The achievement, reported in Chemical Senses, may provide tools needed to identify new taste compounds and fully understand how tastes are detected and interpreted in the mouth, said the authors, led by Dr. Hakan Ozdener of the Monell Center.
Speaking with FoodNavigator, senior author of the study Dr. Nancy Rawson said the research aims to “create models to help understand human taste.”
“We know that compounds present in foods interact with taste cells in a variety of ways … This model can be used to explore some of these …and could also be used to evaluate potential toxic or undesirable effects of flavor candidates, as well as to examine the impact of longer duration or repeated exposures,” said Rawson.
Enormous advantage
“The myriad advantages to being able to study taste cells and all of their machinery in a controlled in vitro environment is enormous … we know relatively little about the whole taste story,” explained Dr. Paul Breslin, a sensory biologist at Monell who also worked on the research.
“Assays using receptors expressed in non-taste cells … have different intracellular machinery, that may not replicate the machinery used by the native taste cell when it is responding to a taste stimulus,” said Dr. Rawson.
Rawson added that that the new in vitro model “provides a way to study the taste detection process in an environment that can be completely controlled by the investigator”. She explained that this allows much more precise manipulation and measurements of stimuli and responses.
The cell cultures also could be used to screen and identify molecules that activate taste receptors in order to identify compounds that work as salt replacer or enhancers, the researchers said.
Tasty cultures
Taste cells contain receptors that interact with chemicals in foods to allow us to sense sweet, salty, sour, bitter, and umami tastes. They also are among the few cells in the body with the special capacity to regenerate – new taste cells mature from progenitor 'stem' cells every 10-14 days.
Ozdener and his team explained that for many years it was believed that taste cells could not be ‘grown’ in vitro because they needed to be attached to nerves in order to both function properly and regenerate.
Many scientists thought that it was not possible to isolate and grow these cells in culture, and this has limited the scope of studies into understanding how human taste cells function, said the authors.
However, by taking tiny samples of tongue tissue from human volunteers, and adapting an existing technique that had been shown to work in rats, the researchers were able to demonstrate that the human taste cells indeed can regenerate in culture.
The study reports that the cultured taste cells maintained all of the important molecular and physiological properties characteristics of ‘parent’ cells.
The great unknown
Breslin told FoodNavigator that currently research does not have “a handle on much of taste transduction.” He explained that there are many areas that remain unknown, including many of the pathways for bitter taste, details of how sour and salty taste signaling occur, and the subtypes of cells that sense sour and salty tastes.
“To address these questions, we need to study the intact taste cells, which contain not only the receptor but also the rest of the machinery used to convert the information from a taste stimulus bound to its receptor into a signal that the brain can understand,” explained Dr Rawson.
Ozdener added that the technique will allow scientists to begin to understand the finer details of taste cell signaling pathways induced by different tastants.
“Being able to focus on distinct human taste cell subtypes in vitro that will remain alive for long periods and generate new cells is a unique opportunity to try to answer some or even all of these questions,” said Dr. Breslin.
Source: Chemical Senses
Published online ahead of print, doi:10.1093/chemse/bjr012
“Characterization of Human Fungiform Papillae Cells in Culture”
Authors: M.H. Ozdener, J.G. Brand, A.I. Spielman, F.W. Lischka, J.H. Teeter, P.A.S. Breslin, N.E. Rawson