Epidermal lipid metabolism of cultured skin substitutes during healing of full‐thickness wounds in athymic mice

Abstract

Cultured epidermal keratinocytes provide an abundant supply of biologic material for wound treatment. Because restoration of barrier function is a definitive criterion for efficacy of wound closure and depends on the lipids present in the epidermis, we analyzed lipid composition of the epidermis in cultured skin substitutes in vitro and after grafting to athymic mice. The cultured skin substitutes were prepared from human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan substrates. After 14 days of incubation, cultured skin substitutes were grafted orthotopically onto full-thickness wounds in athymic mice. Samples for lipid analysis were collected after 14 and 34 days of in vitro incubation, and 3 weeks and 4 months after grafting. Both in vitro samples show disproportions in epidermal lipid profile as compared with the native human epidermis, i.e., a low amount of phospholipids (indicating imbalance in proliferation and differentiation); a large excess of triglycerides (storage lipids); and low levels of free fatty acids, gluco-sphingolipids, cholesterol sulfate, and ceramides-suggesting abnormal composition of stratum corneum barrier lipids. Fatty acid analysis of cultured skin substitutes in vitro revealed insufficient uptake of linoleic acid, which resulted in increased synthesis of and substitution with monounsaturated fatty acids, mainly oleic acid. These abnormalities were partially corrected by 3 weeks after grafting; and 4 months after grafting, all epidermal lipids, with some minor exceptions, were synthesized in proportions very similar to human epidermis. Results of this study show that grafting of cultured skin substitutes to a physiologic host permits the recovery of lipid in proportion to that required for barrier formation in normal human epidermis.

Royal jelly enhances migration of human dermal fibroblasts and alters the levels of cholesterol and sphinganine in anin vitrowound healing model

“…3A). In contrast to our results, previous reports found that in cultured skin substitutes grown in vitro the levels of cholesterol and free fatty acids were increased during the healing process with grafting [10,26]. An increase in the levels of lipids in HDFn, in particular sphingolipids such as ceramides and glucosylceramides, has been noted to occur in the wound healing process [27,28].…”

“…Recent evidence indicates that increased lipid biosynthesis may also enhance wound healing closure and restoration of the barrier function of the skin during the wound healing process. The skin barrier is formed from the lipid-enriched membrane of the stratum corneum, which is the outer most layer of the epidermis, and is organized with a repetitive lamellar structure of sphingolipids, cholesterol, and fatty acids [3,10]. Reduced lipid synthesis delays wound healing [11] and enhanced wound closure with an increased level of skin barrier lipids has been reported during the wound healing process of skin [11,12].…”

3D skin models for 3R research: The potential of 3D reconstructed skin models to study skin barrier function

“…In the stratum corneum of HSEs, the chain length of FFAs is shorter when compared to native human skin, but improvement of the lipid profile has been achieved by the supplementation of fatty acids in the medium . More recently, two different HSE and one HEE model and their ceramide profiles were examined .…”

Studying the penetration of fatty acids into human skin by ex vivo TOF-SIMS imaging

“…FFAs, naturally present in the SC, predominantly have saturated and straight chains of 22 (docosanoic acid), 24 (lignocerin acid) and 26 (hexacosanoic acid) carbon atoms [3,4]. Oleic and linoleic acids are the only unsaturated fatty acids detected in SC [5]. Freeze-fracture [6,7] and ruthenium tetroxide post-fixation [8] electron microscopy studies revealed that lipids are arranged into bilayers [9,10].…”