Injectable, self-gelling, biodegradable, and immunomodulatory DNA hydrogel for antigen delivery

Abstract

DNA nanotechnology-based nanosystems and macrosystems have attracted much attention in the biomedical research field. The nature of DNA endows these systems with biodegradable, biocompatible, and immunomodulatory properties. Here, we present an injectable hydrogel system that consists only of chemically synthesized short DNA strands, water, and salts. Several preparations of polypod-like structured DNA, or polypodna, were designed, including tri-, tetra-, penta- and hexapodna, as the building blocks of self-gelling DNA hydrogel. Under physiological conditions, properly designed polypodna preparations formed a hydrogel. The analysis of the modulus data of the hydrogel consisting of two sets of hexapodna preparations showed that this injectable hydrogel was reorganized at a time scale of 0.25s. Then, DNA hydrogel containing unmethylated cytosine-phosphate-guanine (CpG) dinucleotides was used to stimulate innate immunity through Toll-like receptor 9, the receptor for CpG DNA. Gel formation significantly increased the activity of immunostimulatory CpG DNA, retarded the clearance after intradermal injection into mice, and increased the immune responses to ovalbumin (OVA) incorporated into the hydrogel as a model antigen. OVA/CpG DNA hydrogel induced much less local or systemic adverse reactions than OVA injected with complete Freund's adjuvant or alum. GpC DNA hydrogel containing no CpG sequences was less effective, indicating the importance of immunomodulation by CpG DNA hydrogel. Thus, we have created an efficient system for sustained delivery of antigens or other bioactive compounds.

Induction of Potent Antitumor Immunity by Sustained Release of Cationic Antigen from a DNA‐Based Hydrogel with Adjuvant Activity

“…[ 21 ] GpC DNA hydrogel was prepared by replacing CpG sequences in the ODNs of the CpG DNA hydrogel with GpC sequences, and was used as a control. Complex formation of OVA or ED-OVAs with DNA was examined by PAGE.…”

“…[ 21 ] However, OVA was released from the hydrogel with a half-life of about 2.5 h, and this rapid release reduced the potency of the injectable CpG DNA hydrogel as a controlled antigen delivery system with adjuvant activity.…”

CpG oligodeoxynucleotide nanomedicines for the prophylaxis or treatment of cancers, infectious diseases, and allergies

“…Furthermore, it has also been reported that increasing the concentration of these polypod-like CpG ODNs, increasing the salt concentration in the solvent, or forcing the polypodlike CpG ODNs to self-associate with other DNA results in the formation of a hydrogel by the CpG ODNs. 80 In the self-association process where the polypod-like CpG ODNs are forced to undergo self-association with other DNA, it is possible to incorporate antigens into the self-gelling DNA. Ishii-Mizuno et al 81 prepared a CpG ODN hydrogel, containing the Japanese cedar pollen allergen Cryj1, through self-gelling of two types of hexapod-like CpG ODNs with a 5′-end complementary sequence.…”

“…Moreover, in mice injected with a CpG ODN hydrogel loaded with the model antigen ovalbumin (OVA), the OVA-specific CTL was activated. 80 Thus, the CpG ODN hydrogel could be applied to the treatment of infectious diseases and to cancer immunotherapy.…”

Double-stranded phosphodiester cytosine-guanine oligodeoxynucleotide complexed with calcium phosphate as a potent vaccine adjuvant for activating cellular and Th1-type humoral immunities

“…55 For the crystal structure of CaP prepared for ds CpG-B72-PD complexation, we detected a band attributed to the CO 3 2− group at 862 cm −1 in the FTIR spectrum. The band for the CO 3 2− group of hydroxyapatite generally appears around 1,400-1,600 cm −1 ( Figure S9), but we did not observe this band in our CaP.…”