A mannosylated cell-penetrating peptide-graft-polyethylenimine as a gene delivery vector

Co-Delivery of Dacarbazine and miRNA 34a Combinations to Synergistically Improve Malignant Melanoma Treatments

Purpose

The incidence of malignant melanoma (MM) has risen over the past three decades, and despite advancements in treatment, there is still a need to improve treatment modalities. This study developed a promising strategy for tumor-targeted co-delivery of Dacarbazine (DTIC) and miRNA 34a-loaded PHRD micelles (Co-PHRD) for combination treatment of MM.

Methods

To construct the dual drug-loaded delivery system Co-PHRD, poly (L-arginine)-poly (L-histidine)-polylactic acid (PLA) was employed as a building block. In this system, poly (L-arginine) and PLA function as hydrophilic and hydrophobic blocks, respectively, which self-assemble into micelles in aqueous solution. Poly(L-arginine) and poly(L-histidine) are efficiently taken up by cells and perform efficient gene condensation, which facilitate the release of encapsulated miRNA 34a into the cytoplasm. Due to its lipophilic properties, PLA can effectively encapsulate DTIC. The polypeptide aptamer DR5-TAT (D21) was used as a targeting ligand. The properties of Co-PHRD and its in vitro release behaviour were characterized. Additionally, the synergetic effects of DTIC and miRNA 34a in melanoma therapy were investigated in vitro and in vivo.

Results

Compared to DTIC treatment alone, Co-PHRD treatment exhibited 1.84-fold greater cytotoxicity in A375 cells, demonstrating that miRNA 34a enhanced the efficacy of DTIC. The particle size of Co-PHRD at an N/P ratio of 10 was 164.1 ± 4.5 nm, and the zeta potential of Co-PHRD was 27.3 ± 1.38 mV. The flow cytometry and CLSM results revealed both DTIC and miRNA 34a were avidly taken up by A375 cells at 1 h and 4 h in PHRD. In addition, in vivo results indicated that Co-PHRD micelles can significantly inhibit tumor growth without causing significant damage to major organs.

Conclusion

Co-delivery of DTIC and miRNA 34a via polypeptide micelles showed synergistic effects against MM, offering a new strategy for gene and chemotherapy.

RNA technology and nanocarriers empowering in vivo chimeric antigen receptor therapy

The remarkable success of mRNA-based coronavirus 2019 (COVID-19) vaccines has propelled the advancement of nanomedicine, specifically in the realm of RNA technology and nanomaterial delivery systems. Notably, significant strides have been made in the development of RNA-based in vivo chimeric antigen receptor (CAR) therapy. In comparison to the conventional ex vivo CAR therapy, in vivo CAR therapy offers several benefits including simplified preparation, reduced costs, broad applicability and decreased potential for carcinogenic effects. This review summarises the RNA-based CAR constructs in in vivo CAR therapy, discusses the current applications of in vivo delivery vectors and outlines the immune cells edited with CAR molecules. We aim for the conveyed messages to contribute towards the advancement of in vivo CAR application.

Immune response and protective efficacy of mannosylated polyethylenimine (PEI) as an antigen delivery vector, administered with a Streptococcus agalactiae DNA vaccine in Nile tilapia (Oreochromis niloticus)

This study examined the effectiveness of a DNA vaccine for S. agalactiae that was delivered by mannose-based polyethyleneimine (Man-PEI). The results showed that Man-PEI/pcDNA-Sip stimulated a higher serum antibody titer compared to control or other vaccine groups (p < 0.05). Additionally, it induced higher expression of immune-related genes, and increased activities of superoxide dismutase (SOD), acid phosphatase (ACP) and alkaline phosphatase (AKP). Furthermore, the Man-PEI/pcDNA-Sip group showed an improved relative percent survival (RPS) of 85.71%. These results demonstrate the potential value of Man-PEI as a vaccine delivery vehicle, and suggest that it can be effective in boosting the immune protective rate induced by pcDNA-Sip vaccines.

Research progress of physical transdermal enhancement techniques in tumor therapy

The advancement and popularity of transdermal drug delivery (TDD) based on the physical transdermal enhancement technique (PTET) has opened a new paradigm for local tumor treatment. The drug can be directly delivered to the tumor site through the skin, thus avoiding the toxic side effects caused by the first-pass effect and achieving high patient compliance. Further development of PTETs has provided many options for antitumor drugs and laid the foundation for future applications of wearable closed-loop targeting drug delivery systems. In this highlight, the different types of PTETs and related mechanisms, and applications of PTET-related tumor detection and therapy are highlighted. According to their type and characteristics, PTETs are categorized as follows: (1) iontophoresis, (2) electroporation, (3) ultrasound, (4) thermal ablation, and (5) microneedles. PTET-related applications in the local treatment of tumors are categorized as follows: (1) melanoma, (2) breast tumor, (3) squamous cell carcinoma, (4) cervical tumor, and (5) others. The challenges and future prospects of existing PTETs are also discussed. This highlight will provide guidance for the design of PTET-based wearable closed-loop targeting drug delivery systems and personalized therapy for tumors.

Biomaterials promote in vivo generation and immunotherapy of CAR-T cells

Chimeric antigen receptor-T (CAR-T) cell therapy based on functional immune cell transfer is showing a booming situation. However, complex manufacturing processes, high costs, and disappointing results in the treatment of solid tumors have limited its use. Encouragingly, it has facilitated the development of new strategies that fuse immunology, cell biology, and biomaterials to overcome these obstacles. In recent years, CAR-T engineering assisted by properly designed biomaterials has improved therapeutic efficacy and reduced side effects, providing a sustainable strategy for improving cancer immunotherapy. At the same time, the low cost and diversity of biomaterials also offer the possibility of industrial production and commercialization. Here, we summarize the role of biomaterials as gene delivery vehicles in the generation of CAR-T cells and highlight the advantages of in-situ construction in vivo. Then, we focused on how biomaterials can be combined with CAR-T cells to better enable synergistic immunotherapy in the treatment of solid tumors. Finally, we describe biomaterials' potential challenges and prospects in CAR-T therapy. This review aims to provide a detailed overview of biomaterial-based CAR-T tumor immunotherapy to help investigators reference and customize biomaterials for CAR-T therapy to improve the efficacy of immunotherapy.

Carbohydrates based stimulus responsive nanocarriers for cancer-targeted chemotherapy: A review of current practices

INTRODUCTION

Many nanocarriers have been developed to react physicochemically to exterior stimuli like ultrasonic, light, heat, and magnetic fields, along with various internal stimuli including pH, hypoxia, enzyme, and redox potential. Nanocarriers are capable to respond various stimuli within the cancer cells to enable on-demand drug delivery, activation of bioactive compounds, controlled drug release, and targeting ligands, as well as size, charge, and conformation conversion, enabling sensing and signaling, overcoming multidrug resistance, accurate diagnosis, and precision therapy.

AREAS COVERED

Carbohydrates are ubiquitous biomolecules with a high proclivity for supramolecular network formation. Numerous carbohydrate-based nanomaterials have been used in biological solicitations and stimuli-based responses. Particular emphasis has been placed on the utilization of carbohydrate-based NPs and nanogels in various fields including imaging, drug administration, and tissue engineering. Because the assembly process is irreversible, carbohydrate-based systems are excellent ingredients for the development of stimulus-responsive nanocarriers for cancer-targeted chemotherapy. This review aims to summarise current research on carbohydrate-based nanomaterials, with an emphasis on stimuli-sensitive nanocarriers for cancer-targeted chemotherapy.

EXPERT OPINION

Carbohydrates-based stimulus-responsive nanomaterials have been proved highly efficient for targeted delivery of anticancer drugs, thus leading to effective chemotherapy with minimum off-target effects.

Controlled pVEGF delivery via a gene-activated matrix comprised of a peptide-modified non-viral vector and a nanofibrous scaffold for skin wound healing

Regulating cell function and tissue formation by combining gene delivery with functional scaffolds to create gene-activated matrices (GAMs) is a promising strategy for tissue engineering. However, fabrication of GAMs with low cytotoxicity, high transfection efficiency, and long-term gene delivery properties remains a challenge. In this study, a non-viral DNA delivery nanocomplex was developed by modifying poly (D, L-lactic-co-glycolic acid)/polyethylenimine (PLGA/PEI) nanoparticles with the cell-penetrating peptide KALA. Subsequently, the nanocomplex carrying plasmid DNA encoding vascular endothelial growth factor (pVEGF) was immobilized onto a polydopamine-coated electrospun alginate nanofibrous scaffold, resulting in a GAM for enhanced skin wound healing. The nanocomplex exhibited much lower cytotoxicity and comparable or even higher transfection efficiency compared with PEI. The GAM enabled sustained gene release and long-tern transgene expression of VEGF in vitro. In an excisional full-thickness skin wound rat model, the GAM could accelerate wound closure, promote complete re-epithelization, reduce inflammatory response, and enhance neovascularization, ultimately enhancing skin wound healing. The current GAM comprising a low-toxic gene delivery nanocomplex and a biocompatible 3D nanofibrous scaffold demonstrates great potential for mediating long-term cell functions and may become a powerful tool for gene delivery in tissue engineering. STATEMENT OF SIGNIFICANCE: Gene delivery is a promising strategy in promoting tissue regeneration as an effective alternative to growth factor delivery, but the study on three-dimensional gene-activated scaffolds remains in its infancy. Herein, a biodegradable nanofibrous gene-activated matrix integrating non-viral nanoparticle vector was designed and evaluated both in vitro and in vivo. The results show that the nanoparticle vector provided high transfection efficiency with minimal cytotoxicity. After surface immobilization of the nanocomplexes carrying plasmid DNA encoding vascular endothelial growth factor (pVEGF), the nanofibrous scaffold enabled sustained DNA release and long-term transgene expression in vitro. In a rat full-thickness skin wound model, the scaffold could accelerate wound healing. This innovative gene-activated matrix can be a promising candidate for tissue regeneration.

Transcutaneous tumor vaccination combined with anti-programmed death-1 monoclonal antibody treatment produces a synergistic antitumor effect

Transcutaneous immunization (TCI) has the advantages of safety, high efficiency, non-invasiveness and convenient use. The key for a TCI system is transdermal targeted delivery of antigen to dendritic cells (DCs), the most powerful antigen presenting cells. DCs also play an important role in tumor immunotherapy, which provides a huge imagination for the application of TCI to tumor treatment. In this study, a transcutaneous tumor vaccine (TTV) delivery system was developed using the electrospun silk fibroin (SF) and polyvinyl alcohol (PVA) composite nanofibrous patch loaded with mannosylated polyethyleneimine (PEI^man)-modified ethosome (Eth) (termed Eth-PEI^man). Eth-PEI^man showed a good performance in targeting DCs, and the carriers loaded with antigen (encapsulated in Eths) and adjuvant (absorbed in PEI^man) were observed effectively induce DCs maturation in vitro. With the tyrosinase-related protein-2 (TRP2) peptide as antigen and oligodeoxynucleotides containing unmethylated CpG motifs as adjuvant, the TTV-loaded patches (TTVP) significantly inhibited the growth of melanoma in a syngeneic mouse model for melanoma by subcutaneous injection of B16F10 cell lines. Moreover, the combined application of the TTVP and anti-programmed death-1 monoclonal antibody (aPD-1) produced a synergistic antitumor effect, which could be related to the infiltration of more CD4⁺ and CD8⁺ T cells in the tumor tissues. The application of TTVP also increased the expression of IL-12, which may be part of the mechanism of synergistic antitumor effect between the TTVP and aPD-1. These results suggest that the combination of the TTVP and immune checkpoint blockers could be an effective strategy for tumor treatment. STATEMENT OF SIGNIFICANCE: Transcutaneous immunization has the advantages of safety, high efficiency, non-invasiveness and convenient use. In this study, a novel transcutaneous tumor vaccine patch (TTVP) was developed using tumor antigens-loaded ethosomes that can target dendritic cells percutaneously. Our data demonstrated that the TTVP can significantly inhibit tumor growth. Furthermore, the combination of TTVP and aPD-1 produced a synergistic anti-melanoma effect. Considering its convenience and non-invasiveness, this TTVP system could find good application prospects in immunotherapy. The combination of TTVP and aPD-1 could be a useful strategy for the prevention and treatment of tumors.

Microneedle systems for delivering nucleic acid drugs

Background

Nucleic acid-based gene therapy is a promising technology that has been used in various applications such as novel vaccination platforms for infectious/cancer diseases and cellular reprogramming because of its fast, specific, and effective properties. Despite its potential, the parenteral nucleic acid drug formulation exhibits instability and low efficacy due to various barriers, such as stability concerns related to its liquid state formulation, skin barriers, and endogenous nuclease degradation. As promising alternatives, many attempts have been made to perform nucleic acid delivery using a microneedle system. With its minimal invasiveness, microneedle can deliver nucleic acid drugs with enhanced efficacy and improved stability.

Area covered

This review describes nucleic acid medicines' current state and features and their delivery systems utilizing non-viral vectors and physical delivery systems. In addition, different types of microneedle delivery systems and their properties are briefly reviewed. Furthermore, recent advances of microneedle-based nucleic acid drugs, including featured vaccination applications, are described.

Expert opinion

Nucleic acid drugs have shown significant potential beyond the limitation of conventional small molecules, and the current COVID-19 pandemic highlights the importance of nucleic acid therapies as a novel vaccination platform. Microneedle-mediated nucleic acid drug delivery is a potential platform for less invasive nucleic acid drug delivery. Microneedle system can show enhanced efficacy, stability, and improved patient convenience through self-administration with less pain.

Polymer-based Non-viral Vectors for Gene Therapy in the Skin

Gene therapy has emerged as a versatile technique with the potential to treat a range of human diseases; however, examples of the topical application of gene therapy as a treatment...

Treatment of Melanoma by Nano-conjugate-Delivered Wee1 siRNA

Small interfering RNA (siRNA)-based drugs have shown tremendous potential to date in cancer gene therapy. Despite the considerable efforts in siRNA design and manufacturing, unsatisfactory delivery systems persist as a limitation for the application of siRNA-based drugs. In this work, the cholesterol, cell-penetrating peptide conjugate cRGD (R8-cRGD), and polyethylene glycol (PEG) were introduced into low-molecular-weight polyethyleneimine (LMW PEI) to form cRGD-R9-cholesterol-PEI-PEG (RRCPP) nanoparticles with specific targeting and highly penetrating abilities. The enhanced siRNA uptake efficiency of the RRCPP delivery system benefited from R8-cRGD modification. Wee1 is an oncogenic nuclear kinase that can regulate the cell cycle as a crucial G2/M checkpoint. Overexpression of Wee1 in melanoma may lead to a poor prognosis. In the present study, RRCPP nanoparticles were designed for Wee1 siRNA delivery to form an RRCPP/siWee1 complex, which significantly silenced the expression of the WEE1 gene (>60% inhibition) and induced B16 tumor cell apoptosis by abrogating the G2M checkpoint and DNA damage in vitro. Furthermore, the RRCPP/siWee1 complex suppressed B16 tumor growth in a subcutaneous xenograft model (nearly 85% inhibition rate) and lung metastasis (nearly 66% inhibition rate) with ideal in vivo safety. Briefly, our results support the validity of RRCPP as a potential Wee1 siRNA carrier for melanoma gene therapy.

Conventional and hybrid nanoparticulate systems for the treatment of hepatocellular carcinoma: An updated review

Hepatocellular carcinoma (HCC) is considered a serious malignancy which affects a large number of people worldwide. Despite the presence of some diagnostic techniques for HCC, the fact that its symptoms somehow overlap with other diseases causes it to be diagnosed at a late stage, hence negatively affecting the prognosis of the disease. The currently available treatment strategies have many shortcomings such as high cost, induction of serious side effects as well as multiple drug resistance, hence resulting in therapeutic failure. Accordingly, nanoformulations have been developed in order to overcome the clinical challenges, enhance the therapeutic efficacy, and elicit chemotherapy tailor-ability. Hybrid nanoparticulate carriers in particular, which are composed of two or more drug vehicles with different physicochemical characteristics combined together in one system, have been recently reported to advance nanotechnology-based therapies. Therefore, this review sheds the light on HCC, and the role of nanotechnology and hybrid nanoparticulate carriers as well as the latest developments in the use of conventional nanoparticles in combating this disease.

Evaluation and Optimization of Poly-d-Lysine as a Non-Natural Cationic Polypeptide for Gene Transfer in Neuroblastoma Cells

Cationic polypeptides and cationic polymers have cell-penetrating capacities and have been used in gene transfer studies. In this study, we investigate the capability of a polymer of d-lysine (PDL), a chiral form of α–Poly-lysine, as a possible nonviral vector for releasing genetic materials to neuroblastoma cells and evaluate its stability against proteases. We tested and compared its transfection effectiveness in vitro as a vehicle for the EGFP plasmid DNA (pDNA) reporter in the SH-SY5Y human neuroblastoma, HeLa, and 3T3 cell lines. Using fluorescent microscopy and flow cytometry, we demonstrated high transfection efficiencies based on EGFP fluorescence in SH-SY5Y cells, compared with HeLa and 3T3. Our results reveal PDL as an efficient vector for gene delivery specifically in the SH-SY5Y cell line and suggest that PDL can be used as a synthetic cell-penetrating polypeptide for gene therapy in neuroblastoma cells.

Glycosylated Nanoparticles for Cancer-Targeted Drug Delivery

Nanoparticles (NPs) are novel platforms that can carry both cancer-targeting molecules and drugs to avoid severe side effects due to nonspecific drug delivery in standard chemotherapy treatments. Cancer cells are characterized by abnormal membranes, metabolic changes, the presence of lectin receptors, glucose transporters (GLUT) overexpression, and glycosylation of immune receptors of programmed death on cell surfaces. These characteristics have led to the development of several strategies for cancer therapy, including a large number of carbohydrate-modified NPs, which have become desirable for use in cell-selective drug delivery systems because they increase nanoparticle-cell interactions and uptake of carried drugs. Currently, the potential of NP glycosylation to enhance the safety and efficacy of carried therapeutic antitumor agents has been widely acknowledged, and much information is accumulating in this field. This review seeks to highlight recent advances in NP stabilization, toxicity reduction, and pharmacokinetic improvement and the promising potential of NP glycosylation from the perspective of molecular mechanisms described for drug delivery systems for cancer therapy. From preclinical proof-of-concept to demonstration of therapeutic value in the clinic, the challenges and opportunities presented by glycosylated NPs, with a focus on their applicability in the development of nanodrugs, are discussed in this review.

Progress and perspective of microneedle system for anti-cancer drug delivery

Transdermal drug delivery exhibited encouraging prospects, especially through superficial drug administration routes. However, only a few limited lipophilic drug molecules could cross the skin barrier, those are with low molecular weight and rational Log P value. Microneedles (MNs) can overcome these limitations to deliver numerous drugs into the dermal layer by piercing the outermost skin layer of the body. In the case of superficial cancer treatments, topical drug administration faces severely low transfer efficiency, and systemic treatments are always associated with side effects and premature drug degradation. MN-based systems have achieved excellent technical capabilities and been tested for pre-clinical chemotherapy, photothermal therapy, photodynamic therapy, and immunotherapy. In this review, we will focus on the features, progress, and opportunities of MNs in the anticancer drug delivery system. Then, we will discuss the strategies and advantages in these works and summarize challenges, perspectives, and translational potential for future applications.

"Layer peeling" co-delivery system for enhanced RNA interference-based tumor associated macrophages-specific chemoimmunotherapy

RNA interference (RNAi)-based immunotherapy combined with chemotherapy has emerged as a promising therapeutic strategy for cancer treatment. The transport of siRNA and small molecular agents from the tumor vasculature to a separate therapeutic target has been impeded by multiple physiological barriers, which has restricted the development of RNAi-based chemoimmunotherapy. A nanotechnology-based co-delivery system was superior in improving the co-localization of gene and drug in the same tumor cell, while a co-delivery system for chemoimmunotherapy was expected to realize xenotype cell-targeting, which means delivering immunotherapy agents and chemotherapy drugs to immune cells and tumor cells, respectively. A multilayer structure co-delivery system was outstanding in crossing these barriers and targeting different cells in tumor tissue. Herein, a "layer peeling" co-delivery system (CDMPR) was developed with co-loaded IKKβ-siRNA and doxorubicin (DOX), in which IKKβ-siRNA was used for RNAi-based tumor associated macrophages (TAMs) polarization for immunotherapy and DOX was used for chemotherapy. A transwell assay in vitro and an immunofluorescence assay in Hepa1-6 tumor-bearing mice indicated that CDMPR exhibited a pH-sensitive disassembly ability in tumor tissue, IKKβ-siRNA was precisely delivered to M2-type TAMs and DOX was internalized into tumor cells. An M2-type TAMs polarization ability study of CDMPR demonstrated that M2-type TAMs could be polarized to M1-type TAMs by CDMPR in vitro and in vivo. In Hepa1-6 tumor-bearing mice, CDMPR exhibited improved antitumor efficiency with M2-type re-polarization ability by the precise delivery of IKKβ-siRNA and DOX to M2-type TAMs and tumor cells, respectively. Consequently, the combination of RNAi-based TAMs polarization and chemotherapy by the "layer peeling" co-delivery system would achieve an enhanced chemoimmunotherapy effect, which provides a novel strategy to improve cancer therapeutic effects.

Engineered Nanodelivery Systems to Improve DNA Vaccine Technologies

DNA vaccines offer a flexible and versatile platform to treat innumerable diseases due to the ease of manipulating vaccine targets simply by altering the gene sequences encoded in the plasmid DNA delivered. The DNA vaccines elicit potent humoral and cell-mediated responses and provide a promising method for treating rapidly mutating and evasive diseases such as cancer and human immunodeficiency viruses. Although this vaccine technology has been available for decades, there is no DNA vaccine that has been used in bed-side application to date. The main challenge that hinders the progress of DNA vaccines and limits their clinical application is the delivery hurdles to targeted immune cells, which obstructs the stimulation of robust antigen-specific immune responses in humans. In this updated review, we discuss various nanodelivery systems that improve DNA vaccine technologies to enhance the immunological response against target diseases. We also provide possible perspectives on how we can bring this exciting vaccine technology to bedside applications.

Glycyrrhizin Acid and Glycyrrhetinic Acid Modified Polyethyleneimine for Targeted DNA Delivery to Hepatocellular Carcinoma

In the last 2-3 decades, gene therapy represented a promising option for hepatocellular carcinoma (HCC) treatment. However, the design of safe and efficient gene delivery systems is still one of the major challenges that require solutions. In this study, we demonstrate a versatile method for covalent conjugation of glycyrrhizin acid (GL) or glycyrrhetinic acid (GA) to increase the transfection efficiency of Polyethyleneimine (PEI, Mw 1.8K) and improve their targeting abilities of hepatoma carcinoma cells. GA and GL targeting ligands were grafted to PEI via N-acylation, and we systematically investigated their biophysical properties, cytotoxicity, liver targeting and transfection efficiency, and endocytosis pathway trafficking. PEI-GA0.75, PEI-GL10.62 and PEI-GL20.65 conjugates caused significant increases in gene transfection efficiency and superior selectivity for HepG2 cells, with all three conjugates showing specific recognition of HepG2 cells by the free GA competition assay. The endocytosis inhibition and intracellular trafficking results indicated that PEI-GA0.75 and GL10.62 conjugates behaved similarly to SV40 virus, by proceeding via the caveolae- and clathrin-independent mediated endocytosis pathway and bypassing entry into lysosomes, with an energy independent manner, achieving their high transfection efficiencies. In the HepG2 intraperitoneal tumor model, PEI-GA0.75 and PEI-GL10.62 carrying the luciferase reporter gene gained high gene expression, suggesting potential use for in vivo application.

A new cancer immunotherapy via simultaneous DC-mobilization and DC-targeted IDO gene silencing using an immune-stimulatory nanosystem

The activity of negative immune regulatory molecules, such as indoleamine 2,3-oxygenase (IDO), significantly attenuates DC (Dendritic cells)-mediated immunotherapy. We have previously reported that knockdown of IDO using siRNA can reinstall anti-tumor immunity. However, a DC-targeted siRNA delivery system for in vivo mobilized DCs remains to be developed, while gene silencing in mobilized DCs for cancer immunotherapy has never been explored. In our study, we developed a novel DC-targeted siRNA delivery system, man-GNR-siIDO, using as a nanocarrier of siRNA specific for IDO (siIDO) and mannose (man) as a guide molecule for targeting DCs. We explored the immunostimulatory man-GNR-siIDO nano-construct in DCs mobilized by Flt3-L, a receptor-type tyrosine kinase ligand, for lung cancer immunotherapy. In vivo DC-targeted gene silencing of IDO resulted in robust anti-tumor immunity as evidenced by promoting DC maturation, up-regulating tumor antigen-specific T-cell proliferation and enhancing tumor-specific cytotoxicity. A combinatorial treatment for Lewis Lung Carcinoma (LLC)-bearing mice, with man-GNR-siIDO and Flt3-L, significantly attenuated tumor growth and delayed tumor formation, suggesting the treatment feasibility of the man-GNR-siIDO system in Flt3-L mobilized DCs in the immunotherapy of lung cancer. Therefore, our study highlights a clinical potential for a first-in-class anti-cancer immunotherapy through simultaneous DC-mobilization and DC-targeted gene silencing of IDO with man-GNR-siIDO and Flt3-L treatments.

Current and future technological advances in transdermal gene delivery

Transdermal gene delivery holds significant advantages as it is able to minimize the problems of systemic administration such as enzymatic degradation, systemic toxicity, and poor delivery to target tissues. This technology has the potential to transform the treatment and prevention of a range of diseases. However, the skin poses a great barrier for gene delivery because of the "bricks-and-mortar" structure of the stratum corneum and the tight junctions between keratinocytes in the epidermis. This review systematically summarizes the typical physical and chemical approaches to overcome these barriers and facilitate gene delivery via skin for applications in vaccination, wound healing, skin cancers and skin diseases. Next, the advantages and disadvantages of different approaches are discussed and the insights for future development are provided.

Non-viral gene delivery systems for tissue repair and regeneration

Critical tissue defects frequently result from trauma, burns, chronic wounds and/or surgery. The ideal treatment for such tissue loss is autografting, but donor sites are often limited. Tissue engineering (TE) is an inspiring alternative for tissue repair and regeneration (TRR). One of the current state-of-the-art methods for TRR is gene therapy. Non-viral gene delivery systems (nVGDS) have great potential for TE and have several advantages over viral delivery including lower immunogenicity and toxicity, better cell specificity, better modifiability, and higher productivity. However, there is no ideal nVGDS for TRR, hence, there is widespread research to improve their properties. This review introduces the basic principles and key aspects of commonly-used nVGDSs. We focus on recent advances in their applications, current challenges, and future directions.

Versatile Supermolecular Inclusion Complex Based on Host-Guest Interaction for Targeted Gene Delivery

A facile and targeted gene delivery system was prepared by conjugating β-cyclodextrin modified polyethylenimine (PEI-CD) and adamantyl peptide (AdGRGDS) based on host-guest interaction. With the rational design between PEI-CD and AdGRGDS, the PEI-CD/AdGRGDS gene delivery system showed excellent DNA binding capability and exhibited good ability to compact DNA into uniform spherical nanoparticles. In vitro luciferase assay showed that gene expression transfected by PEI-CD/AdGRGDS was stronger than that by PEI-CD in HeLa cells, whereas gene expression transfected by PEI-CD/AdGRGDS and PEI-CD was similar to each other in COS7 cells. Internalization of complexes was qualitatively studied using a confocal laser scanning microscope (CLSM) and quantitatively analyzed by flow cytometry, respectively, and targeting specificity was also evaluated by CLSM. Results of CLSM and flow cytometry indicated that PEI-CD/AdGRGDS had good targeting specificity to tumor cells with integrin αvβ3 overexpression. To further evaluate the targeting specificity and transfection efficiency in vivo, a rat model with murine hepatic carcinoma cell line H22 was used. PEI-CD/AdGRGDS showed stronger gene expression efficiency than PEI-CD via in vivo transfection of pORF-LacZ and pGL-3 plasmids after subcutaneous injection. Interestingly, PEI-CD/AdGRGDS also showed high targeting specificity and transfection distribution to tumor xenograft after tail-vein injection. In vitro and in vivo assays highlighted the importance of GRGDS targeting specificity to tumor cells with integrin αvβ3 overexpression and demonstrated that the PEI-CD/AdGRGDS gene delivery system would have great potential for targeted tumor therapy.

Engineering intranasal mRNA vaccines to enhance lymph node trafficking and immune responses

Intranasal mRNA vaccination provides immediate immune protection against pandemic diseases. Recent studies have shown that diverse forms of polyethyleneimine (PEI) have potent mucosal adjuvant activity, which could significantly facilitate the delivery of intranasal mRNA vaccines. Nevertheless, optimizing the chemical structure of PEI to maximize its adjuvanticity and decrease its toxicity remains a challenge. Here we show that the chemical structure of PEI strongly influences how well nanocomplexes of PEI and mRNA migrate to the lymph nodes and elicit immune responses. Conjugating cyclodextrin (CD) with PEI600 or PEI2k yielded CP (CD-PEI) polymers with different CD/PEI ratios. We analyzed the delivery efficacy of CP600, CP2k, and PEI25k as intranasal mRNA vaccine carriers by evaluating the lymph nodes migration and immune responses. Among these polymers, CP2k/mRNA showed significantly higher in vitro transfection efficiency, stronger abilities to migrate to lymph nodes and stimulate dendritic cells maturation in vivo, which further led to potent humoral and cellular immune responses, and showed lower local and systemic toxicity than PEI25k/mRNA. These results demonstrate the potential of CD-PEI2k/mRNA nanocomplex as a self-adjuvanting vaccine delivery vehicle that traffics to lymph nodes with high efficiency.

STATEMENT OF SIGNIFICANCE

As we face outbreaks of pandemic diseases such as Zika virus, intranasal mRNA vaccination provides instant massive protection against highly variant viruses. Various polymer-based delivery systems have been successfully applied in intranasal vaccine delivery. However, the influence of molecular structure of the polymeric carriers on the lymph node trafficking and dendritic cell maturation is seldom studied for intranasal vaccination. Therefore, engineering polymer-based vaccine delivery system and elucidating the relationship between molecular structure and the intranasal delivery efficiency are essential for maximizing the immune responses. We hereby construct self-adjuvanting polymer-based intranasal mRNA vaccines to enhance lymph node trafficking and further improve immune responses.

Ternary complex of plasmid DNA with NLS-Mu-Mu protein and cationic niosome for biocompatible and efficient gene delivery: a comparative study with protamine and lipofectamine

Non-viral gene delivery methods are considered due to safety and simplicity in human gene therapy. Since the use of cationic peptide and niosome represent a promising approach for gene delivery purposes we used recombinant fusion protein and cationic niosome as a gene carrier. A multi-domain fusion protein including nuclear localization motif (NLS) and two DNA-binding (Mu) domains, namely NLS-Mu-Mu (NMM) has been designed, cloned and expressed in E. coli DE3 strain. Afterward, the interested protein was purified by affinity chromatography. Binary vectors based on protein/DNA and ternary vectors based on protein/DNA/niosome were prepared. Protamine was used as a control. DNA condensing properties of NMM and protamine were evaluated by various experiments. Furthermore, we examined cytotoxicity, hemolysis and transfection potential of the binary and ternary complexes in HEK293T and MCF-7 cell lines. Protamine and Lipofectamine™2000 were used as positive controls, correspondingly. The recombinant NMM was expressed and purified successfully and DNA was condensed efficiently at charge ratios that were not harmful to cells. Peptidoplexes showed transfection efficiency (TE) but ternary complexes had higher TE. Additionally, NMM ternary complex was more efficient compared to protamine ternary vectors. Our results showed that niosomal ternary vector of NMM is a promising non-viral gene carrier to achieve an effective and safe carrier system for gene therapy.

Modification of Human Umbilical Cord Blood Stem Cells Using Polyethylenimine Combined with Modified TAT Peptide to Enhance BMP-2 Production

With the emerging role of umbilical cord blood-derived mesenchymal stem cells (hUCB-MSC) for bone regeneration and delivery of therapeutic proteins, there is an increasing need for effective gene delivery systems to modify such cells. mTAT, a TAT peptide sequence bearing histidine and cysteine residues, has been successfully used for intracellular gene delivery. Using a gWiz-GFP plasmid, we demonstrated that polyethylenimine combined with mTAT (mTAT/PEI) displayed good transfection efficacy in hUCB-MSC. hUCB-MSC transfected with mTAT/PEI were shown to express more BMP-2 protein and mRNA, indicating the feasibility of using the cells as a BMP-2 delivery system. Importantly, compared to PEI25, a "gold standard" nonviral transfection polymer, mTAT/PEI had limited toxicity to the cells. Furthermore, we demonstrated enhanced osteogenic activity in vitro for BMP-2 expressing hUCB-MSC. These results provide encouraging evidence for the potential use of mTAT/PEI to genetically modify hUCB-MSC as an approach to enhance tissue regeneration.

The effect of cell penetrating peptides on transfection activity and cytotoxicity of polyallylamine

Introduction: Cationic polymers have the potential to be modified to achieve an ideal gene vector lacking viral vector defects. The aim of the present study was to improve polyallylamine (PAA) transfection efficiency and to reduce cytotoxicity by incorporating of cell-penetrating peptides (CPPs).

Methods: To prepare the peptide-based polyplexes, PAA (15 kDa) was modified with 2 peptides (TAT and CyLoP-1) by covering the 0.5% and 1% of amines. Buffer capacity and DNA condensation ability of modified polymer, particle size and zeta potential of nanoparticles, cell viability, and transfection activity of vectors were evaluated.

Results: In low carrier to plasmid (C/P) weight ratios such as 0.5 and 1, the unmodified polymer was more capable to condense the DNA compared to the synthesized vectors. In C/P ratio of 2, the plasmid was fully condensed in all vectors. The size of polyplexes ranged from 195 to 240 nm. The zeta potential was almost as the same as PAA and varied from 25 to 27 mV. All polyplexes increased the buffer capacity compared to PAA. The transfection efficiency was improved compared to unmodified polymer especially in the vectors modified with 1% of TAT or CyLoP-1 peptides in C/P ratio of 2. The cytotoxicity of prepared vectors was less than PAA. In most ratios, the cytotoxicity of the CyLoP-1 modified samples was less than the TAT modified ones.

Conclusion: Modification of PAA with CPPs improved the transfection activity of vector.

Polyethylenimine-based micro/nanoparticles as vaccine adjuvants

Vaccines have shown great success in treating and preventing tumors and infections, while adjuvants are always demanded to ensure potent immune responses. Polyethylenimine (PEI), as one of the well-studied cationic polymers, has been used as a transfection reagent for decades. However, increasing evidence has shown that PEI-based particles are also capable of acting as adjuvants. In this paper, we briefly review the physicochemical properties and the broad applications of PEI in different fields, and elaborate on the intracellular processes of PEI-based vaccines. In addition, we sum up the proof of their in vivo and clinical applications. We also highlight some mechanisms proposed for the intrinsic immunoactivation function of PEI, followed by the challenges and future perspectives of the applications of PEI in the vaccines, as well as some strategies to elicit the desirable immune responses.

Multi-targeting peptides for gene carriers with high transfection efficiency

Non-viral gene carriers for gene therapy have been developed for many years.

Peptide-Mediated Tumor Targeting by a Degradable Nano Gene Delivery Vector Based on Pluronic-Modified Polyethylenimine

Polyethylenimine (PEI) is considered to be a promising non-viral gene delivery vector. To solve the toxicity versus efficacy and tumor-targeting challenges of PEI used as gene delivery vector, we constructed a novel non-viral vector DR5-TAT-modified Pluronic-PEI (Pluronic-PEI-DR5-TAT), which was based on the attachment of low-molecular-weight polyethylenimine (LMW-PEI) to the amphiphilic polymer Pluronic to prepare Pluronic-modified LMW-PEI (Pluronic-PEI). This was then conjugated to a multifunctional peptide containing a cell-penetrating peptide (TAT) and a synthetic peptide that would bind to DR5-a receptor that is overexpressed in cancer cells. The vector showed controlled degradation, favorable DNA condensation and protection performance. The Pluronic-PEI-DR5-TAT/DNA complexes at an N/P ratio of 15:1 were spherical nanoparticles of 122 ± 11.6 nm and a zeta potential of about 22 ± 2.8 mV. In vitro biological characterization results indicated that Pluronic-PEI-DR5-TAT/DNA complexes had a higher specificity for the DR5 receptor and were taken up more efficiently by tumor cells than normal cells, compared to complexes formed with PEI 25 kDa or Pluronic-PEI. Thus, the novel complexes showed much lower cytotoxicity to normal cells and higher gene transfection efficiency in tumor cells than that exhibited by PEI 25 kDa and Pluronic-PEI. In summary, our novel, degradable non-viral tumor-targeting vector is a promising candidate for use in gene therapy.

Progresses towards safe and efficient gene therapy vectors

The emergence of genetic engineering at the beginning of the 1970′s opened the era of biomedical technologies, which aims to improve human health using genetic manipulation techniques in a clinical context. Gene therapy represents an innovating and appealing strategy for treatment of human diseases, which utilizes vehicles or vectors for delivering therapeutic genes into the patients' body. However, a few past unsuccessful events that negatively marked the beginning of gene therapy resulted in the need for further studies regarding the design and biology of gene therapy vectors, so that this innovating treatment approach can successfully move from bench to bedside. In this paper, we review the major gene delivery vectors and recent improvements made in their design meant to overcome the issues that commonly arise with the use of gene therapy vectors. At the end of the manuscript, we summarized the main advantages and disadvantages of common gene therapy vectors and we discuss possible future directions for potential therapeutic vectors.

Cell-penetrating peptides with intracellular organelle targeting

INTRODUCTION

One of the major limiting steps in order to have an effective drug is the passage through one or more cell membranes to reach its site of action. To reach the action-site, the specific macromolecules are required to be delivered specifically to the cell compartment/organelle in their (pre)active form. Areas covered: In this review, we will discuss cell-penetrating peptides (CPPs) developed in the last decade to transport small RNA/DNA, plasmids, antibodies, and nanoparticles into specific sites of the cell. The article describes CPPs in complex with cargo molecules that target specific intracellular organelles and their potential for pharmacological or clinical use. Expert opinion: Organelle targeting is the ultimate goal to ensure selective delivery to the site of action in the cells. CPP technologies represent an important strategy to address drug delivery to specific intracellular compartments by covalent conjugation to targeting sequences, potentially enabling strategies to combat genomic diseases as well as infections, cancer, neurodegenerative and hereditary diseases. They have proven to be successful in delivering various therapeutic agents into cells however, further in vivo experiments and clinical trials are required to demonstrate the efficacy of this technology.

Microneedles: an innovative platform for gene delivery

The advent of microneedle (MN) technology has provided a revolutionary platform for the delivery of therapeutic agents, particularly in the field of gene therapy. For over 20 years, the area of gene therapy has undergone intense innovation and progression which has seen advancement of the technology from an experimental concept to a widely acknowledged strategy for the treatment and prevention of numerous disease states. However, the true potential of gene therapy has yet to be achieved due to limitations in formulation and delivery technologies beyond parenteral injection of the DNA. Microneedle-mediated delivery provides a unique platform for the delivery of DNA therapeutics clinically. It provides a means to overcome the skin barriers to gene delivery and deposit the DNA directly into the dermal layers, a key site for delivery of therapeutics to treat a wide range of skin and cutaneous diseases. Additionally, the skin is a tissue rich in immune sentinels, an ideal target for the delivery of a DNA vaccine directly to the desired target cell populations. This review details the advancement of MN-mediated DNA delivery from proof-of-concept to the delivery of DNA encoding clinically relevant proteins and antigens and examines the key considerations for the improvement of the technology and progress into a clinically applicable delivery system.

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.

Cell-penetrating peptides transport therapeutics into cells

Nearly 30years ago, certain small, relatively nontoxic peptides were discovered to be capable of traversing the cell membrane. These cell-penetrating peptides, as they are now called, have been shown to not only be capable of crossing the cell membrane themselves but can also carry many different therapeutic agents into cells, including small molecules, plasmid DNA, siRNA, therapeutic proteins, viruses, imaging agents, and other various nanoparticles. Many cell-penetrating peptides have been derived from natural proteins, but several other cell-penetrating peptides have been developed that are either chimeric or completely synthetic. How cell-penetrating peptides are internalized into cells has been a topic of debate, with some peptides seemingly entering cells through an endocytic mechanism and others by directly penetrating the cell membrane. Although the entry mechanism is still not entirely understood, it seems to be dependent on the peptide type, the peptide concentration, the cargo the peptide transports, and the cell type tested. With new intracellular disease targets being discovered, cell-penetrating peptides offer an exciting approach for delivering drugs to these intracellular targets. There are hundreds of cell-penetrating peptides being studied for drug delivery, and ongoing studies are demonstrating their success both in vitro and in vivo.

Peptide-mediated delivery: an overview of pathways for efficient internalization

Poor cellular delivery and low bioavailability of novel potent therapeutic molecules continue to remain the bottleneck of modern cancer and gene therapy. Cell-penetrating peptides have provided immense opportunities for the intracellular delivery of bioactive cargos and have led to the first exciting successes in experimental therapy of muscular dystrophies. This review focuses on the mechanisms by which cell-penetrating peptides gain access to the cell interior and deliver cargos. Recent advances in augmenting delivery efficacy and facilitation of endosomal escape of cargo are presented, and the cell-penetrating peptide-mediated delivery of two of the most popular classes of cargo molecules, oligonucleotides and proteins, is analyzed. The arsenal of tools for oligonucleotide delivery has dramatically expanded in the last decade enabling harnessing of cell-surface receptors for targeted delivery.

Multifunctional poly(methacrylate) polyplex libraries: A platform for gene delivery inspired by nature

Polymer-based gene delivery systems have enormous potential in biomedicine, but their efficiency is often limited by poor biocompatibility. Poly(methacrylate)s (PMAs) are an interesting class of polymers which allow to explore structure-activity relationships of polymer functionalities for polyplex formation in oligonucleotide delivery. Here, we synthesized and tested a library of PMA polymers, containing functional groups contributing to the different steps of gene delivery, from oligonucleotide complexation to cellular internalization and endosomal escape. By variation of the molar ratios of the individual building blocks, the physicochemical properties of the polymers and polyplexes were fine-tuned to reduce toxicity as well as to increase activity of the polyplexes. To further enhance transfection efficiency, a cell-penetrating peptide (CPP)-like functionality was introduced on the polymeric backbone. With the ability to synthesize large libraries of polymers in parallel we also developed a workflow for a mid-to-high throughput screening, focusing first on safety parameters that are accessible by high-throughput approaches such as blood compatibility and toxicity towards host cells and only at a later stage on more laborious tests for the ability to deliver oligonucleotides. To arrive at a better understanding of the molecular basis of activity, furthermore, the effect of the presence of heparan sulfates on the surface of host cells was assessed and the mechanism of cell entry and intracellular trafficking investigated for those polymers that showed a suitable pharmacological profile. Following endocytic uptake, rapid endosomal release occurred. Interestingly, the presence of heparan sulfates on the cell surface had a negative impact on the activity of those polyplexes that were sensitive to decomplexation by heparin in solution. In summary, the screening approach identified two polymers, which form polyplexes with high stability and transfection capacity exceeding the one of poly(ethylene imine) also in the presence of serum.