Stem cells: an overview

I spent this past Sunday at the Les Nouvelles Esthetiques tradeshow in Philadelphia. I walked the floor, met some great spa industry people, got to speak French with my girlfriend Christele de la Haye, the LNE marketing director, and, most fun of all, got to speak at the General Session. Thank you LNE for inviting me! For those of you who couldn’t be there, I thought I would give you a summary of my presentation, which was on “Stem Cells: An Overview.”

What are stem cells?  Stem cells are undifferentiated cells characterized by self-renewal (they can multiply to produce new stem cells) and by differentiation: upon exposure to tissue-specific biochemical signals, they turn into tissue-specific specialized cells. They play a key role in tissue development and regeneration.

There are two major categories of stem cells: embryonic and adult.

Embryonic stem cells have the extraordinary potential to form all tissues of the body. They can be found in the early embryos (human embryos between 0 and 3-5 days) and are also present in the umbilical cord blood collected at birth.

Adult stem cells have been found in most tissues and organs of fetuses, children, and adults, including the skin. They contribute to tissue quality and ensure tissue renewal. Adult stem cells are somewhat less powerful than embryonic stem cells, as they are already “pre-determined”, i.e., engaged in a certain direction for differentiation. Their potential is thus more limited: for example, adult stem cells cannot reproduce a whole organism.

In adults, stem cells are not randomly distributed, but are concentrated in tiny regions called “niches”. In the skin, “niches” are found in hair follicles which maintain skin stem cells in a non-differentiated state. The epidermis stem cells are essentially located in the erector muscle of hairs. Skin stem cells may migrate either towards the surface of the skin to replenish the epidermis or towards the basis of the hair follicle to give rise to its constituents. Skin stem cells also continuously renew the skin.

There is one third type of stem cell – plant stem cells, which have increasingly been of interest to the beauty industry. Like human skin, plants contain stem cells that are located at their apical and root meristem. The meristems are composed of stem cells capable of generating an entire organism. Plant stem cells are found in those regions of the plant where growth takes place. There are nearly inexhaustible reservoirs of undifferentiated cells capable of self-sustaining and of providing precursors for differentiated cells.

It is therefore possible, from only small fragments of a plant’s meristem, to create multiple copies of the same plant, as well as to produce plant stem cell extract. Why should we care about plant stem cells? Well, plant stem cell extracts have already an anti-wrinkle effect on human skin (in vitro and in vivo).

Plant stem cell extracts likely contain natural growth factors that will be of interest in future cosmetic developments, an interest that is being confirmed by preliminary clinical results from various sources, and by cosmetic companies integrating these ingredients into their products.

You can read more in the September issue of Les Nouvelles Esthetiques.