Microneedle fractional radiofrequency increases epidermal hyaluronan and reverses age‐related epidermal dysfunction

Background and Objective Skin aging results in physiological alterations in keratinocyte activities and epidermal function, as well as dermal changes. Yet, the cellular and molecular mechanisms that cause epidermal dysfunction during skin aging are not well understood. Recently, the role of epidermal hyaluronan (HA) as an active regulator of dynamic cellular processes is getting attention and alterations in HA metabolism are thought to be important in age‐related epidermal dysfunction. Microneedle fractional radiofrequency (RF) has shown effects for improving cutaneous aging. However, little is known about the effects of fractional RF on the epidermal HA and epidermal function. We investigated the effect of microneedle fractional RF on the expression of epidermal HA in young and aged mice epidermis. Materials and Methods We performed fractional RF on the dorsal skin of 30 8‐week‐old (young) hairless mice and 15 47‐week‐old (aged) C57BL/6J mice. Skin samples were collected on day 1, 3, and 7. HA content was measured by ELISA. Gene expressions of CD 44 , HABP4 , and HAS3 were measured using real time RT‐PCR. Immunohistochemistry for detection of HA, CD44, PCNA, and filaggrin were performed. Results HA content and the mRNA levels of HABP4 , CD44 , and HAS3 were upregulated in the epidermis of both young and aged mice after microneedle fractional RF treatment. The expression was increased from day 1 after treatment and increased expression persisted on day 7. Fractional RF treatment significantly increased PCNA and filaggrin expression only in the aged mice skin. Conclusion Microneedle fractional RF increased epidermal HA and CD44 expression in both young and aged mice and reversed age‐related epidermal dysfunction especially in aged mice, suggesting a new mechanism involved in the skin rejuvenation effect of microneedle fractional RF. Lasers Surg. Med. 48:140–149, 2016. © 2015 Wiley Periodicals, Inc.