Mechanical epilation exerts complex biological effects on human hair follicles and perifollicular skin: An ex vivo study approach
Marta Bertolini,
Jennifer Gherardini,
Jérémy Chéret
et al.
Abstract:ObjectiveElectrical epilation of unwanted hair is a widely used hair removal method, but it is largely unknown how this affects the biology of human hair follicles (HF) and perifollicular skin. Here, we have begun to explore how mechanical epilation changes selected key biological read‐out parameters ex vivo within and around the pilosebaceous unit.MethodsHuman full‐thickness scalp skin samples were epilated ex vivo using an electro‐mechanical device, organ‐cultured for up to 6 days in serum‐free, supplemented… Show more
“…Recently, it has been shown that mechanical epilation removes most of the hair shafts, often together with fragments of the outer and inner root sheath and hair matrix. This mechanically induced trauma to the hair follicle triggers complex biological responses [6]. These range from increased hair follicle keratinocyte apoptosis to differentially expressed key players of skin inflammation.…”
Background: Epilation is a very effective way to remove unwanted hair because of its long-lasting effects. However, there are some disadvantages such as pain during the procedure, the possibility of ingrown hairs and perifollicular inflammation. In the present study, we investigated whether a protease-containing post-epilation microemulsion is effective in improving epilation performance and alleviating the above problems. Methods: The application characteristics and effects of the tested microemulsion were evaluated during and after three applications in 30 female volunteers. This was conducted by measuring hair density, assessing hair strength, and evaluating the subjective experience of the volunteers using a questionnaire. Results: The measurements showed that after three applications, the apparent hair density in the axilla was reduced from 43.89 ± 12.44 hairs/cm2 to 16.67 ± 6.61 hairs/cm2 (p < 0.0001). In general, volunteers observed a reduced hair regrowth rate, resulting in longer epilation intervals, and more soothed and moisturized skin. Volunteers who previously experienced ingrown hairs or perifollicular inflammation reported the absence or improvement of these problems. Conclusions: The protease-containing microemulsion not only improves the performance of the epilation procedure, leading to less frequent epilation, but also improves possible negative effects of epilation such as ingrown hairs and perifollicular inflammation.
“…Recently, it has been shown that mechanical epilation removes most of the hair shafts, often together with fragments of the outer and inner root sheath and hair matrix. This mechanically induced trauma to the hair follicle triggers complex biological responses [6]. These range from increased hair follicle keratinocyte apoptosis to differentially expressed key players of skin inflammation.…”
Background: Epilation is a very effective way to remove unwanted hair because of its long-lasting effects. However, there are some disadvantages such as pain during the procedure, the possibility of ingrown hairs and perifollicular inflammation. In the present study, we investigated whether a protease-containing post-epilation microemulsion is effective in improving epilation performance and alleviating the above problems. Methods: The application characteristics and effects of the tested microemulsion were evaluated during and after three applications in 30 female volunteers. This was conducted by measuring hair density, assessing hair strength, and evaluating the subjective experience of the volunteers using a questionnaire. Results: The measurements showed that after three applications, the apparent hair density in the axilla was reduced from 43.89 ± 12.44 hairs/cm2 to 16.67 ± 6.61 hairs/cm2 (p < 0.0001). In general, volunteers observed a reduced hair regrowth rate, resulting in longer epilation intervals, and more soothed and moisturized skin. Volunteers who previously experienced ingrown hairs or perifollicular inflammation reported the absence or improvement of these problems. Conclusions: The protease-containing microemulsion not only improves the performance of the epilation procedure, leading to less frequent epilation, but also improves possible negative effects of epilation such as ingrown hairs and perifollicular inflammation.
We have previously shown that the thyroid hormones triiodothyronine (T3) and thyroxine (T4) prolong anagen, mitigate stem cell apoptosis, and stimulate mitochondrial functions in microdissected human scalp HFs ex vivo. To circumvent the systemic adverse effects of T3/T4, we have asked in the current pilot study whether topically applied T3/T4 retains hair growth-promoting properties. To prove this, we have topically treated healthy full-thickness human scalp skin with T3 (1, 10nM) and T4 (1, 10μM) for six days in serum-free organ culture, using an HF-targeting vehicle that contains only FDA-approved ingredients. This showed that, at distinct doses, topical T3 and T4 significantly increased the percentage of HFs in anagen, decreased the percentage of proliferative (Ki-67+) cells in the hair matrix, did not promote melanogenesis (as measured by quantitative Warthin-Starry histochemistry), and significantly increased keratin 15 expression in the bulge. Finally, T3 and T4, at low concentrations, increase the expression of the hair growth promoters IGF-1 and FGF-7. The lower concentration of T3 and both of T4 also significantly increases the number of CD31+ endothelial cells, suggesting a pro-angiogenic effect, which is also important for hair growth promotion. These preliminary results strongly suggest that topically applied thyroid hormones promote hair growth in intact human scalp on multiple levels ex vivo. This invites the intermittent pulse application of topical T3 and T4 as a novel therapeutic intervention for managing hair loss disorders associated with telogen effluvium, such as androgenetic alopecia.
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