Adult stem cells

• Brief reminder of skin structure

• Stem cells... What are they?

• SEPPIC and stem cells

• Our products

Brief reminder of skin structure

The skin is a complex organ, the heaviest and largest in the human body. It has a surface area of 1.5-2 m2 and weighs 8-15% of body weight. It varies from 1.5 to 4 mm thick depending on where it is on the body and on environmental conditions.
Skin morphogenesis requires coordination between three embryonic tissues (ectoderm, mesoderm and neuro-ectoderm) to form the skin three layers: the epidermis, the outer tissue, largely epithelial; the dermis, dense conjuctive tissue; and the hypodermis, adipose sub-cutaneous tissue (Figure 1).

Figure 1 : Skin structure

Stem cells... What are they?

A few clarifications...
Stem cells (SC) are undifferentiated cells that can both renew themselves and differentiate into many different cell types. This multipotent character reduces as the cells "specialize" to form tissue.

What are the different types of stem cells?
Stem cells are present in the embryonic stage, where they help the body to develop correctly. However, there are also adult stem cells in a number of different tissues. Their main function is to maintain the structure of the tissue or the system they are involved with (immune system, for example). How pluri- or multi-potent they are is debated and seems to depend on the tissues. However, everything depends above all, on the context in which they evolve.
In adult tissue, SC are localized in 'niches', i.e. micro-environments that include other cells, structural elements and soluble messengers. The niches ensure the maintenance of stem cell characteristics.
On the other hand, in a new environment, for example in an in vitro culture using suitable media, SC, whether embryonic or adult, may be able to proliferate and differentiate in different ways. This type of adaptation may be a trump card. This is how tissue can be reconstructed in vitro or in vivo (after injecting stem cells).

SEPPIC and stem cells

Why is SEPPIC interested in stem cells?
SEPPIC has great expertise in skin biology and a variety of facilities and methods of investigating the responses of cells or tissues to different processes and treatments.
Studying stem cells, particularly skin tissue stem cells, is therefore of great interest to SEPPIC. Better understanding the characteristics and functions of these cells will help us to understand better skin structure, renewal, healing and ageing.

Adult skin stem cells (ASSC) and skin ageing
Currently, not many studies exist that discuss the consequences of ASSC ageing and it remains somewhat controversial. However, in humans, ageing seems to affect ASSC in a different way, at least partially, than what is observed in other organisms, such as mice.
Recent data suggest that the number of ASSC decreases with age. Preliminary data published by SEPPIC also suggest that whether SC can be maintained in ex vivo cultivated skin explants (i.e. pieces) could depend upon age of the donor (Dumont et al. 2009). These explants come from operating wastes from plastic or reparative surgery, they are fed artificially and maintained in an atmosphere similar to that of the human body.

Our products

Although we need to do many more studies to more completely understand how the ASSC markers and functions can be affected by ageing, SEPPIC has developed an active ingredient, SURVICODE, that can regulate gene and protein expression (see cosmetogenomic) involved in ASSC survival: survivin and sirtuin (the latter is also a marker for longevity). Moreover, SEPPIC recently communicated new data (IFSCC 2010, Buenos Aires) on this active ingredient since our studies have shown that SURVICODE (link to product data sheet) could protect ASSC from apoptosis (programmed cell death) caused by various forms of stress: UV irradiation, oxidative stress, loss of adherence to structural elements (a phenomenon called anoikis).

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