First it was stem cells from rare apples touted as a revolution in anti-aging skin care. Then every other plant (seller) decided to get into the game. So is it true, or is it a con? Can stem cells from plants benefit your skin, and if so how? Is “stem cell” just a buzz word that unscrupulous marketers use to dupe you into thinking they are scientifically on the leading edge?
Plant Stem Cell Basics
A fertilized ovum (egg) is the ultimate stem cell. Every animal and plant that reproduces sexually begins as a fertilized ovum, with half of its genetic material contributed by the male parent and half from the female parent. In the case of flowering plants, structures within the flower play both roles. Pollen from the stamen is the equivalent of animal sperm and the pistol is the female receptive organ. A stem cell with the ability to repeatedly sub-divide and eventually differentiate into all types of cells found within an individual animal or plant is termed totipotential.
In the animal kingdom, a fertilized ovum divides, creating daughter totipotential stem cells, for only about four days. Daughter cells subsequently differentiate into pluripotential stem cells, which can differentiate into different various types of cells, but not all types. Plants, on the other hand, have totipotential stem cells throughout their life. These cells can develop into a complete adult plant.
Totipotential plant stem cells exist in very small numbers and are found in highly specialized tissues, structures called meristems. Meristems exist in root and shoot sprouts and are the cells from which all other plant cells and structures originate. Every root and stem shoot tip contains a very small number of these extraordinarily important cells. Meristems in shoot sprouts are called apical meristems, and those on the tips of roots are called root meristems. Remove the meristem and all growth in that part of the plant ceases.
Meristem stem cells are under external control and respond to local humoral factors from adjacent cells (quiescent cells) as well as more systemic plant hormones called cytokinin and auxin. Apical and root meristems have different specific, but complementary, controlling mechanisms. Generally speaking, hormonal influences that make an apical meristem grow may be inhibitory to root meristems, and vice versa. It is an intricately coordinated process in which stem cell activity is very tightly controlled and the number of totipotential stem cells is maintained at a very sparse population in comparison to the total plant cellular number.
Of paramount interest for this discussion is the fact that both apical and root meristems have control systems that act upon them, which are controlled by the needs of the entire plant. Without these outside influences, the cells in the meristem do not divide to produce daughter cells. While indispensable for plant growth, meristem stem cells are incapable of function without external influences dictating their response. These cells are followers, not leaders.
The photos show the relative size of structures within the meristem regions of a growing plant.
In the first photo (at right), the stem cells within the root meristem and adjacent quiescent cells are colored blue. The root meristem is also extremely tiny, consisting of only a few, albeit very important cells.
In the second photo (below) , apical meristem totipotential stem cells are colored red and the quiescent controlling cells are colored blue. From the 0.1 mm white line reference, the reader can see the cluster of stem cells is so small as to be barely visible to the naked eye (if it is even visible at all!)
Logical and Troubling Facts
From this information, three conclusions regarding the “beneficial uses” of plant stem cells in skin care products are logical and obvious.
1) No matter what species of plant is chosen from which to harvest stem cells, selectively separating these cells in any significant quantity from surrounding plant tissue and cells is hugely challenging and more likely impossible.
2) Plant stem cells are followers, not leaders, and downstream differentiated plant cells are the only ones that possess the biochemical machinery required to produce the myriad of known substances derived from plants that indeed have pharmaceutical or other value (e.g. quinine, digitalis, aloe vera, etc.)
3) Plant totipotential stem cells do not produce substances capable of affecting other cells of the plant in any meaningful way, let alone be suitable for use in influencing the behavior of cells in the animal kingdom, e.g. human skin.
The “Rationale” for Alleging Non-existent Benefits of Plant Stem Cells
Marketers want to sell stuff – that is their job. With very lax regulation in this area of commerce, they are quick to seize upon fanciful notions, wrap them in beguiling prose and postulates, and foist them upon an unwary and naïve consumer population. Throw in the timeliness of the stem cell “buzz”, and the emotional appeal to the consumer to look as young as possible, and, presto, you have sales of nonsense products – with the right photos and sales pitch, lots of sales. The ways in which this charade is promulgated can be ingenious.
Three examples of many:
- A type of Swiss apple, grown preferentially during the 1800′s because of its ability to be cellared for long periods of time without shriveling and rotting, makes it the perfect stem cell “source” to help prevent and treat wrinkles in human skin.
- The Alpine edelweiss, which grows at high altitudes and thrives while being bombarded with increased UV exposure from the sun, is the perfect stem cell “source” for products that prevent and help repair the skin damage of sun exposure.
- Because date palms thrive in very arid and hot climates, they are the perfect “source” for stem cells that can help protect the skin from the effects of arid and hot conditions.
“Can anyone say snake oil?”
Language Difficulties between the Kingdoms
The discussion again turns to the troublesome world of science.
There are several important questions that marketers of plant derived stem cell products are unable to answer. But, hey, if they are never asked, why worry about the answer? BFT is asking.
1) If the totipotential stem cells found in the apical and root meristems of plants are obligatory “followers” , how can it be alleged that when their extracts are combined into a skin care product they are now capable of “leading” other cells to do their bidding?”
2) If science has thus far shown that plant stem cells do not have their own intrinsic “language” i.e. organic compounds with which they influence the behavior of other cells, how does preparation of an extract now give them a “voice?”
3) If it is scientifically proved that human cells are influenced by an intricate and complex symphony of biochemical signals or “words” exclusive to the animal kingdom, how can a “mute”, “aphonic” extract of plant stem cells communicate with them?
These might be good questions to consider before buying that next expensive vial of European Swiss apple stem cell extract to treat your crow’s feet.
Direct control of shoot meristem activity by a cytokinin-activating enzyme Nature 445, 652-655
Cytokinin-Deficient Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity
The Plant Cell, Vol. 15, 2532-2550, November 2003
Auxin cross-talk: integration of signalling pathways to control plant development
Control of Outgrowth and Dormancy in Axillary Buds.
Plant Physiology; December 2001 vol. 127 no. 4 1405-1413
Cytokinin regulates root meristem activity via modulation of the polar auxin transport
PNAS March 17, 2009 vol. 106 no. 11 4284-4289
Stem cells and cellular communication in the animal kingdom
Ways in which real stem cell science can yield real results