Genome editing of PD-L1 mediated by nucleobase-modified polyamidoamine for cancer immunotherapy

Immune checkpoint blockade therapy against programmed death protein-1 and its ligand (PD-1/PD-L1) has been accepted as a promising approach to activate the immune system's anti-tumor response. Although small interfering RNA...

Fluoropolymer-Mediated Intracellular Delivery of miR-23b for the Osteocyte Differentiation in Osteoblasts

Emerging evidence suggests that microRNAs (miRNAs) play key roles in the regulation of multiple biological processes, including the differentiation of osteoblasts. Although miRNA-based gene therapy holds immense potential in the treatment of a variety of diseases, the intracellular delivery of miRNA remains challenging owing to the lack of efficient and safe gene carriers. In this study, a fluoropolymer (FP) is constructed through the modification of polyamidoamine (PAMAM) using heptafluorobutyric anhydride and then is used as a carrier for miR-23b transfection to induce osteocyte differentiation of osteoblasts. The derivative FP is found to facilitate miR-23b transfection due to its favorable endosomal escape from the "proton sponge" effect. Compared to PAMAM/miR-23b, the FP/miR-23b nanocomplex efficiently promotes the differentiation of osteoblasts and formation of calcified nodules, attributable to enhanced expression of various osteogenesis genes (runt-related transfection factor 2 [RUNX2], alkaline phosphatase [ALP], osteopontin [OPN], and osteocalcin [OCN]). Thus, FP-mediated miR-23b transfection may be used as an effective strategy to facilitate osteogenic differentiation.

Stimuli-responsive graphene-based hydrogel driven by disruption of triazine hydrophobic interactions

The study reported here concerns the preparation of a novel graphene-diaminotriazine (G-DAT) nanocomposite hydrogel for application in the drug delivery field. The hybrid nature of this material is founded on two key elements: the presence of the DAT backbone induced the formation of hydrophobic regions that allowed efficient loading of a series of drugs of increasing hydrophobicity (Metronidazole, Benzocaine, Ibuprofen, Naproxen and Imipramine), while simultaneously endowing swelling-induced pH-responsiveness to the hydrogel. Additionally, the incorporation of graphene was found to interfere with these hydrophobic domains through favourable non-covalent interactions, thus leading to the partial disruption of these aggregates. As a consequence, graphene facilitated and enhanced the release of model hydrophobic drug Imipramine in a synergistic manner with the pH trigger, and increased the swelling capacities and improved mechanical performance. This hybrid hydrogel can therefore be envisaged as a proof-of-concept system for the release of hydrophobic compounds in the field of drug delivery.

A PEG-b-poly(disulfide-l-lysine) based redox-responsive cationic polymer for efficient gene transfection

Gene therapy is concerned with the transfer of complement genes to functionally defective cells in a safe and directed manner for the treatment of the most challenging diseases. But safety issues and low transfection efficiency of the gene vectors are the major challenges, which need to be overcome. Recently, redox-responsive bioreducible polymers containing disulfide linkages have been considered as efficient gene vectors, owing to the selective degradation of the disulfide bond in the reducing environment of the cells. This enables spatiotemporal release of pDNA with no or minimum toxicity. Herein, we reported a bioreducible poly(ethyleneglycol)-b-poly(disulfide-l-lysine) cationic polymer (denoted as PEG-SSL) via a Michael addition reaction of poly(ethyleneglycol)tetraacrylate PEG(Ac)₄ and the terminal amine group of poly(disulfide-l-lysine). PEG-SSL efficiently condensed the plasmid ZNF580 gene (pZNF580) forming nano-sized polyplexes (155 ± 4 to 285 ± 3 nm) with zeta potentials of 1.9 ± 0.1 to 26.7 ± 0.4 mV. PEG-SSL successfully retarded pZNF580 at a small polymer/pDNA weight ratio of 10/1 and higher. When exposed to a reducing environment of 5 mM DTT, it rapidly released genes even at higher weight ratios of the PEG-SSL polymer in the PEG-SSL/pDNA complexes. The PEG-SSL/pZNF580 complexes exhibited good stability when exposed to DNase I and efficiently protected pDNA from degradation. In vitro transfection and cytotoxicity were investigated in EA.hy926 cells. The results showed that PEG-SSL successfully delivered pZNF580 into the cells with less cytotoxicity compared to PEI25kDa. The flow cytometry and confocal scanning laser microscopy results indicated that PEG-SSL polyplexes exhibited good cellular uptake and nuclear co-localization rates. All these results implied that PEG-SSL had the potential as a non-viral vector for gene transfection.

Poly(vinyl diaminotriazine): From Molecular Recognition to High-Strength Hydrogels

Poly(2-vinyl-4,6-diamino-1,3,5-triazine), (PVDT) with diaminotriazine residues is found to form not only intramolecular hydrogen bonds, but also three robust, complementary hydrogen bonds with nucleobases such as thymine and uracil. Taking advantage of the three complementary hydrogen bonds, molecular recognition of a nucleic acid base has been investigated in previous work. Over the past few years, the use of PVDT has been extended to the construction of gene delivery vectors and nonswellable, high-strength hydrogels by copolymerization with a hydrophilic monomer and/or crosslinker. In particular, many fascinating properties, such as excellent mechanical properties, stimuli responsiveness, the shape memory effect, and biodegradability, have emerged in PVDT-based hydrogels. In this article, the molecular recognition and self-assembly of diaminotriazine are introduced first, and then a particular focus is placed on the development of PVDT-based high performance hydrogels, especially their biorelated applications.

MDM2 knockdown mediated by a triazine-modified dendrimer in the treatment of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and the five-year survival rate is lower in advanced NSCLC patients. Chemotherapy is a widely used strategy in NSCLC treatment, but is usually limited by poor therapeutic efficacy and adverse effects. Therefore, a new therapeutic regimen is needed for NSCLC treatment. Gene therapy is a new strategy in the treatment of NSCLC. However, the lack of efficient and low toxic vectors remains the major obstacle. Here, we developed a biocompatible dendrimer as a non-viral vector for the delivery of mouse double minute2 (MDM2) siRNA in vitro and in vivo to treat NSCLC. The triazine-modified dendrimer efficiently stimulates the down-regulation of MDM2 gene in NSCLC PC9 cells, which induces significant cell apoptosis through the activation of apoptosis markers such as caspase-8 and poly(ADP-ribose) polymerase (PARP) cleavage. Furthermore, the dendrimer/MDM2 siRNA polyplexes showed excellent activity in the inhibition of tumor growth in a PC9 xenograft tumor model. These results suggested that inhibition the expression of MDM2 might be a potential target in NSCLC treatment.

A supramolecular approach to improve the gene transfection efficacy of dendrimers

Cyanuric acid is able to form complementary hydrogen bonds with melamine. Here, the specific recognition between cyanuric acid and melamine is used to significantly improve the gene transfection efficacy of low generation dendrimers via a supramolecular approach.

Bioreducible poly(2-ethyl-2-oxazoline)-PLA-PEI-SS triblock copolymer micelles for co-delivery of DNA minicircles and Doxorubicin

The co-delivery of minicircle DNA (mcDNA) and small anti-cancer drugs via stimuli-sensitive nanocarriers is a promising approach for combinatorial cancer therapy. However, the simultaneous loading of drugs and DNA in nanosized delivery systems is remarkably challenging. In this study we describe the synthesis of triblock copolymer micelles based on poly(2-ethyl-2-oxazoline)-poly(L-lactide) grafted with bioreducible polyethylenimine (PEOz-PLA-g-PEI-SS) for co-delivery of supercoiled (sc) mcDNA vectors and Doxorubicin (Dox). These amphiphilic carriers take advantage of non-fouling oxazolines to confer biological stability, of PLA to provide a hydrophobic core for drug encapsulation and of bioreducible PEI-SS to provide mcDNA complexation and an on-demand stimuli-responsive release. The obtained results show that mcDNA-loaded micelleplexes penetrate into in vitro tumor spheroid models with specific kinetics and exhibit a higher gene expression when compared to non-bioreducible nanocarriers. Moreover, in vivo bioluminescence imaging showed that gene expression is detected up to 8days following mcDNA-micelles intratumoral administration. Furthermore, drug-gene co-delivery in PEOz-PLA-g-PEI-SS carriers was verified by successful encapsulation of both Dox and mcDNA with high efficacy. Moreover, dual-loaded micelleplexes presented significant uptake and a cytotoxic effect in 2D cultures of cancer cells. The co-delivery of mcDNA-Dox to B16F10-Luciferase tumor bearing mice resulted in a reduction in tumor volume and cancer cells viability. Overall, such findings indicate that bioreducible triblock micelles are efficient for focal delivery in vivo and have potential for future application in combinatorial DNA-drug therapy.