Versatile delivery platform for nucleic acids, negatively charged protein drugs, and genome-editing ribonucleoproteins using a multi-step transformable polyrotaxane.

Various biopharmaceuticals, such as nucleic acids, proteins, and genome-editing molecules, have been developed. Generally, carriers are prepared for each biopharmaceutical to deliver it intracellularly; thus, the applications of individual carriers are limited. Moreover, the development of carriers is laborious and expensive. Therefore, in the present study, versatile and universal delivery carriers were developed for various biopharmaceuticals using aminated polyrotaxane libraries. Step-by-step and logical screening revealed that aminated polyrotaxane, including the carbamate bond between the axile molecule and endcap, is suitable as a backbone polymer. Movable and flexible properties of the amino groups modified on polyrotaxane facilitated efficient complexation with various biopharmaceuticals, such as small interfering RNA, antisense oligonucleotides, messenger RNA, ß-galactosidase, and genome-editing ribonucleoproteins. Diethylenetriamine and cystamine modifications of polyrotaxane provided endosomal-escape abilities and drug-release properties in the cytosol, allowing higher delivery efficacies than commercially available high-standard carriers without cytotoxicity. Thus, the resulting polyrotaxane might serve as a versatile and universal delivery platform for various biopharmaceuticals.

Polyrotaxane-Based Supramolecular Material for Improvement of Pharmaceutical Properties of Protein Drugs.

Pharmaceutical excipients, such as surfactants, amino acids, and polymers, have often been used to improve the physicochemical properties of protein drugs. However, the effects of these additives are limited because of factors such as their weak interactions with protein drugs. In the present study, we evaluated the application of a supramolecular polymer, aminated polyrotaxane (NH2-PRX), which can strongly interact with protein drugs via its dynamic and transformable properties, as a new pharmaceutical excipient for these agents. As a conventional control polymer with low mobility and average complexation ability, aminated dextran (NH2-DEX) was also prepared. NH2-PRX significantly reduced the aggregation of antibodies induced by shaking, compared with NH2-DEX. The adsorption of insulin onto glass and polypropylene containers was also reduced by the addition of NH2-PRX. In addition, the in vivo bioactivity of insulin was completely retained in the presence of NH2-PRX. Moreover, severe adverse effects were not observed following the administration of NH2-PRX. These findings indicate the potential use of NH2-PRX as a transformable pharmaceutical excipient for protein drugs.

Supramolecular polymer-based transformable material for reversible PEGylation of protein drugs.

We herein developed a transformable mixing-type material for reversible PEGylation of protein drugs using a supramolecular backbone polymer, that is, polyrotaxane possessing both amino groups and PEG chains (PEG-NH2-PRX). We expected that PEG-NH2-PRX provides amino groups to interact with protein drugs on demand because the mobility of amino groups in PEG-NH2-PRX was high. In fact, PEG-NH2-PRX formed complexes with protein drugs efficiently compared to PEGylated amino-dextran (PEG-NH2-DEX), a control material fabricated with a macromolecular backbone polymer. Moreover, PEG-NH2-PRX markedly improved the stability of antibodies and prolonged the hypoglycemic effects of insulin without loss of bioactivity, compared to PEG-NH2-DEX. These findings suggest that the supramolecular material, PEG-NH2-PRX, is a promising reversible PEGylation material for protein drugs compared to macromolecular materials.

Efficient Anticancer Drug Delivery for Pancreatic Cancer Treatment Utilizing Supramolecular Polyethylene-Glycosylated Bromelain.

Pancreatic cancer is one of the most difficult cancers to treat largely because of the inability of anticancer drugs to penetrate into the cancer tissue as the result of the dense extracellular matrix (ECM). On the other hand, bromelain is known to degrade the ECM in cancerous tissue. However, the half-life of bromelain in blood is short, leading to its low accumulation in tissues. Recently, we developed a reversible poly(ethylene glycol) (PEG) modification technology that is able to improve blood retention of proteins without loss of activity and termed it "Self-assembly PEGylation Retaining Activity (SPRA)" technology. Here, we prepared reversible PEGylated bromelain using SPRA technology (SPRA-bromelain) possessing high activity, long blood retention, and high tumor accumulation and evaluated its potential as a drug delivery system for pancreatic cancer. SPRA-bromelain was prepared by mixing adamantane-modified bromelain and multisubstituted-PEGylated ß-cyclodextrins (ß-CyDs) containing 2 or 20 kDa PEG chains in water. SPRA-bromelain was formed by a host-guest interaction between adamantane and ß-CyD (Kc > 104 M-1). SPRA-bromelain showed high in vitro gelatin-degrading activity and enhanced not only the accumulation of fluorescein isothiocyanate (FITC)-dextran (2 MDa) in the tumor but also the in vivo antitumor activities of doxorubicin and doxorubicin encapsulated in PEGylated liposomes (DOXIL) after intravenous administration in tumor-bearing mice. These findings suggest that SPRA-bromelain could be a powerful tool for drug delivery in pancreatic cancer.