Are We Ready to Measure Skin Permeation of Modern Antiaging GHK-Cu Tripeptide Encapsulated in Liposomes?
This review paper examines the current state of knowledge and methodology surrounding the skin permeation of GHK-Cu (glycyl-L-histidyl-L-lysine copper tripeptide), a naturally occurring cosmetically active compound (CAC) associated with properties such as reducing fine lines and wrinkles, improving skin elasticity, and tightening skin. The authors highlight a central challenge: GHK-Cu is relatively hydrophilic, which limits its ability to penetrate the lipophilic stratum corneum, the skin's outermost barrier. The paper reviews liposomal encapsulation as a strategy to improve GHK-Cu's skin permeation potential, and surveys existing methods used to study transdermal transport of CACs—both free and liposome-encapsulated. A key finding from the literature analysis is that research specifically examining liposome-mediated transport of GHK-Cu is sparse, representing a notable gap in the field. The authors argue this gap motivates further methodological development to better assess how liposomes affect GHK-Cu trafficking through skin layers. As a review, the paper synthesizes existing literature rather than presenting original experimental data, and it does not include clinical trials or controlled human studies. Its conclusions about efficacy are therefore inferential and limited by the quality and quantity of the underlying studies reviewed.
Why this grade: This is a narrative review that synthesizes existing literature on GHK-Cu skin permeation methods without presenting original experimental or clinical data, precluding a direct evidence grade for human efficacy.
Cosmetically active compounds (CACs), both of lipophilic and hydrophilic origin, have difficulty reaching the deeper layers of the skin, and this shortcoming significantly reduces their efficacy. One such CAC that occurs naturally in the human body and displays many beneficial properties (via reducing fine lines and wrinkles, tightening skin, improving its elasticity, etc.) is the glycyl-L-histidyl-L-lysine tripeptide complex of copper (GHK-Cu). GHK-Cu is a fairly hydrophilic compound with limited permeation through the lipophilic stratum corneum. On the other hand, liposomes capable of encapsulating GHK-Cu may improve its permeation potential. The present review discusses various issues related to obtaining insight into the permeation of CACs through the skin. Methods for studying the transport of CACs encapsulated by liposomes and free GHK-Cu across the skin barrier are summarized. An analysis of the literature data reveals that the transport of liposomes containing GHK-Cu received little attention. This research gap gives an impetus to the methodological developments for assessing the effect of liposomes on GHK-Cu transportation and trafficking.
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