Olfactory mucosa for transplant‐mediated repair: A complex tissue for a complex injury?

Abstract

Damage to the brain and spinal cord leads to permanent functional disability because of the very limited capacity of the central nervous system (CNS) for repair. Transplantation of cells into regions of CNS damage represents one approach to enhancing this repair. At present, the ideal cell type for transplant-mediated repair has not been identified but autologous transplantation would be advantageous. Olfactory tissue, in part because of its capacity for regeneration, has emerged as a promising source of cells and several clinical centers are using olfactory cells or tissues in the treatment of CNS damage. Until now, the olfactory ensheathing cell, a specialized glial cell of the olfactory system has been the main focus of attention. Transplants of this cell have been shown to have a neuroprotective function, support axonal regeneration, and remyelinate demyelinated axons. However, the olfactory mucosa is a heterogeneous tissue, composed of a variety of cells supporting both its normal function and its regenerative capacity. It is therefore possible that it contains several cell types that could participate in CNS repair including putative stem cells as well as glia. Here we review the cellular composition of the olfactory tissue and the evidence that equivalent cell types exist in both rodent and human olfactory mucosa suggesting that it is potentially a rich source of autologous cells for transplant-mediated repair of the CNS.

Engraftment of human nasal olfactory stem cells restores neuroplasticity in mice with hippocampal lesions

“…The olfactory mucosa is a permanently self-renewing nervous tissue, even in elderly persons, which harbors a variety of cells supporting both its normal function and its regenerative capacity (18). Olfactory ensheathing cells, involved in axonal outgrowth guidance, have already been described as a valid tool to promote neuroplasticity after brain transplantation (19).…”

The role of olfactory ensheating cells in regenerative medicine: review of the literature

“…This may take several weeks following cell purification. It is important to know that if the purification of OECs from the olfactory mucosa or bulb is not carried out, a large number of other cell types ("contaminating cell types") will be isolated and propagated in culture, including fibroblast-like cells, mesenchymal stem cells, connective cells, immune cells and pericytes 25,26,27 . The conditions of cell culture are very important in obtaining rapid and stable proliferation and also to maintain cellular morphological characteristics and antigenic properties 18 .…”

“…Based on its capacity for regeneration, olfactory tissue represent a promising donor site of cells. Scientists are already using olfactory cells, in animal models or early clinical studies, for the treatment of central nervous system damage, from different injuries and neurodegenerative diseases 27 . The possibility of using OECs for neural repair after injuries demonstrates an important property of those cells: the ability to manifest a substantial plasticity 29 .…”

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“…119 They are relatively quiescent and are thought to divide only occasionally to give rise to GBCs, which are assumed to then give rise to ORNs and sustentacular cells. 114,120,121 In the event of severe damage to the OE, HBCs have been found to divide more frequently to give rise to multiple cell types.…”

“…113 Globose Basal Cells Globose basal cells (GBCs) lie above the HBCs and have a rounder morphology. 119 They can be labeled using cytokeratin, p75NGFR, and GBC-1, a monoclonal antibody that exclusively labels GBCs. 66,68,122 In animal models, GBCs are found to be necessary for regeneration of OE after lesion.…”