The plasma/extracellular fluid exchange between the vessels and the underlying tissues depends on the vessel itself and actual requirements of the given organ. This balance called permeability, is fine-tuned by proper function of the innermost cellular layer of the vessels, the endothelial cells. Therefore, it is not surprising that several factors are recognized, which are able to activate or damage endothelial cells leading to an increased permeability and its serious consequence: edematous pathological conditions. The measurement of permeability, however, is currently not simple but quite expensive, and only low-throughput methods are available.

We have previously shown that the function of endothelial cells can be measured by a label-free optical biosensor (EPIC), which is able to detect the cellular reactions in a real-time, high-throughput manner. The signal generated in this system is, however, not specific, it is the sum of several cellular events. Therefore, we aimed to modify this method by utilizing gold nanoparticles (AuNPs), having strong signal in EPIC system, to make the signal specific for permeability.

To measure permeability by AuNPs in EPIC system, it is necessary that AuNPs do not interact with cells, the generated signal should only be proportional to the ability of the AuNPs to reach the sensor-surface area, the evanescence space, where cellular gaps are formed. Thus, our first step is to modify the surface chemistry of the AuNPs to form a cell-repellent, inert layer on the surface of the particles. Simultaneously, we determine the optimal size-range of the AuNPs that can be optimal in EPIC system in the presence of endothelial cells. When the set-up of the system is successfully conducted, we are going to validate it by using classical, well-known permeability methods.

Measuring permeability by AuNPs in an in vitro real-time, label-free, high-throughput system based on optical biosensor may well lead to routine testing of drugs and research reagents on endothelial cells as therapeutic “bystander” cells.

László Cervenak - István László Lagzi - Róbert Horváth

Report I. - 2018. April