Mammalian Cells Exocytose Alkylated Gold Nanoparticles via Extracellular Vesicles

Role of ESCCAL-1 in regulating exocytosis of AuNPs in human esophageal squamous carcinoma cells

Exocytosis is a critical factor for designing efficient nanocarriers and determining cytotoxicity. However, the research on the exocytosis mechanism of nanoparticles, especially the role of long non-coding RNAs (lncRNAs), has not been reported. In this study, the exocytosis of AuNPs in the KYSE70 cells and the involved molecular pathways of exocytosis are analyzed. It demonstrates that nanoparticles underwent time-dependent release from the cells by exocytosis, and the release of β-hexosaminidase confirms that AuNPs are excreted through lysosomes. Mechanistic studies reveal that lncRNA ESCCAL-1 plays a vital role in controlling the exocytosis of AuNPs through activation of the MAPK pathway, including the phosphorylation of ERK and JNK. The study implies that the ESCCAL-1-mediated pathway plays an important role in the exocytosis of AuNPs in KYSE70 cells. This finding has implications for the role of ESCCAL-1 on the drug resistance of esophagus cancer by controlling lysosome-mediated exocytosis.

Physiological principles underlying the kidney targeting of renal nanomedicines

Kidney disease affects more than 10% of the global population and is associated with considerable morbidity and mortality, highlighting a need for new therapeutic options. Engineered nanoparticles for the treatment of kidney diseases (renal nanomedicines) represent one such option, enabling the delivery of targeted therapeutics to specific regions of the kidney. Although they are underdeveloped compared with nanomedicines for diseases such as cancer, findings from preclinical studies suggest that renal nanomedicines may hold promise. However, the physiological principles that govern the in vivo transport and interactions of renal nanomedicines differ from those of cancer nanomedicines, and thus a comprehensive understanding of these principles is needed to design nanomedicines that effectively and specifically target the kidney while ensuring biosafety in their future clinical translation. Herein, we summarize the current understanding of factors that influence the glomerular filtration, tubular uptake, tubular secretion and extrusion of nanoparticles, including size and charge dependency, and the role of specific transporters and processes such as endocytosis. We also describe how the transport and uptake of nanoparticles is altered by kidney disease and discuss strategic approaches by which nanoparticles may be harnessed for the detection and treatment of a variety of kidney diseases.

Effects of Different Surface Functionalizations of Silica Nanoparticles on Mesenchymal Stem Cells

Physicochemical properties of nanoparticles, such as particle size, surface charge, and particle shape, have a significant impact on cell activities. However, the effects of surface functionalization of nanoparticles with small chemical groups on stem cell behavior and function remain understudied. Herein, we incorporated different chemical functional groups (amino, DETA, hydroxyl, phosphate, and sulfonate with charges of +9.5, + 21.7, -14.1, -25.6, and -37.7, respectively) to the surface of inorganic silica nanoparticles. To trace their effects on mesenchymal stem cells (MSCs) of rat bone marrow, these functionalized silica nanoparticles were used to encapsulate Rhodamine B fluorophore dye. We found that surface functionalization with positively charged and short-chain chemical groups facilitates cell internalization and retention of nanoparticles in MSCs. The endocytic pathway differed among functionalized nanoparticles when tested with ion-channel inhibitors. Negatively charged nanoparticles mainly use lysosomal exocytosis to exit cells, while positively charged nanoparticles can undergo endosomal escape to avoid scavenging. The cytotoxic profiles of these functionalized silica nanoparticles are still within acceptable limits and tolerable. They exerted subtle effects on the actin cytoskeleton and migration ability. Last, phosphate-functionalized nanoparticles upregulate osteogenesis-related genes and induce osteoblast-like morphology, implying that it can direct MSCs lineage specification for bone tissue engineering. Our study provides insights into the rational design of biomaterials for effective drug delivery and regenerative medicine.

Programming Intracellular Clustering of Spiky Nanoparticles via Liposome Encapsulation

The intracellular clustering of anisotropic nanoparticles is crucial to the improvement of the localized surface plasmon resonance (LSPR) for phototherapy applications. Herein, we programmed the intracellular clustering process of spiky nanoparticles (SNPs) by encapsulating them into an anionic liposome via a frame-guided self-assembly approach. The liposome-encapsulated SNPs (lipo-SNPs) exhibited distinct and enhanced lysosome-triggered aggregation behavior while maintaining excellent monodispersity, even in acidic or protein-rich environments. We explored the enhancement of the photothermal therapy performance for SNPs as a proof of concept. The photothermal conversion efficiency of lipo-SNPs clusters significantly increased 15 times compared to that of single lipo-SNPs. Upon accumulation in lysosomes with a 2.4-fold increase in clustering, lipo-SNPs resulted in an increase in cell-killing efficiency to 45% from 12% at 24 μg/mL. These findings indicated that liposome encapsulation provides a promising approach to programing nanoparticle clustering at the target site, which facilitates advances in the development of smart nanomedicine with programmable enhancement in LSPR.

Review of Advances in Coating and Functionalization of Gold Nanoparticles: From Theory to Biomedical Application

Nanoparticles, especially gold nanoparticles (Au NPs) have gained increasing interest in biomedical applications. Used for disease prevention, diagnosis and therapies, its significant advantages in therapeutic efficacy and safety have been the main target of interest. Its application in immune system prevention, stability in physiological environments and cell membranes, low toxicity and optimal bioperformances are critical to the success of engineered nanomaterials. Its unique optical properties are great attractors. Recently, several physical and chemical methods for coating these NPs have been widely used. Biomolecules such as DNA, RNA, peptides, antibodies, proteins, carbohydrates and biopolymers, among others, have been widely used in coatings of Au NPs for various biomedical applications, thus increasing their biocompatibility while maintaining their biological functions. This review mainly presents a general and representative view of the different types of coatings and Au NP functionalization using various biomolecules, strategies and functionalization mechanisms.

Celebrating 60 Years of The Chinese University of Hong Kong: Research Highlights in Nanoscience and Nanotechnology

Recent breakthroughs and advances in nanoscience and nanotechnology have profoundly impacted young-generation education, accelerated knowledge transfer to enhance the quality of life, and improved environmental and economic sustainability. The Chinese University of Hong Kong (CUHK), a globally recognized education and research institute, has played a crucial role in promoting major strategic research directions in nanoscience, including translational biomedicine and information and automation technology, as well as environment and sustainability. To celebrate the 60th Anniversary of CUHK, we present this Virtual Issue that showcases the cutting-edge research at CUHK published in ACS Nano.

Remodeling of intestinal epithelium derived extracellular vesicles by nanoparticles and its bioeffect on tumor cell migration

Extracellular vesicles (EVs) are an effective tool to elucidate the bioeffect of nanomedicines. To clarify the interaction between oral nanomedicines and intestinal epithelial cells, and their bioeffects on downstream cells, polystyrene nanoparticles (PS-NPs) with different sizes were used as the model nanomedicines for EVs induction. Caco-2 monolayers were selected as the model of the intestinal epithelium and DLD-1 cells as the colorectal cancer model proximal to the gastrointestinal tract. It is found that compared with small-sized (25, 50, 100 nm) PS-NPs, the large-sized (200 and 500 nm) exhibited higher co-localization with multivesicular bodies and lysosomes, and more significant reduction of lysosomal acidification in Caco-2 cells. Proteomic and western-blotting analysis showed that the EVs remodeled by large-sized PS-NPs exhibited a higher extent of protein expression changes. The in vitro and in vivo signaling pathway detection in DLD-1 cells and DLD-1 cell xenograft nude mice showed that the remodeled EVs by large-sized PS-NPs inhibited the activation of multiple signaling pathways including Notch3, EGF/EGFR, and PI3K/Akt pathways, which resulted in the inhibition of tumor cell migration. These results primarily clarify the regulation mechanisms of nanomedicines-EVs-receptor cells chain. It provides a new perspective for the rational design and bioeffect evaluation of oral drug nanomaterials and sets up the fundamental knowledge for novel tumor therapeutics in the future.

Uptake and Intracellular Fate of Fluorophore Labeled Metal-Organic-Framework (MOF) Nanoparticles

The uptake and the fate of Zr-based metal-organic-framework nanoparticles labeled with organic fluorophores in HeLa cells has been monitored with fluorescence detection and elemental analysis. The nanoparticles have been selected as a model system of carrier nanoparticles (here Zr-based metal-organic-framework nanoparticles) with integrated cargo molecules (here organic fluorophores), with aze that does not allow for efficient exocytosis, a material which only partly degrades under acidic conditions as present in endosomes/lysosomes, and with limited colloidal stability. Data show that, for Zr-based metal-organic-framework nanoparticles of 40 nm size as investigated here, the number of nanoparticles per cells decreases faster due to particle redistribution upon proliferation than due to nanoparticle exocytosis and that, thus, also for this system, exocytosis is not an efficient pathway for clearance of the nanoparticles from the cells.

Cellular Export Fate of Liposomal Spherical Nucleic Acids

Liposomal spherical nucleic acids (LSNAs) are useful structures for oligonucleotide-based cell modulation because of their biocompatibility and ability to readily enter cells without transfection agents. Understanding LSNA trafficking is key to developing applications, but while much is understood about LSNA cell uptake, little is known about their export fate. Here, we study LSNA export through pulse-chase studies with fluorophore-labeled LSNAs. Our findings show that the components of LSNAs are differentially exported by cells, with the phospholipids showing 90-100% export and the oligonucleotides showing 30-45% export over 24 h in RAW264.7 macrophages. Despite the increase in the level of uptake of LSNAs, these percentages are not significantly influenced by whether the materials are taken up as LSNAs or as the individual components. The exported oligonucleotide material consists of a full-length oligonucleotide with the phospholipid anchor modified by loss of a fatty acid. The exported liposome-derived phospholipids also had a fatty acid removed. Moreover, the exported oligonucleotide-lysophospholipid conjugates retain immunostimulatory potential. These findings indicate that after cellular entry LSNAs are degraded into lysophospholipids, something to which they are susceptible due to the presence of hydrolyzable ester bonds. The export percentage of the resultant materials over 24 h is independent of the amount imported, such that greater initial import leads to a similar fold increase in exported material. This work therefore reveals an intracellular feature of LSNAs and shows that the enhanced uptake achieved with LSNAs can be exploited to maximize the amount of material subsequently exported, suggesting avenues for leveraging pharmacologic effects from exported LSNA components.

Applications and Research Advances in the Delivery of CRISPR/Cas9 Systems for the Treatment of Inherited Diseases

The rapid advancements in gene therapy have opened up new possibilities for treating genetic disorders, including Duchenne muscular dystrophy, thalassemia, cystic fibrosis, hemophilia, and familial hypercholesterolemia. The utilization of the clustered, regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein (Cas) system has revolutionized the field of gene therapy by enabling precise targeting of genes. In recent years, CRISPR/Cas9 has demonstrated remarkable efficacy in treating cancer and genetic diseases. However, the susceptibility of nucleic acid drugs to degradation by nucleic acid endonucleases necessitates the development of functional vectors capable of protecting the nucleic acids from enzymatic degradation while ensuring safety and effectiveness. This review explores the biomedical potential of non-viral vector-based CRISPR/Cas9 systems for treating genetic diseases. Furthermore, it provides a comprehensive overview of recent advances in viral and non-viral vector-based gene therapy for genetic disorders, including preclinical and clinical study insights. Additionally, the review analyzes the current limitations of these delivery systems and proposes avenues for developing novel nano-delivery platforms.

Exocytosis of Nanoparticles: A Comprehensive Review

Both biomedical applications and safety assessments of manufactured nanomaterials require a thorough understanding of the interaction between nanomaterials and cells, including how nanomaterials enter cells, transport within cells, and leave cells. However, compared to the extensively studied uptake and trafficking of nanoparticles (NPs) in cells, less attention has been paid to the exocytosis of NPs. Yet exocytosis is an indispensable process of regulating the content of NPs in cells, which in turn influences, even decides, the toxicity of NPs to cells. A comprehensive understanding of the mechanisms and influencing factors of the exocytosis of NPs is not only essential for the safety assessment of NPs but also helpful for guiding the design of safe and highly effective NP-based materials for various purposes. Herein, we review the current status and progress of studies on the exocytosis of NPs. Firstly, we introduce experimental procedures and considerations. Then, exocytosis mechanisms/pathways are summarized with a detailed introduction of the main pathways (lysosomal and endoplasmic reticulum/Golgi pathway) and the role of microtubules; the patterns of exocytosis kinetics are presented and discussed. Subsequently, the influencing factors (initial content and location of intracellular NPs, physiochemical properties of NPs, cell type, and extracellular conditions) are fully discussed. Although there are inconsistent results, some rules are obtained, like smaller and charged NPs are more easily excreted. Finally, the challenges and future directions in the field have been discussed.

Emerging extracellular vesicle-based carriers for glioblastoma diagnosis and therapy

Glioblastoma (GBM) treatment is still a big clinical challenge because of its highly malignant, invasive, and lethal characteristics. After treatment with the conventional therapeutic paradigm of surgery combined with radio- and chemotherapy, patients bearing GBMs generally exhibit a poor prognosis, with high mortality and a high disability rate. The main reason is the existence of the formidable blood-brain barrier (BBB), aggressive growth, and the infiltration nature of GBMs. Especially, the BBB suppresses the delivery of imaging and therapeutic agents to lesion sites, and thus this leads to difficulties in achieving a timely diagnosis and treatment. Recent studies have demonstrated that extracellular vesicles (EVs) exhibit favorable merits including good biocompatibility, a strong drug loading capacity, long circulation time, good BBB crossing efficiency, specific targeting to lesion sites, and high efficiency in the delivery of a variety of cargos for GBM therapy. Importantly, EVs inherit physiological and pathological molecules from the source cells, which are ideal biomarkers for molecularly tracking the malignant progression of GBMs. Herein, we start by introducing the pathophysiology and physiology of GBMs, followed by presenting the biological functions of EVs in GBMs with a special focus on their role as biomarkers for GBM diagnosis and as messengers in the modulation of the GBM microenvironment. Furthermore, we provide an update on the recent progress of using EVs in biology, functionality, and isolation applications. More importantly, we systematically summarize the most recent advances of EV-based carriers for GBM therapy by delivering different drugs including gene/RNA-based drugs, chemotherapy drugs, imaging agents, and combinatory drugs. Lastly, we point out the challenges and prospects of future research on EVs for diagnosing and treating GBMs. We hope this review will stimulate interest from researchers with different backgrounds and expedite the progress of GBM treatment paradigms.

Pre-exposure to titanium or iron oxide nanoparticles suppresses the subsequent cellular uptake of gold nanoparticles

Humans are exposed to a wide variety of natural and engineered nanoparticles (NPs) during their lifetime. However, the effects of pre-exposure to NPs on subsequent uptake of other NPs have not been investigated. In the present study, we investigated the effects of pre-exposure to three NPs (TiO₂, Fe₂O₃, and SiO₂ NPs) on the subsequent uptake of gold NPs (AuNPs) by hepatocellular carcinoma cells (HepG2). When HepG2 cells were pre-exposed to TiO₂ or Fe₂O₃ NPs, but not SiO₂ NPs for 2 days, their subsequent uptake of AuNPs was inhibited. Such inhibition was also observed in human cervical cancer (HeLa) cells, suggesting that this phenomenon is present in different cell types. The mechanisms underlying the inhibitory effect of NP pre-exposure include altered plasma membrane fluidity due to changes in lipid metabolism and reduced intracellular ATP production due to decreased intracellular oxygen. Despite the inhibitory effects of NP pre-exposure, full recovery was observed after transferring the cells to medium without NPs, even when the pre-exposure time was extended from 2 days to 2 weeks. Overall, the pre-exposure effects observed in the present study should be considered in the biological application and risk evaluation of NPs.

Proximal tubules eliminate endocytosed gold nanoparticles through an organelle-extrusion-mediated self-renewal mechanism

Proximal tubules energetically internalize and metabolize solutes filtered through glomeruli but are constantly challenged by foreign substances during the lifespan. Thus, it is critical to understand how proximal tubules stay healthy. Here we report a previously unrecognized mechanism of mitotically quiescent proximal tubular epithelial cells for eliminating gold nanoparticles that were endocytosed and even partially transformed into large nanoassemblies inside lysosomes/endosomes. By squeezing ~5 µm balloon-like extrusions through dense microvilli, transporting intact gold-containing endocytic vesicles into the extrusions along with mitochondria or other organelles and pinching the extrusions off the membranes into the lumen, proximal tubular epithelial cells re-eliminated >95% of endocytosed gold nanoparticles from the kidneys into the urine within a month. While this organelle-extrusion mechanism represents a new nanoparticle-elimination route, it is not activated by the gold nanoparticles but is an intrinsic 'housekeeping' function of normal proximal tubular epithelial cells, used to remove unwanted cytoplasmic contents and self-renew intracellular organelles without cell division to maintain homoeostasis.

Quantifying Intracellular Nanoparticle Distributions with Three-Dimensional Super-Resolution Microscopy

Super-resolution microscopy can transform our understanding of nanoparticle-cell interactions. Here, we established a super-resolution imaging technology to visualize nanoparticle distributions inside mammalian cells. The cells were exposed to metallic nanoparticles and then embedded within different swellable hydrogels to enable quantitative three-dimensional (3D) imaging approaching electron-microscopy-like resolution using a standard light microscope. By exploiting the nanoparticles' light scattering properties, we demonstrated quantitative label-free imaging of intracellular nanoparticles with ultrastructural context. We confirmed the compatibility of two expansion microscopy protocols, protein retention and pan-expansion microscopy, with nanoparticle uptake studies. We validated relative differences between nanoparticle cellular accumulation for various surface modifications using mass spectrometry and determined the intracellular nanoparticle spatial distribution in 3D for entire single cells. This super-resolution imaging platform technology may be broadly used to understand the nanoparticle intracellular fate in fundamental and applied studies to potentially inform the engineering of safer and more effective nanomedicines.

Principles of Nanoparticle Delivery to Solid Tumors

The effective treatment of patients with cancer hinges on the delivery of therapeutics to a tumor site. Nanoparticles provide an essential transport system. We present 5 principles to consider when designing nanoparticles for cancer targeting: (a) Nanoparticles acquire biological identity in vivo, (b) organs compete for nanoparticles in circulation, (c) nanoparticles must enter solid tumors to target tumor components, (d) nanoparticles must navigate the tumor microenvironment for cellular or organelle targeting, and (e) size, shape, surface chemistry, and other physicochemical properties of nanoparticles influence their transport process to the target. This review article describes these principles and their application for engineering nanoparticle delivery systems to carry therapeutics to tumors or other disease targets.

Recent advances in the delivery and applications of nonviral CRISPR/Cas9 gene editing

The CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 genome editing system has been a major technological breakthrough that has brought revolutionary changes to genome editing for therapeutic and diagnostic purposes and precision medicine. With the advent of the CRISPR/Cas9 system, one of the critical limiting factors has been the safe and efficient delivery of this system to cells or tissues of interest. Several approaches have been investigated to find delivery systems that can attain tissue-targeted delivery, lowering the chances of off-target editing. While viral vectors have shown promise for in vitro, in vivo and ex vivo delivery of CRISPR/Cas9, their further clinical applications have been restricted due to shortcomings including limited cargo packaging capacity, difficulties with large-scale production, immunogenicity and insertional mutagenesis. Rapid progress in nonviral delivery vectors, including the use of lipid, polymer, peptides, and inorganic nanoparticle-based delivery systems, has established nonviral delivery approaches as a viable alternative to viral vectors. This review will introduce the molecular mechanisms of the CRISPR/Cas9 gene editing system, current strategies for delivering CRISPR/Cas9-based tools, an overview of strategies for overcoming off-target genome editing, and approaches for improving genome targeting and tissue targeting. We will also highlight current developments and recent clinical trials for the delivery of CRISPR/Cas9. Finally, future directions for overcoming the limitations and adaptation of this technology for clinical trials will be discussed.

Resolution of MoS2 Nanosheets-Induced Pulmonary Inflammation Driven by Nanoscale Intracellular Transformation and Extracellular-Vesicle Shuttles

Pulmonary exposure to some engineered nanomaterials can cause chronic lesions as a result of unresolved inflammation. Among 2D nanomaterials and graphene, MoS₂ has received tremendous attention in optoelectronics and nanomedicine. Here an integrated approach is proposed to follow up the transformation of MoS₂ nanosheets at the nanoscale and assesss their impact on lung inflammation status over 1 month after a single inhalation in mice. Analysis of immune cells, alveolar macrophages, extracellular vesicles, and cytokine profiling in bronchoalveolar lavage fluid (BALF) shows that MoS₂ nanosheets induced initiation of lung inflammation. However, the inflammation is rapidly resolved despite the persistence of various biotransformed molybdenum-based nanostructures in the alveolar macrophages and the extracellular vesicles for up to 1 month. Using in situ liquid phase transmission electron microscopy experiments, the dynamics of MoS₂ nanosheets transformation triggered by reactive oxygen species could be evidenced. Three main transformation mechanisms are observed directly at the nanoscale level: 1) scrolling of the dispersed sheets leading to the formation of nanoscrolls and folded patches, 2) etching releasing soluble MoO₄ ^- , and 3) oxidation generating oxidized sheet fragments. Extracellular vesicles released in BALF are also identified as a potential shuttle of MoS₂ nanostructures and their degradation products and more importantly as mediators of inflammation resolution.

Cytotoxicity of mini gold nanorods: intersection with extracellular vesicles

It is well-known that there are size- and shape-dependencies to nanoparticle uptake and processing by living cells. Small gold nanorods have shown to exhibit low toxicity and high clearance rates when compared to larger ones, making smaller particles more desirable for biomedical applications. In this study gold mini-rods (approximately 9.5 × 23, 8 × 26, and 6 × 26 nm, corresponding to aspect ratios 2.5, 3.2 and 4.1) and gold nanospheres (15.6 nm average diameter) were synthesized, and wrapped with cationic and anionic polyelectrolytes. This library of colloidally stable nanomaterials was exposed to human dermal fibroblasts at the relatively low concentration of 1 nM for each nanoparticle type. The cytotoxic profile of these nanoparticles and their influence on the small extracellular vesicles released by the cells was assessed. It was observed that although the nanoparticles were found in vesicles inside the cells, the cell viability, the mitochondrial membrane potential and levels of reactive oxygen species were not markedly affected by the mini gold nanorods. The production of extracellular vesicles by the cells was unaffected by gold nanoparticle exposure; moreover, no gold nanoparticles were observed in extracellular vesicles in the exosomal size range. Taken together, these results suggest that these mini gold nanorods are suitable for a wide range of cellular applications for relatively short-term studies.