Enhanced gene expression in tumors after intravenous administration of arginine-, lysine- and leucine-bearing polyethylenimine polyplex

The intracellular visualization of exogenous DNA in fluorescence microscopy

In the development of non-viral gene delivery vectors, it is essential to reliably localize and quantify transfected DNA inside the cell. To track DNA, fluorescence microscopy methods are commonly applied. These mostly rely on fluorescently labeled DNA, DNA binding proteins fused to a fluorescent protein, or fluorescence in situ hybridization (FISH). In addition, co-stainings are often used to determine the colocalization of the DNA in specific cellular compartments, such as the endolysosomes or the nucleus. We provide an overview of these DNA tracking methods, advice on how they should be combined, and indicate which co-stainings or additional methods are required to draw precise conclusions from a DNA tracking experiment. Some emphasis is given to the localization of exogenous DNA inside the nucleus, which is the last step of DNA delivery. We argue that suitable tools which allow for the nuclear detection of faint signals are still missing, hampering the rational development of more efficient non-viral transfection systems.

GalNAc- or Mannose-PEG-Functionalized Polyplexes Enable Effective Lectin-Mediated DNA Delivery

A cationic, dendrimer-like oligo(aminoamide) carrier with four-arm topology based on succinoyl tetraethylene pentamine and histidines, cysteines, and N-terminal azido-lysines was screened for plasmid DNA delivery on various cell lines. The incorporated azides allow modification with various shielding agents of different polyethylene glycol (PEG) lengths and/or different ligands by copper-free click reaction, either before or after polyplex formation. Prefunctionalization was found to be advantageous over postfunctionalization in terms of nanoparticle formation, stability, and efficacy. A length of 24 ethylene oxide repetition units and prefunctionalization of ≥50% of azides per carrier promoted optimal polyplex shielding. PEG shielding resulted in drastically reduced DNA transfer, which could be successfully restored by active lectin targeting via novel GalNAc or mannose ligands, enabling enhanced receptor-mediated endocytosis of the carrier system. The involvement of the asialoglycoprotein receptor (ASGPR) in the uptake of GalNAc-functionalized polyplexes was confirmed in the ASGPR-positive hepatocarcinoma cell lines HepG2 and Huh7. Mannose-modified polyplexes showed superior cellular uptake and transfection efficacy compared to unmodified and shielded polyplexes in mannose-receptor-expressing dendritic cell-like DC2.4 cells.

Pumpkin seed proteins rival animal gelatin in increasing the cytoaffinity of edible microbeads for cell-based meat culture

Edible microbeads are hotly sought after for emerging cell-based meat culture but there are no major breakthroughs so far. Herein we report a functional edible microbead with alginate as core coated with pumpkin proteins as shell. Proteins from 11 plant-seeds were extracted and tested their cytoaffinity as gelatin replacer by grafting them on alginate microbeads and pumpkin seed protein coated microbeads shown the best performance in stimulating proliferation of C2C12 cells (by 17 folds in a week), 3T3-L1 adipocytes, chicken muscle satellite cells and primary porcine myoblast. The cytoaffinity of pumpkin seed protein coated microbeads comparable with that of animal gelatin microbeads. Protein sequencing analysis on pumpkin seed proteins found that it is rich in RGD tripeptide moiety, which are known to be enhance cytoaffinity. Our work advances our search for edible microbeads as ECM materials for cell-based meat culture.

Lysine-embedded cellulose-based nanosystem for efficient dual-delivery of chemotherapeutics in combination cancer therapy

Combination therapy by two or multiple drugs with different mechanisms of action is a promising strategy in cancer treatment. In this regard, a wide range of chemotherapeutics has used simultaneously to achieve the synergistic effect and overcome the adverse side effects of single-drug therapy. Herein, we developed a biocompatible nanoparticle-based system composed of nanocrystalline cellulose (NCC) and amino acid l-lysine for efficient co-delivery of model chemotherapeutic methotrexate (MTX) and polyphenol compound curcumin (CUR) to the MCF-7 and MDA-MB-231 cells. The drugs could release in a sustained and acidic-facilitate manner. In vitro cytotoxicity results represented the superior anti-tumor efficacy of the dual-drug-loaded nanocarriers. Possible inhibition of cell growth and induction of apoptosis in the cells treated with different formulations of CUR and MTX were explored by cell cycle analysis and DAPI staining. Overall, the engineered nanosystem can be used as suitable candidates to achieve efficient multi-drug delivery for combination cancer therapy.

Comparison of Structure and Local Dynamics of Two Peptide Dendrimers with the Same Backbone but with Different Side Groups in Their Spacers

In this paper, we perform computer simulation of two lysine-based dendrimers with Lys-2Lys and Lys-2Gly repeating units. These dendrimers were recently studied experimentally by NMR (Sci. Reports, 2018, 8, 8916) and tested as carriers for gene delivery (Bioorg. Chem., 2020, 95, 103504). Simulation was performed by molecular dynamics method in a wide range of temperatures. We have shown that the Lys-2Lys dendrimer has a larger size but smaller fluctuations as well as lower internal density in comparison with the Lys-2Gly dendrimer. The Lys-2Lys dendrimer has larger charge but counterions form more ion pairs with its NH 3 + groups and reduce the bare charge and zeta potential of the first dendrimer more strongly. It was demonstrated that these differences between dendrimers are due to the lower flexibility and the larger charge (+2) of each 2Lys spacers in comparison with 2Gly ones. The terminal CH 2 groups in both dendrimers move faster than the inner CH 2 groups. The calculated temperature dependencies of the spin-lattice relaxation times of these groups for both dendrimers are in a good agreement with the experimental results obtained by NMR.

Folate-Mediated Targeted Delivery of siPLK1 by Leucine-Bearing Polyethylenimine

BACKGROUND

siRNA-mediated polo-like kinase 1 (PLK1) silencing has been proposed as a promising therapeutic method for multiple cancers. However, the clinic application of this method is still hindered by the low specific delivery of siPLK1 to desired tumor lesions. Herein, folate (FA)-modified and leucine-bearing polyethylenimine was successfully synthesized and showed excellent targeted silencing to folate receptor overexpressed cells.

MATERIALS AND METHODS

The condensation of siPLK1 by FA-N-Ac-L-Leu-PEI (NPF) was detected by the gel retardation assay. The targeted and silencing efficiency was evaluated by flow cytometry and confocal laser scanning microscope. The PLK1 expressions at gene or protein levels were detected by quantitative real-time PCR and Western blotting assay. Further impacts of the PLK1 silencing on cell viability, cell cycle, migration, and invasion were studied by MTT, colony formation, wound healing and transwell assays.

RESULTS

The NPF and siPLK1 could efficiently assemble to stable nanoparticles at a weight ratio of 3.0 and showed excellent condensation and protection effect. Owing to the FA-mediated targeted delivery, the uptake and silencing efficiency of NPF/siPLK1 to SGC-7901 cells was higher than that without FA modification. Moreover, NPF-mediated PLK1 silencing showed significant antitumor activity in vitro. The anti-proliferation effect of PLK1 silencing was induced via the mitochondrial-dependent apoptosis pathway with the cell cycle arrest of 45% at G2 phase and the apoptotic ratio of 28.3%.

CONCLUSION

FA-N-Ac-L-Leu-PEI (NPF) could generate targeted delivery siPLK1 to FA receptor overexpressed cells and dramatically downregulate the expression of PLK1 expression.

Optimized polyethylenimine (PEI)-based nanoparticles for siRNA delivery, analyzed in vitro and in an ex vivo tumor tissue slice culture model

The non-viral delivery of small RNA molecules like siRNAs still poses a major bottleneck for their successful application in vivo. This is particularly true with regard to crossing physiological barriers upon systemic administration. We have previously established polyethylenimine (PEI)-based complexes for therapeutic RNA formulation. These nanoplexes mediate full RNA protection against nucleolytic degradation, delivery to target tissues as well as cellular uptake, intracellular release and therapeutic efficacy in preclinical in vivo models. We herein present data on different polyplex modifications for the defined improvement of physicochemical and biological nanoparticle properties and for targeted delivery. (i) By non-covalent modifications of PEI polyplexes with phospholipid liposomes, ternary complexes ("lipopolyplexes") are obtained that combine the favorable features of PEI and lipid systems. Decreased cytotoxicity and highly efficient delivery of siRNA is achieved. Some lipopolyplexes also allow prolonged storage, thus providing formulations with higher stability. (ii) Novel tyrosine modifications of low molecular weight PEI offer further improvement of stability, biocompatibility, and knockdown efficacy of resulting nanoparticles. (iii) For ligand-mediated uptake, the shielding of surface charges is a critical requirement. This is achieved by PEI grafting with polyethylene glycol (PEG), prior to covalent coupling of anti-HER1 antibodies (Erbitux®) as ligand for targeted delivery and uptake. Beyond tumor cell culture, analyses are extended towards tumor slice cultures from tumor xenograft tissues which reflect more realistically the in vivo situation. The determination of siRNA-mediated knockdown of endogenous target genes, i.e., the oncogenic survival factor survivin and the oncogenic receptor tyrosine kinase HER2, reveals nanoparticle penetration and biological efficacy also under intact tissue and stroma conditions.

Structure-activity relationship of dendrimers engineered with twenty common amino acids in gene delivery

Systematic explorations on the structure-activity relationship of surface-engineered dendrimers are essential to design high efficient and safe gene vectors. The chemical diversity of residues in naturally occurring amino acids allows us to generate a library of dendrimers with various surface properties. Here, we synthesized a total number of 40 dendrimers engineered with the twenty common amino acids and investigated their performances in gene delivery. The results show that gene transfection efficacy of the synthesized materials depends on both the type of amino acid and the conjugation ratio. Dendrimers engineered with cationic and hydrophobic amino acids possess relatively higher transfection efficacies. Engineering dendrimers with cationic amino acids such as arginine and lysine facilitates polyplex formation and cellular uptake, with histidine improves endosomal escape of the polyplexes, and with hydrophobic amino acids such as tyrosine and phenylalanine modulates the balance between hydrophobicity and hydrophilicity on dendrimer surface, which is beneficial for efficient cellular internalization. Dendrimers engineered with anionic or hydrophilic amino acids show limited transfection efficacy due to poor DNA binding capacity and/or limited cellular uptake. In the aspect of cytotoxicity, dendrimers engineered with arginine, lysine, tyrosine, phenylalanine and tryptophan show much higher cytotoxicity than other engineered dendrimers. These results are helpful for us to tailor the surface chemistry of dendrimers for efficient gene delivery.

STATEMENT OF SIGNIFICANCE

Cationic polymers such as dendrimers were widely used as gene vectors but are limited by relatively low delivery efficacy and high toxicity. To achieve efficient and low toxic gene delivery, the polymers were modified with various ligands. However, these ligand-modified polymers in gene delivery are reported by independent researchers using different polymer scaffolds and cell lines. It is hard to provide structure-function information of these materials based on current knowledge and experience, which are essential for the design of ideal polymeric vectors for gene delivery. Here, we prepared a small library of amino acid-modified dendrimers, which is used as a screening pool to discover efficient gene vectors. The results obtained from this study, especially the structure-activity relationship of the screened materials are helpful for us to further design efficient and biocompatible polymers for gene delivery. This manuscript will appeal to a wide readership such as nanomaterial chemist, dendrimer chemist, biological chemist, pharmaceutical scientist, and biomedical researchers.

Tumor regression following intravenous administration of lactoferrin- and lactoferricin-bearing dendriplexes

The possibility of using gene therapy for the treatment of cancer is limited by the lack of safe, intravenously administered delivery systems able to selectively deliver therapeutic genes to tumors. In this study, we investigated if the conjugation of the polypropylenimine dendrimer to lactoferrin and lactoferricin, whose receptors are overexpressed on cancer cells, could result in a selective gene delivery to tumors and a subsequently enhanced therapeutic efficacy. The conjugation of lactoferrin and lactoferricin to the dendrimer significantly increased the gene expression in the tumor while decreasing the non-specific gene expression in the liver. Consequently, the intravenous administration of the targeted dendriplexes encoding TNFα led to the complete suppression of 60% of A431 tumors and up to 50% of B16-F10 tumors over one month. The treatment was well tolerated by the animals. These results suggest that these novel lactoferrin- and lactoferricin-bearing dendrimers are promising gene delivery systems for cancer therapy.

From the Clinical Editor

Specific targeting of cancer cells should enhance the delivery of chemotherapeutic agents. This is especially true for gene delivery. In this article, the authors utilized a dendrimer-based system and conjugated this with lactoferrin and lactoferricin to deliver anti-tumor genes. The positive findings in animal studies should provide the basis for further clinical studies.

Hyaluronic acid–PEI–cyclodextrin polyplexes: implications for in vitro and in vivo transfection efficiency and toxicity

The present study reveals novel HA–PEI–CyD polyplexes as non-viral vectors for gene delivery.

Development of Magnetic Nanoparticles for Cancer Gene Therapy: A Comprehensive Review

Since they were first proposed as nonviral transfection agents for their gene-carrying capacity, magnetic nanoparticles have been studied thoroughly, both in vitro and in vivo. Great effort has been made to manufacture biocompatible magnetic nanoparticles for use in the theragnosis of cancer and other diseases. Here we survey recent advances in the study of magnetic nanoparticles, as well as the polymers and other coating layers currently available for gene therapy, their synthesis, and bioconjugation processes. In addition, we review several gene therapy models based on magnetic nanoparticles.