The Impact of Aging on Sensory Health
Beyond identifying the roles of specific cell types, the study also delved into the inevitable decline of sensory function associated with getting older. It is a common clinical observation that the sense of smell weakens as people age, yet the underlying cellular causes have been difficult to pin down.
Using their organoid model, Lin and his colleagues compared cells harvested from young mice with those taken from older subjects. The 3D cultures provided a clear window into the aging process. They observed a marked decline in the ability of cells from older mice to generate new neurons compared to their younger counterparts.
"We found a decline in the ability of the older mice cells to generate new neurons," Lin says. The team hypothesizes that this decline is linked to a diminishing population of globose basal cells (GBCs) as the organism ages. While the HBCs may still be present, the overall "pool" of active progenitor cells seems to shrink or become less efficient over time. "We need to do more work to test this hypothesis and if so, develop ways to rejuvenate them," Lin adds, pointing toward a future where age-related sensory loss might be reversible.
An Easy-To-Use Model
One of the most significant contributions of this study is the model itself. In the world of modern biology, researchers often rely on organoids—miniaturized, simplified versions of organs grown in a lab that mimic the three-dimensional architecture and biological function of real tissue. While organoids have been successfully developed for the lungs, kidneys, and intestines, the olfactory system has proven more elusive.
The lead author of the study, Juliana Gutschow Gameiro, played a pivotal role in designing a model that was not only effective but also accessible. A former Ph.D. student visiting the Graduate School of Biomedical Sciences at Tufts from the State University of Londrina in Brazil, Gameiro was dedicated to the idea of "democratizing" this research. She worked to develop a 3D olfactory tissue model that was easy to create, even for laboratories that might lack the massive funding or specialized equipment often required for high-end stem cell research.
The timing of this development is critical. In the wake of the COVID-19 pandemic, interest in olfactory research has exploded. Millions of people worldwide experienced a loss of smell as a primary symptom of the virus, and for many, the sense has not fully returned. This has drawn researchers from disparate fields—neurology, immunology, and geriatrics—to study the nasal cavity.
"Because loss of smell is associated with COVID-19, as well as with Parkinson’s disease and other conditions, a much larger number of researchers from a variety of different fields have begun researching olfactory epithelial cells in the last few years," says Lin. "We wanted to develop an easy-to-use model so that non-stem cell biologists and those working in labs with limited resources could use it to better understand how olfactory neurons regenerate and what happens that causes that process to diminish or fail completely."
