Figure 5

Higher differentiation processes of keratinocytes in epidermis of Caucasian in vitro RS models compared to those in epidermis of African RS. (a) Representative histology of RS and protein expression patterns in the different epidermal layers for keratin 14, filaggrin and filaggrin 2 in African and Caucasian RS. Nuclei were counterstained with DAPI. Scale bars: 25 µm for HES and 100 µm for immunostainings. Note that epidermis of Caucasian RS showed more granular layers, indicated by arrows, as compared to that of African RS (b) Quantification of immunofluorescent detection of keratin 14, filaggrin and filaggrin 2 (N-term region) in RS (n = 3 donors per skin type). Mean are reported ± SE (n = 3 replicates per donor). (c) Permeability to Lucifer yellow was tested at day 9 of the emersion phase of new RS experiments. Mean are reported ± SE (n = 4 donors per skin type). Note that fluorescent detection showed that the dye was retained in the SC of epidermis of both African RS and Caucasian RS. However, it appears that fluorescent dye have diffused down more in the SC layers of African RS. Scale bar: 50 µm. Statistical significance between African and Caucasian RS groups were determined using the non-parametric Mann-Whitney test, denoted with *(P < 0.05).