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Developing and evaluating release systems for VHH nanobodies based on hydrogel systems

Hiemstra, J. (2021) Developing and evaluating release systems for VHH nanobodies based on hydrogel systems.

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Abstract:Osteoarthritis (OA) is a chronic joint disease affecting nearly 1.5 million people in the Netherlands only. Currently, there are only treatments available that treat the symptoms of OA and not the disease itself. Variable domain of the heavy chain only antibodies (VHHs) can potentially play a role in the treatment of OA. Due to the low retention time of these VHHs in the body, it is beneficial to use an injectable hydrogel as release system for these VHHs. In this research the effect of electrostatic interactions between the VHHs and the polymers on the release profiles of three types of VHHs from multiple hydrogels was evaluated. The release profiles were obtained by measuring the fluorescence intensity of released VHHs that were labelled with a FITC-NHS dye over a time frame of 10 days. The fluorescence intensity of the hydrogels themselves was also determined over a time frame of 10 days. The release profiles of Dextran-Tyramine (Dex-TA) based hydrogels with Gelatin-Tyramine (positively charged) or Heparin-Tyramine (negatively charged) added to them clearly showed the influence of electrostatic interactions between the polymer backbone and the incorporated VHHs. Hyaluronic Acid-Tyramine (HA-TA) and Chondroitin Sulfate-Tyramine (CS-TA) hydrogels did not show a clear influence of electrostatic interactions on the VHH release. Furthermore, the presence of VHHs in collected PBS samples and the binding specificity of the VHHs after release from the hydrogels were assessed with an ELISA assay. The results of the ELISA assay to determine the presence of VHHs in the collected PBS samples showed clear similarities with the fluorescence intensity measurements of the Dex-TA based hydrogels. These similarities were not visible in the measurements of the HA-TA and CS-TA hydrogels. For all types of hydrogel VHH presence in the collected PBS samples was confirmed. Regarding the binding specificity of the VHHs after release, it can be concluded that there was an almost complete loss of binding affinity to the VHH targets. However, further research is necessary to confirm or refute these findings. Finally, the interactions between cartilage tissue and the VHHs were studied by monitoring these interactions over time in two experiments. These experiments showed that the VHHs interacted with the cartilage tissue, but the exact mechanism of this interaction could not be determined. In conclusion, Dex-TA based hydrogels show great potential as release systems for VHH nanobodies, since it seems that the VHH release from this type of hydrogel can easily be tuned by varying the polymer charge.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Programme:Biomedical Technology BSc (56226)
Link to this item:http://purl.utwente.nl/essays/87767
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