Usefulness of Skin Explants for Histologic Analysis after Fractional Photothermolysis

Abstract

BackgroundFractional laser resurfacing treatment has been extensively investigated and is widely used. However, the mechanism underlying its effects is poorly understood because of the ethical and cosmetic problems of obtaining skin biopsies required to study the changes after laser treatment.ObjectiveTo evaluate the usefulness of human skin explants for the investigation of fractional photothermolysis.MethodsFull-thickness discarded skin was treated in 4 ways: no treatment (control), fractional carbon dioxide laser, fractional Er:YAG laser, and fractional 1,550-nm erbium-doped fiber laser. Both treated and non-treated skin samples were cultured ex vivo at the air-medium interface for 7 days. Frozen tissue was sectioned and stained with hematoxylin & eosin for histologic examination and nitro blue tetrazolium chloride for viability testing.ResultsSkin explants cultured for up to 3 days exhibited histologic changes similar to those observed in in vivo studies, including microscopic treatment zones surrounded by a thermal coagulation zone, re-epithelialization, and formation of microscopic epidermal necrotic debris. However, the explant structure lost its original form within 7 days of culture. The viability of skin explants was maintained for 3 days of culture but was also lost within 7 days.ConclusionThe skin explant model may be a useful tool for investigating the immediate or early changes following fractional photothermolysis, but further improvements are required to evaluate the long-term and dermal changes.

Human skin explant model for the investigation of topical therapeutics

“…Cytokine stimulation of HESC provoked immune cell responses with release of chemokines, antimicrobial peptides and keratinocyte differentiation markers associated with clinical psoriasis 10 . However, in the HESC model literature 1 , 6 , 11 – 13 , a general increase in epidermal thickness is noted over the first week in culture with a decrease in tissue integrity and keratinocyte differentiation occurring after ~ 14 days. In addition, a loss of keratinocyte proliferation is accompanied by an increase in keratinocyte apoptosis evident after the first week 9 .…”

Ex vivo culture of keratinocytes on papillary and reticular dermal layers remodels skin explants differently: towards improved wound care

“…1f, g) and poor reproducibility beyond 21 days partly due to coiling up of the explant, which enclosed the exposed surface (data not shown). However, human dermal explants cultured at a liquid–air interface in vitro have been shown by others to remain viable after 7 days [12] and in some cases 75 days [11]. While no keratinocytes were detected on explant surfaces after 7 days (Fig.…”

“…1i, l). This varied keratinocyte distribution may be due to differences in the physical features of the two dermal layers, though others have demonstrated variation in ECM biochemistry, including that which affects keratinocyte proliferation and migration (i.e., hyaluronan and other proteins) as well as ECM remodelling, across dermal layers [11].…”

Changes in antioxidant, inflammatory and metabolic markers during 1 week cultivation of human skin explants

“…The difference may be linked to the lower concentration of calcium ions in the culture medium. While we and Frade et al () used media with a high concentration of calcium (~1.35 and 1.8 mmol/L, respectively), Park et al () used RPMI 1640 medium with 0.4 mmol/L of calcium. This phenomenon was earlier described by Varani et al .…”

“…This agrees with previous reports by Frade et al () and Balaji et al (). On the other hand, Park et al showed detachment of the spinous layer in the epidermis and degenerative changes in dermal collagen after 7 days of HSE in culture Park et al (). The difference may be linked to the lower concentration of calcium ions in the culture medium.…”