Non-viral gene delivery utilizing RALA modulates sFlt-1 secretion, important for preeclampsia

Background: Overexpression of sFlt-1 or modulation of FKBPL, key antiangiogenic proteins, are important in the pathogenesis of preeclampsia. Methods: A newly developed nonviral gene-delivery system, RALA, capable of overexpressing sFlt-1 (e15a isoform) was delivered in vivo in transgenic haploinsufficient (Fkbpl^+/-) mice. RALA was also used in vitro to deliver human Flt1 (hFlt1) in trophoblast cells. Results: Serum stable and nontoxic RALA/DNA-based nanoparticles induced an increase in sFlt-1 protein levels in the blood and total protein in the urine; the effect was more pronounced in Fkbpl^+/- mice. In vitro, RALA-hFlt nanoparticles significantly reduced secretion of sFlt-1 in trophoblast cells. Conclusion: The RALA-based genetic nanodelivery system can be safely and effectively applied to emulate preeclampsia-like features or reduce sFlt-1 levels in vitro.

Exploiting the anticancer effects of a nitrogen bisphosphonate nanomedicine for glioblastoma multiforme

Glioblastoma multiforme (GBM) is an incurable aggressive brain cancer in which current treatment strategies have demonstrated limited survival benefit. In recent years, nitrogen-containing bisphosphonates (N-BPs) have demonstrated direct anticancer effects in a number of tumour types including GBM. In this study, a nano-formulation with the RALA peptide was used to complex the N-BP, alendronate (ALN) into nanoparticles (NPs) < 200 nm for optimal endocytic uptake. Fluorescently labelled AlexaFluor®647 Risedronate was used as a fluorescent analogue to visualise the intracellular delivery of N-BPs in both LN229 and T98G GBM cells. RALA NPs were effectively taken up by GBM where a dose-dependent response was evidenced with potentiation factors of 14.96 and 13.4 relative to ALN alone after 72 h in LN229 and T98G cells, respectively. Furthermore, RALA/ALN NPs at the IC_50, significantly decreased colony formation, induced apoptosis and slowed spheroid growth in vitro. In addition, H-Ras membrane localisation was significantly reduced in the RALA/ALN groups compared to ALN or controls, indicative of prenylation inhibition. The RALA/ALN NPs were lyophilised to enhance stability without compromising the physiochemical properties necessary for functionality, highlighting the suitability of the NPs for scale-up and in vivo application. Collectively, these data show the significant potential of RALA/ALN NPs as novel therapeutics in the treatment of GBM.

Design of a novel electrospun PVA platform for gene therapy applications using the CHAT peptide

The electrospinning of polymers has previously shown excellent potential for localised gene therapy. Thus, it was proposed that for the first time, the cell-penetrating CHAT peptide could be utilised to deliver DNA via electrospun nanofibres for localised gene therapy treatment. CHAT is an effective delivery system that encapsulates pDNA to form nanoparticles with the physicochemical characteristics for cellular uptake and protein generation. In this study, the production of smooth, bead-free PVA nanofibres by electrospinning was optimised through a Design of Experiments approach. Bead-free PVA nanofibres were consistently produced using the optimised parameters as follows: applied voltage (8 kV); collector-emitter distance (8 cm); polymer flow rate (4 µL/min); polymer concentration (9 wt% polymer); PVA M_W (146-180 kDa). PVA nanofibres were subsequently crosslinked in 1 vol% glutaraldehyde in methanol to confer stability under aqueous conditions with minimal change to morphology, and no compromise to biocompatibility. Nanoparticles of CHAT/pDNA were synthesised and incorporated into the crosslinked nanofibres via soak-loading. Evaluation studies indicated that 100% of the loaded cargo was released within 48 h from the nanofibres. Furthermore, the released pDNA retained structural integrity and functionality as confirmed by gel electrophoresis and transfection studies in NCTC-929 fibroblast cells. Taken together, this data demonstrates that delivery of CHAT/pDNA nanoparticles from electrospun PVA nanofibres represents a solution for localised gene therapy.

Rational design and characterisation of an amphipathic cell penetrating peptide for non-viral gene delivery

RALA is a cationic amphipathic peptide which has shown great promise as an efficient, multifunctional delivery system for the delivery of nucleic acids. Rational peptide design was utilised in this study to understand the essential amino acids required for delivery and if any improvements to the RALA peptide could be made. Six amphipathic peptides were synthesised with strategic sequences and amino acid substitutions to reduce peptide sequence, while maintaining the functional characteristics of RALA including amphipathicity, alpha-helicity and pH responsiveness for endosomal escape. Data demonstrated that all six peptides complexed pEGFP-N1 to produce cationic nanoparticles <200 nm in diameter, but not all peptides resulted in successful transfection; indicating the influence of peptide design for cellular uptake and endosomal escape. Pep2, produced nanoparticles with similar characteristics and transfection efficiency to the parent peptide, RALA. However, Pep2 had issues with toxicity and a lack of pH-responsive alpha-helcity. Therefore, RALA remains the superior sequence for non-toxic gene delivery.

Rational design and characterisation of a linear cell penetrating peptide for non-viral gene delivery

The design of a non-viral gene delivery system that can release a functional nucleic acid at the intracellular destination site is an exciting but also challenging proposition. The ideal gene delivery vector must be non-toxic, non-immunogenic, overcome extra- and intra-cellular barriers, protect the nucleic acid cargo from degradation with stability over a range of temperatures. A new 15 amino acid linear peptide termed CHAT was designed in this study with the goal of delivering DNA with high efficiency into cells in vitro and tissues in vivo. Rational design involved incorporation of key amino acids including arginine for nucleic acid complexation and cellular uptake, tryptophan to enhance hydrophobic interaction with cell membranes, histidine to facilitate endosomal escape and cysteine for stability and controlled cargo release. Six linear peptides were synthesised with strategic sequences and amino acid substitutions. Data demonstrated that all six peptides complexed pDNA to produce cationic nanoparticles less than 200 nm in diameter, but not all peptides resulted in successful transfection; indicating the influence of peptide design for endosomal escape. Peptide 4, now termed CHAT, was non-cytotoxic, traversed the plasma membrane of breast and prostate cancer cell lines, and elicited reporter-gene expression following intra-tumoural and intravenous delivery in vivo. CHAT presents an exciting new peptide for the delivery of nucleic acid therapeutics.

Gene therapy with RALA/iNOS composite nanoparticles significantly enhances survival in a model of metastatic prostate cancer

BACKGROUND

Recent approvals of gene therapies by the FDA and the EMA for treatment of inherited disorders have further opened the door for assessment of nucleic acid pharmaceuticals for clinical usage. Arising from the presence of damaged or inappropriate DNA, cancer is a condition particularly suitable for genetic intervention. The RALA peptide has been shown to be a potent non-viral delivery platform for nucleic acids. This study examines the use of RALA to deliver a plasmid encoding inducible nitric oxide synthase (iNOS) as an anti-cancer treatment.

METHODS

The physiochemical properties of the RALA/DNA nanoparticles were characterized via dynamic light scattering and transmission electron microscopy. The nanoparticles were labelled with fluorophores and tracked over time using confocal microscopy with orthogonal sections to determine cellular location. In vitro studies were employed to determine functionality of the nanoparticles both for pEGFP-N1 and CMV-iNOS. Nanoparticles were injected intravenously into C57/BL6 mice with blood and serum samples analysed for immune response. PC3-luc2M cells were injected into the left ventricle of SCID mice followed by treatment with RALA/CMV-iNOS nanoparticles to evaluate the tumour response in a metastatic model of prostate cancer.

RESULTS

Functional cationic nanoparticles were produced with gene expression in PC-3 prostate cancer cells. Furthermore, repeated administrations of RALA/DNA nanoparticles into immunocompetent mice did not produce any immunological response: neutralization of the vector or release of inflammatory mediators. RALA/CMV-iNOS reduced the clonogenicity of PC-3 cells in vitro, and in an in vivo model of prostate cancer metastasis, systemically delivered RALA/CMV-iNOS significantly improved the survival of mice.

CONCLUSION

These studies further validate RALA as a genetic cargo delivery vehicle and iNOS as a potent therapy for the treatment of cancer.

Delivery of nucleic acids for cancer gene therapy: overcoming extra- and intra-cellular barriers

The therapeutic potential of cancer gene therapy has been limited by the difficulty of delivering genetic material to target sites. Various biological and molecular barriers exist which need to be overcome before effective nonviral delivery systems can be applied successfully in oncology. Herein, various barriers are described and strategies to circumvent such obstacles are discussed, considering both the extracellular and intracellular setting. Development of multifunctional delivery systems holds much promise for the progression of gene delivery, and a growing body of evidence supports this approach involving rational design of vectors, with a unique molecular architecture. In addition, the potential application of composite gene delivery platforms is highlighted which may provide an alternative delivery strategy to traditional systemic administration.