Comparative study of cytotoxicity and genotoxicity of commercial Jeffamines® and polyethylenimine in CHO-K1 cells

Strategies for accelerating osteogenesis through nanoparticle-based DNA/mitochondrial damage repair

The efficiency of gene therapy is often dictated by the gene delivery system. Cationic polymers are essential elements of gene delivery systems. The relatively cheap cationic polymer, polyethyleneimine, has high gene delivery efficiency and is often used for gene delivery. However, the efficiency of gene therapy with polyethyleneimine-pDNA polyplex (PEI) is low. Human mesenchymal stem cells transfected with polyethyleneimine and a plasmid carrying the important osteogenic differentiation gene runt-related transcription factor 2 (RUNX2) accumulated DNA double-strand breaks and mitochondrial damage proportional to the amount of polyethyleneimine, reducing viability. Genomic/cellular stabilizer mediating RUNX2 delivery (GuaRD), a new reagent incorporating RS-1 NPs developed in this study, promoted DNA repair and prevented the accumulation of cell damage, allowing the delivery of pRUNX2 into hMSCs. while maintaining genome and mitochondrial stability. DNA damage was significantly lower and the expression of DNA repair-related genes significantly higher with GuaRD than with PEI. In addition, GuaRD improved mitochondrial stability, decreased the level of reactive oxygen species, and increased mitochondrial membrane potential. Osteogenic extracellular matrix (ECM) expression and calcification were higher with GuaRD than with PEI, suggesting improved osteogenic differentiation. These results indicate that lowering the cytotoxicity of PEI and improving cell stability are key to overcoming the limitations of conventional gene therapy, and that GuaRD can help resolve these limitations.

Targeting Human Osteoarthritic Chondrocytes with Ligand Directed Bacteriophage-Based Particles

Osteoarthritis (OA) is a degenerative joint disease characterized by progressive deterioration and loss of articular cartilage. There is currently no treatment to reverse the onset of OA. Thus, we developed a targeted delivery strategy to transfer genes into primary human chondrocytes as a proof-of-concept study. We displayed a chondrocyte-affinity peptide (CAP) on the pIII minor coat protein of the M13 filamentous bacteriophage (phage)-based particle carrying a mammalian transgene cassette under cytomegalovirus CMV promoter and inverted terminal repeats (ITRs) cis elements of adeno-associated virus serotype 2 (AAV-2). Primary human articular chondrocytes (HACs) were used as an in vitro model, and the selectivity and binding properties of the CAP ligand in relation to the pathogenic conditions of HACs were characterized. We found that the CAP ligand is highly selective toward pathogenic HACs. Furthermore, the stability, cytotoxicity, and gene delivery efficacy of the CAP-displaying phage (CAP.Phage) were evaluated. We found that the phage particle is stable under a wide range of temperatures and pH values, while showing no cytotoxicity to HACs. Importantly, the CAP.Phage particle, carrying a secreted luciferase (Lucia) reporter gene, efficiently and selectively delivered transgene expression to HACs. In summary, it was found that the CAP ligand preferably binds to pathogenic chondrocytes, and the CAP.Phage particle successfully targets and delivers transgene to HACs.

TNFα siRNA delivery by nanoparticles and photochemical internalization for psoriasis topical therapy

Psoriasis is a chronic inflammatory skin disease that presents increased expression of tumor necrosis factor α (TNFα), a proinflammatory cytokine. The discovery of RNA interference (RNAi), mediated by short interfering RNA (siRNA), made it possible for the expression of some genes to be eliminated. However, for its application, it is necessary to use carriers that can protect siRNA and release it in the target cells. Herein, we developed a delivery system for siRNA based on hybrid polymer-lipid nanoparticles (PLNs) and combined this system with photochemical internalization (PCI), photoactivating the photosensitizer TPPS2a, to optimize the endosomal escape of TNFα siRNA in the cytoplasm, aiming to use the system as a topical formulation to treat psoriasis. The PLNs composed of 2.0% of Compritol® 888 ATO (lipid), 1.5% of poloxamer 188 and 0.1% of the cationic polymer poly(allylamine hydrochloride) showed an average nanoparticle size of 142 nm, a zeta potential of +25 mV, and the ability to efficiently coencapsulate TPPS2a and complexed siRNA. In addition, these materials did not present cellular toxicity and showed high cellular uptake. In vitro delivery studies using porcine skin model revealed that the PLNs delivered siRNA and TPPS2a into the skin. The efficacy was verified using an in vivo psoriasis animal (hairless mouse) model induced by imiquimod (IMQ) cream. The results revealed that PLN-TPPS2a-TNFα siRNA combined with PCI resulted in a decrease in the levels of TNFα, showing the efficiency of the treatment to silence this cytokine in psoriatic lesions, which was accompanied by a reduction in the redness and scaling of the mouse skin. The results showed the potential of the developed PLNs in combined silencing gene therapy and PCI for topical treatment of psoriasis.

Polymeric Nanoparticles Based on Tyrosine-Modified, Low Molecular Weight Polyethylenimines for siRNA Delivery

A major hurdle for exploring RNA interference (RNAi) in a therapeutic setting is still the issue of in vivo delivery of small RNA molecules (siRNAs). The chemical modification of polyethylenimines (PEIs) offers a particularly attractive avenue towards the development of more efficient non-viral delivery systems. Here, we explore tyrosine-modified polyethylenimines with low or very low molecular weight (P2Y, P5Y, P10Y) for siRNA delivery. In comparison to their respective parent PEI, they reveal considerably increased knockdown efficacies and very low cytotoxicity upon tyrosine modification, as determined in different reporter and wildtype cell lines. The delivery of siRNAs targeting the anti-apoptotic oncogene survivin or the serine/threonine-protein kinase PLK1 (polo-like kinase 1; PLK-1) oncogene reveals strong inhibitory effects in vitro. In a therapeutic in vivo setting, profound anti-tumor effects in a prostate carcinoma xenograft mouse model are observed upon systemic application of complexes for survivin or PLK1 knockdown, in the absence of in vivo toxicity. We thus demonstrate the tyrosine-modification of (very) low molecular weight PEIs for generating efficient nanocarriers for siRNA delivery in vitro and in vivo, present data on their physicochemical and biological properties, and show their efficacy as siRNA therapeutic in vivo, in the absence of adverse effects.

Doramectin induced cytotoxic and genotoxic effects on bovine peripheral lymphocytes and cumulus cells in vitro

The effect of doramectin (DOR) was tested on two experimental somatic bovine cells in vitro: peripheral lymphocytes (PL) and cumulus cells (CC). The cytotoxicity and genotoxicity of DOR were assessed using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, single cell gel electrophoresis assay (SCGE) and cytokinesis-block micronucleus cytome (CBMN Cyt) assay. Both cells were treated with three concentrations of DOR (20, 40, 60 ng mL^-1) for 24 h. The results obtained from PL demonstrated that DOR was able to induce cytotoxic effect and DNA damage with all concentrations tested. Additionally, DOR increased micronuclei (MNi) frequency and nuclear buds (NBuds) with 20, 40, 60 ng mL^-1, and nucleoplasmic bridges (NPBs) only with 40 ng mL^-1. On the other hand, the three concentrations of DOR were not able to induce cytotoxic effect and DNA damage using SCGE in the bovine CC. Nevertheless, the two higher concentrations of DOR (20, 40 µg mL^-1) significantly increased the frequency of micronucleus formation in bovine CC. These results represent the first experimental evidence of genotoxic and cytotoxic effects exerted by DOR on bovine PL and CC.

Shaping Rolling Circle Amplification Products into DNA Nanoparticles by Incorporation of Modified Nucleotides and Their Application to In Vitro and In Vivo Delivery of a Photosensitizer

Rolling circle amplification (RCA) is a robust way to generate DNA constructs, which are promising materials for biomedical applications including drug delivery because of their high biocompatibility. To be employed as a drug delivery platform, however, the DNA materials produced by RCA need to be shaped into nanoparticles that display both high cellular uptake efficiency and nuclease resistance. Here, we showed that the DNA nanoparticles (DNPs) can be prepared with RCA and modified nucleotides that have side-chains appended on the nucleobase are capable of interacting with the DNA strands of the resulting RCA products. The incorporation of the modified nucleotides improved cellular uptake efficiency and nuclease resistance of the DNPs. We also demonstrated that these DNPs could be employed as carriers for the delivery of a photosensitizer into cancer cells to achieve photodynamic therapy upon irradiation at both the in vitro and in vivo levels.