How do we constantly replace all our dead skin cells with brand new, healthy ones??

The Answer – Stem Cells.??
And that is why there are an increasing amount of products on the market claiming that by activating your Stem Cells, you are guaranteed to look 10 years younger due to all these new skin cells being created!
But what’s the science behind it all?? We thought we best Ask an Expert about this one.

Bob Isfort, is a technical supervisor at P&G and has recently been involved in some really cool research on Stem Cells alongside Sheffield University. They have been using virtual skin models to try and crack the importance of Stem Cells in the process of ageing.

We decided to find out more about this exciting research and whether or not it hold the answers to turning back the clock!!

BBTG: – What is a Stem Cell and why are these important in skin?

B: – Stem Cells are unspecialized cells that have two characteristic properties: self-renewal and differentiation. When stem cells divide, they have the potential to produce two types of cells – an exact copy of themselves and/or a cell that will further divide to produce all the cells of an organ.  Stem cells can continuously produce daughter cells which are an exact copy of the original stem cell. Stem cells can be described as undifferentiated (they haven’t changed into any other type of cell) but have the potential to differentiate (change) into a wide variety of tissue.

Stem cells are found throughout the body but can also be found in the skin including the outermost layer of skin, the epidermis. Generally speaking, they ensure the maintenance of adult skin function, by providing new cells to replace those that are constantly lost during tissue turnover or following injury.

BBTG: – Can you outline the current theory of how the skin regenerates? What are Stem cells role in the regeneration?

B: – There are 3 proposed ways that skin regenerates itself to maintain functions as follows:

  1. The first hypothesis describes a system in which a type of cell known as a stem cell give rises to 2 types of cells – another stem cell and a cell (transient amplifying cell) that divides a limited number of times to produce the cells of the outermost skin layer. This system reproducibly gives rise to these two cell types independent of the type of stress the skin undergoes.
  2. The second hypothesis describes a system in which there are no stem cells but only a type of cell (progenitor cells) that has three choices – divide to produce two copies of itself (8% of the time), divide to produce a copy of itself  and a cell that goes on the produce the cells of the outermost layer of skin (84% of the time), or divide to produce two cells that go on to produce the cells of the outermost layer of skin (8% of the time).
  3. The third hypothesis describes a system that is a combination of the first two hypothesis in which the skin contains both stem cells and progenitor cells but with a twist: the stem cell divides to produce either two copies of itself (10% of the time), a copy of itself and a progenitor cell (80% of the time), or two progenitor cells (10% of the time); whereas the progenitor cell can then divide to either produce two more progenitor cells (10% of the time), a progenitor cell and a cell that produces the cells of the outermost layer of skin (80% of the time), or two cells that produce the cells of the outermost layer of skin (10% of the time).

The third hypothesis appears to be the correct one since it was that only one that is able to create stable, self renewing skin that is able respond to environmental insults.

BBTG: -What is meant by ‘sleeping stem cells’?

The term ‘sleeping’ stem cells – or more correctly quiescent stem cells – describes stem cells in a state in which they don’t divide and produce daughter cells. This state is reversible, so when needed (for example following wounding), these stem cells can be (re)activated.

BBTG: – What kinds of factors cause these stem cells to wake- up? What happens when they do?

So called sleeping stem cells can be reactivated and called into action for example if the skin is damaged, or if the numbers of other types of more mature skin cells (such as keratinocytes- a type of skin cell) decrease, ensuring that the skin can be constantly regenerated under all conditions and optimal skin functionality is maintained.  The signals that wake up the stem cells are numerous including hormones, growth and differentiation factors, ultraviolet light, etc.

BBTG: – Why is computer modelling the latest step in skin biology?

Generally speaking, computer models are tools that allow us to take information and make knowledge.  These tools allow us to quickly and efficiently test ideas, design prototypes and understand where our knowledge is lacking so that we can fill in the gaps.  In skin biology, computer modelling allows scientists to project the detailed activity of tissues like skin that are difficult or impossible to follow in live systems for extended periods.  For example, currently, 3-dimensional cultures of engineered human skin are viable only for a few weeks and clinical studies in humans are only practical for a few months.  However, with the development of in silico models, scientists can predict for the first time what happens in skin over years and even over decades. In addition, these models permit exploration of hypotheses in very short periods of time, relative to the lab based bench work (if the bench work is even possible).  In silico modelling can therefore significantly shorten R&D programs, identify promising new technical approaches and help focus subsequent lab or clinical work on the technologies with the greatest chance to work.

BBTG: – Is there any cosmetic significance of these findings? Could the activation of the ‘sleeping’ stem cells lead to younger looking skin? Is this a potential target for anti-ageing products?

First and foremost this type of research allows our scientists to better understand existing skin rules—how the skin reacts under prescriptive variables—and theories, as well as discover new ones. This should help us better anticipate skin’s response to various environmental insults and to product ingredients, and predict the likelihood of success of our experiments and theories, accelerating the research and product development processes.

BBTG: – What are the next steps with this research?

We are continuing our work on skin models with the ultimate goal of developing in silico models that accurately portray skin function.

About Bob Isfort – Bob has worked at Procter & Gamble for the past 24 years in the Corporate Research, Pharmaceutical and Personal Health Care Divisions in a number of research areas including toxicology, cancer biology, musculoskeletal disease, respiratory infections, gastrointestinal illness and Systems Biology.
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