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Najafloo R, Majidi J, Asghari A, Aleemardani M, Kamrava SK, Simorgh S, Seifalian A, Bagher Z, Seifalian AM. Mechanism of Anosmia Caused by Symptoms of COVID-19 and Emerging Treatments. ACS Chem Neurosci 2021; 12:3795-3805. [PMID: 34609841 PMCID: PMC8507153 DOI: 10.1021/acschemneuro.1c00477] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/20/2021] [Indexed: 01/08/2023] Open
Abstract
The occurrence of anosmia, the loss or change in sense of smell, is one of the most common symptoms of COVID-19 experienced by almost 53% of those affected. Several hypotheses explain the mechanism of anosmia in patients suffering from COVID-19. This study aims to review the related mechanisms and answer the questions regarding COVID-19-related anosmia as well as propose a new strategy for treatment of long-term anosmia as a result of COVID-19 infection. This paper covers all of the studies investigating olfactory disorders following COVID-19 infection and explains the possible reasons for the correlated anosmia, including olfactory cleft syndrome, local inflammation in the nasal epithelium, early apoptosis of olfactory cells, changes in olfactory cilia and odor transmission, damage to microglial cells, effect on olfactory bulbs, epithelial olfactory injury, and impairment of olfactory neurons and stem cells. The key questions that arise in this field have been discussed, such as why prevalent anosmia is varied among the age categories and among sexes and the correlation of anosmia with mild or severe COVID-19 infection. The angiotensin-converting enzyme 2 receptor is a significant player in the mechanism of anosmia in COVID-19 patients. Based on current studies, a novel approach to treat long-COVID-19 with ongoing anosmia has been proposed. The fields of smart drug delivery, tissue engineering, and cell therapy provide a hypothesized strategy that can minimize the side effects of current treatments and support efficient recovery of the olfactory system.
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Affiliation(s)
- Raziyeh Najafloo
- Department
of Tissue Engineering & Regenerative Medicine, Faculty of Advanced
Technologies in Medicine, Iran University
of Medical Sciences (IUMS), Tehran 1449614535, Iran
| | - Jila Majidi
- Department
of Tissue Engineering & Regenerative Medicine, Faculty of Advanced
Technologies in Medicine, Iran University
of Medical Sciences (IUMS), Tehran 1449614535, Iran
| | - Alimohamad Asghari
- Skull
Base Research Center, Hazrat Rasoul Akram Hospital, The Five Senses
Health Institute, Iran University of Medical
Sciences (IUMS), Tehran 1445613131, Iran
| | - Mina Aleemardani
- Biomaterials
and Tissue Engineering Group, Department of Materials Science and
Engineering, Kroto Research Institute, The
University of Sheffield, Sheffield S3 7HQ, United Kingdom
| | - Seyed Kamran Kamrava
- ENT
and Head and Neck Research Center and Department, Hazrat Rasoul Akram
Hospital, The Five Senses Health Institute, Iran University of Medical Sciences (IUMS), Tehran 1445613131, Iran
| | - Sara Simorgh
- Department
of Tissue Engineering & Regenerative Medicine, Faculty of Advanced
Technologies in Medicine, Iran University
of Medical Sciences (IUMS), Tehran 1449614535, Iran
| | - Amelia Seifalian
- University
College London Medical School (UCL), London WC1E 6BT, United
Kingdom
- Watford
General Hospital, Watford WD18 0HB, United Kingdom
| | - Zohreh Bagher
- Department
of Tissue Engineering & Regenerative Medicine, Faculty of Advanced
Technologies in Medicine, Iran University
of Medical Sciences (IUMS), Tehran 1449614535, Iran
- ENT
and Head and Neck Research Center and Department, Hazrat Rasoul Akram
Hospital, The Five Senses Health Institute, Iran University of Medical Sciences (IUMS), Tehran 1445613131, Iran
| | - Alexander M. Seifalian
- Nanotechnology
and Regenerative Medicine Commercialisation Centre (NanoRegMed Ltd.), London BioScience Innovation Centre, London NW1 0NH, United Kingdom
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