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Deli Mária
Modulation of brain endothelial surface charge changes the transfer of charged molecules and targeted nanoparticles

Aug 30 - szerda

14:54 – 15:12

Sejtanalitika biofizikai megközelítéssel

E35

Modulation of brain endothelial surface charge changes the transfer of charged molecules and targeted nanoparticles

Mária Mészáros¹, Szilvia Veszelka^1,2, Fruzsina R Walter^1,2, András Kincses¹, Sándor Valkai¹, András Dér¹, Mária A Deli¹

¹ Institute of Biophysics, Biological Research Centre, Szeged

The highly negative surface charge of brain endothelial cells is part of the blood-brain barrier (BBB)defense systems. It is derived from charged membrane lipids and the endothelial surface glycocalyx. We showed that physiological factors inducing BBB properties (co-culture, fluid flow, targeting signaling pathways) increase the surface glycocalyx thickness and makes the zeta potential of the cells more negative measured by laser-Doppler velocimetry (LDv).

Zeta potential by LDv can only be measured on cells in suspension, so we designed and fabricated a novel lab-on-a-chip (LOC) device to monitor streaming potential parallel to the surface of confluent cell layers. Streaming potential measured on brain endothelial cell monolayers in the LOC device were recorded and verified by comparing to zeta potential results measured by LDv and model simulations. Changes in the negative surface charge of the BBB model by neuraminidase (cleaving negatively charged sialic acid residues from the glycocalyx) or lidocaine (interacts with lipid membranes) could be measured by both the LOC device and LDv.

Lidocaine, a cationic and lipophilic anesthetic and antiarrhythmic drug turned more positive the negative zeta potential of brain endothelial cells. It also decreased the flux of a cationic lipophilic molecule (rhodamine 123) across the BBB model without changing the penetration of hydrophilic neutral or negatively charged markers. Neuraminidase and the cationic lipid TMA-DPH, which elevated the surface charge, increased the uptake of vesicular nanoparticles targeted by alanine and glutathione in brain endothelial cells.

In conclusion, the negative surface charge of brain endothelial cells is a fundamental BBB property. It is important in the transfer of charged molecules and the uptake mechanism of charged nanoparticles and can be modulated by modification of plasma membrane lipid composition or the glycocalyx.

Kincses András
Lab-on-a-chip device for the monitoring of surface charge properties of confluent cell monolayers

Aug 30 - szerda

11:30 – 11:45

Bioszenzorika és bio-nanotechnológia

E28

Lab-on-a-chip device for the monitoring of surface charge properties of confluent cell monolayers

András Kincses¹, Ana R. Santa-Maria^1,#, Fruzsina R. Walter^1,2, László Dér¹, Judit Vígh¹, Sándor Valkai¹, Mária A. Deli¹, András Dér¹

¹ Institute of Biophysics, Biological Research Centre, Szeged, Hungary

^2. Department of Cell Biology and Molecular Medicine, University of Szeged, Hungary

^# Current affiliation: Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA 02115, USA

Lab-on-a-chip devices emerged to play pivotal role in the in vitro modelling of biological barriers. The microfluidic channels combined with integrated electrodes provide controlled environment for the tightly interconnecting cell monolayers of intestinal, pulmonary and vascular models. The convenient and fast measurement of the trans-endothelial/epithelial resistance (TEER) and passive permeability provide important information about the integrity of the cell monolayer under healthy and pathological conditions.

We developed a versatile lab-on-a-chip device that can measure the TEER and the passive permeability and also enables the visual monitoring of the cell monolayer via phase contrast microscopy and immunohistochemistry [1]. The device was standardized under static and dynamic condition (without and with fluid flow, respectively) using epithelial and endothelial barrier models. We studied how the shear stress effects the blood-brain barrier properties and the glycocalyx [2]. The latter is especially important, since it contributes to the high negative surface charge of the luminal surface of the barrier forming cells. The negative surface charge plays crucial role in transport processes, infections and other pathologies, so it is very important to investigate the relationship between the surface charge and the overall barrier function. There are very few studies focusing on the surface charge and all of these measures the zeta potential of cell-suspensions. We upgraded our lab-on-a-chip device with a pair of Ag/AgCl electrodes to monitor the surface charge of confluent monolayers via the measurement of transient streaming potential signals [3].

Acknowledgment

OTKA PD-143268

References

[1] Walter FR, Valkai S, Kincses A, et al (2016) Sens. Actuators, B 222, 1209–1219.

[2] Santa-Maria AR, Walter FR, Figueiredo R, Kincses A, et al. (2021) J. Cereb. Blood Flow Metab. 41, 2201–2215.

[3] Kincses A, Santa-Maria AR, Walter FR, el al. (2020) Lab Chip, 20, 3792–3805.

Valkai Sándor
Could the SARS-CoV-2 S1 subunit cross the blood-brain barrier? – a lab-on-a-chip model study

Aug 30 - szerda

12:15 – 12:30

Bioszenzorika és bio-nanotechnológia

E31

Could the SARS-CoV-2 S1 subunit cross the blood-brain barrier? – a lab-on-a-chip model study

Sándor Valkai¹, Dániel Petrovszki¹, Fruzsina R. Walter¹, Judit P. Vígh¹, Anna E. Kocsis¹, Mária A. Deli¹ and András Dér¹

¹ Biological Research Centre, Szeged, Institute of Biophysics

The outbreak of the global pandemic caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) has pulled several clinical aspects of the disease into attention. Besides its primary route of infection through the respiratory system, SARS-CoV-2 is known to have neuroinvasive capacity, causing multiple neurological symptoms with increased neuroinflammation and blood–brain barrier (BBB) damage. The viral spike protein disseminates via circulation during infection, and when reaching the brain could possibly cross the BBB, which was demonstrated in mice. Therefore, its medical relevance is of high importance. The aim of our study was to evaluate the barrier penetration of the S1 subunit of spike protein in model systems of human organs highly exposed to the infection. For this purpose, in vitro human BBB and intestinal barrier cell-culture model systems were applied, in combination with an optical biosensing method.

We found that spike protein crossed the human brain endothelial cell barrier effectively. Additionally, spike protein passage was found in a lower amount through the intestinal barrier cell layer too. These observations were corroborated with parallel specific ELISA tests.

The findings on the BBB model could provide a further basis for studies focusing on the mechanism and consequences of spike protein penetration across the BBB to the brain. [1]

Keywords:

biosensor; coronavirus spike-protein permeability; tissue barriers; human brain endothelial cells; Caco-2 cells; integrated optics; Mach–Zehnder interferometer

Reference

[1] Dániel Petrovszki, Fruzsina R. Walter, Judit P. Vigh, Anna Kocsis, Sándor Valkai, Mária A. Deli and András Dér (2022) MDPI Biomedicines 10(1), 188 DOI: https://doi.org/10.3390/biomedicines10010188