Dermatologists have known for years that collagen, hyaluronic acid, and elastin decline in concentration with advancing age. Many products have been convincingly shown to increase synthesis of collagen, such as retinoids, vitamin C, and glycolic acid.
However, elastin production is more elusive. Elastin is of particular interest because its loss is responsible for the sagging of the skin with aging, and it also may play a role in the formation of stretch marks. Although I have been unable to find an original reference proving this, many people say that elastin production ceases after puberty. Obviously, increasing collagen and elastin production would be beneficial to the skin's appearance.
Collagen and elastin are made by fibroblasts. These cells play a vital role in wound healing, as they deliver extracellular matrix components that facilitate the migration of other cell types to the wound site (Exp. Dermatol. 2003;12:396-402). This column will briefly discuss some of the research and concepts pertaining to electric stimulation of fibroblasts as a way of promoting the synthesis of collagen and elastin. In fact, the existence and importance of bioelectricity in the human body have been acknowledged for years in relation to wound healing, insofar as electric fields were measured at the sites of human dermal wounds more than 150 years ago, and modern techniques have verified the existence of endogenous electric fields in wounds (Methods Mol. Biol. 2009;571:77-97).
History
Although German physiologist Emil DuBois-Reymond is credited as being the first to identify endogenous electric fields in wounds (based on his paper in 1843 [Ann. Phys. u. Chem. 1843;58:1-30] and his book in 1860 [DuBois-Reymond E. "Untersuchungen uber Thierische Elektricitat, Zweiter Band, Zweite Abtheilung" (Erste Lieferung) Berlin: Georg Reimer; 1860]) and as a founder of modern electrophysiology, several others made key discoveries along the way.
According to a review of bioelectricity by McCaig et al., in the 1700s Italian physician Luigi Galvani, whose surname is the basis for the word "galvanism," witnessed the bioelectric response while dissecting a frog and performing various related experiments (Physiol. Rev. 2005;85:943-78). He termed the phenomenon "animal electricity."
Notably, Italian physicist Alessandro Volta studied the phenomenon and applied its principles to develop the first battery in 1800. Later, in 1831, Italian physicist and neurophysiologist Carlo Matteucci built on Galvani's work by using a galvanometer (named for Galvani, of course) to measure the injury potential of damaged frog muscle (Physiol. Rev. 2005;85:943-78). In the process, Matteucci became the first to demonstrate the action potential in nerves and muscle. DuBois-Reymond subsequently used these findings as the foundation for his considerable contributions revealing injury currents in the skin.
Given the discovery of the formation of an electrical gradient on the skin, its transmission to neighboring cells might be said to make intuitive sense, given how close cells are in relation to one another.
Wound Healing
Contemporary studies continue to shed light on the role of bioelectricity in cutaneous health. Some recent studies also appear to offer potential implications for antiaging therapies.
In 1997, a review by Beech indicated that the migration of cells into wound sites and the stimulation of quiescent cells at the wound margins can be fostered by exogenous, extremely low frequency fields positioned close to the target site, as well as endogenous tissues with enough zeta potential (Bioelectromagnetics 1997;18:341-8).
In 2009, Zhao concluded that electric fields of physiological strength play an overriding role in directing cell migration during epithelial wound healing (Semin. Cell Dev. Biol. 2009;20:674-82). In 2006, Zhao et al. demonstrated experimentally that electric fields, equal in strength to endogenous ones, direct the migration of inflammatory cells, fibroblasts, and epithelial cells in wound healing as the predominant directional signal. In their experiment, the investigators determined that the tumor suppressor phosphatase and tensin homolog (PTEN) and phosphatidylinositol-3-OH kinase-gamma control electrotaxis. They also identified the first genes that influence cellular movement and are necessary for wound healing prompted by electrical signaling (Nature 2006;442:457-60).
More recently, some of the same investigators, including Zhao and McCaig, noted the inherent vectoral nature of electric fields, and again investigated galvanotaxis/electrotaxis or directional cell migration in wound healing. They established several experimental systems, and found that electric fields of potency equal to those identified at in vivo wounds direct cell migration and supersede other guidance cues (e.g., contact inhibition). They concluded that endogenous electric fields may represent significant signaling mechanisms for guiding cellular movement and migration in vivo, and that exogenously applied electric fields may play a clinical role in guiding cell migration in wound healing, with greater versatility than other guidance cues (such as chemical ones) (Methods Mol. Biol. 2009;571:77-97).