Development of microfluidic devices for analysis of cardiac tissue ex vivo

Polydimethylsiloxane (POMS)-based (Generation 1) and glass-based (Generation 2) microfluidic devices for heart tissue maintenance have been developed. Rat and human heart biopsies were electrically-paced in a 37 QC environment constantly perfused with oxygenated media, and waste products were continuously removed, mimicking the in vivo conditions. Tissue damage was indicated by assaying the lactate dehydrogenase (LOH) activity in the effluent samples. Heart tissues were kept viable in the biomimetic microenvironment within these devices once optimised, for up to 3.5 hours (human, Generation 1); 5 hours (rat, Generation 1), and 24 hours (rat, Generation 2). Mechanical contraction was observed in some of the tissue biopsies, suggesting that they were functioning as it is in the body. Sensitive, accurate and robust electrochemical analytical probes were established to measure the total reactive oxygen species (ROS) and creatine kinase MB (CK-MB) concentration in the effluent from the tissue biopsies. The total ROS probe was integrated with the Generation 1 microfluidic device to give a real-time measurement of the tissue insult. Both of these devices were also used to investigate the effects of on-chip ischaemia reperfusion (IR) procedures on the expression levels of a series of genes, which were analysed off-chip by semi-quantitative PCR. In addition, mixing within the Generation 1 microfluidic device was induced by redox-magnetohydrodynamics (redox-MHO), where a redox species, hexamineruthenium (Ill) chroride (Ruhex) and magnet were used to generate a magnetic force, thus causing the fluid to rotate around the electrodes. Qualitative microscopy recordings on polystyrene microbeads movement were provided in the supplementary OVO, showing the effects of MHO and Ruhex-MHO. This application could be of particular importance when the tissue sample is exposed to certain therapeutic drugs during perfusion for defined periods of time, to test the responsiveness of cardiac tissue to treatment. This proof-of-principle microfluidic technique will hopefully serve as a platform technology for future cardiac research and may also be exploited and modified for investigation of other clinical tissues, hence reducing reliance on animal models. The full potential of this technology remains to be discovered as other groups adopt this approach to analyse diseased and normal tissues.EThOS - Electronic Theses Online ServiceGBUnited Kingdo