Measuring Endothelial Barrier Integrity

TEER measurements were performed as previously described [27 (link)]. The electrical resistance across the endothelial monolayer was assessed using an EndOhm™ chamber coupled to a resistance meter (EVOMX; World Precision Instruments, Inc, Sarasota, FL, USA). The TEER readings were collected before (0 h) and after (2 and 4 h) extracts addition. After subtracting the values of empty inserts (without cells and extracts) and multiplying by the area of the insert (1.12 cm²), TEER values expressed as Ω × cm² were obtained and the percentage of variation from average control readings (without extracts) were determined. After the last reading, the media from both compartments were collected and used for the transport studies mentioned above, and then the empty inserts were used for the following permeability assay.