Development of a PLGA-based nanoparticle drug delivery system for the targeting of macrophages

Macrophages are involved in many biological processes and are therefore, unfortunetaly, involved in several conditions. That’s why they may serve as therapeutic targets during infection, cancer or inflammatory diseases, but can also be addressed for antigen presentation. Due to their phagocytic nature, macrophages are attractive candidates for particle-based drug delivery systems. Nanoparticles gained a lot of interest lately as drug delivery platforms because of their unique properties. This thesis focused on the evaluation of modified poly (lactic-co-glycolic acid) (PLGA) nanoparticles and their potential to target macrophages, as an alternative for free drugs enhancing the cellular uptake and reducing the toxicity. Main points of interest were production process parameters and their influence on nanoparticle size, zeta potential and encapsulation efficiency. Equally important was the effect of these nanoparticle properties on in vitro nanoparticle uptake, cytotoxicity, and intracellular fate in macrophages. Studies have shown benefits from chitosan coatings to target macrophages, however, cytotoxicity was considered an inconvenience. PLGA nanoparticles were altered with chitosan (glutamate) and the parameters incubation time, size class, PLGA derivative, and chitosan derivative were assessed for uptake kinetics and cell viability. It was found that chitosan coatings were the major determining factor for enhancing nanoparticle uptake, combined with the acid-terminated PLGA derivative and small size. Cytotoxicity was more favourable for small, chitosan glutamate-coated, acid-terminated PLGA nanoparticles compared to its larger-sized, uncoated and chitosan coated counterparts. Formulations based on ester-terminated PLGA nanoparticles showed the least toxic properties. Furthermore, different sized nanoparticles consisting of ((polyethylene glycol) (PEG)) PLGA, loaded with fluorescein (dye) or auranofin (anti-rheumatic drug), were evaluated for nanoparticle uptake and intracellular fate; or cell viability in sialoadhesin-expressing macrophages, while being functionalized with anti-sialoadhesin antibody. The receptor sialoadhesin is expressed on certain populations of tissue macrophages, yet can be upregulated in inflammatory conditions. Small dye-loaded antibody-functionalized PEG PLGA nanoparticles showed the highest cellular uptake after 24 hours. No co-localization between small-sized (PEG) PLGA nanoparticles and (early/late) endosomes nor lysosomes could be observed. The functionalized auranofin-loaded PLGA nanocarriers showed a higher impact on cell viability in reference to the control groups in low dose, but often not in a higher dose. Surprisingly, auranofin-loaded PEG PLGA nanoparticles were found to be less effective. To conclude, chitosan- and antibody-modified PLGA nanoparticles are promising tools for the targeting of macrophages. However, the production method, characteristics and surface properties need to be optimized according to the compound and purpose of the formulation.

Publication year:2022

Keywords:Doctoral thesis

Accessibility:Closed