Impedimetric monitoring of IGF-1 protection of in vitro cortical neurons under ischemic conditions

Microelectrode arrays (MEAs) incorporated with the electric cell substrate impedance sensing (ECIS) technique provide a method for acquiring cellular electrophysiological information, which is useful for the time-course monitoring of cellular outgrowth and damage. This research utilizes the ECIS technique for monitoring the time-course impedimetric changes in normal and insulin-like growth factor 1 (IGF-1)-protected cortical neurons under the ischemic insult of oxygen glucose deprivation (OGD) created in a microperfusion environment. The neuronal apoptosis is reflected by the relatively low cell viability (28 ± 11.5 %) after 30-min OGD followed by 24 h of re-oxygenation. Also the hyperpolarization phase of mitochondrial membrane potential (MMP) occurs during 2 h of the re-oxygenation period. In contrast, cortical neurons treated with 50 and 100 ng/mL IGF-1 show higher survival rates of 45 ± 5.2 % and 49 ± 9.2 %, respectively, and no occurrence of the hyperpolarization of MMP during the re-oxygenation period. The ECIS results demonstrate that the measured impedance of cortical neurons decreased from 826 ± 86 kΩ to 224 ± 32 kΩ due to cell detachment under the insult of OGD. The measured impedance of IGF-1-protected cortical neurons slowly decreased to about 50 % of the original value (560 ± 45 kΩ for 50 ng/mL and 593 ± 44 kΩ for 100 ng/mL) compared to saline control of 232 ± 37 kΩ, which indicates improved cell adhesion under OGD conditions. The time-course impedimetric results show that the proposed ECIS-based MEAs platform incorporated with a microperfusion environment can be used for the real-time monitoring of cortical neurons under in vitro OGD and the IGF-1 protective effect against OGD-induced ischemic neuronal death.