Delivery of a granzyme B inhibitor gene using carbamate-mannose modified PEI protects against cytotoxic lymphocyte killing

PEGylated nanohydrogels delivering anti-MicroRNA-21 suppress ovarian tumor-associated angiogenesis in matrigel and chicken chorioallantoic membrane models

Introduction: Recently, MicroRNAs have gained increasing popularity as a novel nucleic acid-mediated medicine to regulate cancer-related protein expression. MicroRNA-21 (miR-21) is known as an oncogenic microRNA which is overexpressed in almost all cancers, including ovarian carcinoma that causes cisplatin (cis-Pt) resistance and vascular endothelial growth factor (VEGF) upregulation. So, miRNA-based therapy can be regarded as knocking down miR-21 expression, inducing tumor cell apoptosis, and suppressing tumor-associated angiogenesis. Methods: PEG5k-carboxymethylated polyethyleneimine nanohydrogels (PEG5k-CMPEI) were loaded with AntagomiR-21 (As-21) at different ratios of nitrogen to phosphorus (N/P). Particle size and ζ potential were determined for the As-21 loaded nanohydrogels. In the cellular experiments, miR-21 expression, cytotoxicity, and cis-Pt sensitivity were studied on A2780 ovarian cancer cell lines. Finally, tumor cell apoptosis and tumor cell-associated angiogenesis were explored in vitro and in vivo. Results: The nanohydrogels, featuring homogeneous size distribution and redox-responsiveness, were steadily loaded by As-21 at the optimum N/P ratio of 5 without any aggregation as determined by transmission electron microscopy (TEM). As-21-loaded nanohydrogels caused sequence-specific suppression of miR-21 expression and provoked apoptosis through ROS generation and caspase 3 activation. Cisplatin cytotoxicity was remarkably enhanced in A2780R as compared to A2780S following co-incubation with As-21-loaded nanohydrogels. Interestingly, the condition of the medium derived from As-21 nanohydrogel-treated A2780R cells inhibited VEGF suppression in human umbilical vein endothelial cells (HUVECs) and the formation of tubes in Matrigel. Moreover, the condition medium caused angiogenesis inhibition in the chicken chorioallantoic membrane (CAM) model. Conclusion: These results suggest that nanohydrogel-based delivery of As-21 can be a promising neoadjuvant therapy for treating resistant tumors via apoptosis induction and angiogenesis suppression.

Therapeutic effect of pH-Responsive dexamethasone prodrug nanoparticles on acute lung injury

Acute lung injury/inflammation (ALI) is usually caused by various injury factors inside and outside the lung, which can be transformed into acute respiratory distress syndrome (ARDS) in severe cases. Alveolar macrophages play a key role in the pathogenesis of ALI, which regulate inflammatory responses by secreting inflammatory mediators. Therefore, we prepared dexamethasone (DXM)/mannose co-modified branched polyethyleneimine (PEI) (DXM-PEI-mannose, DPM) prodrug nanopartcales, which could effectively target the mannose receptor (MR) on the surface of alveolar macrophages and be used for the treatment of ALI. The DXM-PEI (DP) prodrug was obtained by linking DXM with branched PEI through Schiff base reaction. Subsequently, the pH-responsive DPM prodrug was obtained by using mannose-targeted head modification. The DPM prodrug NPs with a particle size of 115 ± 1 nm, a polydispersity index (PDI) value of 0.054 ± 0.018, and a zeta potential of 31 ± 1 mV were obtained by cross-linking. The drug loading of DPM prodrug NPs measured by the acid hydrolysis method was 51.88%, which had good serum stability and biocompatibility. By comparing the stability and property release of prodrug NPs under different pH (7.4 and 5.0) conditions, it showed that DPM prodrug NPs had certain sensitivity to the micro-acid environment. To study the targeting of mouse mononuclear macrophages, mannose-modified prodrug NPs showed significant in vitro targeting. Moreover, prodrug NPs showed good anti-inflammatory activity in vitro, which was significantly different from free drugs. In vivo biodistribution experiments also showed that it had a long-term lung targeting effect. DPM prodrug NPs also had a good therapeutic effect on ALI. In conclusion, the mannose-modified DXM prodrug NPs delivery system could specifically target lung tissues and have a good therapeutic effect, which might be useful for the treatment of lung diseases.

Ratiometric Fluorescent Mapping of pH and Glutathione Dictates Intracellular Transport Pathways of Micellar Nanoparticles

Visualization of intracellular transport pathways is crucial to investigate the internalization mechanism and understand the intracellular behavior of nanomaterials. Herein, we rationalized the design of micellar nanoparticles (NPs) for ratiometric fluorescent mapping of intracellular pH and glutathione (GSH), two essential parameters for maintaining normal cellular functions. Specifically, pH-sensitive naphthalimide-based probe (NPI) and pH-inert rhodamine B (RhB) were covalently labeled to double hydrophilic block copolymers (DHBCs) using the thiolactone chemistry, enabling the covalent attachment of NPI and RhB to one molecule with a redox-responsive disulfide linkage. The dually labeled DHBCs exhibited blue/orange dual emissions in acidic pH, which was further converted into green/orange dual emissions in neutral pH because of the deprotonation of NPI moieties and the sole green emission in the presence of GSH at neutral pH because of the decreased Förster resonance energy transfer efficiency between an NPI donor and an RhB acceptor as a result of GSH-mediated cleavage of disulfide bonds. These remarkable ratiometric fluorescence changes allowed for not only the simultaneous mapping of the intracellular pH and GSH but also the intracellular transport pathways of internalized NPs.

A combinatorial library of biodegradable polyesters enables non-viral gene delivery to post-mitotic human stem cell-derived polarized RPE monolayers

Safe and effective delivery of DNA to post-mitotic cells, especially highly differentiated cells, remains a challenge despite significant progress in the development of gene delivery tools. Biodegradable polymeric nanoparticles (NPs) offer an array of advantages for gene delivery over viral vectors due to improved safety, carrying capacity, ease of manufacture, and cell-type specificity. Here we demonstrate the use of a high-throughput screening (HTS) platform to synthesize and screen a library of 148 biodegradable polymeric nanoparticles, successfully identifying structures that enable efficient transfection of human pluripotent stem cell differentiated human retinal pigment epithelial (RPE) cells with minimal toxicity. These NPs can deliver plasmid DNA (pDNA) to RPE monolayers more efficiently than leading commercially available transfection reagents. Novel synthetic polymers are described that enable high efficacy non-viral gene delivery to hard-to-transfect polarized human RPE monolayers, enabling gene loss- and gain-of-function studies of cell signaling, developmental, and disease-related pathways. One new synthetic polymer in particular, 3,3'-iminobis(N,N-dimethylpropylamine)-end terminated poly(1,5-pentanediol diacrylate-co-3 amino-1-propanol) (5-3-J12), was found to form self-assembled nanoparticles when mixed with plasmid DNA that transfect a majority of these human post-mitotic cells with minimal cytotoxicity. The platform described here can be utilized as an enabling technology for gene transfer to human primary and stem cell-derived cells, which are often fragile and resistant to conventional gene transfer approaches.

Multiply clustered gold-based nanoparticles complexed with exogenous pDNA achieve prolonged gene expression in stem cells

Development of a stable and prolonged gene delivery system is a key goal in the gene therapy field. To this end, we designed and fabricated a gene delivery system based on multiply-clustered gold particles that could achieve prolonged gene delivery in stem cells, leading to improved induction of differentiation.

Methods: Inorganic gold nanoparticles (AuNPs) underwent three rounds of complexation with catechol-functionalized polyethyleneimine (CPEI) and plasmid DNAs (pDNAs), in that order, with addition of heparin (HP) between rounds, yielding multiply-clustered gold-based nanoparticles (mCGNPs). Via metal-catechol group interactions, the AuNP surface was easily coordinated with positively charged CPEIs, which in turn allowed binding of pDNAs.

Results: Negatively charged HP was encapsulated with the positive charge of CPEIs via electrostatic interactions, making the NPs more compact. Repeating the complexation process yielded mCGNPs with improved transfection efficiency in human mesenchymal stem cells (hMSCs); moreover, these particles exhibited lower cytotoxicity and longer expression of pDNAs than conventional NPs. This design was applied to induction of chondrogenesis in hMSCs using pDNA harboring SOX9, an important chondrogenic transcription factor. Prolonged expression of SOX9 induced by mCGNPs triggered expression of chondrocyte extracellular matrix (ECM) protein after 14 days, leading to more efficient chondrogenic differentiation in vitro and in vivo.

Design of cyclodextrin-based systems for intervention execution

Technologies for nucleic acid delivery have displayed high practical potential in mediating genetic manipulation to modulate metabolic pathways to combat aging. In the previous chapter, we have delineated a series of techniques for designing and developing polymeric vectors as nonviral carriers. Based on what we have discussed, this chapter will introduce how the delivery performance and versatility of polymeric vectors can be further enhanced by using cyclodextrins (CDs). Over the years, CDs have shown promising application potential in different areas, ranging from controlled drug release to chiral separation of basic drugs. These applications are largely mediated by the ability of CDs to undergo host–guest inclusion complexation. Upon incorporation of CDs into the design of a polymeric vector, not only can the flexibility of the design be increased, but the development of a multifunctional carrier for genetic manipulation can also be facilitated.

A new developing class of gene delivery: messenger RNA-based therapeutics

Gene therapy has long been held as having the potential to become a front line treatment for various genetic disorders. However, the direct delivery of nucleic acids to correct a genetic disorder has numerous limitations owing to the inability of naked nucleic acids (DNA and RNA) to traverse the cell membrane. Recently, messenger RNA (mRNA) based delivery has become a more attractive alternative to DNA due to the relatively easier transfection process, higher efficiency and safety profile. As with all gene therapies, the central challenge that remains is the efficient delivery of nucleic acids intracellularly. This review presents the recent progress in mRNA delivery, focusing on comparing the advantages and limitations of non-viral based delivery vectors.

A reduction-responsive liposomal nanocarrier with self-reporting ability for efficient gene delivery

In the past few decades, although various reduction-responsive nanocarriers have been designed and explored for gene delivery, it is difficult to directly detect or monitor the reduction capability of these carriers, especially under intracellular conditions. Taking advantage of the generated fluorescence signal in the reduction process of the naphthalimide-sulfonamide (NS) group, we developed a novel liposomal nanocarrier, FNSL, which showed reduction-sensitive property and self-reporting character. As a new reduction-responsive site in a gene delivery system, the NS group in FNSL is capable of responding to glutathione (GSH) and simultaneously emitting green fluorescence at 500 nm in both extra- and intracellular circumstances. Hence, it will be very convenient to assess the reducibility of this carrier and monitor the stimuli-responsive gene release via fluorescence signal. FNSL has high affinity for DNA and can condense it into nanoparticles with a proper nano-size and zeta potential. Compared with the non-reducible FNAL, FNSL showed enhanced gene release capability, higher transfection efficiency (TE), and lower cytotoxicity. Furthermore, treatment of FNSL-mediated transfection with slightly exogenous GSH greatly improved the TE of FNSL in HepG2 cells, and its TE was even higher than that of Lipofectamine 2000. These results demonstrate that FNSL possesses great potential for efficient and low-toxicity gene delivery, and this study on a bioreducible liposome with self-reporting ability would be a guide for further research on the development of biodegradable gene carriers.

Delivery of NF-κB shRNA using carbamate-mannose modified PEI for eliminating cancer stem cells

The presence of cancer stem cells (CSCs) is one of the main reasons that cause cancer relapse and metastasis. In this study, NF-κB shRNA was delivered to target CSCs using carbamate-mannose modified PEI (CMP) as a non-viral gene vector. The polymer was synthesized by blocking primary amine groups of branched PEI (10kDa) through nucleophilic addition between PEI and protected mannose-functionalized cyclic carbonate, followed by mannose deprotection. CMP/control shRNA nanocomplexes showed lower cytotoxicity and higher transfection efficiency in 4T1 murine breast cancer cells than unmodified PEI/control shRNA nanocomplexes. Importantly, CMP/NF-κB shRNA nanocomplexes (CMPN) were capable of inhibiting migration and invasion, decreasing mammosphere and colony formation and lowering ALDH⁺ CSC population. Furthermore, CMPN not only induced apoptosis and inhibited cell proliferation, but also sensitized the cells to the treatment with doxorubicin-loaded micellar nanoparticles. Therefore, CMPN may provide a promising approach for eliminating CSCs to prevent cancer relapse and metastasis.

d-Fructose-Decorated Poly(ethylene imine) for Human Breast Cancer Cell Targeting

The high affinity of GLUT5 transporter for d-fructose in breast cancer cells has been discussed intensely. In this contribution, high molar mass linear poly(ethylene imine) (LPEI) is functionalized with d-fructose moieties to combine the selectivity for the GLUT5 transporter with the delivery potential of PEI for genetic material. The four-step synthesis of a thiol-group bearing d-fructose enables the decoration of a cationic polymer backbone with d-fructose via thiol-ene photoaddition. The functionalization of LPEI is confirmed by 2D NMR techniques, elemental analysis, and size exclusion chromatography. Importantly, a d-fructose decoration of 16% renders the polymers water-soluble and eliminates the cytotoxicity of PEI in noncancer L929 cells, accompanied by a reduced unspecific cellular uptake of the genetic material. In contrast, the cytotoxicity as well as the cell specific uptake is increased for triple negative MDA-MB-231 breast cancer cells. Therefore, the introduction of d-fructose shows superior potential for cell targeting, which can be assumed to be GLUT5 dependent.

Conjugates of small targeting molecules to non-viral vectors for the mediation of siRNA

To use siRNA (small interfering RNA) for gene therapy, a gene delivery system is often necessary to overcome several challenging requirements including rapid excretion, low stability in blood serum, non-specific accumulation in tissues, poor cellular uptake and inefficient intracellular release. Active and/or passive targeting should help the delivery system to reach the desired tissue or cell, to be internalized, and to deliver siRNA to the cytoplasm so that siRNA can inhibit protein synthesis. This review covers conjugates of small targeting molecules and non-viral delivery systems for the mediation of siRNA, with a focus on their transfection properties in order to help the development of new and efficient siRNA delivery systems, as the therapeutic solutions of tomorrow.

STATEMENT OF SIGNIFICANCE

The delivery of siRNA into cells or tissues remains to be a challenge for its applications, an alternative strategy for siRNA delivery systems is direct conjugation of non-viral vectors with targeting moieties for cellular delivery. In comparison to macromolecules, small targeting molecules have attracted great attention due to their many potential advantages including significant simplicity and ease of production, good repeatability and biodegradability. This review will focus on the most recent advances in the delivery of siRNA using conjugates of small targeting molecules and non-viral delivery systems. Based the editor's suggestions, we hope the revised manuscript could provide more profound understanding to the conjugates of targeting molecules to vectors for mediation of siRNA.

Co-delivery of drugs and plasmid DNA for cancer therapy

Cancer is an extremely complex disease involving multiple signaling pathways that enable tumor cells to evade programmed cell death, thus making cancer treatment extremely challenging. The use of combination therapy involving both gene therapy and chemotherapy has resulted in enhanced anti-cancer effects and has become an increasingly important strategy in medicine. This review will cover important design parameters that are incorporated into delivery systems for the co-administration of drug and plasmid-based nucleic acids (pDNA and shRNA), with particular emphasis on polymers as delivery materials. The unique challenges faced by co-delivery systems and the strategies to overcome such barriers will be discussed. In addition, the advantages and disadvantages of combination therapy using separate carrier systems versus the use of a single carrier will be evaluated. Finally, future perspectives in the design of novel platforms for the combined delivery of drugs and genes will be presented.

Antimicrobial silica particles synthesized via ring-opening grafting of cationic amphiphilic cyclic carbonates: effects of hydrophobicity and structure

In this study, cationic amphiphilic cyclic carbonates with varying hydrophobicity and structure were synthesized and grafted onto silica particles to impart antimicrobial properties.

Facile carbohydrate-mimetic modifications of poly(ethylene imine) carriers for gene delivery applications

PEI was chemically-modified with carbohydrates and carbohydrate-mimetics to improve biocompatibility.

Poly(trimethylene carbonate)-based polymers engineered for biodegradable functional biomaterials

This review presents recent examples of applications and functionalization strategies of poly(trimethylene carbonate), its copolymers, and its derivatives to exploit the unique physicochemical properties of the aliphatic polycarbonate backbone.

Unique Surface Modification of Silica Nanoparticles with Polyethylenimine (PEI) for siRNA Delivery Using Cerium Cation Coordination Chemistry

The discovery of RNA interference (RNAi) as a naturally occurring mechanism for gene knockdown has attracted considerable attention toward the use of small interfering RNAs (siRNAs) for therapeutic purposes. The main obstacles of harnessing siRNAs as drugs are their inefficient delivery to cells and off-target effect making clinical applications very challenging. The positively charged, branched 25 kDa polyethylenimine (b-PEI) polymer is widely regarded as one of the most efficient nonviral commercially available transfection agents. However, it has also been shown that 25 kDa b-PEI is highly cytotoxic and can readily lead to cell death. In this specific context, this study presents the preparation and characterization of innovative 25 kDa b-PEI-decorated polycationic silica nanoparticles (SiO2 NPs) for cellular siRNA delivery and subsequent gene silencing. A new method of b-PEI attachment onto the SiO2 NP surface has been developed that makes use of cerium(III) cations (Ce(3+)), a lanthanide group element, as an effective noncovalent inorganic linker between both polyNH2-SiO2 nanoparticle (SPA NPs) surface and polycationic 25 kDa b-PEI polymer. Two resulting novel SPA-Ce-PEI NPs consist of similar amounts of b-PEI, while possessing different amounts of Ce(3+). Various analytical techniques (TEM, DLS, ζ potential, ICP-AES, and TGA) have been used to deeply characterize NPs physicochemical qualities. The observed results of Ce(3+)-dependent gene silencing and cytotoxic activities led us to conclusions about the role of Ce(3+)-N bonding during the chemical attachment of the 25 kDa b-PEI shell onto the NP surface.

Dendritic glycopolymers based on dendritic polyamine scaffolds: view on their synthetic approaches, characteristics and potential for biomedical applications

The potential of dendritic glycopolymers based on dendritic polyamine scaffolds for biomedical applications is presented and compared with that of the structurally related anti-adhesive dendritic glycoconjugates.

Engineering and functionalization of biomaterials via surface modification

Recent progress pertaining to the surface treatment of implantable macro-scale biomaterials and using micro- and nano-biomaterials for disease diagnosis and drug/gene delivery is reviewed.

Silica nanoparticles and polyethyleneimine (PEI)-mediated functionalization: a new method of PEI covalent attachment for siRNA delivery applications

Small-interfering RNA (siRNA) is a synthetic double-stranded RNA that consists of approximately 21 nucleotides (nts). It induces degradation of target mRNAs in a sequence-specific manner by the RNA interference (RNAi) mechanism. Thus, siRNAs offer a potential strategy for silencing mutated or defective genes that cause a variety of human diseases. The main obstacles of harnessing siRNAs as drugs are their inefficient delivery to cells and off-target effect making clinical applications very challenging. To address these issues, researchers have studied a variety of nanocarrier systems for siRNA delivery. This study presents the design, fabrication, and full characterization of innovative polyethyleneimine (PEI)-decorated polycationic 34.2 ± 4.2 nm silica (SiO2) NPs for siRNA-mediated gene silencing. More specifically, a new means of introduction (covalent mode of attachment) of the polycationic 25 kDa PEI polymer onto the SiO2 NP surface has been developed that makes use of an effective electrophilic double Michäel acceptor, divinyl sulfone (DVS). The resulting novel SiO2-PEI nanoparticles (SPEI NPs) have been fully characterized using a wide range of analytical, spectroscopic, and microscopic methods (TEM, DLS, ζ potential, elemental analysis (EA), XPS, TGA, and FTIR). Disclosing quite low cytotoxicity due to this unique mode of PEI covalent grafting, SPEI NPs/siRNA polyplexes have been successfully tested for the induction of gene silencing using dual-reporter luciferase transfected human osteosarcoma U2OS cells. The corresponding gene silencing data showed a clear correlation between PEI/siRNA ratios, siRNA concentration(s), and the level of gene silencing. Moreover, these SPEI NPs have been demonstrated to be thermodynamically stable with an ability to efficiently bind siRNAs and induce silencing for at least a one-year-long storage.

Synthesis and characterization of glycol chitosan DNA nanoparticles for retinal gene delivery

Given the number of monogenic ocular diseases and the number of non-monogenic degenerative ocular diseases for which gene therapy is considered as a treatment, the development of effective therapeutic delivery strategies for DNA is a critical research goal. In this work, nonviral nanoparticles (NPs) composed of glycol chitosan (GCS) and plasmid DNA (pDNA) were generated, characterized, and evaluated. These particles are stable, do not aggregate in saline, are resistant to DNases, and have a hydrodynamic diameter of approximately 250 nm. Furthermore, the plasmid in these NPs was shown to maintain its proper conformation and can be released and expressed inside the cell. To determine whether these NPs would be suitable for intraocular use, pDNA carrying the ubiquitously expressed CBA-eGFP expression cassette was compacted and subretinally injected into adult wild-type albino mice. At day 14 post-injection (PI), substantial green fluorescent protein (GFP) expression was observed exclusively in the retinal pigment epithelium (RPE) in eyes treated with GCS NPs but not in those treated with uncompacted pDNA or vehicle (saline). No signs of gross retinal toxicity were observed, and at 30 days PI, there was no difference in electroretinogram function between GCS NP-, pDNA-, or vehicle-treated eyes. These results suggest that with further development, GCS NPs could be a useful addition to the available repertoire of genetic therapies for the treatment of RPE-associated diseases.

Cyclodextrins in non-viral gene delivery

Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides. They consist of (α-1,4)-linked glucose units, and possess a basket-shaped topology with an "inner-outer" amphiphilic character. Over the years, substantial efforts have been undertaken to investigate the possible use of CDs in drug delivery and controlled drug release, yet the potential of CDs in gene delivery has received comparatively less discussion in the literature. In this article, we will first discuss the properties of CDs for gene delivery, followed by a synopsis of the use of CDs in development and modification of non-viral gene carriers. Finally, areas that are noteworthy in CD-based gene delivery will be highlighted for future research. Due to the application prospects of CDs, it is anticipated that CDs will continue to emerge as an important tool for vector development, and will play significant roles in facilitating non-viral gene delivery in the forthcoming decades.

Self-crosslinked human serum albumin nanocarriers for systemic delivery of polymerized siRNA to tumors

The safe and effective systemic delivery of siRNA is a prerequisite for the successful development of siRNA-based cancer therapeutics. For the enhanced delivery of siRNA, cationic lipids and polymers have been widely used as siRNA carriers to form electrolyte complexes with anionic siRNA. However, the considerable toxicity of strong cationic-charged molecules hampers their clinical use. In this study, we utilized human serum albumin (HSA), which is the most abundant of the plasma proteins, as a siRNA carrier for systemic tumor-targeted siRNA delivery. Both HSA and siRNA molecules were thiol-introduced to improve the binding affinity for each other. The resulting thiolated HSA (tHSA) and polymerized siRNA (psi) formed stable nanosized complexes (psi-tHSAs) by chemical crosslinking and self-crosslinking. After internalization, the psi-tHSAs showed target gene silencing activity in vitro comparable to conventional Lipofectamine™-siRNA complexes, without remarkable cytotoxicity. After intravenous injection in tumor-bearing mice, psi-tHSAs accumulated specifically at the tumor sites, leading to efficient gene silencing in the tumors in a sequential manner. The therapeutic VEGF siRNA was loaded into psi-tHSAs, which significantly inhibited tumor-related angiogenesis in PC-3 tumor xenografts and resulted in retarding the growth of PC-3 tumors. The results showed that self-crosslinked psi-tHSA nanocarriers might provide a promising approach for the systemic siRNA therapy of various human cancers.