ability to sequester glucose and modulate key protein interactions or cell signaling pathways, can be exploited clinically such as in the treatment of diabetes and its complications.

Reversal Activity and Toxicity of Heparin-Binding Copolymer after Subcutaneous Administration of Enoxaparin in Mice

Uncontrolled bleeding after enoxaparin (ENX) is rare but may be life-threatening. The only registered antidote for ENX, protamine sulfate (PS), has 60% efficacy and can cause severe adverse side effects. We developed a diblock copolymer, heparin-binding copolymer (HBC), that reverses intravenously administered heparins. Here, we focused on the HBC inhibitory activity against subcutaneously administered ENX in healthy mice. BALB/c mice were subcutaneously injected with ENX at the dose of 5 mg/kg. After 110 min, vehicle, HBC (6.25 and 12.5 mg/kg), or PS (5 and 10 mg/kg) were administered into the tail vein. The blood was collected after 3, 10, 60, 120, 360, and 600 min after vehicle, HBC, or PS administration. The activities of antifactors Xa and IIa and biochemical parameters were measured. The main organs were collected for histological analysis. HBC at the lower dose reversed the effect of ENX on antifactor Xa activity for 10 min after antidote administration, whereas at the higher dose, HBC reversed the effect on antifactor Xa activity throughout the course of the experiment. Both doses of HBC completely reversed the effect of ENX on antifactor IIa activity. PS did not reverse antifactor Xa activity and partially reversed antifactor IIa activity. HBC modulated biochemical parameters. Histopathological analysis showed changes in the liver, lungs, and spleen of mice treated with HBC and in the lungs and heart of mice treated with PS. HBC administered in an appropriate dose might be an efficient substitute for PS to reverse significantly increased anticoagulant activity that may be connected with major bleeding in patients receiving ENX subcutaneously.

Potential toxicity of nanoparticles on the reproductive system animal models: A review

Over the past two decades, nanotechnology has been involved in an array of applications in various fields, including diagnostic kits, disease treatment, drug manufacturing, drug delivery, and gene therapy. But concerns about the toxicity of nanoparticles have greatly hindered their use; also, due to their increasing use in various industries, all members of society are exposed to the toxicity of these nanoparticles. Nanoparticles have a negative impact on various organs, including the reproductive system. They also can induce abortion in women, reduce fetal growth and development, and can damage the reproductive system and sperm morphology in men. In some cases, it has been observed that despite the modification of nanoparticles in composition, concentration, and method of administration, there is still damage to the reproductive organs. Therefore, understanding how nanoparticles affect the reproductive system is of very importance. In several studies, the nanoparticle toxicity effect on the genital organs has been investigated at the clinical and molecular levels using the in vivo and in vitro models. This study reviews these investigations and provides important data on the toxicity, hazards, and safety of nanoparticles in the reproductive system to facilitate the optimal use of nanoparticles in the industry.

Photoresponsive PAMAM-Assembled Nanocarrier Loaded with Autophagy Inhibitor for Synergistic Cancer Therapy

As one of the most promising drug-delivery carriers due to its small size, easy surface modifiability, and hydrophobic interior, cationic poly(amidoamine) (PAMAM) per se, demonstrated by previous reports and the authors' present study, indicate potential anticancer capability, however, which are restricted by autophagy elicitation. Besides, its side-toxicity profile, having also been extensively documented, limits its translation into the clinic. Herein, the authors design a photoresponsive PAMAM-assembled nanoparticle loaded with the autophagy inhibitor (chloroquine, CQ), which exhibits light responsiveness for precisely controlling drug release and superior dark biosafety. Upon light irradiation, the nanoparticle can dissociate into charged small PAMAM for a significant antitumor effect. Meanwhile, the released CQ can inhibit pro-survival autophagy induced by PAMAM to achieve an excellent synergistic anticancer efficacy in vitro and in vivo. The authors' study provided a vision of utilizing PAMAM as self-carried anticancer therapeutics in combination with an autophagy inhibitor and proposing a cancer therapy with high antitumor efficacy and low side effects to normal tissues.

There and back again: a dendrimer's tale

The development of molecular nanostructures with well-defined particle size and shape is of eminent interest in biomedicine. Among many studied nanostructures, dendrimers represent the group of those most thoroughly characterized ones. Due to their unique structure and properties, dendrimers are very attractive for medical and pharmaceutical applications. Owing to the controllable cavities inside the dendrimer, guest molecules may be encapsulated, and highly reactive terminal groups are susceptible to further modifications, e.g., to facilitate target delivery. To understand the potential of these nanoparticles and to predict and avoid any adverse cellular reactions, it is necessary to know the mechanisms responsible for an efficient dendrimer uptake and the destination of their intracellular journey. In this article, we summarize the results of studies describing the dendrimer uptake, traffic, and efflux mechanisms depending on features of specific nanoparticles and cell types. We also present mechanisms of dendrimers responsible for toxicity and alteration in signal transduction pathways at the cellular level.

Lipodendriplexes mediated enhanced gene delivery: a cellular to pre-clinical investigation

Clinical success of effective gene therapy is mainly hampered by the insufficiency of safe and efficient internalization of a transgene to the targeted cellular site. Therefore, the development of a safe and efficient nanocarrier system is one of the fundamental challenges to transfer the therapeutic genes to the diseased cells. Polyamidoamine (PAMAM) dendrimer has been used as an efficient non-viral gene vector (dendriplexes) but the toxicity and unusual biodistribution induced by the terminal amino groups (–NH₂) limit its in vivo applications. Hence, a state of the art lipid modification with PAMAM based gene carrier (lipodendriplexes) was planned to investigate theirs in vitro (2D and 3D cell culture) and in vivo behaviour. In vitro pDNA transfection, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) generation, cellular protein contents, live/dead staining and apoptosis were studied in 2D cell culture of HEK-293 cells while GFP transfection, 3D cell viability and live/dead staining of spheroids were performed in its 3D cell culture. Acute toxicity studies including organ to body index ratio, hematological parameters, serum biochemistry, histopathological profiles and in vivo transgene expression were assessed in female BALB/c mice. The results suggested that, in comparison to dendriplexes the lipodendriplexes exhibited significant improvement of pDNA transfection (p < 0.001) with lower LDH release (p < 0.01) and ROS generation (p < 0.05). A substantially higher cellular protein content (p < 0.01) and cell viability were also observed in 2D culture. A strong GFP expression with an improved cell viability profile (p < 0.05) was indicated in lipodendriplexes treated 3D spheroids. In vivo archives showed the superiority of lipid-modified nanocarrier system, depicted a significant increase in green fluorescent protein (GFP) expression in the lungs (p < 0.01), heart (p < 0.001), liver (p < 0.001) and kidneys (p < 0.001) with improved serum biochemistry and hematological profile as compared to unmodified dendriplexes. No tissue necrosis was evident in the animal groups treated with lipid-shielded molecules. Therefore, a non-covalent conjugation of lipids with PAMAM based carrier system could be considered as a promising approach for an efficient and biocompatible gene delivery system.

Are Poly(amidoamine) Dendrimers Safe for Ocular Applications? Toxicological Evaluation in Ocular Cells and Tissues

Purpose: The human eye is a sophisticated and sensitive sensory organ. Because of the existence of the blood-ocular barrier and corneal-scleral barrier, safe and efficient ocular drug delivery system is highly desired; yet, it remains an unsolved issue. Due to the unique structure and drug loading property, Poly(amidoamine) (PAMAM) has received much attention in the ocular drug delivery investigation. Herein, we evaluated the ocular cytotoxicity and biosafety of PAMAM dendrimers. Methods: The ocular cytotoxicity and biosafety of PAMAM dendrimers were evaluated by conducting in vitro and in vivo experiments on ocular systems. The in vitro effect of PAMAM dendrimer of different generations (G4.0, G5.0, and G6.0) and concentrations on ocular cell metabolism, apoptosis, and oxidative damage were quantitatively assessed. In vivo biosafety of PAMAM dendrimers were further investigated on intraocular tissue by ocular irritation and intravitreal injection approaches. Results: It is found that that the cytotoxicity of PAMAM was time and generation dependent. PAMAM at a concentration below 50 μg/mL had minimal impact on the ocular tissue, whereas it caused apparent damage when above 50 μg/mL in the investigated situation. Further, our in vivo results showed that higher concentration of dendrimer (100 μg/mL) was associated with functional impairment demonstrated via optical coherence tomography and electroretinogram, although macroscopic structural changes were absent in fundus and histopathological studies. Overall, a higher concentration of PAMAM, such as above 50 μg/mL, may cause ocular functional damage. Conclusion: The PAMAM at the concentrations lower than 50 μg/mL showed good biocompatibility and biosafety in human ocular cells and tissues.

Nanomaterial-mediated autophagy: coexisting hazard and health benefits in biomedicine

BACKGROUND

Widespread biomedical applications of nanomaterials (NMs) bring about increased human exposure risk due to their unique physicochemical properties. Autophagy, which is of great importance for regulating the physiological or pathological activities of the body, has been reported to play a key role in NM-driven biological effects both in vivo and in vitro. The coexisting hazard and health benefits of NM-mediated autophagy in biomedicine are nonnegligible and require our particular concerns.

MAIN BODY

We collected research on the toxic effects related to NM-mediated autophagy both in vivo and in vitro. Generally, NMs can be delivered into animal models through different administration routes, or internalized by cells through different uptake pathways, exerting varying degrees of damage in tissues, organs, cells, and organelles, eventually being deposited in or excreted from the body. In addition, other biological effects of NMs, such as oxidative stress, inflammation, necroptosis, pyroptosis, and ferroptosis, have been associated with autophagy and cooperate to regulate body activities. We therefore highlight that NM-mediated autophagy serves as a double-edged sword, which could be utilized in the treatment of certain diseases related to autophagy dysfunction, such as cancer, neurodegenerative disease, and cardiovascular disease. Challenges and suggestions for further investigations of NM-mediated autophagy are proposed with the purpose to improve their biosafety evaluation and facilitate their wide application. Databases such as PubMed and Web of Science were utilized to search for relevant literature, which included all published, Epub ahead of print, in-process, and non-indexed citations.

CONCLUSION

In this review, we focus on the dual effect of NM-mediated autophagy in the biomedical field. It has become a trend to use the benefits of NM-mediated autophagy to treat clinical diseases such as cancer and neurodegenerative diseases. Understanding the regulatory mechanism of NM-mediated autophagy in biomedicine is also helpful for reducing the toxic effects of NMs as much as possible.

Nanoparticles induce autophagy via mTOR pathway inhibition and reactive oxygen species generation

Due to their unique physicochemical properties, nanoparticles (NPs) have been increasingly developed for use in various fields. However, there has been both growing negative concerns with toxicity and positive realization of opportunities in nanomedicine, coming from the growing understanding of the associations between NPs and the human body, particularly relating to their cellular autophagic effects. This review summarizes NP-induced autophagy via the modulation of the mTOR signaling pathway and other associated signals including AMPK and ERK and also demonstrates how reactive oxygen species generation greatly underlies the regulation processes. The perspectives in this review aim to contribute to NP design, particularly in consideration of nanotoxicity and the potential for the precise application of NPs in nanomedicine.

Nifedipine inhibits oxidative stress and ameliorates osteoarthritis by activating the nuclear factor erythroid-2-related factor 2 pathway

Nifedipine is a voltage-gated calcium channel inhibitor widely used in the treatment of hypertension. Nifedipine has been reported to have antioxidant and anti-apoptotic effects and promotes cell proliferation. However, the effects of nifedipine on oxidative stress and apoptosis in osteoarthritic (OA) chondrocytes are still unclear. In this study, we sought to investigate whether nifedipine alleviates oxidative stress and apoptosis in OA through nuclear factor erythroid-2-related factor 2 (Nrf2) activation. The cytotoxicity of nifedipine against human chondrocytes was detected using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) kit, whereas mRNA and protein expression levels were measured using reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The oxidative stress level was analyzed by measuring reactive oxygen species (ROS), glutathione peroxidase (GSH-px), catalase (CAT) and superoxide dismutase (SOD) activities. The role of Nrf2 in the effect of nifedipine on OA was analyzed using an Nrf2 inhibitor brusatol (BR). The result showed that nifedipine inhibited the expression of matrix metalloprotein(MMP)-13, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, cyclooxygenase (COX)-2, inducible nitric oxide (NO) synthase (iNOS), and prostaglandin E2 (PGE2), as well as reduced ROS production in human OA chondrocytes, which was partially reversed by BR. Nifedipine prevented cartilage degeneration and contributed to the expression of Nrf-2 in chondrocytes. These results indicate that nifedipine inhibited inflammation and oxidative stress in chondrocytes via activation of Nrf-2/HO-1 signaling.

Non-small-cell lung cancer homing peptide-labeled dendrimers selectively transfect lung cancer cells

AIM

Lung cancer gene therapies require reagents to selectively transfect lung tumors after systemic administration.

MATERIALS & METHODS

We created a reagent called NSCLC-NP by attaching a peptide with binding affinity for lung cancer to polyamidoamine dendrimers. The positively charged dendrimers electrostatically bind negatively charged nucleic acids, inhibit endogenous nucleases and transfect cells targeted by the attached peptide.

RESULTS

In vitro, NSCLC-NP complexed to DNA plasmids bound and transfected three human lung cancer cell lines producing protein expression of the plasmid's gene. In vivo, systemically administered NSCLC-NP selectively transfected lung cancer cells growing in RAG1KO mice.

CONCLUSION

The capability of NSCLC-NP to selectively transfect lung cancer allows its future use as a vehicle to implement human lung cancer gene therapy strategies.

Chronic administration of nano-sized PAMAM dendrimers in vivo inhibits EGFR-ERK1/2-ROCK signaling pathway and attenuates diabetes-induced vascular remodeling and dysfunction

We investigated whether chronic administration of nano-sized polyamidoamine (PAMAM) dendrimers can have beneficial effects on diabetes-induced vascular dysfunction by inhibiting the epidermal growth factor receptor (EGFR)-ERK1/2-Rho kinase (ROCK)-a pathway known to be critical in the development of diabetic vascular complications. Daily administration of naked PAMAMs for up to 4 weeks to streptozotocin-induced diabetic male Wistar rats inhibited EGFR-ERK1/2-ROCK signaling and improved diabetes-induced vascular remodeling and dysfunction in a dose, generation (G6 > G5) and surface chemistry-dependent manner (cationic > anionic > neutral). PAMAMs, AG1478 (a selective EGFR inhibitor), or anti-EGFR siRNA also inhibited vascular EGFR-ERK1/2-ROCK signaling in vitro. These data showed that naked PAMAM dendrimers have the propensity to modulate key (e.g. EGFR) cell signaling cascades with associated pharmacological consequences in vivo that are dependent on their physicochemical properties. Thus, PAMAMs, alone or in combination with vasculoprotective agents, may have a beneficial role in the potential treatment of diabetes-induced vascular complications.

Autophagy in exposure to environmental chemicals

Autophagy is a catabolic pathway, which breaks down old and damaged cytoplasmic material into basic biomolecules through lysosome-mediated digestion thereby recycling cellular material. In this way, autophagy prevents the accumulation of damaged cellular components inside cells and reduces metabolic stress and toxicity. The basal level of autophagy is generally low but essential for maintaining the turnover of proteins and other molecules. The level is, however, increased in response to various stress conditions including chemical stress. This elevation in autophagy is intended to restore energy balance and improve cell survival in stress conditions. However, aberrant and/or deficient autophagy may also be involved in the aggravation of chemical-caused insults. Thus, the overall role of autophagy in chemical-induced toxicity is complex and only a limited number of environmental chemicals have been studied from this point of view. Autophagy is associated with many of the chemical-caused cytotoxic mechanisms, including mitochondrial dysfunction, DNA damage, oxidative stress, changes in the endoplasmic reticulum, impairment of lysosomal functions, and inflammation. This mini-review describes autophagy and its involvement in the responses to some common environmental exposures including airborne particulate matter, nanoparticles and tobacco smoke as well as to some common single environmental chemicals.

Crosstalk between Autophagy and Nanomaterials: Internalization, Activation, Termination

Nanomaterials (NMs) are comprehensively applied in biomedicine due to their unique physical and chemical properties. Autophagy, as an evolutionarily conserved cellular quality control process, is closely associated with the effect of NMs on cells. In this review, the recent advances in NM-induced/inhibited autophagy (NM-phagy) are summarized, with an aim to present a comprehensive description of the mechanisms of NM-phagy from the perspective of internalization, activation, and termination, thereby bridging autophagy and nanomaterials. Several possible mechanisms are extensively reviewed including the endocytosis pathway of NMs and the related cross components (clathrin and adaptor protein 2 (AP-2), adenosine diphosphate (ADP)-ribosylation factor 6 (Arf6), Rab, UV radiation resistance associated gene (UVRAG)), three main stress mechanisms (oxidative stress, damaged organelles stress, and toxicity stress), and several signal pathway-related molecules. The mechanistic insight is beneficial to understand the autophagic response to NMs or NMs' regulation of autophagy. The challenges currently encountered and research trend in the field of NM-phagy are also highlighted. It is hoped that the NM-phagy discussion in this review with the focus on the mechanistic aspects may serve as a guideline for future research in this field.

In-vivo & in-vitro toxicity test of molecularly engineered PCMS: A potential drug for wireless remote controlled treatment

PC, PCM, PCS, and PCMS are our designed & synthesized ∼8 nm PAMAM dendrimer (P) -based organic supramolecular systems, for example, PCMS has 32 molecular motors (M), 4 pH sensors (S) and 2 multi-level molecular electronic switches (C). We have reported earlier following a preliminary in-vitro test that the synthesized PCMS can selectively target cancer cell nucleotides if triggered wirelessly by an electromagnetic pulse. Here to further verify its drug potential, we have studied the preliminary efficacy, toxicity, and pharmacokinetics of P derivatives (PC, PCM, PCMS) in-vivo and in-vitro. We used ethanol-induced gastric inflammation model and cultured human gastric epithelial cells AGS to examine to the toxicity of PAMAM dendrimers cell permeability and toxicity, in (a) the cultured human gastric epithelium cells (AGS), and in (b) the gastric ulcer mice model. Here we report that the toxicity of PAMAM dendrimer (>G3.5) P can be reduced by adding C, M and S. Gastric ulcer is the primary stage of the manifestation of acute inflammation, even gastric epithelial cancer. Ethanol causes ulceration (ulcer index 30), thus upregulates both pro and active MMP-9. A 50 μl PCMS dose prior to ethanol administration reduces ulceration by ∼80% and downregulates MMP-9 and prevents oxidative damages of gastric tissue by ECM remodeling. Alcohol's inflammation of mouse stomach causes up-regulation of both pro and active MMP-9, resulting in oxidative damages of gastric tissue by ECM remodeling. PCMS in particular dose window reverses & alters ECM remodeling, thus, neutralizing alcohol-induced inflammation & generation of ROS.

The Role of Autophagy in Nanoparticles-Induced Toxicity and Its Related Cellular and Molecular Mechanisms

In the past decades, nanoparticles have been widely used in industry and pharmaceutical fields for drug delivery, anti-pathogen, and diagnostic imaging purposes because of their unique physicochemical characteristics such as special ultrastructure, dispersity, and effective cellular uptake properties. But the nanotoxicity has been raised over the extensive applications of nanoparticles. Researchers have elucidated series of mechanisms in nanoparticles-induced toxicity, including apoptosis, necrosis, oxidative stress, and autophagy. Among upon mechanisms, autophagy was recently recognized as an important cell death style in various nanoparticles-induced toxicity, but the role of autophagy and its related cellular and molecular mechanisms during nanoparticles-triggered toxicity were still confusing. In the chapter, we briefly introduced the general process of autophagy, summarized the different roles of autophagy in various nanoparticle-treated different in vitro/in vivo models, and deeply analyzed the physicochemical and biochemical (cellular and molecular) mechanisms of autophagy during nanoparticles-induced toxicity through listing and summarizing representative examples. Physicochemical mechanisms mainly include dispersity, size, charge, and surface chemistry; cellular mechanisms primarily focus on lysosome impairment, mitochondria dysfunction, mitophagy, endoplasmic reticulum stress and endoplasmic reticulum autophagy; while molecular mechanisms were mainly including autophagy related signaling pathways, hypoxia-inducible factor, and oxidative stress. This chapter highlighted the important role of autophagy as a critical mechanism in nanoparticles-induced toxicity, and the physicochemical and biochemical mechanisms of autophagy triggered by nanoparticles might be useful for establishing a guideline for the evaluation of nanotoxicology, designing and developing new biosafety nanoparticles in the future.

Role of autophagy in cell-penetrating peptide transfection model

Cell-penetrating peptides (CPPs) uptake mechanism is still in need of more clarification to have a better understanding of their action in the mediation of oligonucleotide transfection. In this study, the effect on early events (1 h treatment) in transfection by PepFect14 (PF14), with or without oligonucleotide cargo on gene expression, in HeLa cells, have been investigated. The RNA expression profile was characterized by RNA sequencing and confirmed by qPCR analysis. The gene regulations were then related to the biological processes by the study of signaling pathways that showed the induction of autophagy-related genes in early transfection. A ligand library interfering with the detected intracellular pathways showed concentration-dependent effects on the transfection efficiency of splice correction oligonucleotide complexed with PepFect14, proving that the autophagy process is induced upon the uptake of complexes. Finally, the autophagy induction and colocalization with autophagosomes have been confirmed by confocal microscopy and transmission electron microscopy. We conclude that autophagy, an inherent cellular response process, is triggered by the cellular uptake of CPP-based transfection system. This finding opens novel possibilities to use autophagy modifiers in future gene therapy.

Recent Advances in Nanotechnology for Autophagy Detection

Autophagy is closely related to various diseases, and is a diagnostic and therapeutic target for some diseases. In recent years, tremendous efforts have been made to develop excellent probes for detection of autophagy. Nanostructure-based probes are interesting and promising approaches for in vivo biological imaging due to their unique structural and functional characteristics, e.g., modulating pharmacokinetics property by biocompatible coatings, multimodality capacity by delivering multiple imaging agents and highly specific targeting by antibody ligands. In this Review, we first introduce recent advancements in the development of nanostructure-based probes for detection of autophagy, including inorganic hybrid nanomaterials and self-assembled peptide polymeric nanoparticles. Meanwhile, a nanoprobe based on a "in vivo self-assembly" strategy is highlighted. The "in vivo self-assembly" endows nanoprobes with higher accumulation, and longer and better signal stability for in vivo detection of autophagy. Furthermore, this novel strategy could be widely used for biomedical imaging/diagnostics and therapeutics, which would attract more attention to this research area.

Interleukin-22 ameliorated renal injury and fibrosis in diabetic nephropathy through inhibition of NLRP3 inflammasome activation

Diabetic nephropathy (DN) is one of the most lethal complications of diabetes mellitus with metabolic disorders and chronic inflammation. Although the cytokine IL-22 was initially implicated in the pathogenesis of chronic inflammatory diseases, recent studies suggested that IL-22 could suppress inflammatory responses and alleviate tissue injury. Herein, we examined the role of IL-22 in DN. We found that serum levels of IL-22 were significantly downregulated in both patients and mice with DN. The expression of IL-22 was further decreased with the progression of DN, whereas IL-22 gene therapy significantly ameliorated renal injury and mesangial matrix expansion in mice with established nephropathy. IL-22 could also markedly reduce high glucose-induced and TGF-β1-induced overexpression of fibronectin and collagen IV in mouse renal glomerular mesangial cells in a dose-dependent manner, suggesting the potential role of IL-22 to inhibit the overproduction of ECM in vitro. Simultaneously, IL-22 gene therapy drastically alleviated renal fibrosis and proteinuria excretion in DN. In addition, IL-22 gene therapy markedly attenuated hyperglycemia and metabolic disorders in streptozotocin-induced experimental diabetic mice. Notably, IL-22 drastically reversed renal activation of NLRP3, cleavage of caspase-1, and the maturation of IL-1β in DN, suggesting unexpected anti-inflammatory function of IL-22 via suppressing the activation of NLRP3 inflammasome in vivo. Moreover, IL-22 markedly downregulated high glucose-induced activation of NLRP3 inflammasome in renal mesangial cells in a dose-dependent manner, indicating that the effects of IL-22 on NLRP3 inflammasome activation was independent of improved glycemic control. These results suggested that nephroprotection by IL-22 in DN was most likely associated with reduced activation of NLRP3 inflammasome. In conclusion, our finding demonstrated that IL-22 could exert favorable effects on DN via simultaneously alleviating systemic metabolic syndrome and downregulating renal NLRP3/caspase-1/IL-1β pathway, suggesting that IL-22 might have therapeutic potential for the treatment of DN.

Inhibition of Kupffer Cell Autophagy Abrogates Nanoparticle-Induced Liver Injury

The possible adverse effects of engineered nanomaterials on human health raise increasing concern as our research on nanosafety intensifies. Upon entry into a human body, whether intended for a theranostic purpose or through unintended exposure, nanomaterials tend to accumulate in the liver, leading to hepatic damage. A variety of nanoparticles, including rare earth upconversion nanoparticles (UCNs), have been reported to elicit hepatotoxicity, in most cases through inducing immune response or activating reactive oxygen species. Many of these nanoparticles also induce autophagy, and autophagy inhibition has been shown to decrease UCN-induced liver damage. Herein, using UCNs as a model engineered nanomaterial, this study uncovers a critical role for Kupffer cells in nanomaterial-induced liver toxicity, as depletion of Kupffer cells significantly exacerbates UCN-induced liver injury. Furthermore, UCN-induced prodeath autophagy in Kupffer cells, and inhibition of autophagy with 3-MA, a well-established chemical inhibitor of autophagy, enhances Kupffer cell survival and further abrogates UCN-induced liver toxicity. The results reveal the critical importance of Kupffer cell autophagy for nanoparticle-induced liver damage, and inhibition of autophagy may constitute a novel strategy for abrogating nanomaterial-elicited liver toxicity.

Persistency of Enlarged Autolysosomes Underscores Nanoparticle-Induced Autophagy in Hepatocytes

The diverse biological effects of nanomaterials form the basis for their applications in biomedicine but also cause safety issues. Induction of autophagy is a cellular response after nanoparticles exposure. It may be beneficial in some circumstances, yet autophagy-mediated toxicity raises an alarming concern. Previously, it has been reported that upconversion nanoparticles (UCNs) elicit liver damage, with autophagy contributing most of this toxicity. However, the detailed mechanism is unclear. This study reveals persistent presence of enlarged autolysosomes in hepatocytes after exposure to UCNs and SiO₂ nanoparticles both in vitro and in vivo. This phenomenon is due to anomaly in the autophagy termination process named autophagic lysosome reformation (ALR). Phosphatidylinositol 4-phosphate (PI(4)P) relocates onto autolysosome membrane, which is a key event of ALR. PI(4)P is then converted into phosphatidylinositol 4,5-bisphosphate (PI(4,5)P₂ ) by phosphatidylinositol-4-phosphate 5-kinase. Clathrin is subsequently recruited by PI(4,5)P₂ and leads to tubule budding of ALR. Yet it is observed that PI(4)P cannot be converted in nanoparticle-treated hepatocytes cells. Exogenous supplement of PI(4,5)P₂ suppresses the enlarged autolysosomes in vitro. Abolishment of these enlarged autolysosomes by autophagy inhibitor relieves the hepatotoxicity of UCNs in vivo. The results provide evidence for disrupted ALR in nanoparticle-treated hepatocytes, suggesting that the termination of nanoparticle-induced autophagy is of equal importance as the initiation.

Impact of PAMAM delivery systems on signal transduction pathways in vivo: Modulation of ERK1/2 and p38 MAP kinase signaling in the normal and diabetic kidney

The in vivo impact of two generation 6 cationic polyamidoamine (PAMAM) dendrimers on cellular signaling via extracellular-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (p38 MAPK), as well as their relationship to epidermal growth factor receptor (EGFR), were studied in the normal and/or diabetic rat kidney. A single 10mg/kg/i.p administration of Polyfect (PF; with an intact branching architecture) or Superfect (SF; with a fragmented branching architecture) modulated renal ERK1/2 and p38 MAPK phosphorylation in a dendrimer-specific and animal model-dependent manner. AG1478 treatment (a selective EGFR inhibitor) confirmed that renal ERK1/2 and p38 MAPK signaling was downstream of EGFR. Surprisingly, both PAMAMs induced hyperphosphorylation of ERK1/2 and p38 MAPK (at 1 or 5mg/kg) despite inhibiting EGFR phosphorylation in the diabetic kidney. PAMAMs did not alter renal morphology but their effects on p38 MAPK and EGFR phosphorylation were reversed by ex vivo treatment of kidneys with the anti-oxidant, Tempol. Thus, PAMAMs can intrinsically modulate signaling of mitogen-activated protein kinases (MAPKs) depending on the type of dendrimer (fragmented vs intact branching architecture) and animal model (normal vs diabetic) used and likely occurs via an EGFR-independent and oxidative-stress dependent mechanism. These findings might have important toxicological implications for PAMAM-based delivery systems.

Biomedical Potential of mTOR Modulation by Nanoparticles

Modulation of the mammalian target of rapamycin (mTOR), the principal regulator of cellular homeostasis, underlies the biological effects of engineered nanoparticles, including regulation of cell death/survival and metabolic responses. Understanding the mechanisms and biological actions of nanoparticle-mediated mTOR modulation may help in developing safe and efficient nanotherapeutics to fight human disease.

Far upstream element-binding protein 1 is a prognostic biomarker and promotes nasopharyngeal carcinoma progression

Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor with tremendous invasion and metastasis capacities, and it has a high incidence in southeast Asia and southern China. Previous studies identified that far upstream element-binding protein 1 (FBP1), a transcriptional regulator of c-Myc that is one of the most frequently aberrantly expressed oncogenes in various human cancers, including NPC, is an important biomarker for many cancers. Our study aimed to investigate the expression and function of FBP1 in human NPC. Quantitative real-time RT-PCR (qRT-PCR), western blot and immunohistochemical staining (IHC) were performed in NPC cells and biopsies. Furthermore, the effect of FBP1 knockdown on cell proliferation, colony formation, side population tests and tumorigenesis in nude mice were measured by MTT, clonogenicity analysis, flow cytometry and a xenograft model, respectively. The results showed that the mRNA and protein levels of FBP1, which are positively correlated with c-Myc expression, were substantially higher in NPC than that in nasopharyngeal epithelial cells. IHC revealed that the patients with high FBP1 expression had a significantly poorer prognosis compared with the patients with low expression (P=0.020). In univariate analysis, high FBP1 and c-Myc expression predicted poorer overall survival (OS) and poorer progression-free survival. Multivariate analysis indicated that high FBP1 and c-Myc expression were independent prognostic markers. Knockdown of FBP1 reduced cell proliferation, clonogenicity and the ratio of side populations, as well as tumorigenesis in nude mice. These data indicate that FBP1 expression, which is closely correlated with c-Myc expression, is an independent prognostic factor and promotes NPC progression. Our results suggest that FBP1 can not only serve as a useful prognostic biomarker for NPC but also as a potential therapeutic target for NPC patients.

Interplay of Oxidative Stress and Autophagy in PAMAM Dendrimers-Induced Neuronal Cell Death

Poly-amidoamine (PAMAM) dendrimers are proposed to be one of the most promising drug-delivery nanomaterials. However, the toxicity of PAMAM dendrimers on the central nervous system seriously hinders their medical applications. The relationship between oxidative stress and autophagy induced by PAMAM dendrimers, and its underlying mechanism remain confusing. In this study, we reported that PAMAM dendrimers induced both reactive oxygen species and autophagy flux in neuronal cells. Interestingly, autophagy might be triggered by the formation of reactive oxygen species induced by PAMAM dendrimers. Suppression of reactive oxygen species could not only impair PAMAM dendrimers-induced autophagic effects, but also reduce PAMAM dendrimers-induced neuronal cell death. Moreover, inhibition of autophagy could protect against PAMAM dendrimers-induced neuronal cell death. These findings systematically elucidated the interplay between oxidative stress and autophagy in the neurotoxicity of PAMAM dendrimers, which might encourage the application of antioxidants and autophagy inhibitors to ameliorate the neurotoxicity of PAMAM dendrimers in clinic.

Cationic Polyamidoamine Dendrimers as Modulators of EGFR Signaling In Vitro and In Vivo

Cationic polyamidoamine (PAMAM) dendrimers are branch-like spherical polymers being investigated for a variety of applications in nanomedicine including nucleic acid drug delivery. Emerging evidence suggests they exhibit intrinsic biological and toxicological effects but little is known of their interactions with signal transduction pathways. We previously showed that the activated (fragmented) generation (G) 6 PAMAM dendrimer, Superfect (SF), stimulated epidermal growth factor receptor (EGFR) tyrosine kinase signaling-an important signaling cascade that regulates cell growth, survival and apoptosis- in cultured human embryonic kidney (HEK 293) cells. Here, we firstly studied the in vitro effects of Polyfect (PF), a non-activated (intact) G6 PAMAM dendrimer, on EGFR tyrosine kinase signaling via extracellular-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) in cultured HEK 293 cells and then compared the in vivo effects of a single administration (10mg/kg i.p) of PF or SF on EGFR signaling in the kidneys of normal and diabetic male Wistar rats. Polyfect exhibited a dose- and time-dependent inhibition of EGFR, ERK1/2 and p38 MAPK phosphorylation in HEK-293 cells similar to AG1478, a selective EGFR inhibitor. Administration of dendrimers to non-diabetic or diabetic animals for 24h showed that PF inhibited whereas SF stimulated EGFR phosphorylation in the kidneys of both sets of animals. PF-mediated inhibition of EGFR phosphorylation as well as SF or PF-mediated apoptosis in HEK 293 cells could be significantly reversed by co-treatment with antioxidants such as tempol implying that both these effects involved an oxidative stress-dependent mechanism. These results show for the first time that SF and PF PAMAM dendrimers can differentially modulate the important EGFR signal transduction pathway in vivo and may represent a novel class of EGFR modulators. These findings could have important clinical implications for the use of PAMAM dendrimers in nanomedicine.