Local release of siRNA using polyplex-loaded thermosensitive hydrogels

Nanoscale, vol. 12, pp. 10347–10360

Abstract

One of the challenges for the clinical translation of RNA interference (RNAi)-based therapies concerns the deposition of therapeutically effective doses of the nucleic acids, like siRNA, at a local tissue level without severe off-target effects. To address this issue, hydrogels can be used as matrices for the local and sustained release of the siRNA cargo. In this study, the formation of polyplexes based on siRNA and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA)-based polymers was investigated, followed by their loading in a thermosensitive hydrogel to promote local siRNA release. A multifunctional NPD triblock copolymer consisting of a thermosensitive poly(N-isopropylacrylamide) (PNIPAM, N), a hydrophilic poly(ethylene glycol) (PEG, P), and a cationic PDMAEMA (D) block was used to study the binding properties with siRNA taking the non-thermosensitive PD polymer as control. For both polymers, small polyplexes with sizes ranging from 10-20 nm were formed in aqueous solution (HBS buffer, 20 mM HEPES, 150 mM NaCl, pH 7.4) when prepared at a N/P charge ratio of 5 or higher. Formulating the siRNA into NPD or PD polyplexes before loading into the thermosensitive PNIPAM-PEG-PNIPAM hydrogel resulted in a more controlled and sustained release compared to free siRNA release from the hydrogel. The polyplexes were released for 128 hours in HBS, when changing the release medium twice a day, while free siRNA was completely released within 50 hours with already 40% being released after changing the release medium just once. The release of the polyplexes was dependent on the dissolution rate of the hydrogel matrix. Moreover, intact polyplexes were released from the hydrogels with a similar size as before loading, suggesting that the hydrogel material did not compromise the polyplex stability. Finally, it was shown that the released polyplexes were still biologically active and transfected FaDu cells, which was observed by siRNA-induced luciferase silencing in vitro. This study shows the development of an injectable thermosensitive hydrogel to promote local and sustained release of siRNA, which can potentially be used to deliver siRNA for various applications, such as the treatment of tumors.

Authors 9

1. Lies A. L. Fliervoet

   Utrecht University

   Affiliation as printed

   3508 TB Utrecht

   Department of Pharmaceutics

   Faculty of Science

   Utrecht Institute for Pharmaceutical Sciences (UIPS)

   Utrecht University

   Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, the Netherlands

2. Heyang Zhang

   Ghent University

   Affiliation as printed

   Belgium

   Faculty of Pharmaceutical Sciences

   Ghent 9000

   Ghent University

   Laboratory of General Biochemistry and Physical Pharmacy

   Laboratory of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ghent 9000, Belgium

3. Emma van Groesen Aachen Institute of Biology Leiden Biological Chemistry Group Sylvius Laboratories

   Leiden University

   Affiliation as printed

   2333 BE Leiden

   Biological Chemistry Group

   Institute of Biology Leiden

   Leiden University

   Sylvius Laboratories

   Biological Chemistry Group, Institute of Biology Leiden, Leiden University, Sylvius Laboratories, 2333 BE Leiden, the Netherlands

4. Kyra Fortuin

   Utrecht University

   Affiliation as printed

   3508 TB Utrecht

   Department of Pharmaceutics

   Faculty of Science

   Utrecht Institute for Pharmaceutical Sciences (UIPS)

   Utrecht University

   Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, the Netherlands

5. Naut J. C. B. Duin

   Utrecht University

   Affiliation as printed

   3508 TB Utrecht

   Department of Pharmaceutics

   Faculty of Science

   Utrecht Institute for Pharmaceutical Sciences (UIPS)

   Utrecht University

   Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, the Netherlands

6. Katrien Remaut

   Ghent University

   Affiliation as printed

   Belgium

   Faculty of Pharmaceutical Sciences

   Ghent 9000

   Ghent University

   Laboratory of General Biochemistry and Physical Pharmacy

   Laboratory of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ghent 9000, Belgium

7. Raymond Michel Schiffelers

   University Medical Center Utrecht

   Affiliation as printed

   3508 GA Utrecht

   Department of Clinical Chemistry and Haematology

   University Medical Center Utrecht

   the Netherlands

   Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht, the Netherlands

8. Wim E. Hennink

   Utrecht University

   Affiliation as printed

   3508 TB Utrecht

   Department of Pharmaceutics

   Faculty of Science

   Utrecht Institute for Pharmaceutical Sciences (UIPS)

   Utrecht University

   Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, the Netherlands

9. Tina Vermonden corresponding

   Utrecht University

   Affiliation as printed

   3508 TB Utrecht

   Department of Pharmaceutics

   Faculty of Science

   Utrecht Institute for Pharmaceutical Sciences (UIPS)

   Utrecht University

   Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, the Netherlands