3 research outputs found
DNA Vaccines—How Far From Clinical Use?
Two decades ago successful transfection of antigen presenting cells (APC) in vivo was demonstrated which resulted in the induction of primary adaptive immune responses. Due to the good biocompatibility of plasmid DNA, their cost-efficient production and long shelf life, many researchers aimed to develop DNA vaccine-based immunotherapeutic strategies for treatment of infections and cancer, but also autoimmune diseases and allergies. This review aims to summarize our current knowledge on the course of action of DNA vaccines, and which factors are responsible for the poor immunogenicity in human so far. Important optimization steps that improve DNA transfection efficiency comprise the introduction of DNA-complexing nano-carriers aimed to prevent extracellular DNA degradation, enabling APC targeting, and enhanced endo/lysosomal escape of DNA. Attachment of virus-derived nuclear localization sequences facilitates nuclear entry of DNA. Improvements in DNA vaccine design include the use of APC-specific promotors for transcriptional targeting, the arrangement of multiple antigen sequences, the co-delivery of molecular adjuvants to prevent tolerance induction, and strategies to circumvent potential inhibitory effects of the vector backbone. Successful clinical use of DNA vaccines may require combined employment of all of these parameters, and combination treatment with additional drugs
Surface Modification of Polysaccharide-Based Nanoparticles with PEG and Dextran and the Effects on Immune Cell Binding and Stimulatory Characteristics
Surface
modifications of nanoparticles can alter their physical
and biological properties significantly. They effect particle aggregation,
circulation times, and cellular uptake. This is particularly critical
for the interaction with primary immune cells due to their important
role in particle processing. We can show that the introduction of
a hydrophilic PEG layer on the surface of the polysaccharide-based
nanoparticles prevents unwanted aggregation under physiological conditions
and decreases unspecific cell uptake in different primary immune cell
types. The opposite effect can be observed with a parallel-performed
introduction of a layer of low molecular weight dextran (3.5 and 5
kDa) on the particle surface (DEXylation) that encourages the nanoparticle
uptake by antigen-presenting cells like macrophages and dendritic
cells. Binding of DEXylated particles to these immune cells results
in an upregulation of surface maturation markers and elevated production
of proinflammatory cytokines, reflecting cell activation. Hence, DEXylated
particles can potentially be used for passive targeting of antigen
presenting cells with inherent adjuvant function for future immunotherapeutic
applications
Cationic Copolymerization of 3,3-Bis(hydroxymethyl)oxetane and Glycidol: Biocompatible Hyperbranched Polyether Polyols with High Content of Primary Hydroxyl Groups
The cationic ring-opening copolymerization
of 3,3-bisÂ(hydroxymethyl)Âoxetane
(BHMO) with glycidol using different comonomer ratios (BHMO content
from 25 to 90%) and BF<sub>3</sub>OEt<sub>2</sub> as an initiator
has been studied. Apparent molecular weights of the resulting hyperbranched
polyether copolymers ranged from 1400 to 3300 g mol<sup>–1</sup> (PDI: 1.21–1.48; method: SEC, linear PEG standards). Incorporation
of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All
hyperbranched polyether polyols with high content of primary hydroxyl
groups portray good solubility in water, which correlates with an
increasing content of glycerol units. Detailed NMR characterization
was employed to elucidate the copolymer microstructures. Kinetic studies
via FTIR demonstrated a weak gradient-type character of the copolymers.
MTT assays of the copolymers (up to 100 μg mL<sup>–1</sup>) on HEK and fibroblast cell lines (3T3, L929, WEHI) as well as viability
tests on the fibroblast cells were carried out to assess the biocompatibility
of the materials, confirming excellent biocompatibility. Transfection
efficiency characterization by flow cytometry and confocal laser microscopy
demonstrated cellular uptake of the copolymers. Antiadhesive properties
of the materials on surfaces were assessed by adhesion assays with
fibroblast cells