One of the less frequently discussed aspects of aging, perhaps because it is seen as a less critical function, is the progressive loss of the sense of smell. When arising from the underlying cell and tissue damage of aging, this can be considered a form of neurodegeneration. Strategies in the development of regenerative medicine that are aimed at regrowth of neurons and axonal connections between neurons are applicable to this form of age-related dysfunction, and here find a review of some of this ongoing work.
Olfactory loss impacts more than 12% of the population and increases with aging. Multiple conditions can cause loss of smell (hyposmia or anosmia), including post-viral damage from COVID-19 or influenza, head injuries, sinusitis, or neurodegenerative conditions such as Alzheimer's or Parkinson's disease. While treatments including surgery, anti-inflammatories or olfactory training may be of benefit in specific cases, there is an unmet need for effective therapies for many common causes of olfactory dysfunction, especially those thought to be due to damage to the olfactory neurons that have failed to recover spontaneously.
Broadly, regenerative medicine approaches may exert a therapeutic effect by (a) delivering signals to endogenous cells in a damaged tissue that promote a necessary process that has been inhibited or blocked, such as cell division or differentiation; or (b) delivering exogenous cells capable of engrafting appropriately into the damaged tissue and functioning as stem or progenitor cells that can divide and differentiate appropriately.
In either scenario, the organ system must be capable of integrating the newly regenerated cells properly. For instance, a newly produced olfactory sensory neuron in the olfactory epithelium (OE) of the nose must extend an axon through the cribriform plate, enter the central nervous system, and establish a synapse at an appropriate glomerulus in the olfactory bulb of the brain. Because the OE continually produces new olfactory neurons from resident stem cells as needed throughout life, evidence suggests that the presence of local guidance cues and a permissive microenvironment may support repair.
Link: https://doi.org/10.21053/ceo.2025-00065
View the full article at FightAging
