Letter pubs.acs.org/NanoLett
A Peptide-Based Nanofibrous Hydrogel as a Promising DNA Nanovector for Optimizing the Efficacy of HIV Vaccine Yue Tian,†,‡ Huaimin Wang,§ Ye Liu,∥ Lina Mao,§ Wenwen Chen,†,‡ Zhening Zhu,†,‡ Wenwen Liu,†,‡ Wenfu Zheng,† Yuyun Zhao,† Deling Kong,§ Zhimou Yang,*,§ Wei Zhang,† Yiming Shao,*,∥ and Xingyu Jiang*,† †
Beijing Engineering Research Center for BioNanotechnology and CAS Key Lab for Biological Effects of Nanomaterials and Nanosafety, National Center for NanoScience and Technology, No., 11 Zhongguancun Beiyitiao, Beijing 100190, China ‡ University of Chinese Academy of Sciences, Beijing 100049, China § State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, and College of Life Sciences, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin 300071, China ∥ State Key Laboratory for Infectious Disease Prevention and Control, National Center for AIDS/STD Control and Prevention, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Chinese Center for Disease Control and Prevention, 155 Changbai Road, Changping District, Beijing 102206, China S Supporting Information *
ABSTRACT: This report shows that a nanovector composed of peptide-based nanofibrous hydrogel can condense DNA to result in strong immune responses against HIV. This nanovector can strongly activate both humoral and cellular immune responses to a balanced level rarely reported in previous studies, which is crucial for HIV prevention and therapy. In addition, this nanovector shows good biosafety in vitro and in vivo. Detailed characterizations show that the nanofibrous structure of the hydrogel is critical for the dramatically improved immune responses compared to existing materials. This peptide-based nanofibrous hydrogel shows great potential for efficacious HIV DNA vaccines and can be potentially used for delivering other vaccines and drugs. KEYWORDS: Peptide-based nanofibrous hydrogel, HIV DNA vaccine, DNA condensation, immune response, safety evaluation
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activity of DNA during complex preparation.13,14 Therefore, it is still challenging to prepare a proper delivery system that is both safe and effective for broad application. Nanofibers provide an ideal platform to interact with biomolecules or modify their biological functions. They can guide the growth of neurons, improve the limit of detection in disease diagnosis, and elongate DNA through contacts at nanoscale.15−17 The structure of nanofibers can also modulate immune responses of human immune cells and deliver cargos to cells,18,19 indicating a great potential in promoting immune responses of DNA vaccine. Another platform suited for DNA delivery is based on hydrogel because of its high loading capacity, mild working conditions, and good biocompatibility.20,21 Supramolecular hydrogel is a kind of hydrogel composed of nanofibers formed by the self-assembly of small molecules (molecular weight usually 0.05). The antibody titers rose quickly after just two G-NMe/antigen injections, with a significantly (p = 0.0003) improved titer (14fold increase) compared with those induced by naked DNA alone. After the third immunization, antibody titers induced by G-NMe/antigen were from 1:51200−1:204800, significantly higher than that in naked DNA group (p < 0.05). The antibody titers of mice injected with G-NMe/antigen by i.d. and s.c. injections showed a similar trend to i.m. immunizations. These data demonstrated that DNA vaccine administered with GNMe nanovector elicited high antibody titers in all three immunization regimes. High levels of specific antibodies can efficiently inhibit both HIV-1 infection and HIV envelope protein-mediated cell fusion of infected cells and uninfected 1442
dx.doi.org/10.1021/nl404560v | Nano Lett. 2014, 14, 1439−1445
Nano Letters
Letter
Figure 3. Characterization of peptide-based nanofibrous hydrogels formulated with DNA. (a) CD spectrum of DNA with different concentration of supramolecular hydrogel. 1, 0.05 wt %; 2, 0.1 wt %; 3, 0.2 wt %. (b) TEM images of the nanovector/DNA complexes. The arrows show status of DNA after complexation with each gel. Scale bar: 100 nm. (c) Fluorescence images of 293T cells transfected by nanovector/EGFP plasmid. Concentration of precursor in each gel is 0.2 wt %. DNA with PEI and DNA alone were used as positive control and negative control, respectively. Scale bar: 100 μm.
S5a).67 Once combined with G-NMe nanovector, the positive peak of DNA CD signature at 280 nm decreased and the magnitude of the negative CD band further increased. PEI, which condensed DNA efficiently by positive charges, showed a similar CD spectrum change of DNA. Such patterns typically indicate a conversion of the randomly coiled DNA into a condensed form.69 In comparison, DNA composited with GOH or G-OMe showed less conformational change, suggesting that no condensation took place. The different modes of condensation with DNA were also proved by TEM characterization. The DNA was condensed into spheres by G-NMe with diameters ∼30 nm, which was similar to the morphology of condensed DNA in PEI solution, while DNA in G-OMe or GOH exhibit random coil-like structures (Figure 3b and Figure S5b).70,71 These results demonstrated that the left-handed structure of G-NMe can efficiently condense DNA, protect them from degradation, and enhance the efficiency of transfection into cells. To further prove our hypothesis that condensed DNA can easily enter cells and induce protein expression, we evaluated the transfection efficiency of these gels in vitro by using a plasmid for enhanced green fluorescent protein (pEGFP) as a reporter. GFP expression level is higher in G-NMe group than that in G-OH and G-OMe treatment (Figure 3c). The maximal transfection efficiency of G-NMe is 30.38%−36.60%, while the transfection efficiency of G-OH and G-OMe (
