Reactive Oxygen Species-Biodegradable Gene Carrier for the Targeting Therapy of Breast Cancer

Navigating the intricate in-vivo journey of lipid nanoparticles tailored for the targeted delivery of RNA therapeutics: a quality-by-design approach

RNA therapeutics, such as mRNA, siRNA, and CRISPR-Cas9, present exciting avenues for treating diverse diseases. However, their potential is commonly hindered by vulnerability to degradation and poor cellular uptake, requiring effective delivery systems. Lipid nanoparticles (LNPs) have emerged as a leading choice for in vivo RNA delivery, offering protection against degradation, enhanced cellular uptake, and facilitation of endosomal escape. However, LNPs encounter numerous challenges for targeted RNA delivery in vivo, demanding advanced particle engineering, surface functionalization with targeting ligands, and a profound comprehension of the biological milieu in which they function. This review explores the structural and physicochemical characteristics of LNPs, in-vivo fate, and customization for RNA therapeutics. We highlight the quality-by-design (QbD) approach for targeted delivery beyond the liver, focusing on biodistribution, immunogenicity, and toxicity. In addition, we explored the current challenges and strategies associated with LNPs for in-vivo RNA delivery, such as ensuring repeated-dose efficacy, safety, and tissue-specific gene delivery. Furthermore, we provide insights into the current clinical applications in various classes of diseases and finally prospects of LNPs in RNA therapeutics.

Demystifying the management of cancer through smart nano-biomedicine via regulation of reactive oxygen species

Advancements in therapeutic strategies and combinatorial approaches for cancer management have led to the majority of cancers in the initial stages to be regarded as treatable and curable. However, certain high-grade cancers in the initial stages are still regarded as chronic and difficult to manage, requiring novel therapeutic strategies. In this era of targeted and precision therapy, novel strategies for targeted delivery of drug and synergistic therapies, integrating nanotherapeutics, polymeric materials, and modulation of the tumor microenvironment are being developed. One such strategy is the study and utilization of smart-nano biomedicine, which refers to stimuli-responsive polymeric materials integrated with the anti-cancer drug that can modulate the reactive oxygen species (ROS) in the tumor microenvironment or can be ROS responsive for the mitigation as well as management of various cancers. The article explores in detail the ROS, its types, and sources; the antioxidant system, including scavengers and their role in cancer; the ROS-responsive targeted polymeric materials, including synergistic therapies for the treatment of cancer via modulating the ROS in the tumor microenvironment, involving therapeutic strategies promoting cancer cell death; and the current landscape and future prospects.

Redox-Responsive Polymeric Nanoparticle for Nucleic Acid Delivery and Cancer Therapy: Progress, Opportunities, and Challenges

Cancer development and progression of cancer are closely associated with the activation of oncogenes and loss of tumor suppressor genes. Nucleic acid drugs (e.g., siRNA, mRNA, and DNA) are widely used for cancer therapy due to their specific ability to regulate the expression of any cancer-associated genes. However, nucleic acid drugs are negatively charged biomacromolecules that are susceptible to serum nucleases and cannot cross cell membrane. Therefore, specific delivery tools are required to facilitate the intracellular delivery of nucleic acid drugs. In the past few decades, a variety of nanoparticles (NPs) are designed and developed for nucleic acid delivery and cancer therapy. In particular, the polymeric NPs in response to the abnormal redox status in cancer cells have garnered much more attention as their potential in redox-triggered nanostructure dissociation and rapid intracellular release of nucleic acid drugs. In this review, the important genes or signaling pathways regulating the abnormal redox status in cancer cells are briefly introduced and the recent development of redox-responsive NPs for nucleic acid delivery and cancer therapy is systemically summarized. The future development of NPs-mediated nucleic acid delivery and their challenges in clinical translation are also discussed.

Structural Determinants of Stimuli-Responsiveness in Amphiphilic Macromolecular Nano-assemblies

Stimuli-responsive nano-assemblies from amphiphilic macromolecules could undergo controlled structural transformations and generate diverse macroscopic phenomenon under stimuli. Due to the controllable responsiveness, they have been applied for broad material and biomedical applications, such as biologics delivery, sensing, imaging, and catalysis. Understanding the mechanisms of the assembly-disassembly processes and structural determinants behind the responsive properties is fundamentally important for designing the next generation of nano-assemblies with programmable responsiveness. In this review, we focus on structural determinants of assemblies from amphiphilic macromolecules and their macromolecular level alterations under stimuli, such as the disruption of hydrophilic-lipophilic balance (HLB), depolymerization, decrosslinking, and changes of molecular packing in assemblies, which eventually lead to a series of macroscopic phenomenon for practical purposes. Applications of stimuli-responsive nano-assemblies in delivery, sensing and imaging were also summarized based on their structural features. We expect this review could provide readers an overview of the structural considerations in the design and applications of nanoassemblies and incentivize more explorations in stimuli-responsive soft matters.

Advances and Challenges of Stimuli-Responsive Nucleic Acids Delivery System in Gene Therapy

Gene therapy has emerged as a powerful tool to treat various diseases, such as cardiovascular diseases, neurological diseases, ocular diseases and cancer diseases. In 2018, the FDA approved Patisiran (the siRNA therapeutic) for treating amyloidosis. Compared with traditional drugs, gene therapy can directly correct the disease-related genes at the genetic level, which guarantees a sustained effect. However, nucleic acids are unstable in circulation and have short half-lives. They cannot pass through biological membranes due to their high molecular weight and massive negative charges. To facilitate the delivery of nucleic acids, it is crucial to develop a suitable delivery strategy. The rapid development of delivery systems has brought light to the gene delivery field, which can overcome multiple extracellular and intracellular barriers that prevent the efficient delivery of nucleic acids. Moreover, the emergence of stimuli-responsive delivery systems has made it possible to control the release of nucleic acids in an intelligent manner and to precisely guide the therapeutic nucleic acids to the target site. Considering the unique properties of stimuli-responsive delivery systems, various stimuli-responsive nanocarriers have been developed. For example, taking advantage of the physiological variations of a tumor (pH, redox and enzymes), various biostimuli- or endogenous stimuli-responsive delivery systems have been fabricated to control the gene delivery processes in an intelligent manner. In addition, other external stimuli, such as light, magnetic fields and ultrasound, have also been employed to construct stimuli-responsive nanocarriers. Nevertheless, most stimuli-responsive delivery systems are in the preclinical stage, and some critical issues remain to be solved for advancing the clinical translation of these nanocarriers, such as the unsatisfactory transfection efficiency, safety issues, complexity of manufacturing and off-target effects. The purpose of this review is to elaborate the principles of stimuli-responsive nanocarriers and to emphasize the most influential advances of stimuli-responsive gene delivery systems. Current challenges of their clinical translation and corresponding solutions will also be highlighted, which will accelerate the translation of stimuli-responsive nanocarriers and advance the development of gene therapy.

Reactive oxygen species-responsive polymer drug delivery systems

Applying reactive polymer materials sensitive to biological stimuli has recently attracted extensive research interest. The special physiological effects of reactive oxygen species (ROS) on tumors or inflammation and the application of ROS-responsive polymers as drug-delivery systems in organisms have attracted much attention. ROS is a vital disease signal molecule, and the unique accumulation of ROS-responsive polymers in pathological sites may enable ROS-responsive polymers to deliver payload (such as drugs, ROS-responsive prodrugs, and gene therapy fragments) in a targeted fashion. In this paper, the research progress of ROS-responsive polymers and their application in recent years were summarized and analyzed. The research progress of ROS-responsive polymers was reviewed from the perspective of nanoparticle drug delivery systems, multi-responsive delivery systems, and ROS-responsive hydrogels. It is expected that our work will help understand the future development trends in this field.

Polymeric Carriers for Delivery of RNA Cancer Therapeutics

As research uncovers the underpinnings of cancer biology, new targeted therapies have been developed. Many of these therapies are small molecules, such as kinase inhibitors, that target specific proteins; however, only 1% of the genome encodes for proteins and only a subset of these proteins has ‘druggable’ active binding sites. In recent decades, RNA therapeutics have gained popularity due to their ability to affect targets that small molecules cannot. Additionally, they can be manufactured more rapidly and cost-effectively than small molecules or recombinant proteins. RNA therapeutics can be synthesised chemically and altered quickly, which can enable a more personalised approach to cancer treatment. Even though a wide range of RNA therapeutics are being developed for various indications in the oncology setting, none has reached the clinic to date. One of the main reasons for this is attributed to the lack of safe and effective delivery systems for this type of therapeutic. This review focuses on current strategies to overcome these challenges and enable the clinical utility of these novel therapeutic agents in the cancer clinic.

Reactive oxygen species-responsive RNA interference

Due to oxidative instability, arylboronic acids are not compatible with the solid-phase synthesis of nucleic acids. We solved this problem and, based on these findings, developed siRNA prodrugs activated in the presence of reactive oxygen species (ROS) in vivo. These prodrugs can be used for specific targeting of ROS-rich cancer cells.

Doxorubicin-loaded graphene oxide nanocomposites in cancer medicine: Stimuli-responsive carriers, co-delivery and suppressing resistance

INTRODUCTION

The application of doxorubicin (DOX) in cancer therapy has been limited due to its drug resistance and poor internalization. Graphene oxide (GO) nanostructures have the capacity for DOX delivery while promoting its cytotoxicity in cancer.

AREAS COVERED

The favorable characteristics of GO nanocomposites, preparation method, and application in cancer therapy are described. Then, DOX resistance in cancer is discussed. The GO-mediated photothermal therapy and DOX delivery for cancer suppression are described. Preparation of stimuli-responsive GO nanocomposites, surface functionalization, hybrid nanoparticles, and theranostic applications are emphasized in DOX chemotherapy.

EXPERT OPINION

Graphene oxide nanoparticle-based photothermal therapy maximizes the anti-cancer activity of DOX against cancer cells. Apart from DOX delivery, GO nanomaterials are capable of loading anti-cancer agents and genetic tools to minimize drug resistance and enhance the cytolytic impact of DOX in cancer eradication. To enhance DOX accumulation in cancer cells, stimuli-responsive (redox-, light-, enzyme- and pH-sensitive) GO nanoparticles have been developed for DOX delivery. Further development of targeted delivery of DOX-loaded GO nanomaterials against cancer cells may be achieved by surface modification of polymers such as polyethylene glycol, hyaluronic acid, and chitosan. Doxorubicin-loaded GO nanoparticles have demonstrated theranostic potential for simultaneous diagnosis and therapy. Hybridization of GO with other nanocarriers such as silica and gold nanoparticles further broadens their potential anti-cancer therapy applications.

Ultrasound-Enhanced Reactive Oxygen Species Responsive Charge-Reversal Polymeric Nanocarriers for Efficient Pancreatic Cancer Gene Delivery

Inefficient intracellular gene release and transfection limit nonviral gene delivery applications in cancer therapy. Reactive oxygen species (ROS) responsive nonviral gene delivery is the most widely explored strategy for such applications, yet the development of fast and safe ROS responsive nanocarriers proves to be a challenge because of the intracellular chemical equilibrium of high ROS and glutathione levels. Here, we report an ultrasound-enhanced ROS responsive charge-reversal polymeric nanocarrier (BTIL) for fast and efficient pancreatic cancer gene delivery. The BTIL is composed of B-PDEAEA/DNA polyplex-based cores and IR780-loaded liposome coatings. The IR780 is able to produce an excess of ROS under low intensity ultrasound irradiation, thus disequilibrating the chemical equilibrium of ROS and glutathione, and promoting the ROS-responsive positive-to-negative charge-reversal of the B-PDEAEA polymer. This charge conversion results in fast polyplex dissociation and intracellular gene release, inducing efficient gene transfection and cancer cell apoptosis. Moreover, following the intravenous administration, BTIL maintains a stable and long circulation in the bloodstream, achieves orthotopic pancreatic ductal adenocarcinoma distribution, and exhibits potent antitumor activity with negligible side effects. Our results reveal the proposed strategy to be both promising and universal for the development of fast and safe ROS responsive nonviral gene delivery in cancer therapy.

A Degradable, Broad-Spectrum and Resistance-Resistant Antimicrobial Oligoguanidine as Disinfecting and Therapeutic Agent in Aquaculture

The threat of antibiotic resistance to community healthcare and global economy has raised extensive concern, and the over-use of antibiotics in animal husbandry plays a significant role in the occurrence...

Current understandings and clinical translation of nanomedicines for breast cancer therapy

Breast cancer is one of the most frequently diagnosed cancers that is threatening women's life. Current clinical treatment regimens for breast cancer often involve neoadjuvant and adjuvant systemic therapies, which somewhat are associated with unfavorable features. Also, the heterogeneous nature of breast cancers requires precision medicine that cannot be fulfilled by a single type of systemically administered drug. Taking advantage of the nanocarriers, nanomedicines emerge as promising therapeutic agents for breast cancer that could resolve the defects of drugs and achieve precise drug delivery to almost all sites of primary and metastatic breast tumors (e.g. tumor vasculature, tumor stroma components, breast cancer cells, and some immune cells). Seven nanomedicines as represented by Doxil® have been approved for breast cancer clinical treatment so far. More nanomedicines including both non-targeting and active targeting nanomedicines are being evaluated in the clinical trials. However, we have to realize that the translation of nanomedicines, particularly the active targeting nanomedicines is not as successful as people have expected. This review provides a comprehensive landscape of the nanomedicines for breast cancer treatment, from laboratory investigations to clinical applications. We also highlight the key advances in the understanding of the biological fate and the targeting strategies of breast cancer nanomedicine and the implications to clinical translation.

Tumor microenvironment-responsive dynamic inorganic nanoassemblies for cancer imaging and treatment

Dynamic inorganic nanoassemblies (DINAs) have emerged as smart nanomedicine platforms with promising potential for bioimaging and targeted drug delivery. In this review, we keep abreast of the advances in development of tumor microenvironment (TME)-responsive DINAs to meet the challenges associated with precise cancer therapy. TME-responsive DINAs are designed to achieve precise switches of structures/functions in response to TME-specific stimuli including reactive oxygen species (ROS), reduced pH and hypoxia, so as to enhance the tumor accumulation of nanoassemblies, overcome the biological barriers during intratumoral penentration of therapeutics, and achieve tumor-specific imaging and therapy. This progress report will summarize various types of recently reported smart DINAs for TME-responsive tumor imaging and therapy. Their future development towards potential clinical translation will also be discussed.

Treatment of GM2 Gangliosidosis in Adult Sandhoff Mice using an Intravenous Self-Complementary Hexosaminidase Vector

BACKGROUND

GM2 gangliosidosis is a neurodegenerative, lysosomal storage disease caused by the deficiency of β-hexosaminidase A enzyme (HexA), an α/β-subunit heterodimer. A novel variant of the human hexosaminidase α-subunit, coded by HEXM, has previously been shown to form a stable homodimer, HexM, that hydrolyzes GM2 gangliosides (GM2) in vivo.

MATERIALS & METHODS

The current study assessed the efficacy of intravenous (IV) delivery of a self-complementary adeno-associated virus serotype 9 (scAAV9) vector incorporating the HEXM transgene, scAAV9/HEXM, including the outcomes based on the dosages provided to the Sandhoff (SD) mice. Six-week-old SD mice were injected with either 2.5E+12 vector genomes (low dose, LD) or 1.0E+13 vg (high dose, HD). We hypothesized that when examining the dosage comparison for scAAV9/HEXM in adult SD mice, the HD group would have more beneficial outcomes than the LD cohort. Assessments included survival, behavioral outcomes, vector biodistribution, and enzyme activity within the central nervous system.

RESULTS

Toxicity was observed in the HD cohort, with 8 of 14 mice dying within one month of the injection. As compared to untreated SD mice, which have typical survival of 16 weeks, the LD cohort and the remaining HD mice had a significant survival benefit with an average/median survival of 40.6/34.5 and 55.9/56.7 weeks, respectively. Significant behavioral, biochemical and molecular benefits were also observed. The second aim of the study was to investigate the effects of IV mannitol infusions on the biodistribution of the LD scAAV9/HEXM vector and the survival of the SD mice. Increases in both the biodistribution of the vector as well as the survival benefit (average/median of 41.6/49.3 weeks) were observed.

CONCLUSION

These results demonstrate the potential benefit and critical limitations of the treatment of GM2 gangliosidosis using IV delivered AAV vectors.

Targeted Delivery of CRISPR/Cas13 as a Promising Therapeutic Approach to Treat SARS-CoV-2

On a worldwide scale, the outbreak of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has led to extensive damage to the health system as well as the global economy. Hitherto, there has been no approved drug or vaccine for this disease. Therefore, the use of general antiviral drugs is at the first line of treatment, though complicated with limited effectiveness and systemic side effects. Given the pathophysiology of the disease, researchers have proposed various strategies not only to find a more specific therapeutic way but also to reduce the side effects. One strategy to accomplish these goals is to use CRISPR/Cas13 system. Recently, a group of scientists has used the CRISPR/Cas13 system, which is highly effective in eliminating the genome of RNA viruses. Due to the RNA nature of the coronavirus genome, it seems that this system can be effective against the disease. The main challenge regarding the application of this system is to deliver it to the target cells efficiently. To solve this challenge, it seems that using virosomes with protein S on their membrane surface can be helpful. Studies have shown that protein S interacts with its specific receptor in target cells named Angiotensin-Converting Enzyme 2 (ACE2). Here, we propose if CRISPR/Cas13 gene constructs reach the infected cells efficiently using a virosomal delivery system, the virus genome will be cleaved and inactivated. Considering the pathophysiology of the disease, an important step to implement this hypothesis is to embed protein S on the membrane surface of virosomes to facilitate the delivery of gene constructs to the target cells.

Recent Advances in Stimulus-Responsive Nanocarriers for Gene Therapy

Gene therapy provides a promising strategy for curing monogenetic disorders and complex diseases. However, there are challenges associated with the use of viral delivery vectors. The advent of nanomedicine represents a quantum leap in the application of gene therapy. Recent advances in stimulus-responsive nonviral nanocarriers indicate that they are efficient delivery systems for loading and unloading of therapeutic nucleic acids. Some nanocarriers are responsive to cues derived from the internal environment, such as changes in pH, redox potential, enzyme activity, reactive oxygen species, adenosine triphosphate, and hypoxia. Others are responsive to external stimulations, including temperature gradients, light irradiation, ultrasonic energy, and magnetic field. Multiple stimuli-responsive strategies have also been investigated recently for experimental gene therapy.

Reactive oxygen species-responsive nanoplatforms for nucleic acid-based gene therapy of cancer and inflammatory diseases

Nucleic acid-based gene therapy has recently made important progress toward clinical implementation, and holds tremendous promise for the treatment of some life-threatening diseases, such as cancer and inflammation. However, the on-demand delivery of nucleic acid therapeutics in target cells remains highly challenging. The development of delivery systems responsive to specific pathological cues of diseases is expected to offer promising alternatives for overcoming this problem. Among them, the reactive oxygen species (ROS)-responsive delivery systems, which in response to elevated ROS in cancer cells or activated inflammatory cells, can deliver nucleic acid therapeutics on-demand via ROS-induced structural and assembly behavior changes, constitute a promising approach for cancer and anti-inflammation therapies. In this short review, we briefly introduce the ROS-responsive chemical structures, ROS-induced release mechanisms and some representative examples to highlight the current progress in constructing ROS-responsive delivery systems. We aim to provide new insights into the rational design of on-demand gene delivery vectors.

Implantable and Injectable Biomaterial Scaffolds for Cancer Immunotherapy

Cancer immunotherapy has become an emerging strategy recently producing durable immune responses in patients with varieties of malignant tumors. However, the main limitation for the broad application of immunotherapies still to reduce side effects by controlling and regulating the immune system. In order to improve both efficacy and safety, biomaterials have been applied to immunotherapies for the specific modulation of immune cells and the immunosuppressive tumor microenvironment. Recently, researchers have constantly developed biomaterials with new structures, properties and functions. This review provides the most recent advances in the delivery strategies of immunotherapies based on localized biomaterials, focusing on the implantable and injectable biomaterial scaffolds. Finally, the challenges and prospects of applying implantable and injectable biomaterial scaffolds in the development of future cancer immunotherapies are discussed.

Redox-Responsive Self-Assembled Nanoparticles for Cancer Therapy

Chemotherapy, combined with other treatments, is widely applied in the clinical treatment of cancer. However, deficiencies inherited from the traditional route of administration limit its successful application. With the development of nanotechnology, a series of smart nanodelivery systems have been developed to utilize the unique tumor environment (pH changes, different enzymes, and redox potential gradients) and exogenous stimuli (thermal changes, magnetic fields, and light) to improve the curative effect of anticancer drugs. In this review, endogenous and exogenous stimuli are briefly introduced. Among these stimuli, various redox-sensitive linkages are primarily described in detail, and their application with self-assembled nanoparticles is recounted. Finally, the application of redox-responsive self-assembled nanoparticles in cancer therapy is summarized.

In vivo gene delivery mediated by non-viral vectors for cancer therapy

Gene therapy by expression constructs or down-regulation of certain genes has shown great potential for the treatment of various diseases. The wide clinical application of nucleic acid materials dependents on the development of biocompatible gene carriers. There are enormous various compounds widely investigated to be used as non-viral gene carriers including lipids, polymers, carbon materials, and inorganic structures. In this review, we will discuss the recent discoveries on non-viral gene delivery systems. We will also highlight the in vivo gene delivery mediated by non-viral vectors to treat cancer in different tissue and organs including brain, breast, lung, liver, stomach, and prostate. Finally, we will delineate the state-of-the-art and promising perspective of in vivo gene editing using non-viral nano-vectors.

Tumor microenvironment-induced structure changing drug/gene delivery system for overcoming delivery-associated challenges

Nano-drug/gene delivery systems (DDS) are powerful weapons for the targeted delivery of various therapeutic molecules in treatment of tumors. Nano systems are being extensively investigated for drug and gene delivery applications because of their exceptional ability to protect the payload from degradation in vivo, prolong circulation of the nanoparticles (NPs), realize controlled release of the contents, reduce side effects, and enhance targeted delivery among others. However, the specific properties required for a DDS vary at different phase of the complex delivery process, and these requirements are often conflicting, including the surface charge, particle size, and stability of DDS, which severely reduces the efficiency of the drug/gene delivery. Therefore, researchers have attempted to fabricate structure, size, or charge changeable DDS by introducing various tumor microenvironment (TME) stimuli-responsive elements into the DDS to meet the varying requirements at different phases of the delivery process, thus improving drug/gene delivery efficiency. This paper summarizes the most recent developments in TME stimuli-responsive DDS and addresses the aforementioned challenges.

Novel AIEgen-Functionalized Diselenide-Crosslinked Polymer Gels as Fluorescent Probes and Drug Release Carriers

Stimuli-responsive functional gels have shown significant potential for application in biosensing and drug release systems. In this study, aggregation-induced emission luminogen (AIEgen)-functionalized, diselenide-crosslinked polymer gels were synthesized via free radical copolymerization. A series of polymer gels with different crosslink densities or tetraphenylethylene (TPE) contents were synthesized. The diselenide crosslinker in the gels could be fragmented in the presence of H2O2 or dithiothreitol (DTT) due to its redox-responsive property. Thus, the TPE-containing polymer chains were released into the aqueous solution. As a result, the aqueous solution exhibited enhanced fluorescence emission due to the strong hydrophobicity of TPE. The degradation of polymer gels and fluorescence enhancement in an aqueous solution under different H2O2 or DTT concentrations were studied. Furthermore, the polymer gels could be used as drug carriers, suggesting a visual drug release process under the action of external redox agents. The AIEgen-functionalized, diselenide-crosslinked polymer gels hold great potential in the biomedical area for biosensing and controlled drug delivery.

Theranostic small interfering RNA nanoparticles in cancer precision nanomedicine

Due to their ability to effectively downregulate the expression of target genes, small interfering RNA (siRNA) have emerged as promising candidates for precision medicine in cancer. Although some siRNA-based treatments have advanced to clinical trials, challenges such as poor stability during circulation, and less than optimal pharmacokinetics and biodistribution of siRNA in vivo present barriers to the systemic delivery of siRNA. In recent years, theranostic nanomedicine integrating siRNA delivery has attracted significant attention for precision medicine. Theranostic nanomedicine takes advantage of the high capacity of nanoplatforms to ferry cargo with imaging and therapeutic capabilities. These theranostic nanoplatforms have the potential to play a major role in gene specific treatments. Here we have reviewed recent advances in the use of theranostic nanoplatforms to deliver siRNA, and discussed the opportunities as well as challenges associated with this exciting technology. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Biodegradable Polymers for Gene Delivery

The cellular transport process of DNA is hampered by cell membrane barriers, and hence, a delivery vehicle is essential for realizing the potential benefits of gene therapy to combat a variety of genetic diseases. Virus-based vehicles are effective, although immunogenicity, toxicity and cancer formation are among the major limitations of this approach. Cationic polymers, such as polyethyleneimine are capable of condensing DNA to nanoparticles and facilitate gene delivery. Lack of biodegradation of polymeric gene delivery vehicles poses significant toxicity because of the accumulation of polymers in the tissue. Many attempts have been made to develop biodegradable polymers for gene delivery by modifying existing polymers and/or using natural biodegradable polymers. This review summarizes mechanistic aspects of gene delivery and the development of biodegradable polymers for gene delivery.

Light-Induced Production of Reactive Oxygen Species by a Novel Water-Soluble Benzophenone Derivative Containing Quaternary Ammonium Groups and Its Assembly on the Protein Fiber Surface

Developing an efficient antimicrobial surface has important significance in the field of advanced biomaterials. A novel water-soluble benzophenone tetracarboxylamine derivative containing two quaternary ammonium groups, 3,3'-[4,4'-carbonyl-diphthalimide-]-bis(N-benzyl-N,N-dimethyl-N-propyl-1-aminium)dichloride (BPTCA-N), as a photoactive antibacterial agent was designed and synthesized. The ability of BPTCA-N to generate reactive oxygen species (ROS) in solution was investigated by light-induced activity. Its antibacterial activity in a dark environment or UV exposure was tested on Staphylococcus aureus and Escherichia coli. The influences of different solvents and the pH values on the ability of BPTCA-N to generate ROS were also discussed. BPTCA-N possessed high photoactivity and efficient ROS generation ability. The generation of hydroxyl radicals could be greatly affected by addition of other solvents and H⁺ or OH^-. For the BPTCA-N solution at a concentration of 0.2 mmol/L, the reduction of S. aureus and E. coli could all reach 99.99%. The BPTCA-N compound was assembled onto wool protein fibers. The modified protein fabrics also showed excellent photoactivity and antibacterial property against S. aureus and E. coli. For the wool fabric modified with 30 g/L of BPTCA-N, the reduction of S. aureus could reach 99.91% and that of E. coli was 91.23%. BPTCA-N had the synergistic antibacterial effect of quaternary ammonium salt and benzophenones. It has potential application in the biomedical field as highly effective antimicrobial agent or antimicrobial biomaterial.

Recent Advances on Reactive Oxygen Species-Responsive Delivery and Diagnosis System

Reactive oxygen species (ROS) play crucial roles in biological metabolism and intercellular signaling. However, ROS level is dramatically elevated due to abnormal metabolism during multiple pathologies, including neurodegenerative diseases, diabetes, cancer, and premature aging. By taking advantage of the discrepancy of ROS levels between normal and diseased tissues, a variety of ROS-sensitive moieties or linkers have been developed to design ROS-responsive systems for the site-specific delivery of drugs and genes. In this review, we summarized the ROS-responsive chemical structures, mechanisms, and delivery systems, focusing on their current advances for precise drug/gene delivery. In particular, ROS-responsive nanocarriers, prodrugs, and supramolecular hydrogels are summarized in terms of their application for drug/gene delivery, and common strategies to elevate or diminish cellular ROS concentrations, as well as the recent development of ROS-related imaging probes were also discussed.

Tumor microenvironment as the "regulator" and "target" for gene therapy

In this review, we focus on strategies for designing functional nano gene carriers, as well as choosing therapeutic genes targeting the tumor microenvironment. Gene mutations have a great impact on the occurrence of cancer. Thus, gene therapy plays a major role in cancer therapy and has the potential to cure cancer. Well-designed gene therapy largely relies on effective gene carriers, which can be divided into viral carriers and non-viral carriers. A gene carrier delivers functional genes to their intracellular target and avoids nucleic acids being degraded by nucleases in the serum. Most conventional cancer gene therapies only target cancer cells and do not appear to be sufficintly efficient to pass clinical trials. Accumulating evidence has shown that extending the therapeutic strategies to the tumor microenvironment, rather than the tumor cell itself, can allow more options for achieving robust anti-cancer efficiency. In addition, unusual features between tumor microenvironment and normal tissues, such as a lower pH, higher glutathione and reactive oxygen species concentrations, and overexpression of some enzymes, facilitate the design of smart stimuli-responsive gene carriers regulated by the tumor microenvironment. These carriers interact with nucleic acids and then form stable nanoparticles under physiological conditions. By regulation of the tumor microenvironment, stimuli-responsive gene carriers are able to change their properties and achieve high gene delivery efficiency. Considering the tumor microenvironment as the "regulator" and "target" when designing gene carriers and choosing therapeutic genes shows significant benefit with respect to improving the accuracy and efficiency of cancer gene therapy.

miR-1915-3p inhibits Bcl-2 expression in the development of gastric cancer

Many gene expressions changed during the development of gastric cancer, and non-coding RNAs including microRNAs (miRNAs) have been found to regulate cancer progression by participating in the process of tumor cell growth, migration, invasion and apoptosis. Our previous study has identified 29 miRNAs that are highly expressed in gastric cancer stem cells. One of these miRNAs, miR-1915-3p, has shown great potential as a diagnostic and prognostic biomarker for the cancers in liver, colon and thyroid, as well as in immune and kidney diseases. Herein, we found that miR-1915-3p exhibited low expression level in differentiated gastric cancer cell lines and gastric cancer tissues. It was found that the miR-1915-3p inhibited the growth of gastric cancer cells and thus promoted cell apoptosis. We discovered that the expressions of miR-1915-3p were significantly correlated to the lymph node metastasis and overall survival of patients with gastric cancer. Further study showed that there was a negative correlation between miR-1915-3p and Bcl-2 (B cell lymphoma/leukemia-2) expression, suggesting that Bcl-2 was a target gene of miR-1915-3p. Hence, miR-1915-3p possibly contributes to the development and progression of gastric cancer by inhibiting the anti-apoptotic protein Bcl-2. The finding provides a potential therapeutic strategy for gastric cancer.

Multifunctional titanium phosphate nanoparticles for site-specific drug delivery and real-time therapeutic efficacy evaluation

Receptor-targeted delivery systems have been proposed as means of concentrating therapeutic agents to improve therapeutic effects on disease sites and reduce side effects on normal issues. Herein, we synthesized biocompatible folic acid (FA)-functionalized DHE-modified TiP (TiP-PAH-DHE-FA) nanoparticles as a drug delivery system that possessed high drug loading capability and enhanced folate-receptor-mediated cellular uptake. Moreover, it also allowed drug effect evaluation based on the real-time monitoring of the fluorescence intensity of HE molecules that are triggered by intercellular ROS. This acquired drug delivery system provided a novel platform to integrate efficient cell-specific drug delivery with real-time monitoring of therapeutic efficacy.

Peptide-based gene delivery vectors

Gene therapy as a strategy for disease treatment requires safe and efficient gene delivery systems that encapsulate nucleic acids and deliver them to effective sites in the cell.

Reactive Oxygen Species (ROS)-Responsive Charge-Switchable Nanocarriers for Gene Therapy of Metastatic Cancer

The application of nonviral gene vectors has been limited by their insufficient transfection efficiency because of poor serum stability, high endosomal entrapment, limited intracellular release, and low accumulation in the targeted organelle. It is still challenging to design gene carriers with properties that can overcome all of the barriers. We previously developed a reactive oxygen species (ROS)-responsive cationic polymer, poly[(2-acryloyl)ethyl( p-boronic acid benzyl) diethylammonium bromide] (B-PDEAEA), which switches the charge at high concentrations of intracellular ROS to promote intracellular DNA release. However, its gene-delivery efficiency has been limited by serum instability and lysosomal trapping, and coating with an anionic PEGylated lipid only showed mild enhancement. Herein, we coated the ROS-responsive B-PDEAEA polymer with two cationic lipids to form ROS-responsive lipopolyplexes with integrated properties to overcome multiple delivery barriers. The surface cationic lipids endowed the nanocarrier with improved serum stability, effective cellular uptake, and lysosomal evasion. The interior B-PDEAEA/DNA polyplexes, which were highly stable in the extracellular environment, but quickly dissociated, released DNA, promoted nuclei localization, and achieved efficient transcription. The mechanisms of the ROS-responsive and charge-switchable properties of B-PDEAEA were quantitatively studied. The transfection efficiency and antitumor activity of lipopolyplexes were studied in vitro and in vivo. We found that the ROS-responsive lipopolyplexes effectively delivered therapeutic genes into cell nuclei and caused high tumor inhibition in mice bearing peritoneal or lung metastases.

RGD-modified polymer and liposome nanovehicles: Recent research progress for drug delivery in cancer therapeutics

Over the past few decades, as the demand for cancer treatment has increased, more rational treatment options (considering size, mode of administration, biocompatibility, efficacy, etc.) and plenty of specifically active targeted nanovehicles have been developed. Integrin receptors targeting are one of the most frequently used approaches because of its highly expressed in cancer cells. In particular, the arginine-glycine-aspartic acid (RGD) peptide and its derivatives have been widely used as ligands for integrin to increase direct targeting capabilies. Polymers as well as liposomes are commonly used as nanovehicles for drug delivery. A variety of work is focused on the RGD-modified polymer and liposome nanovehicles for cancer therapeutics. The goal of this article is to review the published literature in recent years concerning the RGD-modified liposome and polymer nanovehicles to highlight its successful designs for improving cancer therapy and discuss the current challenges as well as the possible development prospects.

Low molecular weight PEI-based fluorinated polymers for efficient gene delivery

Fluorinated biomaterials have been reported to have promising features as non-viral gene carriers. In this study, a series of fluorinated polymeric gene carriers were synthesized via Michael addition from low molecular weight polyethyleneimine (PEI) and fluorobenzoic acids (FBAs)-based linking compounds with different numbers of fluorine atoms. The structure-activity relationship (SAR) of these materials was systematically investigated. SAR studies showed that fluorine could screen the positive charge of these polymers. However, this shielding effect of fluorine would endow fluorinated polymers with good balance between DNA condensation and release. In vitro transfection results suggested that these fluorinated polymers could mediate efficient gene delivery. Flow cytometry and confocal microscopy studies demonstrated that more efficient cell uptake could be achieved by fluorinated materials with more fluorine atoms. Cytotoxicity assays showed that these fluorinated materials exhibited very low cytotoxicity even at high mass ratios. This study demonstrates that FBA-based fluorinated biopolymers have the potential for practical application.

Bioresponsive polyplexes - chemically programmed for nucleic acid delivery

INTRODUCTION

The whole delivery process of nucleic acids is very challenging. Appropriate carrier systems are needed, which show extracellular stability and intracellular disassembly. Viruses have developed various strategies to meet these requirements, as they are optimized by biological evolution to transfer genetic information into host cells. Taking viruses as models, smart synthetic carriers can be designed, mimicking the efficient delivery process of viral infection. These 'synthetic viruses' are pre-programmed and respond to little differences in their microenvironment, caused by either exogenous or endogenous stimuli.

AREAS COVERED

This review deals with polymer-based, bioresponsive nanosystems (polyplexes) for the delivery of nucleic acids. Strategies utilizing pH-responsiveness, redox-responsiveness as well as sensitivity towards enzymes will be described more in detail. Systems, which respond to other endogenous triggers (i.e. reactive oxygen species, adenosine triphosphate, hypoxia), will be briefly illustrated. Moreover, some examples for combined bioresponsiveness will be presented.

EXPERT OPINION

Bioresponsive polyplexes are a smart way to facilitate programmed, timely delivery of nucleic acids to desired, specific sites. Nevertheless, further optimization is necessary to improve the still moderate transfection efficiency and specificity - also in regard to medical translation. For this purpose, precise carrier structures are desirable and stability issues of bioresponsive systems must be considered.

Near-infrared AIEgen-functionalized and diselenide-linked oligo-ethylenimine with self-sufficing ROS to exert spatiotemporal responsibility for promoted gene delivery

We attempted to synthesize an oligo-ethyleneimine (OEI)-crosslinked polycation, characterized with self-sufficing ROS by virtue of a functional AIE component and an ROS-labile diselenide linkage.