ACTIVATION OF REGENERATION-ASSOCIATED PATHWAYS IN NEURONS FOLLOWING PHOTOCAPACITIVE STIMULATION
Marta Nowakowska1, Silke Patz1, Tony Schmidt2, Ludovico Migliaccio3, Marie Jakešová3, Eric Głowacki3, Vedran Đerek4, Karin Kornüller5, Susanne Scheruebel3, Theresa Rienmüller5, Rainer Schindl2, Muammer Üçal1
1Department of Neurosurgery, Medical University of Graz, Graz, 8010 Austria; 2Gottfried Schatz Research Center – Biophysics, Medical University of Graz, Graz, 8010 Austria; 3Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic; 4Department of Physics, Faculty of Science, University of Zagreb, Bijenička c. 32, 10000, Zagreb, Croatia; 5Institute of Health Care Engineering with European Testing Center of Medical Devices, Graz University of Technology, Austria
Neurostimulation exerts beneficial effects on restorative processes following many debilitating neurological disorders, such as stroke or brain trauma. Current drive to create lightweight and wireless devices for electrical stimulation aims to improve quality of life in patients. Organic photocapacitors rapidly charged upon illumination, which in turn creates an electric field that could be used for stimulation of the cells in their vicinity. We investigate whether these photocapacitive devices could induce regenerative responses in nerve tissue. We cultivated primary neurons from postnatal rats on photocapacitors (round, 11 mm diameter p-n layer of H2PC-PTCDI, 30 mm diameter back electrode of Au-ITO) until their maturation. Then, cells were stimulated by light pulses (5 ms pulse, 500 interpulse, 10 iterations, 5 s break – repeated for 30 min) with an LED source (10 mW) at 660 nm wavelength. Neuronal activation was assessed by c-fos immunoreactivity with immunocytofluorescent staining. Neurotrophin (BDNF, NGF, NT-3, NT-4) expression was analysed with real-time qRT-PCR. Cells exposed to light pulses showed increased expression of c-fos protein compared to the controls without light stimulation, proving neuronal activation on the molecular level. Whilst a broad c-fos positivity was observed in these cells, the signal intensity was lower than the one of positive controls exposed to glutamate, indicative of a room for further optimization of photocap size and stimulation parameters. Three hours post-stimulation no significant change in the neurotrophin expression was detectable. Whether this lies on the stimulation protocol, photocap design or intrinsic temporal dynamics of neurotrophin release will be addressed with future planned experiments.
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