ECIS technology reveals that monocytes isolated by CD14+ve selection mediate greater loss of BBB integrity than untouched monocytes, which occurs to a greater extent with IL-1ß activated endothelium in comparison to TNFα.

BACKGROUND: We have previously shown that TNFα and IL-1ß differentially regulate the inflammatory phenotype of human brain endothelial cells (hCMVECs). In this regard, IL-1ß treatment was considerably more potent than TNFα at increasing expression of inflammatory chemokines and leukocyte adhesion molecules. We therefore hypothesised that interaction of the hCMVECs with human monocytes would also be dependent on the activation status of the endothelium. Therefore, the primary aim of this study was to assess whether brain endothelial cells activated by IL-1ß or TNFα differed in their interaction with monocytes. METHODS: Monocyte interaction was measured using the real time, label-free impedance based ECIS technology, to evaluate endothelial barrier integrity during monocyte attachment and transendothelial migration. RESULTS: ECIS technology revealed that there was a greater loss of barrier integrity with IL-1ß activation and this loss lasted for longer. This was expected and consistent with our hypothesis. However, more striking and concerning was the observation that the method of monocyte enrichment greatly influenced the extent of endothelial barrier compromise. Importantly, we observed that positively isolated monocytes (CD14+ve) caused greater reduction in barrier resistance, than the negatively selected monocytes (untouched). Analysis of the isolated monocyte populations revealed that the CD14+ve isolation consistently yields highly pure monocytes (>92%), whereas the untouched isolation was much more variable, yielding ~70% enrichment on average. These two enrichment methods were compared as it was thought that the presence of non-classical CD16hi monocytes in the untouched enrichment may mediate greater compromise than the classical CD14hi monocytes. This however, was not the case and these observations raise a number of important considerations pertaining to the enrichment strategy, which are essential for generating reliable and consistent data. CONCLUSIONS: We conclude that IL-1ß and TNFα differentially influence monocyte interaction with brain endothelial cells and moreover, the enrichment method also influences the monocyte response as revealed using ECIS technology.

Application of xCELLigence RTCA Biosensor Technology for Revealing the Profile and Window of Drug Responsiveness in Real Time.

The xCELLigence technology is a real-time cellular biosensor, which measures the net adhesion of cells to high-density gold electrode arrays printed on custom-designed E-plates. The strength of cellular adhesion is influenced by a myriad of factors that include cell type, cell viability, growth, migration, spreading and proliferation. We therefore hypothesised that xCELLigence biosensor technology would provide a valuable platform for the measurement of drug responses in a multitude of different experimental, clinical or pharmacological contexts. In this manuscript, we demonstrate how xCELLigence technology has been invaluable in the identification of (1) not only if cells respond to a particular drug, but (2) the window of drug responsiveness. The latter aspect is often left to educated guess work in classical end-point assays, whereas biosensor technology reveals the temporal profile of the response in real time, which enables both acute responses and longer term responses to be profiled within the same assay. In our experience, the xCELLigence biosensor technology is suitable for highly targeted drug assessment and also low to medium throughput drug screening, which produces high content temporal data in real time.