The widely held belief is that some of the epidermal cells are rare, long-lived and infrequently dividing, and generate short-lived, rapidly dividing cells that carry out the daily regeneration of the epidermis. The infrequently dividing stem cells were assumed to be the major epidermal cell population responsible for repairing skin injury.
Researchers in the lab of Tudorita Tumbar, associate professor in the Department of Molecular Biology and Genetics, have a different idea. Tumbar led a study showing the existence of two independent epidermal stem cell populations that divide at different rates, with both contributing to injury repair.
The work was conducted on mouse tail skin, which is a useful model system for stem cell research, and preliminary data also implicate the two stem cells in the back skin, which is more representative of human skin (…)
“Knowing the identity of the skin stem cells, allows examination of how genes function specifically in these cells to maintain normal tissue physiology and how genetic perturbations can lead to disease,” she said.
Tumbar and her group conducted long-term lineage tracing of the stem cells using fluorescent marking within populations of both infrequently dividing, or label-retaining, cells (LRCs) and more proliferative cells (non-LRCs). All of the genetically marked cells’ progeny remain labeled with the fluorescent dye, so the researchers were able to follow their lineage to see if they behaved like stem cells.
“What we found was that there are two populations of epidermal stem cells, one for the LRCs and one for the non-LRCs, and these two stem cells divide at different rates,” Tumbar said (…)
“By using the new markers and genetic tools provided by this study, we will be able to modify genes of interest specifically in the stem cells to address how their behavior is regulated during homeostasis (normal conditions) and what the outcome is when stem cell function is disrupted,” said co-author Aiko Sada, a former post-doctoral fellow in the Tumbar group, now an assistant professor at the University of Tsukuba (Japan).
This work could also be of value in the study of certain diseases, such as cancer, and how the disease originates or manifests itself in one stem cell population over another. Understanding early stages of disease onset is considered crucial for developing preventive strategies (…)
This work was supported by the Empire State Stem Cell Foundation, the New York State Department of Health and grants from the National Institutes of Health.