Towards the electrical stimulation of PC12 cells
Abstract
The electrical stimulation of biological cells has been studied intensively since Galvani’s experiment with a dead frog’s leg muscle. Medical advances such as the pacemaker and the cochlear implants utilize some of the fundamentals of electrical stimulation as a result of these intensive studies. It is also a technique which has been explored in many research laboratories and has been shown to be able to play an important role in neurite outgrowth and the regeneration of transected nerves. Electric stimulation has also been shown to induce the differentiation of PC12 cells, faster than normal chemical means. The pheochromocytoma (PC12) cell line is derived from the pheochromocytoma of the rat adrenal medulla which can be differentiated to display characteristics similar to sympathetic neurons. By being able to induce differentiation faster, this opens the door to using complementary analytical techniques, such as a synchrotron-based Fourier Transform infrared spectromicroscopy to understand some of these molecular processes occurring during the differentiation process.
The long term objective of this project is to couple electrical stimulation and Fourier Transform infrared spectromicroscopy to study the electrically induced differentiation process. The primary focus of this work is to develop the methodology and background required to obtain this objective. This thesis focuses primarily on the PC12 cell line which has been reported in literature to differentiate both through chemical means (nerve growth factor, NGF) and electrical stimulation means. Using NGF, PC12 cells were able to show, within 24 hours, signs of initiating the differentiation process. Neurite outgrowths with a mean ± standard deviations of 10.0 ± 9.9, 14.0 ± 12.5,
21.4 ± 26.5, 21.6 ± 38.9 and 40.7 ± 49.1 μm corresponding to 24, 48, 72, 96 and 120 hours of NGF exposure was observed. PC12 cells grown on FTO conductive glass were electrically stimulated with a pulsing sequence of ±50 mV from the resting potential for 1 hour followed by 24 hours of incubation. These cells displayed a mean ± standard deviation neurite length of 9.35 ± 9.19 μm which is similar to PC12 cells exposed to 24 hours of NGF. The results of the electrical stimulation experiments are promising; however more experiments need to be conducted to determine the ideal electrical stimulation parameters to induce differentiation. The promising results also bring us one step closer to coupling FTIR to better understand the differentiation process from a molecular viewpoint.