Gelatin Nanoparticles as Delivery System for Nucleotide-Based Drugs

The present thesis deals with the development of nanoparticles
based on the proteinaceous macromolecule gelatin as delivery system
for various nucleotide-based drugs. Since a method to produce
homogenous nanoparticles was already described in principle
(Coester et al. 2000), it was the first approach to characterize,
optimize, and standardize this manufacturing process. The next goal
was to advance these plain gelatin nanoparticles via modification
of the surface towards a delivery system for nucleotide-based
drugs. Subsequent to this, the newly established carrier system
should be evaluated in preclinical trials. In addition to these
main projects, it was also an aim of this study to investigate and
influence the biodistribution of gelatin nanoparticles. Due to the
multitude of independent projects, the present work is divided into
five self-contained chapters. In Chapter I, fundamental research
data concerning the preparation of gelatin nanoparticles is
described. Thereby, the work was focused on process optimization of
the existing preparation procedure. Moreover, new analytical tools
to characterize gelatin and the gelatin nanoparticles are
introduced. Chapter II features the data that were produced in
cooperation with the Department of Pharmaceutical Biotechnology at
Ludwig-Maximilians-University Munich. In this cooperation, plasmid
DNA was bound onto the surface of previously modified gelatin
nanoparticles by electrostatic interactions. Subsequent preparation
optimization, this simple non-viral gene delivery system was
investigated in vitro on murine melanoma cells. The major project
of this work, the development and evaluation of gelatin
nanoparticles as carrier system for immunogenic so called CpG
oligonucleotides is presented in Chapter III and Chapter IV. The
data has been generated in cooperation with the Department of
Internal Medicine at the Ludwig-Maximilians-University Munich and
initially during a 3-month research stay at the Faculty of Pharmacy
at the University of Alberta in Edmonton, Canada. Chapter III
features extensive in vitro investigations on the respective
primary murine and human target cells such as dendritic cells and B
cells, whereas in Chapter IV, the results of in vivo experiments
are presented. Here, the immunogenic effects of CpG
oligonucleotide-loaded nanoparticles alone and their adjuvant
activity in combination with the model protein antigen ovalbumin
(OVA) were explored. In the final chapter, Chapter V, first
PEGylation experiments of gelatin nanoparticles are described, with
special emphasis on the establishment of new analytical tools for
the quality control of the PEGylation process. In the second part
of this chapter, radiolabeling strategies were developed in
cooperation with the Department of Nuclear Medicine (TU Munich) to
enable real-time in vivo tracking of the gelatin nanoparticles via
positron emission tomography (PET).