Spicules in Cosmetic Formulation

When it comes to skin aging, East Asian consumers are known to be mostly worried by the onset of age spots. As far as skin homeostasis is concerned, they tend to avoid facultative pigmentation. And because of cultural tradition, they prefer to somehow conceal pigmented skin and make it appear as white.

This might be a reason why the skin care market north of the Tropic of Cancer and east of the 85th Meridian is so eager for whiteners, brighteners and skin lightening products in general.

To make a skin “white” one must, first, remove the pigment from the epidermis, and then, hinder the synthesis of new pigment. Each one of these two actions is a formidable task. Melanin, be it eumelanin or phaeomelanin, is impervious to enzymatic degradation and its color can be changed with hydrogen peroxide, hardly a skin-friendly Reactive Oxygen Species (ROS). The inhibition of melanin production is also quite difficult because there are several enzymes that perform the first steps of the biochemical pathways that end with the melanin-producing oxidative chain reactions.  

The makers of whiteners have followed several strategies to whiten or brighten the skin, all with limited
success. Theoretically, if one could block the production of melanin, one could achieve pigment-free epidermis in about four weeks; that is the time necessary for the complete renewal of the epidermis. Impatient consumers unwilling to wait for a month  are offered some kind of dermabrasion, a procedure that removes the pigment together with the epidermis in only a few sessions. 

For the consumers feeling that this method is too harsh, chemical peeling was proposed as a possibility to accelerate skin lightening without the use of invasive procedures. 

Other manufacturers realized that the inhibitors of pigment production need to penetrate down to the basal layer of the epidermis, and tried ways to disrupt what is called the “barrier” using physical procedures. One of these ways was to perforate the epidermis with microneedles. 

This method was successfully applied to reducing the melasma—associated discoloration using tranexamic acid, by creating holes that allowed the topically applied whitening factor to reach the basement membrane. And yet, microneedles too might appear to be invasive for some consumers.

WHAT ABOUT SPICULES?

What can be gathered from all of the above is that the basic strategy for whiteners requires removing by physical scraping part of the epidermis to impair the barrier function and adding some active able to inhibit the production of the pigment or its transfer to the keratinocytes. 

The latest tool to disrupt the “barrier” is a natural product consisting of needle-like crystalline rods derived from marine or fresh water sponges. They are about 0.1 mm long, and when rubbed on the skin they perform a gross exfoliation that can be slightly painful and is believed to open random ways of access to the lower layers of the epidermis for the desired active ingredients. 

With the creative use of words, characteristic of our epoch, these calcareous or siliceous rods are sometimes called liquid microneedling to evoke the possibility of achieving the effect of stingy, solid microneedles in enhancing the penetration of topically applied active ingredients. 

When rubbed onto the skin, spicules are said to provide a form of “non-invasive,” mechanical exfoliation. One could say that they dig microchannels in the epidermis. These microchannels would allow active ingredients—like serums, niacinamide or other vitamins—to penetrate into the skin rather than remain on the surface. The spicules are said to remain in the skin for approximately 24 to 72 hours before naturally shedding with the skin’s normal renewal cycle, thus suggesting that the estimated depth of penetration of the spicules is about one to three layers of the stratum corneum..  

Spicules are tools of active cosmetics. They have a few undesirable side effects. Tingling, stinging  or prickling sensation upon application are often reported. The mechanical abrasion can cause redness or sensitivity, particularly in consumers with sensitive skin. 

Topical products containing spicules can be found in the market. One of them contains spicules to favor the penetration of 3% tranexamic acid and 5% nicotinamide. 

When topically applied, tranexamic acid is more efficient when it is accompanied by a microneedle treatment. And tranexamic acid in liposomes is as active as hydroquinone against melasma discolorations. Since microneedles and liposomes favor the penetration of the encapsulated material, it is reasonable to associate tranexamic acid with a propenetrant like the spicules.  

On the other hand nicotinamide penetrates freely across the epidermis and will easily exert its inhibitory action on the transfer of melanosomes from melanocytes to keratinocytes even in the absence of spicules.

Another product contains spicules and PDRN—the acronym stands for Poly Deoxy Ribo Nucleotide, the chemical name of DNA. 

The PDRN contained in this product originates from salmon sperm, which does not grant a specific, origin-linked activity. Yet, whatever the origin, PDRN is water-soluble polymer that might help moisturizing the skin at epidermal depth, with the help of spicules. 

Another example of spicules-containing product is a plumping and firming mask with ingredients such as hyaluronic acid, collagen and complex peptides.

COULD BENEFITS BRING SCRUTINY?

Spicules are said to help smooth rough skin and reduce the appearance of enlarged pores. They help unclog pores and deliver anti-inflammatory ingredients to the site of acne. It is also said that products containing spicules can improve the skin permeability of active ingredients, potentially increasing efficacy by up to 342%….and I am very curious about how this number has been determined. 

Last but not least, they are also said to stimulate the skin’s repair mechanisms and, while promoting cell turnover and collagen production, they are said to help improve elasticity and reduce fine lines. I am surprised that the FDA has nothing to say. 

Paolo Giacomoni, PhD

Insight Analysis Consulting
[email protected]

Paolo Giacomoni acts as an independent consultant to the skin care industry. He served as Executive Director of Research at Estée Lauder and was Head of the Department of Biology with L’Oréal. He has built a record of achievements through research on DNA damage and metabolic impairment induced by UV radiation as well as on the positive effects of vitamins and antioxidants. He has authored more than 100 peer-reviewed publications and has more than 20 patents. He is presently Head of R&D with L.RAPHAEL—The science of beauty—Geneva, Switzerland.