A 3D-psoriatic skin model for dermatological testing: The impact of culture conditions.

BACKGROUND: Inadequate representation of the human tissue environment during a preclinical screen can result in inaccurate predictions of compound effects. Consequently, pharmaceutical investigators are searching for preclinical models that closely resemble original tissue for predicting clinical outcomes. METHODS: The current research aims to compare the impact of using serum-free medium instead of complete culture medium during the last step of psoriatic skin substitute reconstruction. Skin substitutes were produced according to the self-assembly approach. RESULTS: Serum-free conditions have no negative impact on the reconstruction of healthy or psoriatic skin substitutes presented in this study regarding their macroscopic or histological appearances. ATR-FTIR results showed no significant differences in the CH2 bands between psoriatic substitutes cultured with or without serum, thus suggesting that serum deprivation did not have a negative impact on the lipid organization of their stratum corneum. Serum deprivation could even lead to a better organization of healthy skin substitute lipids. Percutaneous analyses demonstrated that psoriatic substitutes cultured in serum-free conditions showed a higher permeability to hydrocortisone compared to controls, while no significant differences in benzoic acid and caffeine penetration profiles were observed. CONCLUSIONS: Results obtained with this 3D-psoriatic skin substitute demonstrate the potential and versatility of the model. It could offer good prediction of drug related toxicities at preclinical stages performed in order to avoid unexpected and costly findings in the clinic. GENERAL SIGNIFICANCE: Together, these findings offer a new approach for one of the most important challenges of the 21st century, namely, prediction of drug toxicity.

Characterization of a psoriatic skin model produced with involved or uninvolved cells.

Current knowledge suggests that uninvolved psoriatic skin could demonstrate characteristics associated with both normal and involved psoriatic skins. However, the triggering factor allowing the conversion of uninvolved skin into a psoriatic plaque is not fully understood. To counter this lack of information, we decided to develop pathological skin substitutes produced with uninvolved psoriatic cells, in order to better characterize the uninvolved psoriatic skin. Substitutes were produced using the self-assembly approach. Macroscopic, immunohistochemical, permeability and physicochemical results showed that involved substitutes had a thicker epidermis, higher cell proliferation, abnormal cell differentiation and a more permeable and disorganized stratum corneum compared with normal substitutes. Various results were observed using uninvolved cells, leading to two proposed profiles: profile 1 was suggested for uninvolved skin substitutes mimicking the results obtained with normal skin substitutes; and profile 2 was dedicated to those mimicking involved skin substitutes in all aspects that were analysed. In summary, uninvolved substitutes of profile 1 had a thin, well-organized epidermis with normal cell proliferation and differentiation, such as observed with normal substitutes, while uninvolved substitutes of profile 2 showed an inverse trend, i.e. a thicker epidermis, higher cell proliferation, abnormal cell differentiation and a more disorganized and more permeable stratum corneum, such as seen with involved substitutes. The results suggest that uninvolved substitutes could demonstrate characteristics associated with both normal or involved psoriatic skins.

Effects of serum-free culture at the air-liquid interface in a human tissue-engineered skin substitute.

Previous studies have reported that well-defined culture conditions can improve keratinocytes terminal differentiation and reproducibility. The aim of our study was to compare skin substitutes cultured in a complete medium with those cultured in a serum-free medium at the air-liquid interface to optimize the self-assembly method. Skin substitutes, cultured in a serum-free medium over 7, 14, and 21 days, were compared with others cultured in a complete medium (5% serum) over the complete culture period. Masson's Trichrome staining showed that the substitutes cultured in a serum-free medium generated a well-developed and differentiated epidermis. Immunolabeling analyses between the substitutes cultured without serum and those cultured in complete serum showed similar expression of epidermal differentiation markers, dermo-epidermal junction, and dermal extracellular matrix components. On the basis of our Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) results, the skin substitutes cultured in serum-free condition over 21 days of culture at the air-liquid interface showed lower frequencies of the CH(2) symmetric mode of vibrations, which means a better lipid organization of the stratum corneum. No significant difference in hydrocortisone penetration was observed between serum-free medium substitutes and the controls. Results demonstrate that the absence of serum does not compromise the characteristics of the skin substitutes observed in this study.

Antioxidant, toxicological and antiproliferative properties of Canadian polyphenolic extracts on normal and psoriatic keratinocytes.

AIMS OF THE STUDY: In a first attempt for establishing the possible utilization of polyphenolic extracts from barks of Canadian wood species in psoriasis treatment, we aimed to study (a) their antioxidant capacity, (b) their toxicological properties on normal human keratinocytes (NHK), and (c) their effect on the growth of normal and psoriatic keratinocytes (PK). MATERIALS AND METHODS: Polyphenolic extracts were obtained by 90% ethanolic maceration and hot water extraction (HWE). Scavenging capacity was evaluated towards hydrogen peroxide, hydroxyl, superoxide, nitric oxide and peroxyl radicals. MTT assay and Trypan blue dye exclusion (TBDE) method were used for evaluating the initial toxicity of the most antioxidant extracts on NHK during 24 and 48 h. The effects of extracts on the growth of NHK and PK at non-toxic concentrations were determined after exposure for 48 h. RESULTS: Yellow birch extract obtained by maceration (YB(Mac)) and black spruce extract obtained by HWE (BS(HWE)) were determined to have the highest antioxidant capacity, but BS(HWE) was less toxic on NHK. Toxicity of extracts on keratinocyte plasma membrane and mitochondria after 24 h was attributed to their content of hydroxycinnamic acids and proanthocyanidins. BS(HWE) inhibited the growth of NHK and non-lesional PK, but was not selective for lesional PK. CONCLUSION: Given that BS(HWE) presented elevated content of total phenols and flavonoids and showed a low toxicity on NHK as well as an adequate chemical reactivity towards different radicals and some antiproliferative properties, it was considered as the most valuable extract obtained from barks of Canadian wood species.