Investigation of drug penetration in the aging brain. Age- associated changes in the BBB and BCSFB permeability.

The fundamental role of the increased permeability of the blood-brain barrier (BBB) in the pathogenesis of Alzheimer’s disease in association with aging was discovered during the last decade. It was shown by morphological studies that the expression of tight juction proteins between the endothelial cells decreases and concequently the paracellular transport processes increase. There were other structural changes observed at the BBB, like decreased number of pericytes and astrogliosis during aging. In our laboratory we are focusing on the functional changes of transporter proteins at the BBB in correlation with aging.

Role of drug transporters at the blood-brain barrrier (BBB) and the blood-CSF barrier (BCSFB).

The most important efflux transporter proteins at the BBB are P-gp and BCRP. These two transmembrane proteins protect the brain against the xenobiotics in close collaboration with other elements of the BBB. They are located at the luminal surface of the brain apillary endothelial cells and during the transport process they are pumping their substrates into the blood. At the same time, these efflux transporters are pumping their substrates into the cerebrospinal fluid (and not to blood) in the choroid plexus epithelial cells which are covering the cerebral ventricles. Consequently, the effect of P-gp and BCRP inhibitors at the level of brain parenchyma and the cerebrospinal fluid (CSF) are dual. In our lab w are focusing on the monitoring of substrate levels in the brain and in the CSF in parallel.

Investigations of drug-drug and BCRP-drug interactions at the BBB in vivo.

Severeal drug-drug interactions were described with a background mechanism of membrane transporter binding. In the case of P-gp substrates after the in vitro verification ofdrug interactions on transporters many study could verify the interactions also in vivo in animals. However, this is not the case for the BCRP substrates. The BCRP binding of severeal molecules of different therapeutic indications was shown in cells, but the next step, the in vivo verification of the interaction was not successful. We are working on this project focusing on the blood –brain barrier using in vivo microdialysis techniques.

Pharmacological assay development for educational purposes.

The preparation of practical training lessons beside the lectures is in progress at the Faculty, within the course of Drug Research and Development. Preliminary experiments and pilot investigations are under development in the Laboratory of Microdialysis, during which simple pharmacological models are setting up for demonstrative purposes.

Drug penetration across the cutaneous barrier studied by transdermal microdialysis.

The role of membrane transporter proteins located in different layers of the skin, our largest organ, has been investigated for a couple of years. The most important barrier in the body is the skin itself, wich protects the body from various external insults, and helps in the maintenance its stability and homeostasis. To do so, it should express transporters, which are pumping their substrates outwards or into the blood stream at the dermal capillaries. There are several research groups working on the demonstration of the role transporters in vitro. Our laboratory is focusing on the determination of drug penetration and delivery across the dermal barrier in connection with transporter interactions, in vivo.

Development of a microfluidic lab-on chip device for separation and analysis of multi-component microdialysate samples.

There are two main phases of the microdialysis experiments. The first is the surgery and the sample collection and the second is the bioanalysis of the samples. This second one is usually not as simple as it is thought in theory. The separation of multicomponent solutions and the handling and preparation of microliter samples are not easy tasks. To solve this problems in the biological lab using microchips is one of our research projects. We are working on the design of miniaturized HPLC columns for separation of dialysate samples and on connecting detection methods.

Statistical analysis and critical evaluation of the trends in the utilization of microdialysis techniques for clinical and preclinical purposes on the basis of the PubMed database.