Targeted siRNA delivery to tumor cells by folate-PEG-appended dendrimer/glucuronylglucosyl-β-cyclodextrin conjugate

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.

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.

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.

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.