"Our research suggests that these two stem cells may be interdependent," explains Brian Lin, senior author on the study and a research assistant professor in the Department of Developmental, Molecular and Chemical Biology at Tufts. "One type that we thought was largely dormant—HBCs—may actually play a crucial role in supporting the production of new neurons and the repair of damaged tissue."
This finding suggests that the "dormant" HBCs are actually providing a necessary environment or signal that allows the GBCs to function correctly. This symbiotic relationship means that any therapy aimed at restoring the sense of smell must likely address the health and activity of both cell populations, rather than focusing on a single "master" stem cell.
The Impact of Aging on Sensory Renewal
One of the most pressing questions in olfactory research is why the sense of smell naturally declines as people get older. To investigate this, the Tufts team utilized their organoid model to compare the regenerative capabilities of cells taken from mice of various ages.
The results were telling. The researchers observed a clear and consistent decline in the ability of cells from older mice to generate new neurons within the 3D model. While the exact cause of this decline is still being investigated, the team’s preliminary observations point toward a thinning of the GBC population over time.
"We found a decline in the ability of the older mice cells to generate new neurons," Lin says. "We think this is due to a decrease in the GBC population as we age, but we need to do more work to test this hypothesis and if so, develop ways to rejuvenate them."
By identifying the specific cellular breakdown that occurs with age, the researchers hope to eventually find ways to "reboot" the regenerative process, potentially offering a way to reverse age-related sensory loss.
A Tool for the Global Scientific Community
Beyond the specific biological discoveries, the study is notable for its emphasis on scientific accessibility. The lead author of the study, Juliana Gutschow Gameiro, joined the Tufts team as a visiting Ph.D. student from the State University of Londrina in Brazil. Her mission was to develop a model that did not require the prohibitive costs or specialized equipment often associated with high-level stem cell research.
The timing of this development is critical. In the years following the emergence of COVID-19, the sense of smell has moved from a niche area of study to a frontline concern for neurologists, virologists, and general practitioners.
