Analysis of polyamidoamine dendrimers by isoelectric focusing

Folate-Targeted Transgenic Activity of Dendrimer Functionalized Selenium Nanoparticles In Vitro

Current chemotherapeutic drugs, although effective, lack cell-specific targeting, instigate adverse side effects in healthy tissue, exhibit unfavourable bio-circulation and can generate drug-resistant cancers. The synergistic use of nanotechnology and gene therapy, using nanoparticles (NPs) for therapeutic gene delivery to cancer cells is hereby proposed. This includes the benefit of cell-specific targeting and exploitation of receptors overexpressed in specific cancer types. The aim of this study was to formulate dendrimer-functionalized selenium nanoparticles (PAMAM-SeNPs) containing the targeting moiety, folic acid (FA), for delivery of pCMV-Luc-DNA (pDNA) in vitro. These NPs and their gene-loaded nanocomplexes were physicochemically and morphologically characterized. Nucleic acid-binding, compaction and pDNA protection were assessed, followed by cell-based in vitro cytotoxicity, transgene expression and apoptotic assays. Nanocomplexes possessed favourable sizes (<150 nm) and ζ-potentials (>25 mV), crucial for cellular interaction, and protected the pDNA from degradation in an in vivo simulation. PAMAM-SeNP nanocomplexes exhibited higher cell viability (>85%) compared to selenium-free nanocomplexes (approximately 75%), confirming the important role of selenium in these nanocomplexes. FA-conjugated PAMAM-SeNPs displayed higher overall transgene expression (HeLa cells) compared to their non-targeting counterparts, suggesting enhanced receptor-mediated cellular uptake. Overall, our results bode well for the use of these nano-delivery vehicles in future in vivo studies.

A Mixed-Surface Polyamidoamine Dendrimer for In Vitro and In Vivo Delivery of Large Plasmids

Drug delivery to the brain is highly hindered by the presence of the blood-brain barrier (BBB), which prevents the entry of many potential drugs/biomolecules into the brain. One of the current strategies to achieve gene therapy for neurodegenerative diseases involves direct injection of a viral vector into the brain. There are various disadvantages of viral vectors, including limitations of cargo size and safety concerns. Nanomolecules, such as dendrimers, serve as an excellent alternative to viral delivery. In this study, as proof-of-concept, we used a surface-modified dendrimer complex and delivered large plasmids to cells in vitro and in vivo in healthy rats via intracranial injection. The dendrimers were biodegradable by chemicals found within cells and toxicity assays revealed that the modified dendrimers were much less toxic than unmodified amine-surface dendrimers. As mentioned in our previous publication, these dendrimers with appropriately modified surfaces are safe, can deliver large plasmids to the brain, and can overcome the cargo size limitations associated with viral vectors. The biocompatibility of this dendritic nanomolecule and the ability to finely tune its surface chemistry provides a gene delivery system that could facilitate future in vivo cellular reprograming and other gene therapies.

Novel cystamine-core dendrimer-formulation rescues ΔF508-CFTR and inhibits Pseudomonas aeruginosa infection by augmenting autophagy

BACKGROUND

Cystic fibrosis (CF) is challenged with pathophysiological barriers for effective airway drug-delivery. Hence, we standardized the therapeutic efficacy of the novel dendrimer-based autophagy-inducing anti-oxidant drug, cysteamine.

RESEARCH DESIGN AND METHODS

Human primary-CF epithelial-cells, CFBE41o-cells were used to standardize the efficacy of the dendrimer-cystamine in correcting impaired-autophagy, rescuing ΔF508-CFTR and Pseudomonas-aeruginosa (Pa) infection.

RESULTS

We first designed a novel cystamine-core dendrimer formulation (G4-CYS) that significantly increases membrane-ΔF508CFTR expression in CFBE41o-cells (p < 0.05) by forming its reduced-form cysteamine, in vivo. Additionally, G4-CYS treatment corrects ΔF508-CFTR-mediated impaired-autophagy as observed by a significant decrease (p < 0.05) in Ub-LC3-positive aggresome-bodies. Next, we verified that in non-permeabilized CFBE41o-cells, G4-CYS significantly (p < 0.05) induces ΔF508-CFTR's forward-trafficking to the plasma membrane. Furthermore, cysteamine's known antibacterial and anti-biofilm properties against Pa were enhanced as our findings demonstrate that both G4-CYS and its control DAB-core dendrimer, G4-DAB, exhibited significant (p < 0.05) bactericidal-activity against Pa. We also found that both G4-CYS and G4-DAB exhibit marked mucolytic-activity against porcine-mucus (p < 0.05). Finally, we demonstrate that G4-CYS not only corrects the autophagy-impairment by rescuing ΔF508-CFTR in CFBE41o-cells but also corrects the intrinsic phagocytosis defect (p < 0.05).

CONCLUSIONS

Overall, our data demonstrates the efficacy of novel cystamine-dendrimer formulation in rescuing ΔF508-CFTR to the plasma membrane and inhibiting Pa bacterial-infection by augmenting autophagy.

PAMAM Dendrimers Cross the Blood-Brain Barrier When Administered through the Carotid Artery in C57BL/6J Mice

Drug delivery into the central nervous system (CNS) is challenging due to the blood–brain barrier (BBB) and drug delivery into the brain overcoming the BBB can be achieved using nanoparticles such as dendrimers. The conventional cationic dendrimers used are highly toxic. Therefore, the present study investigates the role of novel mixed surface dendrimers, which have potentially less toxicity and can cross the BBB when administered through the carotid artery in mice. In vitro experiments investigated the uptake of amine dendrimers (G1-NH₂ and G4-NH₂) and novel dendrimers (G1-90/10 and G4-90/10) by primary cortical cultures. In vivo experiments involved transplantation of G4-90/10 into mice through (1) invasive intracranial injections into the striatum; and (2) less invasive carotid injections. The animals were sacrificed 24-h and 1-week post-transplantations and their brains were analyzed. In vivo experiments proved that the G4-90/10 can cross the BBB when injected through the carotid artery and localize within neurons and glial cells. The dendrimers were found to migrate through the corpus callosum 1-week post intracranial injection. Immunohistochemistry showed that the migrating cells are the dendrimer-infected glial cells. Overall, our results suggest that poly-amidoamine (PAMAM) dendrimers may be used as a minimally invasive means to deliver biomolecules for treating neurological diseases or disorders

Dendrimer-Based Selective Proteostasis-Inhibition Strategy to Control NSCLC Growth and Progression

Elevated valosin containing protein (VCP/p97) levels promote the progression of non-small cell lung carcinoma (NSCLC). Although many VCP inhibitors are available, most of these therapeutic compounds have low specificity for targeted tumor cell delivery. Hence, the primary aim of this study was to evaluate the in vitro efficacy of dendrimer-encapsulated potent VCP-inhibitor drug in controlling non-small cell lung carcinoma (NSCLC) progression. The VCP inhibitor(s) (either in their pure form or encapsulated in generation-4 PAMAM-dendrimer with hydroxyl surface) were tested for their in vitro efficacy in modulating H1299 (NSCLC cells) proliferation, migration, invasion, apoptosis and cell cycle progression. Our results show that VCP inhibition by DBeQ was significantly more potent than NMS-873 as evident by decreased cell proliferation (p<0.0001, MTT-assay) and migration (p<0.05; scratch-assay), and increased apoptosis (p<0.05; caspase-3/7-assay) as compared to untreated control cells. Next, we found that dendrimer-encapsulated DBeQ (DDNDBeQ) treatment increased ubiquitinated-protein accumulation in soluble protein-fraction (immunoblotting) of H1299 cells as compared to DDN-control, implying the effectiveness of DBeQ in proteostasis-inhibition. We verified by immunostaining that DDNDBeQ treatment increases accumulation of ubiquitinated-proteins that co-localizes with an ER-marker, KDEL. We observed that proteostasis-inhibition with DDNDBeQ, significantly decreased cell migration rate (scratch-assay and transwell-invasion) as compared to the control-DDN treatment (p<0.05). Moreover, DDNDBeQ treatment showed a significant decrease in cell proliferation (p<0.01, MTT-assay) and increased caspase-3/7 mediated apoptotic cell death (p<0.05) as compared to DDN-control. This was further verified by cell cycle analysis (propidium-iodide-staining) that demonstrated significant cell cycle arrest in the G2/M-phase (p<0.001) by DDNDBeQ treatment as compared to control-DDN. Moreover, we confirmed by clonogenic-assay that DDNDBeQ treatment significantly (p<0.001) inhibits H1299 colony-formation as compared to control/DDN. Overall, encapsulation of potent VCP-inhibitor DBeQ into a dendrimer allows selective VCP-mediated proteostasis-inhibition for controlling NSCLC-tumor growth and progression to allow tumor-targeted sustained drug delivery.