Skin penetration of high molecular weight HA thank to a breakthrough vectorization system
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Presented by: Marie Meunier
Introduction: Hyaluronic acid (HA) is an iconic cosmetic active ingredient, owing multiple skin care benefits according its molecular weight (MW). Indeed, the high molecular weight (HMW) HA of approximatively 1-1.4 million Dalton stay at the skin surface, known to mainly bring skin surface effects such as high moisturizing through film-forming property on skin. Here, we developed an innovative vectorization technology in order to drive HMW HA into skin through better skin penetration to get optimized HA benefits for cosmetic application.
Methods: HMW HA was vectorised thanks to an innovative vectorization technology using a particular type of smectites and was here named e-vector-HA. Skin penetration analysis was done on e-vector-HA versus HA alone by micro-imaging Raman spectroscopy after 8 hours of topical treatment. We conducted several experiments in order to elucidate the mode of action of e-vector-HA. First, HA’s MW was determined by Size Exclusion Chromatography on HA derivatives products. Then, we studied their sensitivity to natural hyaluronidases in tubo by estimating the size of each HA by LC/SEC. Finally, electrical potential of each HA products was studied by Zeta potential analysis with a Zetasizer-Nano-Z. We explored the benefit of e-vector-HA by evaluating the smoothing effect on skin explants cultured in low hygrometry using Scanning Electron Microscopy (SEM). Finally, a clinical study was conducted to measure the benefit of e-vector-HA on crow’s feet surface and skin mattifying by VISIA® 2.3 analysis.
Results: Skin penetration study by Raman spectroscopy on skin evidenced an accumulation of HA alone at the skin surface while e-vector-HA penetrated until 70µm depth. We hypothesized that HMW HA can penetrate into the skin because of HA degradation due to the process, higher sensitivity to hyaluronidase or even depolarization. The MW analysis revealed that the HA conserved the same MW before and after the process. The in tubo test of degradation by hyaluronidase evidenced that HA alone and e-vector-HA had the same sensitivity to hyaluronidase with a degradation by 99.3% and by 99.9% respectively. Finally, the evaluation of zeta potential evidenced that e-vector-HA has a more negative electrical potential than HA alone with a bigger impact of the pH on it. SEM study on skin explants evidenced a clear smoothing effect with e-vector-HA and the clinical study evidenced a significant reduction of crow’s feet wrinkles surface until -22.7% after 28 days. e-vector-HA also bring a mattifying effect with a significant decrease of brightness until -10.2% after 28 days.
Discussion: In this study, we first evidenced that our innovative vectorization technology allowed improving the penetration of HMW HA into the skin while the same HA alone accumulated at the skin surface. The vectorization process did not impact the HA’s MW, which could not explain this difference of penetration into the skin. The two products presented the same sensitivity to hyaluronidase, showing that the difference of penetration could not be explained by a difference of HA degradation between the products. The used vectorization technology is known to favour the anionic charge of HA, thus we hypothesized that this could have modified the electric potential of HA and maybe increased its affinity for the skin. Zeta potential measurement of each product highlighted a difference between the two products: electric potential of e-vector-HA was more negative than those of HA alone, and negativity was enhanced by the increase of pH. We supposed that negatively charged molecules applied at the skin surface will preferentially penetrate into the skin in order to avoid being repelled by the skin surface known to be negatively charged. So, e-vector-HA has a higher affinity for the epidermis than the HA alone, facilitating skin penetration. More, pH increases when going deeper into the skin, contributing to decrease electric potential of e-vector-HA and favouring penetration into the skin. We showed that improving skin penetration of HMW HA allowed improving skin surface has shown ex vivo, bringing an anti-ageing benefit thank to HA and a mattifying effect thank to smectites.
Conclusion: By using an innovative vectorization technology modifying the HA electric potential without altering its MW, and by capitalizing on the natural pH gradient of the skin, we showed for the first time that HMW HA are able to penetrate into the skin, enlarging the clinical benefits of this iconic cosmetic ingredient.
Methods: HMW HA was vectorised thanks to an innovative vectorization technology using a particular type of smectites and was here named e-vector-HA. Skin penetration analysis was done on e-vector-HA versus HA alone by micro-imaging Raman spectroscopy after 8 hours of topical treatment. We conducted several experiments in order to elucidate the mode of action of e-vector-HA. First, HA’s MW was determined by Size Exclusion Chromatography on HA derivatives products. Then, we studied their sensitivity to natural hyaluronidases in tubo by estimating the size of each HA by LC/SEC. Finally, electrical potential of each HA products was studied by Zeta potential analysis with a Zetasizer-Nano-Z. We explored the benefit of e-vector-HA by evaluating the smoothing effect on skin explants cultured in low hygrometry using Scanning Electron Microscopy (SEM). Finally, a clinical study was conducted to measure the benefit of e-vector-HA on crow’s feet surface and skin mattifying by VISIA® 2.3 analysis.
Results: Skin penetration study by Raman spectroscopy on skin evidenced an accumulation of HA alone at the skin surface while e-vector-HA penetrated until 70µm depth. We hypothesized that HMW HA can penetrate into the skin because of HA degradation due to the process, higher sensitivity to hyaluronidase or even depolarization. The MW analysis revealed that the HA conserved the same MW before and after the process. The in tubo test of degradation by hyaluronidase evidenced that HA alone and e-vector-HA had the same sensitivity to hyaluronidase with a degradation by 99.3% and by 99.9% respectively. Finally, the evaluation of zeta potential evidenced that e-vector-HA has a more negative electrical potential than HA alone with a bigger impact of the pH on it. SEM study on skin explants evidenced a clear smoothing effect with e-vector-HA and the clinical study evidenced a significant reduction of crow’s feet wrinkles surface until -22.7% after 28 days. e-vector-HA also bring a mattifying effect with a significant decrease of brightness until -10.2% after 28 days.
Discussion: In this study, we first evidenced that our innovative vectorization technology allowed improving the penetration of HMW HA into the skin while the same HA alone accumulated at the skin surface. The vectorization process did not impact the HA’s MW, which could not explain this difference of penetration into the skin. The two products presented the same sensitivity to hyaluronidase, showing that the difference of penetration could not be explained by a difference of HA degradation between the products. The used vectorization technology is known to favour the anionic charge of HA, thus we hypothesized that this could have modified the electric potential of HA and maybe increased its affinity for the skin. Zeta potential measurement of each product highlighted a difference between the two products: electric potential of e-vector-HA was more negative than those of HA alone, and negativity was enhanced by the increase of pH. We supposed that negatively charged molecules applied at the skin surface will preferentially penetrate into the skin in order to avoid being repelled by the skin surface known to be negatively charged. So, e-vector-HA has a higher affinity for the epidermis than the HA alone, facilitating skin penetration. More, pH increases when going deeper into the skin, contributing to decrease electric potential of e-vector-HA and favouring penetration into the skin. We showed that improving skin penetration of HMW HA allowed improving skin surface has shown ex vivo, bringing an anti-ageing benefit thank to HA and a mattifying effect thank to smectites.
Conclusion: By using an innovative vectorization technology modifying the HA electric potential without altering its MW, and by capitalizing on the natural pH gradient of the skin, we showed for the first time that HMW HA are able to penetrate into the skin, enlarging the clinical benefits of this iconic cosmetic ingredient.