%X Core-shell Nanoparticles offer a highly flexible platform technology for the design of biocompatible, nanoparticulate therapeutics. These core-shell Nanoparticles were decorated with losartan carboxylic acid (EXP3174), that is an antagonist for angiotensin II type 1 receptors (AT1R). It was the superior goal to develop a therapeutical system to inhibit ocular neovascularization during progressive age-related macular degeneration (AMD) or diabetic retinopathy (DR).
Viruses use spike proteins on their surface to target host cells. This architecture was used as a blueprint for the nanoparticle design. EXP3174 molecules were linked to longer polymer chains to raise the ligands out of the nanoparticle shell. Polyethylene glycol (PEG)- polylactide (PLA) block-co-polymers were synthesized with tailored properties. Various functional end groups offered the opportunities to introduce charges and different reactivities. EXP3174 was covalently linked to amino-PEG-PLA block-co-polymers. The synthetized PEG-PLA block-co-polymers as well as a purchased poly(lactic-co-glycolic acid) (PLGA) were utilized to manufacture core-shell nanoparticles via nanoprecipitation. PLGA was linked to fluorescent dyes or ultra-small gold particles, so that the manufactured nanoparticles were traceable via various analytical methods (e.g. flow cytometry, confocal laser scanning microscopy and inductively coupled plasma mass spectrometry). Moreover, the core-shell nanoparticles were successfully tagged with radioactive indium ions. This means that core-shell nanoparticles are traceable via a multitude of analysis techniques and can be applied therapeutically as an untagged preparation.
The designed nanoparticles were extensively characterized. It is worth to mention the established formula for the calculation of the particle number concentration. The formula was based on the total polymer content and the hydrodynamic diameter. This calculation strategy was an essential milestone, since it facilitated the comparison of results obtained from differently sized nanoparticles. Furthermore, it was the basis for numerous binding studies at an AT1R-carrying cell line. Different methods evidenced a sub nanomolar avidity. Consequently, EXP3174-decorated core-shell nanoparticles outperformed their naïve ligand EXP3174 itself. The explanation could be found in the multivalent binding behavior. It was determined that only a single-digit number of ligands bound to the target cells. This is in accordance with the number of spikes per virus.  
Eventually the EXP3174-decorated core-shell nanoparticles were tested at healthy laboratory animals. With the help of computed tomography assisted single-photon emission computed tomography (SPECT-CT) the biodistribution of radioactively tagged core-shell nanoparticles was followed in real time. The results unveiled a renal elimination pathway and a very short half-life. An accumulation in the ocular vasculature could not be substantiated. Hence further development is needed for this field of application.
Beyond that it was focused on the long-term stability of core-shell nanoparticles. Since they were composed of biodegradable polymers, core-shell nanoparticles degrade in an aqueous dispersion. Consequently, the dispersions must be freshly prepared prior every experiment. This aspect indicated the need for the development of an anhydrous formulation. It was possible to remove the dispersing agent water quantitatively via freeze drying into a stable lyophilizate. It is worth to mention that the core-shell nanoparticles retained their full avidity after redispersion. It was necessary to just add sucrose as the only excipient (cryo- and lyoprotector).
Finally, the block-co-polymers allowed to tailor the properties of the needed core-shell nanoparticles precisely. It is possible to decorate the nanoparticles with different ligand densities or to create hetero multivalent nanoparticles as well. Especially the different labelling techniques must be highlighted. They gave access to a multitude of analysis techniques without changing the nanoparticle properties substantially. All in all, a highly promising nanoparticulate platform technology with the potential to become a therapeutical application was developed.
%A Sebastian Beck
%L epub52740
%K Core-Shell; Nanoparticle; Diabetic Retinopathy; Macula Degeneration; Block-Co-Polymer; Ligand; Losartan Carboxylic Acid; EXP3174; Targeting; Avidity; Freeze-Drying; Polyethylenglycol; PEG-PLA; PLGA;
%D 2024
%T Core-Shell Nanoparticles as a Platform Technology for the Treatment of Proliferative Ocular Diseases