A multifunctional envelope-type nanodevice for use in nanomedicine: concept and applications

Nanoparticle-based drug delivery systems targeting cancer cell surfaces

Traditional cancer chemotherapy easily produces serious toxic and side effects due to the lack of specific selection of tumor cells, which restricts its curative effect. Targeted delivery can increase the concentration of drugs in the target site and reduce their toxic and side effects on normal tissues and cells. Biocompatible and surface-modifiable nanocarriers are novel drug delivery systems, which are used to specifically target tumor sites in a controllable way. One of the effective ways to design effective targeting nanocarriers is to decorate with functional ligands, which can bind to specific receptors overexpressed on the surfaces of cancer cells. Various functional ligands, including transferrin, folic acid, polypeptide and hyaluronic acid, have been widely explored to develop tumor-selective drug delivery systems. This review focuses on the research progress of various receptors overexpressed on the surfaces of cancer cells and different nano-delivery systems of anticancer drugs targeted on the surfaces of cancer cells. We believe that through continuous research and development, actively targeted cancer nano-drugs will make a breakthrough and become an indispensable platform for accurate cancer treatment.

Current Principles, Challenges, and New Metrics in pH-Responsive Drug Delivery Systems for Systemic Cancer Therapy

The paradigm of drug delivery via particulate formulations is one of the leading ideas that enable overcoming limitations of traditional chemotherapeutic agents. The trend toward more complex multifunctional drug carriers is well-traced in the literature. Nowadays, the prospectiveness of stimuli-responsive systems capable of controlled cargo release in the lesion nidus is widely accepted. Both endogenous and exogenous stimuli are employed for this purpose; however, endogenous pH is the most common trigger. Unfortunately, scientists encounter multiple challenges on the way to the implementation of this idea related to the vehicles' accumulation in off-target tissues, their immunogenicity, the complexity of drug delivery to intracellular targets, and finally, the difficulties in the fabrication of carriers matching all imposed requirements. Here, we discuss fundamental strategies for pH-responsive drug delivery, as well as limitations related to such carriers' application, and reveal the main problems, weaknesses, and reasons for poor clinical results. Moreover, we attempted to formulate the profiles of an "ideal" drug carrier in the frame of different strategies drawing on the example of metal-comprising materials and considered recently published studies through the lens of these profiles. We believe that this approach will facilitate the formulation of the main challenges facing researchers and the identification of the most promising trends in technology development.

Enhanced tumor penetration for efficient chemotherapy by a magnetothermally sensitive micelle combined with magnetic targeting and magnetic hyperthermia

The high accumulation and poor penetration of nanocarriers in tumor is a contradiction of nanomedicine, which reduces the efficacy of chemotherapy. Due to the positive effect of hyperthermia on in vivo drug diffusion, we designed a magnetothermally sensitive micelle (MTM) by integrating magnetic targeting (MT), magnetic hyperthermia (MH), and magnetothermally responsive drug release to facilitate simultaneous drug accumulation and penetration in tumor. Accordingly, we synthesized a cyanine7-modified thermosensitive polymer with phase transition at 42.3°C, and utilized it to prepare drug-loaded MTMs by encapsulating superparamagnetic MnFe2O4 nanoparticles and doxorubicin (DOX). The obtained DOX–MTM had not only high contents of DOX (9.1%) and MnFe2O4 (38.7%), but also some advantages such as superparamagnetism, high saturation magnetization, excellent magnetocaloric effect, and magnetothermal-dependent drug release. Therefore, DOX–MTM improved in vitro DOX cytotoxicity by enhancing DOX endocytosis under the assistance of MH. Furthermore, MT and MH enhanced in vivo DOX–MTM accumulation and DOX penetration in tumor, respectively, substantially inhibiting tumor growth (84%) with excellent biosafety. These results indicate the development of an optimized drug delivery system with MH and MH-dependent drug release, introducing a feasible strategy to enhance the application of nanomedicines in tumor chemotherapy.

Environment-Responsive Lipid/siRNA Nanoparticles for Cancer Therapy

RNA interference (RNAi) is a promising technology to regulate oncogenes for treating cancer. The primary limitation of siRNA for clinical application is the safe and efficacious delivery of therapeutic siRNA into target cells. Lipid-based delivery systems are developed to protect siRNA during the delivery process and to facilitate intracellular uptake. There is a significant progress in lipid nanoparticle systems that utilize cationic and protonatable amino lipid systems to deliver siRNA to tumors. Among these lipids, environment-responsive lipids are a class of novel lipid delivery systems that are capable of responding to the environment changes during the delivery process and demonstrate great promise for clinical translation for siRNA therapeutics. Protonatable or ionizable amino lipids and switchable lipids as well as pH-sensitive multifunctional amino lipids are the presentative environment-responsive lipids for siRNA delivery. These lipids are able to respond to environmental changes during the delivery process to facilitate efficient cytosolic siRNA delivery. Environment-responsive lipid/siRNA nanoparticles (ERLNP) are developed with the lipids and are tested for efficient delivery of therapeutic siRNA into the cytoplasm of cancer cells to silence target genes for cancer treatment in preclinical development. This review summarizes the recent developments in environment-response lipids and nanoparticles for siRNA delivery in cancer therapy.

CRISPR-Cas9: A Preclinical and Clinical Perspective for the Treatment of Human Diseases

At present, the idea of genome modification has revolutionized the modern therapeutic research era. Genome modification studies have traveled a long way from gene modifications in primary cells to genetic modifications in animals. The targeted genetic modification may result in the modulation (i.e., either upregulation or downregulation) of the predefined gene expression. Clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated nuclease 9 (Cas9) is a promising genome-editing tool that has therapeutic potential against incurable genetic disorders by modifying their DNA sequences. In comparison with other genome-editing techniques, CRISPR-Cas9 is simple, efficient, and very specific. This enabled CRISPR-Cas9 genome-editing technology to enter into clinical trials against cancer. Besides therapeutic potential, the CRISPR-Cas9 tool can also be applied to generate genetically inhibited animal models for drug discovery and development. This comprehensive review paper discusses the origin of CRISPR-Cas9 systems and their therapeutic potential against various genetic disorders, including cancer, allergy, immunological disorders, Duchenne muscular dystrophy, cardiovascular disorders, neurological disorders, liver-related disorders, cystic fibrosis, blood-related disorders, eye-related disorders, and viral infection. Finally, we discuss the different challenges, safety concerns, and strategies that can be applied to overcome the obstacles during CRISPR-Cas9-mediated therapeutic approaches.

Gene therapy in wound healing using nanotechnology

Wound healing is a complex and highly regulated process that is susceptible to a variety of failures leading to delayed wound healing or chronic wounds. This is becoming an increasingly global burden on the healthcare system. Treatment of wounds has evolved considerably to overcome barriers to wound healing especially within the field of regenerative medicine that focuses on the replacement of tissues or organs. Improved understanding of the pathophysiology of wound healing has enabled current advances in technology to allow better optimization of microenvironment within wounds. This approach may help tackle wounds that are difficult to treat and help reduce the global burden of the disease. This article provides an overview of the physiology in wound healing and the application of gene therapy using nanotechnology in the management of wounds.

HPMA-based polymeric conjugates in anticancer therapeutics

Polymer therapeutics has gained prominence due to an attractive structural polymer chemistry and its applications in diseases therapy. In this review, we discussed the development and capabilities of N-(2-hydroxypropyl) methacrylamide (HPMA) and HPMA-drug conjugates in cancer therapy. The design, architecture, and structural properties of HPMA make it a versatile system for the synthesis of polymeric conjugations for biomedical applications. Research suggests that HPMA could be a possible alternative for polymers such polyethylene glycol (PEG) in biomedical applications. Although numerous clinical trials of HPMA-drug conjugates are ongoing, yet no product has been successfully brought to the market. Thus, further research is required to develop HPMA-drug conjugates as successful cancer therapeutics.

Tumor-Oriented Telomerase-Terminated Nanoplatform as Versatile Strategy for Multidrug Resistance Reversal in Cancer Treatment

Multidrug resistance is one of the major problems in chemotherapy, and exploiting impactful targets to reverse drug resistance of most tumors remains a difficult problem. In this study, the tumor-oriented nanoparticle, BIBR1532-loaded peptide dendrimeric prodrug nanoassembly (B-PDPN), is used to assist telomerase inhibition for multidrug resistance reversal. B-PDPN possesses the characteristics of an acid-activated histidine to promote cellular uptake, a redox-sensitive poly(ethylene glycol) (PEG) layer to actualize endosomal escape and telomerase inhibitor release, and an acid sensitive chemical bond to facilitate chemotherapeutic drug release. Telomerase termination weakens the protective effect of hTERT protein on mitochondria and enhances reactive oxygen species (ROS) production, which increases DNA damage and apoptosis. The tumor-oriented nanoparticle B-PDPN achieves a broad-spectrum telomerase inhibition to combat multidrug resistance. In vivo experiments support the evidence that B-PDPN accumulates in the tumor site and reduces the expression of hTERT in tumor tissues to inhibit drug resistant tumor growth. This work introduces an innovative strategy of utilizing features of tumor-activated nanoplatform to assist telomerase termination. The nanoplatform enhances intracellular drug concentration and nucleus delivery of doxorubicin (DOX), and promotes DNA damage to combat multidrug resistance.

The silencing of indoleamine 2,3-dioxygenase 1 (IDO1) in dendritic cells by siRNA-loaded lipid nanoparticles enhances cell-based cancer immunotherapy

Cell-based therapy using dendritic cells (DC) represents a potent cancer immunotherapy. However, activated DC express indoleamine 2,3-dioxygenase 1 (IDO1), a counter-regulatory and tolerogenic molecule, leading to the inhibition of T cell activation and the promotion of T cell differentiation into regulatory T cells. Silencing the IDO1 gene in DC by small interfering RNA (siRNA) represents a potent therapeutic strategy. We report on the successful and efficient introduction of a siRNA targeting IDO1 into mouse DCs by a means of a multifunctional envelope-type nanodevice (MEND) containing a YSK12-C4 (YSK12-MEND). The YSK12-C4 has both fusogenic and cationic properties. The YSK12-MEND induced an effective level of gene silencing of IDO1 at siRNA doses in the range of 1–20 nM, a concentration that commercially available transfection reagents are not able to silence. The YSK12-MEND mediated IDO1 silencing had no effect on the characteristic determinants of DC phenotype such as CD11c, CD80 and MHC class II. The silencing of IDO1 in DC by the YSK12-MEND significantly enhanced the antitumor effect against E.G7-OVA tumor. Moreover, a decrease in the numbers of regulatory T cells in the tumor was observed in mice that were treated with the IDO1-silenced DC. The YSK12-MEND appears to be a potent delivery system for IDO1-silenced DC based cancer immunotherapy.

Strategies to target bioactive molecules to subcellular compartments. Focus on natural compounds

Many potential pharmacological targets are present in multiple subcellular compartments and have different pathophysiological roles depending on location. In these cases, selective targeting of a drug to the relevant subcellular domain(s) may help to sharpen its impact by providing topological specificity, thus limiting side effects, and to concentrate the compound where needed, thus increasing its effectiveness. We review here the state of the art in precision subcellular delivery. The major approaches confer "homing" properties to the active principle via permanent or reversible (in pro-drug fashion) modifications, or through the use of special-design nanoparticles or liposomes to ferry a drug(s) cargo to its desired destination. An assortment of peptides, substituents with delocalized positive charges, custom-blended lipid mixtures, pH- or enzyme-sensitive groups provide the main tools of the trade. Mitochondria, lysosomes and the cell membrane may be mentioned as the fronts on which the most significant advances have been made. Most of the examples presented here have to do with targeting natural compounds - in particular polyphenols, known as pleiotropic agents - to one or the other subcellular compartment.

Poly(amino acid)/ZnO/mesoporous silica nanoparticle based complex drug delivery system with a charge-reversal property for cancer therapy

Negative-to-positive charge-reversal strategy employed in anti-cancer drug delivery systems (DDSs) can improve the utilization of the drugs as well as reduce their side effects efficiently. In this article, a complex DDS named DOX@MSN-ZnO-PLL-PLL(DMA) was prepared. Doxorubicin hydrochloride (DOX) was loaded in mesoporous silica nanoparticles (MSNs), which were then covered by ZnO in situ. Poly-_L-lysine (PLL) and 2,3-dimethylmaleic anhydride functionalized PLL (PLL(DMA)) were finally coated on the nanoparticles through a Layer-by-Layer (LbL) assembly process with PLL(DMA) outside to obtain the carriers. The negative charged PLL(DMA) avoided the unspecific uptake of the carriers by normal cells at pH 7.4. While the charge-reversal property could reverse the zeta-potential of the carriers to positive in weakly acidic tumor tissues at pH 6.5, which promoted the cytophagy of the carriers by cancer cells. ZnO which blocked the pores of MSNs could be dissolved intracellular due to the more acidic environment in endosome/lysosome, and resulting in drug release for cancer cell apoptosis. Zeta-potential measurements, the in vitro cellular uptake behaviors as well as cellular cytotoxicity of the carriers at different pH values were investigated to prove the charge-reversal property. The in vitro drug release studies and the cellular cytotoxicity studies were also investigated to prove the controlled DOX release behavior of the carriers. In summary, the complex DDS with charge-reversal property should be of consideration in cancer therapy.

Recent trends in CRISPR-Cas system: genome, epigenome, and transcriptome editing and CRISPR delivery systems

BACKGROUND

The CRISPR-Cas systems have emerged as a robust genome editing tool useful in various fields of research. With the discovery and development of the orthologous CRISPR-Cas systems, their genome editing efficiency have improved.

OBJECTIVE

In this review, we aim to present the recent developments and applications of the CRISPR-Cas systems.

METHODS

First, we introduce how the advancements of CRISPR technology enabled genome editing to single base precision. Then, we discuss the CRISPR based methods for targeted transcriptional regulation, epigenome editing, and RNA editing. Finally, we review the CRISPR delivery systems highlighting recent attempts to integrate nanotechnology to develop novel CRISPR delivery modalities.

CONCLUSION

Here, we review the recent trends in CRISPR-based biotechnologies, encompassing genome editing, epigenome regulation and direct RNA targeting and provide an overview of methods employed for CRISPR delivery with an emphasis on the most recent nanotechnology-based delivery strategies. We anticipate that the development of CRISPR based technology will continue to explore novel methods.

Low Electric Treatment activates Rho GTPase via Heat Shock Protein 90 and Protein Kinase C for Intracellular Delivery of siRNA

Low electric treatment (LET) promotes intracellular delivery of naked siRNA by altering cellular physiology. However, which signaling molecules and cellular events contribute to LET-mediated siRNA uptake are unclear. Here, we used isobaric tags in relative and absolute quantification (iTRAQ) proteomic analysis to identify changes in the levels of phosphorylated proteins that occur during cellular uptake of siRNA promoted by LET. iTRAQ analysis revealed that heat shock protein 90 (Hsp90)α and myristoylated alanine-rich C-kinase substrate (Marcks) were highly phosphorylated following LET of NIH 3T3 cells, but not untreated cells. Furthermore, the levels of phosphorylated Hsp90α and protein kinase C (PKC)γ were increased by LET both with siRNA and liposomes having various physicochemical properties used as model macromolecules, suggesting that PKCγ activated partly by Ca²⁺ influx as well as Hsp90 chaperone function were involved in LET-mediated cellular siRNA uptake. Furthermore, LET with siRNA induced activation of Rho GTPase via Hsp90 and PKC, which could contribute to cellular siRNA uptake accompanied by actin cytoskeleton remodeling. Collectively, our results suggested that LET-induced Rho GTPase activation via Hsp90 and PKC would participate in actin-dependent cellular uptake of siRNA.

Tumor-Acidity-Cleavable Maleic Acid Amide (TACMAA): A Powerful Tool for Designing Smart Nanoparticles To Overcome Delivery Barriers in Cancer Nanomedicine

Over the past few decades, cancer nanomedicine has been under intensive development for applications in drug delivery, cancer therapy, and molecular imaging. However, there exist a series of complex biological barriers in the path of a nanomedicine from the site of administration to the site of action. These barriers considerably prevent a nanomedicine from reaching its targets in a sufficient concentration and thus severely limit its therapeutic benefits. According to the delivery process, these biological delivery barriers can be briefly summarized in the following order: blood circulation, tumor accumulation, tumor penetration, cellular internalization, and intracellular drug release. The therapeutic effect of a nanomedicine is strongly determined by its ability to overcome these barriers. However, advances in cancer biology have revealed that each barrier has its own distinct microenvironment, which imposes different requirements on the optimal design of nanocarriers, thus further complicating the delivery process. For example, the pH of blood is neutral, while the tumor extracellular environment features an acidic pH (pH_e ≈ 6.5-7.0) and the endosome and lysosome are more acidic (pH 5.5-4.5). The nanoparticles (NPs) should be able to change their properties to adapt to each individual environment for robust and effective delivery. This demand promotes the design and development of smart delivery carriers that can respond to endogenous and exogenous stimuli. It is well-documented that tumors develop acidic extracellular microenvironments with pH ≈ 6.5-7.0 due to their abnormal metabolism in comparison with normal tissues. This provides a unique tool for designing smart NP drug delivery systems. Our studies have revealed that the NPs' physiochemical properties, such as particle size and surface charge, have profound effects on their systemic transport in the body. In different delivery stages, the NPs should possess different sizes or surface charges for optimal performance. We developed a class of stimuli-responsive NPs by incorporating tumor-acidity-cleavable maleic acid amide (TACMAA) as a design feature. TACMAA is produced by the facile reaction of an amino group with 2,3-dimethylmaleic anhydride (DMMA) and its derivatives and can be cleaved under tumor acidity. By virtue of such characteristics, NPs containing TACMAA enable size or surface charge switching at tumor sites so that they can overcome those delivery barriers for improved drug delivery and cancer therapy. In this Account, we systemically review the development and evolution of TACMAA-based delivery systems and elaborate how TACMAA helps the innovation and design of intelligent nanocarriers for overcoming the delivery barriers. In particular, our Account focuses on five parts: TACMAA chemistry, tumor-acidity-triggered charge reversal, tumor-acidity-triggered shell detachment, tumor-acidity-triggered size transition, and tumor-acidity-triggered ligand reactivation. We provide detailed information on how tumor-acidity-triggered property changes correlate with the ability of NPs to overcome delivery barriers.

Delivering CRISPR: a review of the challenges and approaches

Gene therapy has long held promise to correct a variety of human diseases and defects. Discovery of the Clustered Regularly-Interspaced Short Palindromic Repeats (CRISPR), the mechanism of the CRISPR-based prokaryotic adaptive immune system (CRISPR-associated system, Cas), and its repurposing into a potent gene editing tool has revolutionized the field of molecular biology and generated excitement for new and improved gene therapies. Additionally, the simplicity and flexibility of the CRISPR/Cas9 site-specific nuclease system has led to its widespread use in many biological research areas including development of model cell lines, discovering mechanisms of disease, identifying disease targets, development of transgene animals and plants, and transcriptional modulation. In this review, we present the brief history and basic mechanisms of the CRISPR/Cas9 system and its predecessors (ZFNs and TALENs), lessons learned from past human gene therapy efforts, and recent modifications of CRISPR/Cas9 to provide functions beyond gene editing. We introduce several factors that influence CRISPR/Cas9 efficacy which must be addressed before effective in vivo human gene therapy can be realized. The focus then turns to the most difficult barrier to potential in vivo use of CRISPR/Cas9, delivery. We detail the various cargos and delivery vehicles reported for CRISPR/Cas9, including physical delivery methods (e.g. microinjection; electroporation), viral delivery methods (e.g. adeno-associated virus (AAV); full-sized adenovirus and lentivirus), and non-viral delivery methods (e.g. liposomes; polyplexes; gold particles), and discuss their relative merits. We also examine several technologies that, while not currently reported for CRISPR/Cas9 delivery, appear to have promise in this field. The therapeutic potential of CRISPR/Cas9 is vast and will only increase as the technology and its delivery improves.

Construction of perfluorohexane/IR780@liposome coating on Ti for rapid bacteria killing under permeable near infrared light

Near infrared (NIR) light induced photodynamic antibacterial therapy (PDAT) is a promising antibacterial technique in rapid in situ disinfection of bacterially infected artificial implants due to its penetration ability into tissues. However, the lower oxygen content in vivo may restrict the yields of reactive oxygen species (ROS), thus reducing the antibacterial efficacy of PADT significantly. Herein, liposome encapsulated photosensitizers (PS), IR780 and perfluorohexane (PFH), have been constructed on the surface of Ti implants via a covalent linkage to overcome this issue. Thanks to the high oxygen capacity of PFH, more ROS can be generated during NIR irradiation regardless of the low content of oxygen in vivo. As a result, in vitro tests demonstrated that 15 minutes of 808 nm near-infrared irradiation could achieve a high antibacterial efficacy of 99.62% and 99.63% on the implant surface against Escherichia coli and Staphylococcus aureus, respectively. By contrast, the PDAT system without PFH modification shows a lower antibacterial efficacy (only 66.54% and 48.04%, respectively). In addition, this enhanced PDAT system also possesses great biocompatibility based on the in vitro and in vivo subcutaneous assays. This surface system makes it possible for rapid bacteria-killing in artificial implants that have been implanted in vivo under local conditions with lower oxygen content.

Concurrent Drug Unplugging and Permeabilization of Polyprodrug-Gated Crosslinked Vesicles for Cancer Combination Chemotherapy

Combination chemotherapy with both hydrophobic and hydrophilic therapeutic drugs is clinically vital toward the treatment of persistent cancers. Though conventional liposomes and polymeric vesicles possessing hydrophobic bilayers and aqueous interiors can serve as codelivery nanocarriers, it remains a considerable challenge to achieve synchronized release of both types of drugs due to distinct encapsulation mechanisms; premature release of water-soluble cargos from unstable liposomes and ruptured vesicles is also a major concern. Herein, the fabrication of physiologically stable polyprodrug-gated crosslinked vesicles (GCVs) via the self-assembly of camptothecin (CPT) polyprodrug amphiphiles and in situ bilayer crosslinking through traceless sol-gel reaction is reported. Polyprodrug-GCVs possess high CPT loading (>30 wt%) and minimized leakage of encapsulated hydrophilic doxorubicin (DOX) hydrochloride due to the suppressed permeability of crosslinked membrane, exhibiting extended blood circulation (t _1/2 > 13 h) with caged cytotoxicity in physiological circulation. Upon cellular uptake by cancer cells, cytosolic reductive milieu-triggered CPT unplugging from vesicle bilayers is demonstrated to generate hydrophilic mesh channels and make the membrane highly permeable. Concurrently, it will promote DOX corelease from hydrophilic lumen (≈36-fold increase). The reduction-activated combination chemotherapeutic potency based on polyprodrug-GCVs is confirmed by both in vitro and in vivo explorations.

Mesoporous silica nanoparticle-based intelligent drug delivery system for bienzyme-responsive tumour targeting and controlled release

This paper proposes a novel type of multifunctional envelope-type mesoporous silica nanoparticle (MSN) to achieve cancer cell targeting and drug-controlled release. In this system, MSNs were first modified by active targeting moiety hyaluronic acid (HA) for breast cancer cell targeting and hyaluronidases (Hyal)-induced intracellular drug release. Then gelatin, a proteinaceous biopolymer, was grafted onto the MSNs to form a capping layer via glutaraldehyde-mediated cross-linking. To shield against unspecific uptake of cells and prolong circulation time, the nanoparticles were further decorated with poly(ethylene glycol) polymers (PEG) to obtain MSN@HA-gelatin-PEG (MHGP). Doxorubicin (DOX), as a model drug, was loaded into PEMSN to assess the breast cancer cell targeting and drug release behaviours. In vitro study revealed that PEG chains protect the targeting ligand and shield against normal cells. After reaching the breast cancer cells, MMP-2 overpressed by cells hydrolyses gelatin layer to deshield PEG and switch on the function of HA. As a result, DOX-loaded MHGP was selectively trapped by cancer cells through HA receptor-mediated endocytosis and subsequently release DOX due to Hyal-catalysed degradation of HA. This system presents successful bienzyme-responsive targeting drug delivery in an optimal fashion and provides potential applications for targeted cancer therapy.

Amiloride-enhanced gene transfection of octa-arginine functionalized calcium phosphate nanoparticles

Nanoparticles represent promising gene delivery systems in biomedicine to facilitate prolonged gene expression with low toxicity compared to viral vectors. Specifically, nanoparticles of calcium phosphate (nCaP), the main inorganic component of human bone, exhibit high biocompatibility and good biodegradability and have been reported to have high affinity for protein or DNA, having thus been used as gene transfer vectors. On the other hand, Octa-arginine (R8), which has a high permeability to cell membrane, has been reported to improve intracellular delivery systems. Here, we present an optimized method for nCaP-mediated gene delivery using an octa-arginine (R8)-functionalized nCaP vector containing a marker or functional gene construct. nCaP particle size was between 220–580 nm in diameter and all R8-functionalized nCaPs carried a positive charge. R8 concentration significantly improved nCaP transfection efficiency with high cell compatibility in human mesenchymal stem cells (hMSC) and human osteoblasts (hOB) in particular, suggesting nCaPs as a good option for non-viral vector gene delivery. Furthermore, pre-treatment with different endocytosis inhibitors identified that the endocytic pathway differed among cell lines and functionalized nanoparticles, with amiloride increasing transfection efficiency of R8-functionalized nCaPs in hMSC and hOB.

CRISPR/Cas9-Based Genome Editing for Disease Modeling and Therapy: Challenges and Opportunities for Nonviral Delivery

Genome editing offers promising solutions to genetic disorders by editing DNA sequences or modulating gene expression. The clustered regularly interspaced short palindromic repeats (CRISPR)/associated protein 9 (CRISPR/Cas9) technology can be used to edit single or multiple genes in a wide variety of cell types and organisms in vitro and in vivo. Herein, we review the rapidly developing CRISPR/Cas9-based technologies for disease modeling and gene correction and recent progress toward Cas9/guide RNA (gRNA) delivery based on viral and nonviral vectors. We discuss the relative merits of delivering the genome editing elements in the form of DNA, mRNA, or protein, and the opportunities of combining viral delivery of a transgene encoding Cas9 with nonviral delivery of gRNA. We highlight the lessons learned from nonviral gene delivery in the past three decades and consider their applicability for CRISPR/Cas9 delivery. We also include a discussion of bioinformatics tools for gRNA design and chemical modifications of gRNA. Finally, we consider the extracellular and intracellular barriers to nonviral CRISPR/Cas9 delivery and propose strategies that may overcome these barriers to realize the clinical potential of CRISPR/Cas9-based genome editing.

Esterase-Activated Charge-Reversal Polymer for Fibroblast-Exempt Cancer Gene Therapy

Selective gene expression in tumors via responsive dissociation of polyplexes triggered by intracellular signals is demonstrated. An esterase-responsive charge-reversal polymer mediates selective gene expression in the cancer cells high in esterases over fibroblasts low in esterase activity. Its gene therapy with the TRAIL suicide gene effectively induces apoptosis of HeLa cells but does not activate fibroblasts to secrete WNT16B, enabling potent cancer gene therapy with few side effects.

Synthesis of GdAlO3:Mn4+,Ge4+@Au Core-Shell Nanoprobes with Plasmon-Enhanced Near-Infrared Persistent Luminescence for in Vivo Trimodality Bioimaging

The rise of multimodal nanoprobes has promoted the development of new methods to explore multiple molecular targets simultaneously or to combine various bioimaging tools in one assay to more clearly delineate localization and expression of biomarkers. Persistent luminescence nanophosphors (PLNPs) have been qualified as a promising contrast agent for in vivo imaging. The easy surface modification and proper nanostructure design strategy would favor the fabrication of PLNP-based multifunctional nanoprobes for biological application. In this paper, we have proposed novel multifunctional core-shell nanomaterials, applying the Mn⁴⁺ and Ge⁴⁺ co-doped gadolinium aluminate (GdAlO₃:Mn⁴⁺,Ge⁴⁺) PLNPs as the near-infrared persistent luminescence emission center and introducing the gold nanoshell coated on the PLNPs to enhance the luminescence efficiency via plasmon resonance. Our developed core-shell nanoprobes have demonstrated the excellent features of ultrabrightness, superlong afterglow, good monodispersity, low toxicity, and excellent biocompatibility. The well-characterized nanoprobes have been utilized for trimodality in vivo imaging, with near-infrared persistent luminescence for optical imaging, Gd element for magnetic resonance imaging, and Au element for computed tomography imaging.

Development of a multifunctional envelope-type nano device and its application to nanomedicine

Successful nanomedicines should be based on sound drug delivery systems (DDS) the permit intracellular trafficking as well as the biodistribution of cargos to be controlled. We have been developing new types of DDS that are multifunctional envelope-type nano devices referred to as MENDs. First, we will focus the in vivo delivery of siRNA to hepatocytes using a YSK-MEND which is composed of pH-responsive cationic lipids. The YSK-MEND is capable of inducing efficient silencing activity in hepatocytes and can be used to cure mice that are infected with hepatitis C or B. The YSK-MEND can also be applied to cancer immunotherapy through the activation of immune cells by delivering different compounds such as cyclic-di-GMP, siRNA or alpha-galactosylceramide as a lipid antigen. The findings indicate that, as predicted, these compounds, when encapsulated in the YSK-MEND, can be delivered to the site of action and induced immune activation through different mechanisms. Finally, a MITO-Porter, a membrane fusion-based delivery system to mitochondria, is introduced as an organelle targeting DDS and a new strategy for cancer therapy is proposed by delivering gentamicin to mitochondria of cancer cells. These new technologies are expected to extend the therapeutic area of Nanomedicine by increasing the power of DDS, especially from the view point of controlled intracellular trafficking.

Protecting liver sinusoidal endothelial cells suppresses apoptosis in acute liver damage

AIM

Apoptosis is associated with various types of hepatic disorders. We have developed a novel cell-transfer drug delivery system (DDS) using a multifunctional envelope-type nano device that targets liver sinusoidal endothelial cells (LSECs). The purpose of this study was to determine the efficacy of the novel DDS containing siRNA at suppressing apoptosis in LSECs.

METHODS

Bax siRNA was transfected into a sinusoidal endothelial cell line (M1) to suppress apoptosis induced by an anti-Fas antibody and staurosporine. C57BL/6J mice were divided into three groups: (i) a control group, only intravenous saline; (ii) a nonselective group, injections of siRNA sealed in the nonselective DDS; and (iii) an LSEC-transfer efficient group, injections of siRNA sealed in an LSEC-transfer efficient DDS. Hepatic cell apoptosis was induced by an anti-Fas antibody.

RESULTS

Bax siRNA had an anti-apoptotic effect on M1 cells. Serum alanine aminotransferase was reduced in the LSEC-transfer efficient group, as were cleaved caspase-3 and the number of terminal deoxynucleotidyl transferase dUTP nick end labeling positive hepatocytes. Silver impregnation staining indicated that the sinusoidal space was maintained in the LSEC-transfer efficient group but not in the other groups. Electron microscopy showed that the LSECs were slightly impaired, although the sinusoidal structure was maintained in the LSEC-transfer efficient group.

CONCLUSION

Hepatocyte apoptosis was reduced by the efficient suppression of LSEC apoptosis with a novel DDS. Protecting the sinusoidal structure by suppressing LSEC damage will be an effective treatment for acute liver failure.

Mechanisms and biomaterials in pH-responsive tumour targeted drug delivery: A review

As the mainstay in the treatment of various cancers, chemotherapy plays a vital role, but still faces many challenges, such as poor tumour selectivity and multidrug resistance (MDR). Targeted drug delivery using nanotechnology has provided a new strategy for addressing the limitations of the conventional chemotherapy. In the last decade, the volume of research published in this area has increased tremendously, especially with functional nano drug delivery systems (nanocarriers). Coupling a specific stimuli-triggered drug release mechanism with these delivery systems is one of the most prevalent approaches for improving therapeutic outcomes. Among the various stimuli, pH triggered delivery is regarded as the most general strategy, targeting the acidic extracellular microenvironment and intracellular organelles of solid tumours. In this review, we discuss recent advances in the development of pH-sensitive nanocarriers for tumour-targeted drug delivery. The review focuses on the chemical design of pH-sensitive biomaterials, which are used to fabricate nanocarriers for extracellular and/or intracellular tumour site-specific drug release. The pH-responsive biomaterials bring forth conformational changes in these nanocarriers through various mechanisms such as protonation, charge reversal or cleavage of a chemical bond, facilitating tumour specific cell uptake or drug release. A greater understanding of these mechanisms will help to design more efficient drug delivery systems to address the challenges encountered in conventional chemotherapy.

A lipid nanoparticle for the efficient delivery of siRNA to dendritic cells

Applying small interfering RNA (siRNA) to dendritic cell (DC) based therapy represents a potential candidate for cancer immunotherapy. However, delivering siRNA to DCs is a challenging issue for non-viral vectors. To date, only viral vectors have achieved efficient gene silencing in DCs. We report herein that a novel cationic lipid, YSK12-C4, when loaded in a nanoparticle with siRNA (YSK12-C4 multifunctional envelope type nano device [YSK12-MEND]), greatly facilitated gene silencing in mouse DCs. The use of the YSK12-MEND resulted in a gene silencing efficiency in excess of 90%, with a median effective dose (ED50) of 1.5nM, whereas the maximum gene silencing efficiency of Lipofectamine RNAiMAX was less than 60% and the ED50 was 25nM. Furthermore, suppressor of cytokine signaling 1, an immune suppressive molecule in DCs, silenced in the mouse DC by the YSK12-MEND showed a drastic enhancement in cytokine production, resulting in the significant suppression of tumor growth when it was applied to DC-based therapy against a mouse lymphoma. These results clearly indicate that YSK12-MEND overcomes the obstacle associated with non-viral vectors and can be considered to be a promising non-viral vector for siRNA delivery to DCs, thus accelerating DC-based therapies with siRNA.

“Stealthy” chitosan/mesoporous silica nanoparticle based complex system for tumor-triggered intracellular drug release

A pH- and redox-sensitive “stealthy” chitosan/mesoporous silica nanoparticle-based complex system is prepared for tumor-triggered intracellular drug release.

Surface coating of siRNA-peptidomimetic nano-self-assemblies with anionic lipid bilayers: enhanced gene silencing and reduced adverse effects in vitro

Cationic vectors have demonstrated the potential to facilitate intracellular delivery of therapeutic oligonucleotides. However, enhanced transfection efficiency is usually associated with adverse effects, which also proves to be a challenge for vectors based on cationic peptides. In this study a series of proteolytically stable palmitoylated α-peptide/β-peptoid peptidomimetics with a systematically varied number of repeating lysine and homoarginine residues was shown to self-assemble with small interfering RNA (siRNA). The resulting well-defined nanocomplexes were coated with anionic lipids giving rise to net anionic liposomes. These complexes and the corresponding liposomes were optimized towards efficient gene silencing and low adverse effects. The optimal anionic liposomes mediated a high silencing effect, which was comparable to that of the control (cationic Lipofectamine 2000), and did not display any noticeable cytotoxicity and immunogenicity in vitro. In contrast, the corresponding nanocomplexes mediated a reduced silencing effect with a more narrow safety window. The surface coating with anionic lipid bilayers led to partial decomplexation of the siRNA-peptidomimetic nanocomplex core of the liposomes, which facilitated siRNA release. Additionally, the optimal anionic liposomes showed efficient intracellular uptake and endosomal escape. Therefore, these findings suggest that a more efficacious and safe formulation can be achieved by surface coating of the siRNA-peptidomimetic nano-self-assemblies with anionic lipid bilayers.

Multifunctional enveloped nanodevices (MENDs)

It is anticipated that nucleic acid medicines will be in widespread use in the future, since they have the potential to cure diseases based on molecular mechanisms at the level of gene expression. However, intelligent delivery systems are required to achieve nucleic acid therapy, since they can perform their function only when they reach the intracellular site of action. We have been developing a multifunctional envelope-type nanodevice abbreviated as MEND, which consists of functional nucleic acids as a core and lipid envelope, and can control not only biodistribution but also the intracellular trafficking of nucleic acids. In this chapter, we review the development and evolution of the MEND by providing several successful examples, including the R8-MEND, the KALA-MEND, the MITO-Porter, the YSK-MEND, and the PALM.

Switchable Lipids: Conformational Change for Fast pH-Triggered Cytoplasmic Delivery

We report the use of switchable lipids to improve the endosomal escape and cytosolic delivery of cell-impermeable compounds. The system is based on a conformational reorganization of the lipid structure upon acidification, as demonstrated by NMR spectroscopic studies. When incorporated in a liposome formulation, the switchable lipids triggered bilayer destabilization through fusion even in the presence of poly(ethylene glycol). We observed 88 % release of sulforhodamine B in 15 min at pH 5, and the liposome formulations demonstrated high stability at pH 7.4 for several months. By using sulforhodamine B as a model of a highly polar drug, we demonstrated fast cytosolic delivery mediated by endosomal escape in HeLa cells, and no toxicity.

An analysis of membrane fusion between mitochondrial double membranes and MITO-Porter, mitochondrial fusogenic vesicles

To achieve mitochondrial gene therapy, therapeutic molecules need to be transported through the outer and inner membranes of mitochondria into the innermost space (mitochondrial matrix), which contains the mtDNA pool. We previously reported on the construction of a MITO-Porter with a high fusogenic activity for the mitochondrial outer membrane for delivering molecules to the mitochondria of human cells. Here, we report on an investigation of a fusogenic lipid composition for the inner membrane, and an analysis of the fusogenic compositions for the outer and inner membranes. A significant relationship was found between fusion activity and the mitochondrial delivery of nucleic acids.

Influence of Endosomal Escape and Degradation of α-Galactosylceramide Loaded Liposomes on CD1d Antigen Presentation

Alpha-galactosylceramide (GC), a lipid antigen present on CD1d molecules, is a unique adjuvant that enables a strong antitumor effect to be induced via activation of natural killer T cells. We previously reported that a liposomal formulation of GC significantly enhanced GC presentation via CD1d and antitumor immunity. However, the influence of the intracellular fate of liposomes controlled by the lipid composition on GC presentation using GC-loaded liposomes (GC-Lip) remains unclear. In this study, we prepared a GC-Lip formulation by incorporating dioleoyl-phosphatidylethanolamine (DOPE)/cholesterol, egg phosphatidylcholine (EPC)/cholesterol, and distearoyl phosphocholine (DSPC)/cholesterol, and investigated the relationship between the intracellular trafficking of GC-Lip and GC presentation in antigen-presenting cells. When GC-Lip was prepared using DOPE, a fusogenic lipid, the endosomal escape of liposomes was enhanced, resulting in a decrease in GC presentation of CD1d, compared to the EPC based GC-Lip (EPC/GC-Lip). The stability of liposomes in endosomes/lysosomes had no influence on GC presentation. The DSPC based GC-Lip (DSPC/GC-Lip) induced GC presentation without any detectable degradation in liposomal structure, although the EPC/GC-Lip induced GC presentation with degradation of liposomal structure. The efficiency of GC presentation between EPC/GC-Lip and DSPC/GC-Lip was comparable. These GC presentations that were independent of the degradation of liposomes were dominated by saposins, sphingolipid activator proteins. Our findings reveal that GC presentation on CD1d from the fluid liposomes involves the action of saposins, regardless of whether liposome degradation occurs. This insight can be of use in terms of developing GC-Lip formulation for efficient GC presentation.

Multifunctional Envelope-Type Nano Device: Evolution from Nonselective to Active Targeting System

A paradigm shift has occurred in the field of drug delivery systems (DDS), one being intracellular targeting, and the other, active targeting. An important aspect of intracellular targeting involves delivering nucleic acids such as siRNA/pDNA rather than small molecular compounds, since the mechanism responsible for their entering a target cell is usually via endocytosis, and the efficiency of endosomal escape is a critical factor in determining the functional activities of siRNA/pDNA. A multifunctional envelope-type nano device (MEND) was developed to control the intracellular trafficking of nano carriers containing siRNA/pDNA. An octaarginine (R8) modified MEND was developed to achieve this. Considerable progress has been made in active targeting to selective tissue vasculature such as tumor, adipose tissue, and the lung where endothelial barrier is tight against nanoparticles with diameters larger than 50 nm. A dual-ligand system is proposed to enhance active targeting ability by virtue of a synergistic interaction between a selective ligand and a cell penetrating ligand. Prohibitin targeted nanoparticles (PTNP) were developed to target endothelial cells in adipose tissue, which deliver apoptotic peptides/proteins to the adipose vasculature. Lung endothelial cells can be targeted by means of the GALA peptide, which is usually used to enhance endosomal escape. These active targeting systems can induce pharmacological effects in in vivo conditions. Finally, a novel strategy for producing an original ligand has been developed, especially for the tumor vasculature. This progress in DDS promises to extend the area of nanomedicine as a breakthrough technology.

Programmed packaging of mesoporous silica nanocarriers for matrix metalloprotease 2-triggered tumor targeting and release

The development of multifunctional nanocarrier with each unit functioning at the correct time and location is a challenge for clinical applications. With this in mind, a type of intelligent mesoporous silica nanocarrier (PGFMSN) is proposed for matrix metalloprotease 2 (MMP 2)-triggered tumor targeting and release by integrating programmed packing and MMP 2-degradable gelatin. Mesoporous silica nanoparticles (MSN) are first functionalized with folic acid (FA) as a target ligand to improve cell uptake. Then gelatin is introduced onto FA-MSN via temperature-induced gelation, where gelatin layer blocks drugs inside the mesopores and protects the targeting ligand. To prolong blood-circulation lifetime, PEG is further decorated to obtain PGFMSN. All units are programmatically incorporated in a simple way and coordinated in an optimal fashion. Cells, multicellular spheroids and in vivo results demonstrate that PGFMSN is shielded against nonspecific uptake. After circulating to tumor tissue, the up-regulated MMP-2 hydrolyzes gelatin layer to deshield PEG and switch on the function of FA, which facilitate the selective uptake by tumor cells through folate-receptor-mediated endocytosis. Meanwhile, the packaged drug is released due to the shedding of gelatin layer. It is shown that doxorubicin (DOX)-loaded exhibits superior tumor targeting, drug internalization, cytotoxicity, and antitumor efficacy over free DOX, non-PEGylated and non-targeted nanoparticles, which provides potential applications for targeted cancer therapy.

Mitochondrial delivery of antisense RNA by MITO-Porter results in mitochondrial RNA knockdown, and has a functional impact on mitochondria

Mitochondrial genome-targeting nucleic acids are promising therapeutic candidates for treating mitochondrial diseases. To date, a number of systems for delivering genetic information to the cytosol and the nucleus have been reported, and several successful gene therapies involving gene delivery targeted to the cytosol and the nucleus have been reported. However, much less progress has been made concerning mitochondrial gene delivery systems, and mitochondrial gene therapy has never been achieved. Here, we report on the mitochondrial delivery of an antisense RNA oligonucleotide (ASO) to perform mitochondrial RNA knockdown to regulate mitochondrial function. Mitochondrial delivery of the ASO was achieved using a combination of a MITO-Porter system, which contains mitochondrial fusogenic lipid envelopes for mitochondrial delivery via membrane fusion and D-arm, a mitochondrial import signal of tRNA to the matrix. Mitochondrial delivery of the ASO induces the knockdown of the targeted mitochondria-encoded mRNA and protein, namely cytochrome c oxidase subunit II, a component of the mitochondrial respiratory chain. Furthermore, the mitochondrial membrane potential was depolarized by the down regulation of the respiratory chain as the result of the mitochondrial delivery of ASO. This finding constitutes the first report to demonstrate that the nanocarrier-mediated mitochondrial genome targeting of antisense RNA effects mitochondrial function.

A KALA-modified lipid nanoparticle containing CpG-free plasmid DNA as a potential DNA vaccine carrier for antigen presentation and as an immune-stimulative adjuvant

Technologies that delivery antigen-encoded plasmid DNA (pDNA) to antigen presenting cell and their immune-activation are required for the success of DNA vaccines. Here we report on an artificial nanoparticle that can achieve these; a multifunctional envelope-type nanodevice modified with KALA, a peptide that forms α-helical structure at physiological pH (KALA-MEND). KALA modification and the removal of the CpG-motifs from the pDNA synergistically boosted transfection efficacy. In parallel, transfection with the KALA-MEND enhances the production of multiple cytokines and chemokines and co-stimulatory molecules via the Toll-like receptor 9-independent manner. Endosome-fusogenic lipid envelops and a long length of pDNA are essential for this immune stimulation. Furthermore, cytoplasmic dsDNA sensors that are related to the STING/TBK1 pathway and inflammasome are involved in IFN-β and IL-1β production, respectively. Consequently, the robust induction of antigen-specific cytotoxic T-lymphoma activity and the resulting prophylactic and therapeutic anti-tumor effect was observed in mice that had been immunized with bone marrow-derived dendritic cells ex vivo transfected with antigen-encoding pDNA. Collectively, the KALA-MEND possesses dual functions; gene transfection system and immune-stimulative adjuvant, those are both necessary for the successful DNA vaccine.

Novel bivalent spermine-based neutral neogalactolipids for modular gene delivery systems

New bivalent spermine-based neutral neogalactolipids have been synthesized to develop effective modular gene delivery systems targeting hepatocyte asialoglycoprotein receptors.

Advances in an active and passive targeting to tumor and adipose tissues

INTRODUCTION

Data reported during the last decade of the twentieth century indicate that passive targeting is an efficient strategy for delivering nanocarrier systems to tumor tissues. The focus of this review is on active targeting as a next-generation strategy for extending the capacity of a drug delivery system (DDS).

AREAS COVERED

Tumor vasculature targeting was achieved using arginine- glycine-aspartic acid, asparagine-glycine-arginine and other peptides, which are well-known peptides, as ligand against tumor vasculature. An efficient system for delivering small interfering RNA to the tumor vasculature involved the use of a multifunctional envelope-type nanodevice based on a pH-modified cationic lipid and targeting ligands. The active-targeting system was extended from tumor delivery to adipose tissue delivery, where endothelial cells are tightly linked and are impermeable to nanocarriers. In mice, prohibitin-targeted nanoparticles can be used to successfully deliver macromolecules to induce anti-obese effects. Finally, the successful delivery of nanocarriers to adipose tissue in obese mice via the enhanced permeability and retention-effect is reported, which can be achieved in tumor tissue.

EXPERT OPINION

Unlike tumor tissues, only a few reports have appeared on how liposomal carriers accumulate in adipose tissues after systemic injection. This finding, as well as active targeting to the adipose vasculature, promises to extend the capacity of DDS to adipose tissue. Since the site of action of nucleic acids is the cytosol, the intracellular trafficking of carriers and their cargoes as well as cellular uptake must be taken into consideration.