Significant advances in the synthesis of polypeptides by N-carboxyanhydride (NCA) polymerisation over the last decade have enabled the design of advanced polypeptide architectures such as star-shaped polypeptides. These materials combine the functionality offered by amino acids with the flexibility of creating stable nanoparticles with adjustable cargo space for therapeutic delivery. This review highlights recent advances in the synthesis of star polypeptides by NCA polymerisation followed by a critical review of the applications of this class of polymer in the delivery of therapeutic agents. This includes examples of traditional small-molecule drugs as well as the emerging class of biologics such as genetic therapeutics (gene delivery).

The incidence of refractory acute myeloid leukemia (AML) is on the increase due in part to an aging population that fails to respond to traditional therapies. High throughput genomic analysis promises better diagnosis, prognosis, and therapeutic intervention based on improved patient stratification. Relevant preclinical models are urgently required to advance drug development in this area. The collaborating oncogenes, HOXA9 and MEIS1, are frequently co-overexpressed in cytogenetically normal AML (CN-AML), and a conditional transplantation mouse model was developed that demonstrated oncogene dependency and expression levels comparable to CN-AML patients. Integration of gene signatures obtained from the mouse model and a cohort of CN-AML patients using statistically significant connectivity map analysis identified Entinostat as a drug with the potential to alter the leukemic condition toward the normal state. Ex vivo treatment of leukemic cells, but not age-matched normal bone marrow controls, with Entinostat validated the gene signature and resulted in reduced viability in liquid culture, impaired colony formation, and loss of the leukemia initiating cell. Furthermore, in vivo treatment with Entinostat resulted in prolonged survival of leukemic mice. This study demonstrates that the HDAC inhibitor Entinostat inhibits disease maintenance and prolongs survival in a clinically relevant murine model of cytogenetically normal

Lung gene therapy for cystic fibrosis disease has not been successful due to several challenges such as the absence of an appropriate vector. Therefore, optimal delivery of emerging therapeutics to airway epithelial cells demands suitable non-viral systems. In this work, we describe the formulation and the physicochemical investigation of biocompatible and biodegradable polymeric nanoparticles (NPs), including PLGA and chitosan (animal and non-animal), as novel methods for the safe and efficient delivery of CFTR-specific locked nucleic acids (LNAs).

The development of small interfering RNA (siRNA) to silence specific genes offers a new means of understanding and treating a range of respiratory diseases, including inflammatory lung disease. The alveolar macrophage (AM) is a key component of the inflammatory process in the lungs, associated with high levels of gene expression in inflammatory lung disease and therefore an attractive target for therapeutic siRNA. Delivery of siRNA to macrophages presents a significant delivery challenge, as fully differentiated alveolar macrophages are difficult to access and transfect. In this study we engineered particles suitable for inhalation that would efficiently transfect macrophages postinhalation. The process for encapsulation of siRNA in poly(lactic-co-glycolic acid) microparticles (MPs) was optimized using a double emulsion technique, and the resulting particles were characterized for size, shape, aerosol characteristics, encapsulation efficiency, and integrity of encapsulated siRNA. The cell uptake of the siRNA-loaded microparticles was determined by flow cytometry, confocal laser scanning microscopy (CLSM), and high-content analysis (HCA) with MPs capable of transfecting up to 55% of cells. Anti-TNFα siRNA-MPs were then prepared to study the functional activity of encapsulated siRNA in LPS-stimulated macrophages as a model of inflammation. The anti-TNFα siRNA-MPs were able to decrease TNFα expression by 45% over 48 h in the differentiated human monocytic cell line THP-1 compared to negligible knockdown using commercial transfection reagents and offered significant, sustained siRNA knockdown of TNFα in primary monocytes for up to 72 h.

Background Interferon gamma (IFN-γ) is a clinically relevant immunomodulatory cytokine that has demonstrated significant potential in the treatment and management of respiratory diseases such as tuberculosis and pulmonary fibrosis. As with all large biomolecules, clinical translation is dependent on effective delivery to the disease site and delivery of IFN-γ as an aerosol offers a logical means of drug targeting. Effective localization is often hampered by instability and a lack of safe and efficient delivery systems. The present study sought to determine how effectively IFN-γ can be nebulized using two types of vibrating mesh nebulizer, each with differing mesh architectures, and to investigate the comparative efficiency of delivery of therapeutically active IFN-γ to the lungs. Methods Nebulization of IFN-γ was carried out using two different Aerogen vibrating mesh technologies with differing mesh architectures. These technologies represent both a standard commercially available mesh type (Aerogen Solo®) and a new iteration mesh (Photo-defined aperture plate (PDAP®). Extensive aerosol studies (aerosol output and droplet analysis, non-invasive and invasive aerosol therapy) were conducted in line with regulatory requirements and characterization of the stability and bioactivity of the IFN-γ post-nebulization was confirmed using SDS-PAGE and stimulation of Human C-X-C motif chemokine 10 (CXCL 10) also known as IFN-γ-induced protein 10KDa (IP 10) expression from THP-1 derived macrophages (THP-1 cells). Results Aerosol characterization studies indicated that a significant and reproducible dose of aerosolized IFN-γ can be delivered using both vibrating mesh technologies. Nebulization using both devices resulted in an emitted dose of at least 93% (100% dose minus residual volume) for IFN-γ. Characterization of aerosolized IFN-γ indicated that the PDAP was capable of generating droplets with a significantly lower mass median aerodynamic diameter (MMAD) with values of 2.79 ± 0.29 μm and 4.39 ± 0.25 μm for the PDAP and Solo respectively. The volume median diameters (VMD) of aerosolized IFN-γ corroborated this with VMDs of 2.33 ± 0.02 μm for the PDAP and 4.30 ± 0.02 μm for the Solo. SDS-PAGE gels indicated that IFN-γ remains stable after nebulization by both devices and this was confirmed by bioactivity studies using a THP-1 cell model in which an alveolar macrophage response to IFN-γ was determined. IFN-γ nebulized by the PDAP and Solo devices had no significant effect on the key inflammatory biomarker cytokine IP-10 release from this model in comparison to non-nebulized controls. Here we demonstrate that it is possible to combine IFN-γ with vibrating mesh nebulizer devices and facilitate effective aerosolisation with minimal impact on IFN-γ structure or bioactivity. Conclusions It is possible to nebulize IFN-γ effectively with vibrating mesh nebulizer devices without compromising its stability. The PDAP allows for ge...

Modulation of microRNAs (miRNAs), endogenous regulators of gene expression, is a promising strategy for tackling inflammatory lung diseases. In this proof-of-concept study, we tested delivery of miR-17 to bronchial epithelial cells (BECs) using nebulised lipid–polymer hybrid nanoparticles (LPNs). The primary aim was to reduce the induced secretion of miR-17's target, i.e. the pro-inflammatory chemokine interleukin (IL)-8.Synthetic miR-17 mimics were loaded into LPNs composed of poly(dl-lactic-co-glycolic acid) (PLGA) and the cationic lipid 1,2-dioleoyloxy-3-(trimethylammonium)propane (DOTAP) using a double emulsion solvent evaporation method and nebulised using the Aerogen Solo nebuliser. The physicochemical, aerosol, inflammatory and cytotoxic properties of LPNs were characterised. The effect of LPNs on lipopolysaccharide (LPS)-induced IL-8 production from human NuLi-1 BECs was tested by ELISA.The z-average, polydispersity index and ζ-potential of the LPNs and the aerodynamic properties of nebulised suspensions were in a range optimal for deposition in the bronchi and bronchioles post-inhalation. Cytotoxic and pro-inflammatory effects were minimal for LPNs loaded with a model cargo. Nebulisation did not affect the physicochemical or functional properties of the LPNs. Nebulised miR-17-loaded LPNs downregulated LPS-induced IL-8 secretion by >40% in BECs.This study suggests that DOTAP-modified PLGA LPNs are efficient and well-tolerated carriers for delivery of miRNA mimics to BECs.

Aromatase is a critical enzyme in the irreversible conversion of androgens to oestrogens, with inhibition used clinically in hormone-dependent malignancies. We tested the hypothesis that targeted aromatase inhibition in an aggressive brain cancer called glioblastoma (GBM) may represent a new treatment strategy. In this study, aromatase inhibition was achieved using third generation inhibitor, Letrozole, encapsulated within the core of biodegradable poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs). PLGA-NPs were conjugated to human/mouse chimeric anti-GD2 antibody ch14.18/CHO, enabling specific targeting of GD2-positive GBM cells. Treatment of primary and recurrent patient-derived GBM cells with free-Letrozole (0.1 μM) led to significant decrease in cell proliferation and migration; in addition to reduced spheroid formation. Anti-GD2-ch14.18/CHO-NPs displayed specific targeting of GBM cells in colorectal-glioblastoma co-culture, with subsequent reduction in GBM cell numbers when treated with anti-GD2-ch14.18-PLGA-Let-NPs in combination with temozolomide. As miR-191 is an estrogen responsive microRNA, its expression, fluctuation and role in Letrozole treated GBM cells was evaluated, where treatment with premiR-191 was capable of rescuing the reduced proliferative phenotype induced by aromatase inhibitor. The repurposing and targeted delivery of Letrozole for the treatment of GBM, with the potential role of miR-191 identified, provides novel avenues for target assessment in this aggressive brain cancer.

Development of anti-cancer drugs towards clinical application is costly and inefficient. Large screens of drugs, efficacious for non-cancer disease, are currently being used to identify candidates for repurposing based on their anti-cancer properties. Here, we show that low-dose salinomycin, a coccidiostat ionophore previously identified in a breast cancer screen, has anti-leukemic efficacy. AML and MLLr cell lines, primary cells and patient samples were sensitive to submicromolar salinomycin. Most strikingly, colony formation of normal hematopoietic cells was unaffected by salinomycin, demonstrating a lack of hemotoxicity at the effective concentrations. Furthermore, salinomycin treatment of primary cells resulted in loss of leukemia repopulation ability following transplantation, as demonstrated by extended recipient survival compared to controls. Bioinformatic analysis of a 17-gene signature identified and validated in primary MLLr cells, uncovered immunomodulatory pathways, hubs and protein interactions as potential transducers of low dose salinomycin treatment. Additionally, increased protein expression of p62/Sqstm1, encoded for by one of the 17 signature genes, demonstrates a role for salinomycin in aggresome/vesicle formation indicative of an autophagic response.Together, the data support the efficacy of salinomycin as an anti-leukemic at non-hemotoxic concentrations. Further investigation alone or in combination with other therapies is warranted for future clinical trial.