Preparation and evaluation of polyamidoamine dendrimer conjugate with glucuronylglucosyl-β-cyclodextrin (G3) as a novel carrier for siRNA

Stabilization and Movable Ligand-Modification by Folate-Appended Polyrotaxanes for Systemic Delivery of siRNA Polyplex

To achieve a systemic targeted delivery of siRNA using polymeric carriers, there is a dilemma between ligand modification and stabilization of the polyplex. Namely, ligand modification often leads to destabilization of the polyplex in the blood circulation. In fact, we previously developed cyclodextrin (CD)/polyamidoamine dendrimer conjugates (CDE) as siRNA carriers, and the interaction of CDE/siRNA was decreased by the conjugation with folate-polyethylene glycol, leading to the destabilization. To overcome this dilemma, in this study, folate-appended polyrotaxanes (Fol-PRX) were developed. Fol-PRX stabilized CDE/siRNA polyplex by intermolecularly connecting CDE molecules through a host-guest interaction between adamantane at the terminals of Fol-PRX and β-CD in the polyplex. Moreover, the intermolecular connection of the polyplex with Fol-PRX provided movable folate moieties on the surface. As a result, Fol-PRXs enhanced the in vivo antitumor activity of the polyplex after intravenous administration, suggesting their utility as the dual-functional materials for systemic delivery of siRNA polyplexes.

Non-Viral Vectors for Delivery of Nucleic Acid Therapies for Cancer

The research and development of non-viral gene therapy has been extensive over the past decade and has received a big push thanks to the recent successful approval of non-viral nucleic acid therapy products. Despite these developments, nucleic acid therapy applications in cancer have been limited. One of the main causes of this has been the imbalance in development of delivery vectors as compared with sophisticated nucleic acid payloads, such as siRNA, mRNA, etc. This paper reviews non-viral vectors that can be used to deliver nucleic acids for cancer treatment. It discusses various types of vectors and highlights their current applications. Additionally, it discusses a perspective on the current regulatory landscape to facilitate the commercial translation of gene therapy.

Twenty Years of Research on Cyclodextrin Conjugates with PAMAM Dendrimers

Recently, the number of gene and oligonucleotide drugs are increasing. Of various drug delivery systems (DDSs) for gene and oligonucleotide drugs, few examples of the clinical application of polymer as drug carriers are known, despite development of the novel polymers has been progressing. Cyclodextrin (CD) conjugates with starburst polyamidoamine (PAMAM) dendrimer (CDEs), as a new type of polymer-based carriers, were first published in 2001. After that, galactose-, lactose-, mannose-, fucose-, folate-, and polyethyleneglycol (PEG)-appended CDEs have been prepared for passive and active targeting for gene, oligonucleotide, and low-molecular-weight drugs. PEG-appended CDE formed polypsuedorotaxanes with α-CD and γ-CD, which are useful for a sustained release system of gene and oligonucleotide drugs. Interestingly, CDEs were found to have anti-inflammatory effects and anti-amyloid effects themselves, which have potential as active pharmaceutical ingredients. Most recently, CDE is reported to be a useful Cas9-RNA ribonucleoproteins (Cas9 RNP) carrier that induces genome editing in the neuron and brain. In this review, the history and progression of CDEs are overviewed.

First Class of Phosphorus Dendritic Compounds Containing β-Cyclodextrin Units in the Periphery Prepared by CuAAC

A new class of phosphorus dendritic compounds (PDCs) having a cyclotriphosphazene (P₃N₃) core and decorated with six β-cyclodextrin (βCD) units, named P₃N₃-[O-C₆H₄-O-(CH₂)_n-βCD]₆, where n = 3 or 4 was designed, and the synthesis was performed using copper (I) catalyzed alkyne-azide cycloaddition (CuAAC). To obtain the complete substitution of the P₃N₃, two linkers consisting of an aromatic ring and an aliphatic chain of two different lengths were assessed. We found that, with both linkers, the total modification of the periphery was achieved. The two new obtained dendritic compounds presented a considerably high water solubility (>1 g/mL). The compounds comprised in this new class of PDCs are potential drug carrier candidates, since the conjugation of the βCD units to the P₃N₃ core through the primary face will not only serve as surface cover but, also, provide them the faculty to encapsulate various drugs inside the βCDs cavities.

Efficient modification of PAMAM G1 dendrimer surface with β-cyclodextrin units by CuAAC: impact on the water solubility and cytotoxicity

The toxicity of the poly(amidoamine) dendrimers (PAMAM) caused by the peripheral amino groups has been a limitation for their use as drug carriers in clinical applications. In this work, we completely modified the periphery of PAMAM dendrimer generation 1 (PAMAM G1) with β-cyclodextrin (β-CD) units through the Cu(i)-catalyzed azide–alkyne cycloaddition (CuAAC) to obtain the PAMAM G1-β-CD dendrimer with high yield. The PAMAM G1-β-CD was characterized by ¹H- and ¹³C-NMR and mass spectrometry studies. Moreover, the PAMAM G1-β-CD dendrimer showed remarkably higher water solubility than native β-CD. Finally, we studied the toxicity of PAMAM G1-β-CD dendrimer in four different cell lines, human breast cancer cells (MCF-7 and MDA-MB-231), human cervical adenocarcinoma cancer cells (HeLa) and pig kidney epithelial cells (LLC-PK1). The PAMAM G1-β-CD dendrimer did not present any cytotoxicity in cell lines tested which shows the potentiality of this new class of dendrimers.

The toxicity of the poly(amidoamine) dendrimers (PAMAM) caused by the peripheral amino groups has been a limitation for their use as drug carriers in clinical applications.

Genome Editing in a Wide Area of the Brain Using Dendrimer-Based Ternary Polyplexes of Cas9 Ribonucleoprotein

A preassembled Cas9/single-guide RNA complex (Cas9 ribonucleoprotein; Cas9 RNP) induces genome editing efficiently, with small off-target effects compared with the conventional techniques, such as plasmid DNA and mRNA systems. However, penetration of Cas9 RNP through the cell membrane is low. In particular, the incorporation of Cas9 RNP into neurons and the brain is challenging. In the present study, we have reported the use of a dendrimer (generation 3; G3)/glucuronylglucosyl-β-cyclodextrin conjugate (GUG-β-CDE (G3)) as a carrier of Cas9 RNP and evaluated genome editing activity in the neuron and the brain. A Cas9 RNP ternary complex with GUG-β-CDE (G3) was prepared by only mixing the components. The resulting complex exhibited higher genome editing activity than the complex with the dendrimer (G3), Lipofectamine 3000 or Lipofectamine CRISPRMAX in SH-SY5Y cells, a human neuroblastoma cell line. In addition, GUG-β-CDE (G3) enhanced the genome editing activity of Cas9 RNP in the whole mouse brain after a single intraventricular administration. Thus, GUG-β-CDE (G3) is a useful Cas9 RNP carrier that can induce genome editing in the neuron and brain.

A biocompatible poly(amidoamine) (PAMAM) dendrimer octa-substituted with α-cyclodextrin towards the controlled release of doxorubicin hydrochloride from its ferrocenyl prodrug

Facile and efficient methods for the synthesis of the first poly(aminodamine) PAMAM G1.0 dendrimer octa-substituted with α-cyclodextrin and a novel ferrocenyl prodrug of doxorubicin hydrochloride are developed. This vector is non-toxic and can bind the designed ferrocenyl prodrug. It also shows a controlled drug release profile and high cytotoxicity against breast cancer cells (MCF-7), as elucidated by the in vitro biological studies performed with an innovative cell-on-a-chip microfluidic system.

A controlled release of doxorubicin hydrochloride from a novel nanoconjugate comprising PAMAM dendrimer octa-substituted with α-cyclodextrin and ferrocenyl prodrug is presented.

In Vitro and In Vivo Co-delivery of siRNA and Doxorubicin by Folate-PEG-Appended Dendrimer/Glucuronylglucosyl-β-Cyclodextrin Conjugate

We have previously reported the utility of folate-polyethylene glycol-appended dendrimer conjugate with glucuronylglucosyl-β-cyclodextrin (Fol-PEG-GUG-β-CDE) (generation 3) as a tumor-selective carrier for siRNA against polo-like kinase 1 (siPLK1) in vitro. In the present study, we evaluated the potential of Fol-PEG-GUG-β-CDE as a carrier for the low-molecular antitumor drug doxorubicin (DOX). Further, to fabricate advanced antitumor agents, we have prepared a ternary complex of Fol-PEG-GUG-β-CDE/DOX/siPLK1 and evaluated its antitumor activity both in vitro and in vivo. Fol-PEG-GUG-β-CDE released DOX in an acidic pH and enhanced the cellular accumulation and cytotoxic activity of DOX in folate receptor-α (FR-α)-overexpressing KB cells. Importantly, the Fol-PEG-GUG-β-CDE/DOX/siPLK1 ternary complex exhibited higher cytotoxic activity than a binary complex of Fol-PEG-GUG-β-CDE with DOX or siPLK1 in KB cells. In addition, the cytotoxic activity of the ternary complex was reduced by the addition of folic acid, a competitor against FR-α. Furthermore, the ternary complex showed a significant antitumor activity after intravenous administration to the tumor-bearing mice. These results suggest that Fol-PEG-GUG-β-CDE has the potential of a tumor-selective co-delivery carrier for DOX and siPLK1.

Perspectives on dendritic architectures and their biological applications: From core to cell

The challenges of medicine today include the increasing stipulation for sensitive and effective systems that can improve the pathological responses with a simultaneous reduction in accumulation and drug side effects. The demand can be fulfilled through the advancements in nanomedicine that includes nanostructures and nanodevices for diagnosing, treating, and prevention of various diseases. In this respect, the nanoscience provides various novel techniques with carriers such as micelles, dendrimers, particles and vesicles for the transportation of active moieties. Further, an efficient way to improve these systems is through stimuli a responsive system that utilizes supramolecular hyperbranched structures to meet the above criteria. The stimuli-responsive dendritic architectures exhibit spatial, temporal, convenient, effective, safety and controlled drug release in response to specific trigger through electrostatic interactions plus π stacking. The stimuli-responsive systems are capable of sequestering the drug molecules underneath a predefined set of conditions and discharge them in a different environment through either exogenous or endogenous stimulus. The incorporation of photoresponsive moieties at various components of dendrimer such as core, branches or at the peripheral end exaggerates its significance in various allied fields of nanotechnology which includes sensors, photoswitch, electronic widgets and in drug delivery systems. This is due to the light instigated geometrical modifications at the core or at the surface molecules which generates huge conformational changes throughout the hyperbranched structure. Further, numerous synthetic methodologies have been investigated for utilization of dendrimers in therapeutic drug delivery and its applicability towards stimuli responsive systems such as photo-instigated, thermal-instigated, and pH-instigated hyperbranched structures and their advancement in the field of nanomedicine. This paper highlights the fascinating theoretical advances and principal mechanisms of dendrimer synthesis and their ability to capture light that strengthens its applicability from radiant energy to medical photonics.

Recent advances in siRNA delivery

In the 1990s an unexpected gene-silencing phenomena in plants, the later called RNA interference (RNAi), perplexed scientists. Following the proof of activity in mammalian cells, small interfering RNAs (siRNAs) have quickly crept into biomedical research as a new powerful tool for the potential treatment of different human diseases based on altered gene expression. In the past decades, several promising data from ongoing clinical trials have been reported. However, despite surprising successes in many pre-clinical studies, concrete obstacles still need to be overcome to translate therapeutic siRNAs into clinical reality. Here, we provide an update on the recent advances of RNAi-based therapeutics and highlight novel synthetic platforms for the intracellular delivery of siRNAs.

Recent advances in dendrimer-based nanovectors for tumor-targeted drug and gene delivery

Advances in the application of nanotechnology in medicine have given rise to multifunctional smart nanocarriers that can be engineered with tunable physicochemical characteristics to deliver one or more therapeutic agent(s) safely and selectively to cancer cells, including intracellular organelle-specific targeting. Dendrimers having properties resembling biomolecules, with well-defined 3D nanopolymeric architectures, are emerging as a highly attractive class of drug and gene delivery vector. The presence of numerous peripheral functional groups on hyperbranched dendrimers affords efficient conjugation of targeting ligands and biomarkers that can recognize and bind to receptors overexpressed on cancer cells for tumor-cell-specific delivery. The present review compiles the recent advances in dendrimer-mediated drug and gene delivery to tumors by passive and active targeting principles with illustrative examples.