Over the last two decades, the global beauty industry has seen an influx of technology and ingredient trends. As an esthetic researcher, I often find myself at the intersection of skin care science and sensationalism. It is quite easy to fall into the marketing abyss, where manufacturers are more inclined to craft exotic (and often unsubstantiated) stories than deliver well-researched scientific facts. One area of particular interest is the world of stem cells, a big buzzword in the industry today, yet one of the most wildly misunderstood topics. From plants, to animals and humans, the term stem cell is unfortunately used interchangeably no matter the context. Let’s start from the beginning.
STEM CELLS 101
What is a stem cell? The simplest definition of a stem cell is a cell that can both replicate (create new versions of itself) and differentiate (change) into other types of cells and tissues. In both the plant and animal kingdoms, the ultimate stem cell is a fertilized egg. These early stem cells are what is knows as Totipotential, a cell that has the ability to repeatedly divide and differentiate into all types of cells found within the body or the plant. In animals, these early Totipotential cells only exist for about four days, before they further differentiate into Pluripotential cells, or cells that can give rise to all of the cell types that make up the body.
However, in the plant kingdom, Totipontential cells remain that way throughout the lifetime of the plant. These plant stem cells exist in specialized tissue niches within the plant called meristems. In skin care applications, it is the plants meristem that is extracted and cultured in a lab to produce secondary metabolites that ultimately end up in the topical product. Just like with human stem cell products, the actual stem itself is never found within the bottle, it is the cultured cell “extract” that contains molecules with potential therapeutic value.
PLANT STEM CELLS
It is a well-established fact that plants hold significant pharmacological value, with a myriad of medicines having some botanical origin. Often citing the abundant flora that scatters our planet, Hippocrates famously said, “Let food be thy medicine, medicine be thy food.” Whether ingested or applied topically, plants do have the potential to produce chemically diverse compounds. But, can their stem cells manufacture substances that have the ability to affect human skin, let alone behave and perform like the human counterpart technologies?
Meristem cells are actually under external control, meaning their biological activity is dependent on signals from other parts of the plant, such as neighboring quiescent cells and plant hormones known as Cytokinins (not to be confused with human cell messenger proteins known as Cytokines). This intricate symphony of communication is unique and inherent to the plant, and is biologically different from the cross talk that exists between human cells.
It is only down-differentiated plant cells that have the capacity to produce the active constituents that have known value, such as terpenes, anti-oxidants, flavonoids and other chemical compounds. When meristems are removed for culture, they effectively lose the “instructions” given by the rest of the plant for them to achieve specific biological functions. To compensate for this, manufacturers will use genetic sequencing to mimic the biological influence from the whole plant in order for the meristem cells to produce the molecules mentioned in the marketing. From “rare swiss apples” to the Alpine Edelweiss, and every other plant species in between, we must recognize what these plants are and what they aren’t when it comes to their ability to influence human skin cells.
ANIMAL STEM CELLS
In the animal kingdom, all nucleated cells (outside of red blood cells) communicate with each other via specialized protein molecules that get synthesized within the cell, released, and then travel to neighboring cells to attach to surface receptors. These molecules are called growth factors and cytokines. This “symphony” of communication is known as paracrine signaling, and it is how all these nucleated cells “talk” and “listen” to each other.
Growth Factors and Cytokines carry specific coded instructions, and the biological message they carry and transmit is dependent on their unique and innate language. The body produces hundreds of these protein molecules, and it is these complex bio-signals that are used in topical skin care products.
When it comes to utilizing topical growth factors, the source MUST be from a human, as the biological messages that they produce are radically different than that of animals and plants. They just don’t speak the same language.
HARVESTING HUMAN CELLS
Multiple types of cells within the body can be utilized to harvest these growth factors. The most common cell sources for culture found in the topical skin care space include:
- Fibroblasts (the most dominant cell in connective tissue)
- Adipose (Fat) Stem Cells
- Bone Marrow Stem Cells
Each are very different in the types and quantities of messenger proteins they give off. The process of extraction, no matter the cell source, is universally the same (barring some additional steps unique to the manufacturer). The cell of choice is put through a culturing process in a laboratory, where the cell is fed nutrients in order for them to grow and proliferate. Think of a glorified petri dish that contains a solution of enzymes, carbohydrates, etc. that act as a food source for the cells. This solution is called a “media.”
The cell is placed in the media where it feeds off of the solution and then starts to grow. As these cells grow, they begin to naturally release protein molecules into the media, among other molecules. These proteins are those powerful messenger molecules known as growth factors and cytokines. The media is now considered “conditioned.” In fact, that is how all human growth factor products will have the ingredient listed on the bottle for you to recognize; Fibroblast Conditioned Media, Adipose Stem Cell Conditioned Media, and/or Bone Marrow Stem Cell Conditioned Media.
Once the culturing process is complete, the original cell utilized is filtered out (transferred to a new “petri dish” to begin the process all over again), and the media solution with all the growth factors contained within is ready to be processed for bottling and topical application.
It is important to remember that the original cell source used (stem cell or otherwise) is never found inside the bottle, it is just the protein molecules that the cell releases. These are the most valuable tools that can enhance and optimize cell signaling (communication) when applied topically.
Even within the human cell source realm, as noted above, the three commonly used cells produce a vastly different portfolio of proteins when cultured. This is extremely important to recognize and fully understand, as it is the net-pattern of the growth factors produced that will determine the physiological effect when applied to the skin.
Fibroblasts are weak producers of growth factors, and the ones they do produce tend to lean towards the inflammatory side such as IL-6, a potent inflammatory cytokine. This is first-generation GF technology. Adipose (Fat) Stem Cells do produce an abundance of growth factors when cultured, but these proteins are overwhelmingly inflammatory. The various risks and safety concerns associated with the usage of Adipose Stem Cells and their derivatives have not been fully elucidated. Fat serves auxiliary endocrine function and secretes metabolically active hormones such as Leptin, Adipokines, and other inflammatory proteins linked to aggressiveness of malignant cell growth. Adipose Stem Cells play no role in controlled healing throughout the body; they have a singular fate in life, to become fatter.
Bone Marrow Stem Cells, however, are very unique. They are the master healing stem cell in the entire body, and the only mobile stem cell that patrols the body looking for injury. When the injury is found they initiate a regenerative response. When cultured, these stem cells produce an extremely large amount of growth factors, with the net-pattern being strongly anti-inflammatory. They reign supreme as the most effective tool to control the underlying mechanisms to aging.
Education is vital to fully understanding the truth behind the technologies being marketed to us. We can see that there is value in both plant and human sources of ingredients. Plant “stem cell extracts” can harmoniously co-exist with the human stem cell derivatives, and with honest and transparent formulation standards, manufacturers can craft well-rounded, scientifically sound and more importantly safe products that help us achieve all of our esthetic outcomes and objectives.
