What Holds Skin Together?


A study by the Spanish National Cancer Research Centre (CNIO) has demonstrated that interactions between skin stem cells maintain the architecture of skin. Skin stem cells are responsible for the constant renewal of the skin, and without the close connections between these cells, skin is unable to protect our bodies from the constant assaults from bacteria, chemicals, ultraviolet radiation, heat, cold, shear forces and so on.

A loss of proper adhesion between skin cells sometimes occurs during particular inflammatory diseases and cancer as well. This simple fact has stimulated interest in skin research.

Mirna Pérez-Moreno, who heads the Epithelial Cellular Biology Group that led this study, said, “We knew that these junctions [between skin stem cells] were important in skin stem cells but the cellular components involved in their structure and function were not yet understood.”

For this research, Pérez-Moreno and her team used skin stem cells from laboratory mice. They examined structures called “adherens junctions” between stem cells. Adherens junctions are found at the “apical” (or top) surface of the cells, and they hold cells together. Without adherens junctions, cells would fail to stick together properly.

Adherens junctionCellJunctions

Pérez-Moreno and her team discovered that one of the central structures in skin stem cells that stabilized adherens junctions were microtubules. Microtubules are stiff, tube-like structures that act as rebar-like reinforcement for cells and help cells maintain their shape, form, and structure.

microtubulemicrotubulesfigure2

Marta Shahbazi, a member of Pérez-Moreno’s research group, said,” We have seen for the first time that skin stem cell microtubules connect with cell-cell junctions to form velcro-like structures that hold the cells together.”

The microtubules and the adherens junctions are stuck together by means an interaction between two proteins, the CLASP2 and p120 catenin proteins.

“We found that the absence of CLASP2 or p120 catenin in epidermal stem cells caused a loss of their adhesion , and therefore the structure of these cells,” said Shahbazi.

“Our results will open up new paths for exploring how these proteins regulate skin physiology,” said Perez-Moreno. She also added that such knowledge will be important for the possible development of future regenerative medical treatments or anti-cancer treatments.

Micro-Grooved Surfaces Influence Stem Cell Differentiation


Martin Knight and his colleagues from the Queen Mary’s School of Engineering and Materials Science and the Institute of Bioengineering in London, UK have shown that growing adult stem cells on micro-grooved surfaces disrupts a particular biochemical pathway that specified the length of a cellular structure called the “primary cilium.” Disruption of the primary cilium ultimately controls the subsequent behavior of these stem cells.

Primary cilia are about one thousand times narrower than a human hair. They are found in most cells and even though they were thought to be irrelevant at one time, this is clearly not the case.

Primary Cilium

The primary cilium acts as a sensory structure that responds to mechanical and chemical stimuli in the environment, and then communicates that external signal to the interior of the cell.  Most of the basic research on this structure was done using a single-celled alga called Chlamydomonas.

Martin Knight and his team, however, are certain that primary cilia in adult stem cells play a definite role in controlling cell differentiation.  Knight said, “Our research shows that they [primary cilia] play a key role in stem cell differentiation.  We found it’s possible to control stem cell specialization by manipulating primary cilia elongation, and that this occurs when stem cells are grown on these special grooved surfaces.”

When mesenchymal stromal cells were grown on grooved surfaces, the tension inside the cells was altered, and this remodeled the cytoskeleton of the cells.  Cytoskeleton refers to a rigid group of protein inside of cells that act as “rebar.” for the cell.  If you have ever worked with concrete, you will know that structural use of concrete requires the use of reinforcing metal bars to prevent the concrete from crumbling under the force of its own weight.  In the same way, cytoskeletal proteins reinforce the cell, give it shape, help it move, and help it resist shear forces.  Remodeling of the cytoskeleton can greatly change the behavior of the cell.

The primary cilium is important for stem cell differentiation.  Growing mesenchymal stromal cells on micro-grooved surfaces disrupts the primary cilium and prevents stem cell differentiation.  This simple culture technique can help maintain stem cells in an undifferentiated state until they have expanded enough for therapeutic purposes.

Once again we that there are ways to milk adult stem cells for all they are worth.  Destroying embryos is simply not necessary to save the lives of patients.