The Scent of a Therapy for Spinal Cord Injury: Growth Factors and Their Potential to Modulate Olfactory Ensheathing Cells.

Spinal cord injury (SCI) is a debilitating condition resulting in a range of neurological impairments up to complete loss of function below the level of injury. With current clinical management limited to decompression and stabilisation of the injury, there is urgent need to develop effective restorative treatments. In animal models, cell transplantation therapies are being tested that utilise different cell types including olfactory ensheathing cells (OECs), a type of glial cell, to support and promote regeneration. While OECs have a unique combination of properties highly suitable for SCI repair, their efficacy and consistency need to be improved. Evidence suggests a combinational approach using growth factors or compounds alongside OECs may stimulate their innate properties and alter the internal milieu of an injury site in favour of neural repair. Naturally, there is intricate interplay between various growth factors and OECs during development of the olfactory system, and in injury and repair events, which regulate their migration, phagocytosis, and proliferation. Therefore, exploiting different growth factors to selectively enhance OECs' therapeutic potential could lead to restorative treatment of SCI. While some studies have already explored using growth factors to treat SCI in animal models, an optimal 'cocktail' has yet to be identified. In seeking to identify such a cocktail, this review presents the current understanding of SCI and the therapeutic potential of OECs and explores combined use of growth factors and OECs to improve treatment outcomes.