Hierarchy of skin stem cells
The skin is a barrier that protects the body from external influences. The protective properties of the skin are due to its ability to constantly self-renew due to the death of cells of the upper layers and their replacement with new cells. When the body reaches maturity, the number of newly emerging cells should exactly match the number of dying cells. There are several theories explaining the mechanisms of maintaining this delicate balance.
Researchers at the University of Brussels (Universite Libre de Bruxelles), working under the leadership of Professor Cedric Blanpain, together with colleagues from the University of Cambridge, UK, have discovered a previously unknown population of stem cells that give rise to progenitor cells that maintain the normal cellular balance of the epidermis. Moreover, these cells make a significant contribution to the wound healing process.
Scientists using a new technique for studying the origin of cells labeled cells of two different epidermal populations with fluorescent markers and tracked their fate and role in maintaining the state of the epidermis. As a result, they found that the epidermis includes two types of dividing cells. The cells of one of these populations are characterized by the ability to maintain their vital activity for long periods, while the cells of the second population progressively die over time.
Based on the data obtained, the authors suggested that the stem cells of the epidermis have a hierarchically organized structure, at the top of which are slowly dividing cells that give rise to progenitor cells with a short life cycle. These cells, capable of very rapid division, provide continuous renewal of the epidermis. Analysis of the proliferation features of the identified cell populations and differences in the expression profiles of their genes confirmed the formulated hypothesis.
Evaluation of the contributions of cells from two populations to wound healing showed that active tissue regeneration is provided by stem cells themselves, whose population shows a strong surge of proliferative activity during injuries. The number of progenitor cells, on the contrary, increases only slightly, and their contribution to the wound healing process is of a short-term nature.
Similar populations of slowly proliferating cells capable of rapid mobilization in emergency situations have been identified in other tissues, such as blood, muscle tissue and hair follicles. Apparently, the described scheme of "distribution of responsibilities" between different populations of proliferating cells is universal for different tissues of the body.
The authors believe that the results of their work can be used in regenerative medicine, especially in restoring the skin in patients with burns or chronic ulcers.
Article by Guilhem Mascre et al. Distinct contribution of stem and progenitor cells to epidermal maintenance is published in the journal Nature.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of ScienceDaily:
Newly Identified Stem Cell Population in Skin's Epidermis Responsible for Tissue Repair.
04.09.2012