Skin cell monolayer versus Phenion® Full Thickness skin model as tools for identification of skin active natural products

Identification and development of plant derived extracts and natural products for skin regeneration and wound-healing is getting more and more into the focus of dermatological research. Physiological activity of natural products on human skin cells can be investigated in monolayer cell cultures of keratinocytes and dermal fibroblasts. Additionally to that the Phenion® Full Thickness skin model, a three dimensional complex tissue engineered skin substitute, can be used for effective identification of protective and regenerative effects of test compounds.

Two polysaccharide-enriched extracts of the endosperm from Jatropha curcas L. (Euphorbiaceae), a traditionally used medical plant from India and South America, showed strong physiological activity on human skin cells. Treatment of monolayer cell cultures (HaCaT, primary keratinocytes and fibroblasts) with the extract (10 and 100µg/mL) significantly enhanced cell viability (WST1) in all cases, while cellular proliferation (BrdU-incorporation ELISA) was not influenced. The significant induction of keratinocyte differentiation was determined by immuno-blotting of specific proteins keratin K1, K10 and involucrin. Gene expression of proliferation and differentiation markers was maintained by RT-PCR. Native and irritated (1% SDS) Phenion® FT skin substitutes were incubated with test extract (1mg/mL) in order to quantify regenerative and protective effects. Immunoassays indicated an increase of the proliferation markers HGF (Hepatocyte Growth Factor) and KGF (Keratinocyte Growth Factor) in extract-treated native models whereas treatment of SDS-irritated tissue reduced the formation of HGF and KGF significantly. No significant expression of typical inflammation markers was detected. Gene expression analysis showed an increased expression of HGF and TGF-β in all extract-treated tissues, whereas no stimulation of KGF was observed on the transcriptional level.

Summarizing the combination of both, cell culture monolayers as well as tissue substitutes, gives a unique opportunity to increase the generation of valid data for an effective screening and development of skin active products.