Spheroid Culture of Mammalian Olfactory Receptor Neurons: Potential Applications for a Bioelectronic Nose

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.

The Effect of Topical Steroid Nasal Instillation in Induced Anosmic Mice / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate the effect of intranasal Mometasone furoate instillation into the nasal cavity of mice which had peripherally induced anosmia. SUBJECTS AND METHOD: Three groups of mice were studied: normal control group (nasal instillation of normal saline, n=6), Mometasone furoate non-instillation group (no treatment after nasal instillation of zinc sulfate, n=12), and Mometasone furoate instillation group (daily mometasone furoate instillation after nasal instillation of zinc sulfate, n=12). Tissues of olfactory mucosa were obtained on 1, 2, 3, 4 weeks after the instillation of zinc sulfate, and processed for immunohistochemistry using antisera to olfactory marker protein (OMP) for evaluation of olfactory regeneration. RESULTS: No OMP-positive cells were observed in the first week after the instillation of zinc sulfate in both groups. However, OMP-positive cells began appearing in the second week in both groups and gradually increased as time goes by. In the Mometasone furoate instillation group, the increase of OMP-positive cells was significantly greater than that of Mometasone furoate non-instillation group. CONCLUSION: Mometasone furoate instillation enhances regeneration of olfactory receptor cells after injury. Mometasone furoate instillation can be suggested as an effective treatment modality for olfactory dysfunction.

The Impact of Toxicants on the Olfactory System

The olfactory system is valuable in the study of some general properties of neural system and it provides as an excellent model for studying the effects of environmental toxicants on the sensory system. For example, the olfactory receptor neuron has become an important neurobiologic model system in the area of molecular and cell biology for the study of neuronal plasticity and neuronal development, including the developmental steps of cell birth and lineage, differentiation, synaptogenesis, migration, maturation, and death. The olfactory neuroepithelium is characteristic of neuron replacement and regeneration throughout life. Olfactory receptor neurons are rapidly replaced following traumatic lesions and they are the only known projection neurons with this property. Various toxicants put the olfactory system at risk for damage. Toxic agents comprise part of health hazard to human olfaction. However, the direct and indirect effects of these agents on the olfactory system are not completely understood.