Nanomedicine: is it lost in translation?

A, Gota V, Goda JS. Insight into lipid-based nanoplatform-mediated drug and gene delivery in neuro-oncology and their clinical prospects

Tumors of the Central nervous System (CNS) are a spectrum of neoplasms that range from benign lesions to highly malignant and aggressive lesions. Despite aggressive multimodal treatment approaches, the morbidity and mortality are high with dismal survival outcomes in these malignant tumors. Moreover, the non-specificity of conventional treatments substantiates the rationale for precise therapeutic strategies that selectively target infiltrating tumor cells within the brain, and minimize systemic and collateral damage. With the recent advancement of nanoplatforms for biomaterials applications, lipid-based nanoparticulate systems present an attractive and breakthrough impact on CNS tumor management. Lipid nanoparticles centered immunotherapeutic agents treating malignant CNS tumors could convene the clear need for precise treatment strategies. Immunotherapeutic agents can selectively induce specific immune responses by active or innate immune responses at the local site within the brain. In this review, we discuss the therapeutic applications of lipid-based nanoplatforms for CNS tumors with an emphasis on revolutionary approaches in brain targeting, imaging, and drug and gene delivery with immunotherapy. Lipid-based nanoparticle platforms represent one of the most promising colloidal carriers for chemotherapeutic, and immunotherapeutic drugs. Their current application in oncology especially in brain tumors has brought about a paradigm shift in cancer treatment by improving the antitumor activity of several agents that could be used to selectively target brain tumors. Subsequently, the lab-to-clinic transformation and challenges towards translational feasibility of lipid-based nanoplatforms for drug and gene/immunotherapy delivery in the context of CNS tumor management is addressed.

Approved Nanomedicine against Diseases

Nanomedicine is a branch of medicine using nanotechnology to prevent and treat diseases. Nanotechnology represents one of the most effective approaches in elevating a drug‘s treatment efficacy and reducing toxicity by improving drug solubility, altering biodistribution, and controlling the release. The development of nanotechnology and materials has brought a profound revolution to medicine, significantly affecting the treatment of various major diseases such as cancer, injection, and cardiovascular diseases. Nanomedicine has experienced explosive growth in the past few years. Although the clinical transition of nanomedicine is not very satisfactory, traditional drugs still occupy a dominant position in formulation development, but increasingly active drugs have adopted nanoscale forms to limit side effects and improve efficacy. The review summarized the approved nanomedicine, its indications, and the properties of commonly used nanocarriers and nanotechnology.

Neutrophil membrane-coated nanoparticles exhibit increased antimicrobial activities in an anti-microbial resistant K. pneumonia infection model

OBJECTIVE

To investigate the efficacy and safety of neutrophil membrane-coated nanoparticles mediated KLA peptides (KLAKLAKKLAKLAK) and gentamicin in the targeted therapy of anti-microbial resistant Klebsiella pneumoniae (K. pneumonia) lung infection.

METHODS

The characteristics of KLA-neutrophils nanoparticles (NNPs) are identified via dynamic light scattering (DLS), transmission electron microscope (TEM), SDS-PAGE, Western blot, quantitative flow cytometry (QFCM) and confocal microscopy. The safety of KLA-NNPs both in vitro and in vivo is evaluated by hemolysis test, platelet α granule membrane protein concentration, protein adsorption capacity, in vitro macrophage phagocytosis, weight change, liver function indicators, blood biochemical indicators, and pathological changes of vital organs in mice. The efficacy of KLA-NNPs is determined by time-kill assay, fluorescent label test, intracellular bacterial content, caspase-1 activity, survival rate, and HE staining both in vitro and in vivo.

RESULTS

The prepared KLA-NNPs have a typical "core-shell" structure, uniform nanometer size, and retain the membrane proteins on the neutrophil membrane that achieve functional effects. In vitro safety analysis showed that KLA-NNPs have good blood compatibility and can inhibit macrophage phagocytosis in vitro. KLA-NNPs can effectively release KLA and significantly reduce intracellular bacteria and caspase-1 activity. In vivo safety analysis and efficacy analysis revealed that KLA-NNPs have good biocompatibility and could effectively improve the survival rate of mice.

CONCLUSION

The prepared KLA-NNPs have good nano-medicine chemical and physical properties and safety. It can evade immune system clearance, achieve high-efficiency targeted aggregation and drug delivery to bacterial infection sites, and effectively inhibit the development of pneumonia induced by drug-resistant K. pneumonia.

Influence of Elasticity of Hydrogel Nanoparticles on Their Tumor Delivery

Polymeric nanocarriers have a broad range of clinical applications in recent years, but an inefficient delivery of polymeric nanocarriers to target tissues has always been a challenge. These results show that tuning the elasticity of hydrogel nanoparticles (HNPs) improves their delivery efficiency to tumors. Herein, a microfluidic system is constructed to evaluate cellular uptake of HNPs of different elasticity under flow conditions. It is found that soft HNPs are more efficiently taken up by cells than hard HNPs under flow conditions, owing to the greater adhesion between soft HNPs and cells. Furthermore, in vivo imaging reveals that soft HNPs have a more efficient tumor delivery than hard HNPs, and the greater targeting potential of soft HNPs is associated with both prolonged blood circulation and a high extent of cellular adhesion.

Co-Encapsulation of Paclitaxel and JQ1 in Zein Nanoparticles as Potential Innovative Nanomedicine

The manuscript describes the development of zein nanoparticles containing paclitaxel (PTX) and the bromo-and extra-terminal domain inhibitor (S)-tertbutyl2-(4-(4-chlorophenyl)-2,3,9-trimethyl-6H-thieno(3,2-f)(1,2,4)triazolo(4,3-a)(1,4)diazepin-6-yl)acetate (JQ1) together with their cytotoxicity on triple-negative breast cancer cells. The rationale of this association is that of exploiting different types of cancer cells as targets in order to obtain increased pharmacological activity with respect to that exerted by the single agents. Zein, a protein found in the endosperm of corn, was used as a biomaterial to obtain multidrug carriers characterized by mean sizes of ˂200 nm, a low polydispersity index (0.1-0.2) and a negative surface charge. An entrapment efficiency of ~35% of both the drugs was obtained when 0.3 mg/mL of the active compounds were used during the nanoprecipitation procedure. No adverse phenomena such as sedimentation, macro-aggregation or flocculation occurred when the nanosystems were heated to 37 °C. The multidrug nanoformulation demonstrated significant in vitro cytototoxic activity against MDA-MB-157 and MDA-MB-231 cancer cells by MTT-test and adhesion assay which was stronger than that of the compounds encapsulated as single agents. The results evidence the potential application of zein nanoparticles containing PTX and JQ1 as a novel nanomedicine.

FRET as the tool for in vivo nanomedicine tracking

Advanced drug delivery system utilizing a nanocarrier is the major application of nanotechnology on pharmacotherapeutics. However, despite the promising benefits and a leading trend in pharmaceutical research, nanomedicine development suffers from a poor clinical translation problem as only a handful of nanomedicine products reach the market yearly. The conventional pharmacokinetic study generally focuses only on monitoring the level of a free drug but ignores the nanocarrier's role in pharmacokinetics. One hurdle is that it is difficult to directly track intact nanocarriers in vivo to explore their pharmacokinetics. Although several imaging techniques such as radiolabeling, nuclear imaging, fluorescence imaging, etc., have been developed over the past few years, currently, one method that can successfully track the intact nanocarriers in vivo directly is by Förster resonance energy transfer (FRET). This review summarizes the application of FRET as the in vivo nanoparticle tracker for studying the in vivo pharmacokinetics of the organic nanocarriers and gives elaborative details on the techniques utilized.

RNA-Seq Based Toxicity Analysis of Mesoporous Polydopamine Nanoparticles in Mice Following Different Exposure Routes

Mesoporous polydopamine nanoparticles (MPDA NPs) are promising nanomaterials that have the prospect of clinical application for multi-strategy antitumor therapy, while the biosecurity of MPDA NPs remains indistinct. Here, transcriptome sequencing (RNA-Seq) was performed to systematically reveal the toxicity of MPDA NPs to five categories of organs after three different exposure routes, including intravenous injection, intramuscular injection, and intragastric administration. Our results uncovered that MPDA NPs could be deposited in various organs in small amounts after intravenous administration, not for the other two exposure routes. The number of differentially expressed genes (DEGs) identified in the heart, liver, spleen, lung, and kidney from the intragastric administration group was from 22 to 519. Similarly, the corresponding number was from 23 to 64 for the intramuscular injection group and was from 11 to 153 for the intravenous injection group. Functional enrichment analyses showed 6, 39, and 4 GO terms enriched for DEGs in intragastric administration, intramuscular injection, and intravenous injection groups, respectively. One enriched pathway was revealed in intragastric administration group, while no enriched pathway was found in other groups. Our results indicated that MPDA NPs produced only slight changes at the transcriptome level in mice, which provided new insights for further clinical application of MPDA NPs.

Nanoparticle based medicines: approaches for evading and manipulating the mononuclear phagocyte system and potential for clinical translation

For decades, nanomedicines have been reported as a potential means to overcome the limitations of conventional drug delivery systems by reducing side effects, toxicity and the non-ideal pharmacokinetic behaviour typically exhibited by small molecule drugs. However, upon administration many nanoparticles prompt induction of host inflammatory responses due to recognition and uptake by macrophages, eliminating up to 95% of the administered dose. While significant advances in nanoparticle engineering and consequent therapeutic efficacy have been made, it is becoming clear that nanoparticle recognition by the mononuclear phagocyte system (MPS) poses an impassable junction in the current framework of nanoparticle development. Hence, this has negative consequences on the clinical translation of nanotechnology with respect to therapeutic efficacy, systemic toxicity and economic benefit. In order to improve the translation of nanomedicines from bench-to-bedside, there is a requirement to either modify nanomedicines in terms of how they interact with intrinsic processes in the body, or modulate the body to be more accommodating for nanomedicine treatments. Here we provide an overview of the current standard for design elements of nanoparticles, as well as factors to consider when producing nanomedicines that have minimal MPS-nanoparticle interactions; we explore this landscape across the cellular to tissue and organ levels. Further, rather than designing materials to suit the body, a growing research niche involves modulating biological responses to administered nanomaterials. We here discuss how developing strategic methods of MPS 'pre-conditioning' with small molecule or biological drugs, as well as implementing strategic dosing regimens, such as 'decoy' nanoparticles, is essential to increasing nanoparticle therapeutic efficacy. By adopting such a perspective, we hope to highlight the increasing trends in research dedicated to improving nanomedicine translation, and subsequently making a positive clinical impact.

Responsive nanomedicines enhanced by or enhancing physical modalities to treat solid cancer tumors: Preclinical and clinical evidence of safety and efficacy

Nanomedicine has improved cancer treatment but not to the extent anticipated. Responsive nanomedicines enhanced by physical modalities (radiation, ultrasounds, alternating magnetic fields) or enhancing the activity of physical modalities such as radiotherapy to kill cancer represents an important approach in improving the safety and anticancer effectiveness. Importantly, the combined treatments have shown promise for the treatment of difficult to treat tumors, such as tumors that are resistant to chemotherapy (multi drug resistant, MDR) or radiotherapy and hypoxic tumors, and for the prevention of tumor metastasis. In this review, the mechanisms of responsive nanomedicines activity enhancement by physical means and vice versa are presented and preclinical and, most importantly, clinical evidence of the safety and efficacy of nanomedicines enhanced by or enhancing by physical modalities in treating solid tumors are critically discussed.

Click and Bioorthogonal Chemistry: The Future of Active Targeting of Nanoparticles for Nanomedicines?

Over the years, click and bioorthogonal reactions have been the subject of considerable research efforts. These high-performance chemical reactions have been developed to meet requirements not often provided by the chemical reactions commonly used today in the biological environment, such as selectivity, rapid reaction rate, and biocompatibility. Click and bioorthogonal reactions have been attracting increasing attention in the biomedical field for the engineering of nanomedicines. In this review, we study a compilation of articles from 2014 to the present, using the terms "click chemistry and nanoparticles (NPs)" to highlight the application of this type of chemistry for applications involving NPs intended for biomedical applications. This study identifies the main strategies offered by click and bioorthogonal chemistry, with respect to passive and active targeting, for NP functionalization with specific and multiple properties for imaging and cancer therapy. In the final part, a novel and promising approach for "two step" targeting of NPs, called pretargeting (PT), is also discussed; the principle of this strategy as well as all the studies listed from 2014 to the present are presented in more detail.

Thermoresponsive Chitosan-Grafted-Poly(N-vinylcaprolactam) Microgels via Ionotropic Gelation for Oncological Applications

Microgels can be considered soft, porous and deformable particles with an internal gel structure swollen by a solvent and an average size between 100 and 1000 nm. Due to their biocompatibility, colloidal stability, their unique dynamicity and the permeability of their architecture, they are emerging as important candidates for drug delivery systems, sensing and biocatalysis. In clinical applications, the research on responsive microgels is aimed at the development of "smart" delivery systems that undergo a critical change in conformation and size in reaction to a change in environmental conditions (temperature, magnetic fields, pH, concentration gradient). Recent achievements in biodegradable polymer fabrication have resulted in new appealing strategies, including the combination of synthetic and natural-origin polymers with inorganic nanoparticles, as well as the possibility of controlling drug release remotely. In this review, we provide a literature review on the use of dual and multi-responsive chitosan-grafted-poly-(N-vinylcaprolactam) (CP) microgels in drug delivery and oncological applications.

NMR diffusometry: A new perspective for nanomedicine exploration

Nuclear Magnetic Resonance (NMR) based diffusion methods open new perspectives for nanomedicine characterization and their bioenvironment interaction understanding. This review summarizes the theoretical background of diffusion phenomena. Self-diffusion and mutual diffusion coefficient notions are featured. Principles, advantages, drawbacks, and key challenges of NMR diffusometry spectroscopic and imaging methods are presented. This review article also gives an overview of representative applicative works to the nanomedicine field that can contribute to elucidate important issues. Examples of in vitro characterizations such as identification of formulated species, process monitoring, drug release follow-up, nanomedicine interactions with biological barriers are presented as well as possible transpositions for studying in vivo nanomedicine fate.

Cancer Nanomedicine and Immune System—Interactions and Challenges

Nanoparticles have tremendous therapeutic potential in the treatment of cancer as they increase drug delivery, attenuate drug toxicity, and protect drugs from rapid clearance. Since Doxil®, the first FDA-approved nanomedicine, several other cancer nanomedicines have been approved and have successfully increased the efficacy over their free drug counterparts. Although their mechanisms of action are well established, their effects towards our immune system, particularly in the tumor microenvironment (TME), still warrant further investigation. Herein, we review the interactions between an approved cancer nanomedicine with TME immunology. We also discuss the challenges that need to be addressed for the full clinical potential of ongoing cancer nanomedicines despite the encouraging preclinical data.

The past, present, and future of breast cancer models for nanomedicine development

Even given recent advances in nanomedicine development of breast cancer treatment in recent years and promising results in pre-clinical models, cancer nanomedicines often fail at the clinical trial stage. Limitations of conventional in vitro models include the lack of representation of the stromal population, the absence of a three-dimensional (3D) structure, and a poor representation of inter-tumor and intra-tumor heterogeneity. Herein, we review those cell culture strategies that aim to overcome these limitations, including cell co-cultures, advanced 3D cell cultures, patient-derived cells, bioprinting, and microfluidics systems. The in vivo evaluation of nanomedicines must consider critical parameters that include the enhanced permeability and retention effect, the host's immune status, and the site of tumor implantation. Here, we critically discuss the advantages and limitations of current in vivo models and report how the improved selection and application of breast cancer models can improve the clinical translation of nanomedicines.

A brief overview about the use of different bioactive liposome-based drug delivery systems in Peritoneal Dialysis and some other diseases

Peritoneal dialysis (PD) is a promising way of treatment used for patients suffering from End-Stage Renal Failure (ESRF). Liposomes are nanocarriers comprised of lipid bilayers encapsulating an aqueous core. Liposomes are extensively used as drug delivery systems and several liposomal nanomedicines have been approved for clinical applications. Nanomedicine constitutes a new direction in peritonitis prevention using peritoneal dialysis (PD). In case of PD; there is a more risk of bacterial infection in the peritoneal cavity along with subcutaneous tunnel and catheter existing site. These infections are the most common complications associated with prolonged peritoneal dialysis (PD) therapy. To prevent such complications, patients used to treat with suitable antibiotic. Nanocarriers consist of assembly of nano-sized vehicles planned to deliver encapsulated/loaded bioactive(s) to the specific target (tissues or organs) and have provided prominent improved therapeutic efficacy for PD patients. The advantage of bioactive loaded nanocarrier has the efficient capacity to deliver at target specific site in PD. This review focuses mainly on the current use of different liposomal encapsulated bioactive compounds in drug delivery systems in the case of PD and other human diseases and briefly highlights the importance and use of different liposomal encapsulated antimicrobial agents to improve the PD technique.

Modified Gold Nanoparticles for Efficient Delivery of Betulinic Acid to Cancer Cell Mitochondria

Advances in nanomedicine have seen the adaptation of nanoparticles (NPs) for subcellular delivery for enhanced therapeutic impact and reduced side effects. The pivotal role of the mitochondria in apoptosis and their potential as a target in cancers enables selective induction of cancer cell death. In this study, we examined the mitochondrial targeted delivery of betulinic acid (BA) by the mitochondriotropic TPP⁺-functionalized epigallocatechin gallate (EGCG)-capped gold NPs (AuNPs), comparing the impact of polyethylene glycol (PEG) and poly-L-lysine-graft-polyethylene glycol (PLL-g-PEG) copolymer on delivery efficacy. This included the assessment of their cellular uptake, mitochondrial localization and efficacy as therapeutic delivery platforms for BA in the human Caco-2, HeLa and MCF-7 cancer cell lines. These mitochondrial-targeted nanocomplexes demonstrated significant inhibition of cancer cell growth, with targeted nanocomplexes recording IC₅₀ values in the range of 3.12–13.2 µM compared to that of the free BA (9.74–36.31 µM) in vitro, demonstrating the merit of mitochondrial targeting. Their mechanisms of action implicated high amplitude mitochondrial depolarization, caspases 3/7 activation, with an associated arrest at the G0/G1 phase of the cell cycle. This nano-delivery system is a potentially viable platform for mitochondrial-targeted delivery of BA and highlights mitochondrial targeting as an option in cancer therapy.

Characterization of Liposomes Using Quantitative Phase Microscopy (QPM)

The rapid development of nanomedicine and drug delivery systems calls for new and effective characterization techniques that can accurately characterize both the properties and the behavior of nanosystems. Standard methods such as dynamic light scattering (DLS) and fluorescent-based assays present challenges in terms of system's instability, machine sensitivity, and loss of tracking ability, among others. In this study, we explore some of the downsides of batch-mode analyses and fluorescent labeling, while introducing quantitative phase microscopy (QPM) as a label-free complimentary characterization technique. Liposomes were used as a model nanocarrier for their therapeutic relevance and structural versatility. A successful immobilization of liposomes in a non-dried setup allowed for static imaging conditions in an off-axis phase microscope. Image reconstruction was then performed with a phase-shifting algorithm providing high spatial resolution. Our results show the potential of QPM to localize subdiffraction-limited liposomes, estimate their size, and track their integrity over time. Moreover, QPM full-field-of-view images enable the estimation of a single-particle-based size distribution, providing an alternative to the batch mode approach. QPM thus overcomes some of the drawbacks of the conventional methods, serving as a relevant complimentary technique in the characterization of nanosystems.

Polyphenols against infectious diseases: Controlled release nano-formulations

The emergence of multi-drug resistant (MDR) pathogens has become a global threat and a cause of significant morbidity and mortality around the world. Natural products have been used as a promising approach to counter the infectious diseases associated with these pathogens. The application of natural products and their derivatives especially polyphenolic compounds as antibacterial agents is an active area of research, and prior studies have successfully treated a variety of bacterial infections using these polyphenolic compounds. However, delivery of polyphenolic compounds has been challenging due to their physicochemical properties and often poor aqueous solubility. In this regard, nanotechnology-based novel drug delivery systems offer many advantages, including improving bioavailability and the controlled release of polyphenolic compounds. This review summarizes the pharmacological mechanism and use of nano-formulations in developing controlled release delivery systems of naturally occurring polyphenols in infectious diseases.

Smart nano-micro platforms for ophthalmological applications: The state-of-the-art and future perspectives

Smart nano-micro platforms have been extensively applied for diverse biomedical applications, mostly focusing on cancer therapy. In comparison with conventional nanotechnology, the smart nano-micro matrix can exhibit specific response to exogenous or endogenous triggers, and thus can achieve multiple functions e.g. site-specific drug delivery, bio-imaging and detection of bio-molecules. These intriguing techniques have expanded into ophthalmology in recent years, yet few works have been summarized in this field. In this work, we provide the state-of-the-art of diverse nano-micro platforms based on both the conventional materials (e.g. natural or synthetic polymers, lipid nanomaterials, metal and metal oxide nanoparticles) and emerging nanomaterials (e.g. up-conversion nanoparticles, quantum dots and carbon materials) in ophthalmology, with some smart nano/micro platformers highlighted. The common ocular diseases studied in the field of nano-micro systems are firstly introduced, and their therapeutic method and the related drawback in clinic treatment are presented. The recent progress of different materials for diverse ocular applications is then demonstrated, with the representative nano- and micro-systems highlighted in detail. At last, an in-depth discussion on the clinical translation challenges faced in this field and the future direction are provided. This review would allow the researchers to design more smart nanomedicines in a more rational manner for specific ophthalmology applications.

Understanding the burst release phenomenon: toward designing effective nanoparticulate drug-delivery systems

Burst release of encapsulated drug with release of a significant fraction of payload into release medium within a short period, both in vitro and in vivo, remains a challenge for translation. Such unpredictable and uncontrolled release is often undesirable, especially from the perspective of developing sustained-release formulations. Moreover, a brisk release of the payload upsets optimal release kinetics. This account strives toward understanding burst release noticed in nanocarriers and investigates its causes. Various mathematical models to explain such untimely release were also examined, including their strengths and weaknesses. Finally, the account revisits current techniques of limiting burst release from nanocarriers and prioritizes future directions that harbor potential of fruitful translation by reducing such occurrences.

Nanomedicines for Subcellular Targeting: The Mitochondrial Perspective

BACKGROUND

Over the past decade, there has been a surge in the number of mitochondrialactive therapeutics for conditions ranging from cancer to aging. Subcellular targeting interventions can modulate adverse intracellular processes unique to the compartments within the cell. However, there is a dearth of reviews focusing on mitochondrial nano-delivery, and this review seeks to fill this gap with regards to nanotherapeutics of the mitochondria.

METHODS

Besides its potential for a higher therapeutic index than targeting at the tissue and cell levels, subcellular targeting takes into account the limitations of systemic drug administration and significantly improves pharmacokinetics. Hence, an extensive literature review was undertaken and salient information was compiled in this review.

RESULTS

From literature, it was evident that nanoparticles with their tunable physicochemical properties have shown potential for efficient therapeutic delivery, with several nanomedicines already approved by the FDA and others in clinical trials. However, strategies for the development of nanomedicines for subcellular targeting are still emerging, with an increased understanding of dysfunctional molecular processes advancing the development of treatment modules. For optimal delivery, the design of an ideal carrier for subcellular delivery must consider the features of the diseased microenvironment. The functional and structural features of the mitochondria in the diseased state are highlighted and potential nano-delivery interventions for treatment and diagnosis are discussed.

CONCLUSION

This review provides an insight into recent advances in subcellular targeting, with a focus on en route barriers to subcellular targeting. The impact of mitochondrial dysfunction in the aetiology of certain diseases is highlighted, and potential therapeutic sites are identified.

Modulating barriers of tumor microenvironment through nanocarrier systems for improved cancer immunotherapy: a review of current status and future perspective

Cancer immunotherapy suppresses and destroys tumors by re-activating and sustaining the tumor-immune process, and thus improving the immune response of the body to the tumor. Immunotherapeutic strategies are showing promising results in pre-clinical and clinical trials, however, tumor microenvironment (TME) is extremely immunosuppressive. Thus, their translation from labs to clinics still faces issues. Recently, nanomaterial-based strategies have been developed to modulate the TME for robust immunotherapeutic responses. The combination of nanotechnology with immunotherapy potentiates the effectiveness of immunotherapy by increasing delivery and retention, and by reducing immunomodulation toxicity. This review aims to highlight the barriers offered by TME for hindering the efficiency of immunotherapy for cancer treatment. Next, we highlight various nano-carriers based strategies for modulating those barriers for achieving better therapeutic efficacy of cancer immunotherapy with higher safety. This review will add to the body of scientific knowledge and will be a good reference material for academia and industries.

Following the Fate of Dye-Containing Liposomes In Vitro

The rather limited success of translation from basic research to clinical application has been highlighted as a major issue in the nanomedicine field. To identify the factors influencing the applicability of nanosystems as drug carriers and potential nanomedicine, we focused on following their fate through fluorescence-based assays, namely flow cytometry and imaging. These methods are often used to follow the nanocarrier internalization and targeting; however, the validity of the obtained results strictly depends on how much the nanosystem’s fate can be inferred from the fate of fluorescent dyes. To evaluate the parameters that affect the physicochemical and biological stability of the labeled nanosystems, we studied the versatility of two lipid dyes, TopFluor^®-PC and Cy5-DSPE, in conventional liposomes utilizing well-defined in vitro assays. Our results suggest that the dye can affect the major characteristics of the system, such as vesicle size and zeta-potential. However, a nanocarrier can also affect the dye properties. Medium, temperature, time, fluorophore localization and its concentration, as well as their interplay, affect the outcome of tracing experiments. Therefore, an in-depth characterization of the labeled nanosystem should be fundamental to understand the conditions that validate the results within the screening process in optimization of nanocarrier.

Gene Therapy in Cancer Treatment: Why Go Nano?

The proposal of gene therapy to tackle cancer development has been instrumental for the development of novel approaches and strategies to fight this disease, but the efficacy of the proposed strategies has still fallen short of delivering the full potential of gene therapy in the clinic. Despite the plethora of gene modulation approaches, e.g., gene silencing, antisense therapy, RNA interference, gene and genome editing, finding a way to efficiently deliver these effectors to the desired cell and tissue has been a challenge. Nanomedicine has put forward several innovative platforms to overcome this obstacle. Most of these platforms rely on the application of nanoscale structures, with particular focus on nanoparticles. Herein, we review the current trends on the use of nanoparticles designed for cancer gene therapy, including inorganic, organic, or biological (e.g., exosomes) variants, in clinical development and their progress towards clinical applications.

Subchronic and chronic toxicity evaluation of inorganic nanoparticles for delivery applications

Inorganic nanoparticles provide the opportunity to localize bioactive agents to the target sites and protect them from degradation. In many cases, acute toxicities of inorganic nanoparticles used for delivery applications have been investigated. However, little information is available regarding the long-term toxicity of such materials. This review focuses on the importance of subchronic and chronic toxicity assessment of inorganic nanoparticles investigated for delivery applications. We have attempted to provide a comprehensive review of the available literature for chronic toxicity assessment of inorganic nanoparticles. Where possible correlations are made between particle composition, physiochemical properties, duration, frequency and route of administration, as well as the sex of animals, with tissue and blood toxicity, immunotoxicity and genotoxicity. A critical gap analysis is provided and important factors that need to be considered for long-term toxicology of inorganic nanoparticles are discussed.

Towards more accurate bioimaging of drug nanocarriers: turning aggregation-caused quenching into a useful tool

One of the current challenges in the monitoring of drug nanocarriers lies in the difficulties in discriminating the carrier-bound signals from the bulk signals of probes. Environment-responsive probes that enable signal switching are making steps towards a solution to this problem. Aggregation-caused quenching (ACQ), a phenomenon generally regarded as unfavorable in bioimaging, has turned out to be a promising characteristic for achieving environment-responsiveness and eliminating free-probe interference. So-called ACQ probes emit fluorescence when dispersed molecularly within the carrier matrix but quench immediately and absolutely once they are released into the ambient aqueous environment upon the degradation of the nanocarriers. Therefore, the fluorescence observed represents integral nanocarriers. Based on this rationale, the in vivo fates of various nanocarriers have been explored using live imaging equipment, with very interesting findings revealing the role of the particles. The current applications are however restricted to nanocarriers with highly hydrophobic matrices (lipid or polyester nanoparticles) or with a hydrophobic core-hydrophilic shell structure (micelles). The ACQ-based bioimaging strategy is emerging as a promising tool to achieve more accurate bioimaging of drug nanocarriers. This review article provides an overview of the ACQ phenomenon and the rationale for and examples of applications, as well as the limitations of the ACQ-based strategy, with a focus on improving the accuracy of bioimaging of nanoparticles.

Raloxifene nano-micelles effect on triple-negative breast cancer is mediated through estrogen receptor-β and epidermal growth factor receptor

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that differs in progression, recurrence, and prognosis from other forms of breast cancer. The heterogeneity of TNBC has remained a challenge as no targeted therapy is currently available. Previously, we and others have demonstrated that raloxifene, a selective oestrogen receptor modulator, was also acting independently of the oestrogen receptor-α. However, raloxifene is characterised by a low bioavailability in vivo. Thus, we encapsulated raloxifene into a styrene-maleic acid (SMA) micelle to improve its pharmacokinetics. The micellar raloxifene had higher cytotoxicity when compared to the free formulation, promoted a higher cellular uptake and affected critical signalling pathways. Furthermore, SMA-raloxifene reduced TNBC tumour growth more efficiently than free raloxifene. Finally, we showed that this effect was partially mediated through oestrogen receptor-β. In conclusion, we have provided new insight into the role of raloxifene nanoformulation in improving the management of TNBC.

The Effect of Silver Nanoparticles on Learning, Memory and Social Interaction in BALB/C Mice

Silver Nanoparticles (AgNPs), an epitome of nanotechnology, appear in everyday products such as water filters, printer ink, toothpaste, food packaging and cosmetics mostly due to their bactericidal properties. Given this high level of public exposure, the safety of AgNPs has never been fully established. The unsafe use of AgNPs could pose a real threat, not only to public health but also to economic growth in many industries. In this paper, we tested the effect of AgNPs on memory, learning, social behaviour and motor function of BALB/C mice. Outcomes of the present study suggested an impairment of these functions in AgNPs treated groups. Overall, obtained data support the evidence that the systemic exposure to AgNPs may result in alteration of the cerebral cognition and warrants further consideration on the impact of the AgNPs on human health with respect to their potential neurotoxicity.

Curcumin⁻Copper Complex Nanoparticles for the Management of Triple-Negative Breast Cancer

Breast cancer is the most common cancer diagnosed among females worldwide. Although breast cancer survival has largely improved in the past 30 years, it remains highly heterogeneous in its response to treatment. Triple-negative breast cancer (TNBC) is a subtype of breast cancer that lacks the expression of the estrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor-2 (Her2). While TNBC may initially be responsive to chemotherapy, recurrence and subsequent high mortality rates are frequently reported. Studies have shown curcumin and its derivatives to be effective against TNBC cell lines in vitro. To improve its anti-cancer effects, we have synthesized Fe³⁺⁻curcumin (Fe⁻Cur₃) and Cu²⁺⁻curcumin (CD) complexes and investigated them experimentally. Further, CD was encapsulated into a poly(styrene)-co-maleic acid (SMA) micelle to enhance its stability. We assessed the cytotoxicity of these formulations both in vitro and in vivo. SMA⁻CD demonstrated dose-dependent cytotoxicity and abolished TNBC tumor growth in vivo. The encapsulation of the curcumin⁻copper complex improved its anti-cancer activity without overt adverse effects in a murine model of TNBC. These results provide evidence and insights into the value of nanoformulations in enhancing drug-delivery and increasing the potential therapeutic efficacy of curcumin derivatives.

Novel Structural Insight into Inhibitors of Heme Oxygenase-1 (HO-1) by New Imidazole-Based Compounds: Biochemical and In Vitro Anticancer Activity Evaluation

In this paper, the design, synthesis, and molecular modeling of a new azole-based HO-1 inhibitors was reported, using compound 1 as a lead compound, in which an imidazole moiety is linked to a hydrophobic group by means of an ethanolic spacer. The tested compounds showed a good inhibitor activity and possessed IC₅₀ values in the micromolar range. These results were obtained by targeting the hydrophobic western region. Molecular modeling studies confirmed a consolidated binding mode in which the nitrogen of the imidazolyl moiety coordinated the heme ferrous iron, meanwhile the hydrophobic groups were located in the western region of HO-1 binding pocket. Moreover, the new compounds were screened for in silico ADME-Tox properties to predict drug-like behavior with convincing results. Finally, the in vitro antitumor activity profile of compound 1 was investigated in different cancer cell lines and nanomicellar formulation was synthesized with the aim of improving compound's 1 water solubility. Finally, compound 1 was tested in melanoma cells in combination with doxorubicin showing interesting synergic activity.

Tumor targeting via EPR: Strategies to enhance patient responses

The tumor accumulation of nanomedicines relies on the enhanced permeability and retention (EPR) effect. In the last 5-10 years, it has been increasingly recognized that there is a large inter- and intra-individual heterogeneity in EPR-mediated tumor targeting, explaining the heterogeneous outcomes of clinical trials in which nanomedicine formulations have been evaluated. To address this heterogeneity, as in other areas of oncology drug development, we have to move away from a one-size-fits-all tumor targeting approach, towards methods that can be employed to individualize and improve nanomedicine treatments. To this end, efforts have to be invested in better understanding the nature, the complexity and the heterogeneity of the EPR effect, and in establishing systems and strategies to enhance, combine, bypass and image EPR-based tumor targeting. In the present manuscript, we summarize key studies in which these strategies are explored, and we discuss how these approaches can be employed to enhance patient responses.

Recent and future advances in anticancer drug delivery: an interview with Khaled Greish

Khaled Greish speaks to Hannah Makin, Commissioning Editor: Khaled Greish is Associate Professor of Molecular Medicine, and head of the Nano-research unit, at Princes Al-Jawhara Center, Arabian Gulf University, Kingdom of Bahrain. His previous appointments included Senior lecturer of Pharmacology at the University of Otago, New Zealand, and Assistant Professor of Pharmaceutical Chemistry at University of Utah (UT, USA). He has published >70 peer reviewed papers, and ten book chapters in the field of targeted anticancer drug delivery. Controlled Release Society (CRS) awarded him the CRS Postdoctoral Achievement Award in 2008 and in 2010; he was elected as member of the CRS College of Fellows. In recognition of his research, University of Otago awarded him "Early Career Awards for Distinction in Research" in 2014. His research focuses on nanomedicine, tumor vascular biology and anticancer drug discovery/development.