Spheroid Culture of Mammalian Olfactory Receptor Neurons: Potential Applications for a Bioelectronic Nose
Samhwan Kim1, So Yeun Kim1,2, Seong-Kyun Choi3, Jisub Bae1, Won Bae Jeon4, Jae Eun Jang5, and Cheil Moon1,2*
1Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea.
2Convergence Research Advanced Centre for Olfaction, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea.
3Core Protein Resources Center, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea.
4Companion Diagnostics and Medical Technology Research Group, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea.
5Department of Information and Communication Engineering, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea.
Correspondence to: *To whom correspondence should be addressed.
TEL: 82-53-785-6110, FAX: 82-53-785-6109
Received: August 24, 2018; Revised: November 13, 2018; Accepted: November 22, 2018
The olfactory system can detect many odorants with high sensitivity and selectivity based on the expression of nearly a thousand types of olfactory receptors (ORs) in olfactory receptor neurons (ORNs). These ORs have a dynamic odorant detection range and contribute to signal encoding processes in the olfactory bulb (OB). To harness the capabilities of the olfactory system and develop a biomimetic sensor, stable culture and maintenance of ORNs are required. However, in vitro monolayer culture models have several key limitations: i) short available period of cultured neurons, ii) low cultural efficiency, and iii) long-term storage challenges. This study aims to develop a technique: i) to support the spheroid culture of primary ORN precursors facilitating stable maintenance and long-term storage, and ii) to demonstrate the viability of ORN spheroid culture in developing an olfactory system mimetic bioelectronic nose. Recombinant protein (REP; TGPG[VGRGD(VGVPG)6]20WPC) was used to form the ORN spheroids. Spheroid formation enabled preservation of primary cultured ORNs without a significant decrease in viability or the expression of stemness markers for ten days. Physiological characteristics of the ORNs were verified by monitoring intracellular calcium concentration upon odorant mixture stimulation; response upon odorant stimulation were observed at least for ten days in these cultivated ORNs differentiated from spheroids. Coupling ORNs with multi electrode array (MEA) enabled the detection and discrimination of odorants by analyzing the electrical signal patterns generated following odorant stimulation. Taken together, the ORN spheroid culture process is a promising technique for the development of a bioelectronic nose and high-throughput odorant screening device.
Keywords: Cell-based biosensor, Recombinant protein, Olfactory receptor neuron, Spheroid culture, Micro electrode array