Fig. 4: SFRP1 knockdown in human epidermal organoids.

A Schematic diagram of a working model of SFRP1 in the interfollicular epidermis. B Hematoxylin and eosin (H&E) staining on control and SFRP1-depleted epidermal organotypic tissues. Dotted black lines denote the basement membrane. Black arrowheads highlight example regions of collections of progenitor keratinocytes. Scale bar, 150 µm. C Quantification of basal curvature in (B). Each datapoint represents the curvature measurement of the basal layer of a sampled H&E image. Data are median ± interquartile range. (n = 30 from three independent biological replicates, two-tailed unpaired student’s t-test). D Quantification of epidermal area in (B). Each datapoint represents the relative area measurement of the epidermis of a sampled H&E image. Data are median ± interquartile range. (n = 30 from three independent biological replicates, two-tailed unpaired student’s t-test). E Immunofluorescence of epidermal organotypic tissues. Ki-67 marks proliferating keratinocytes. White dotted lines demarcate the basement membrane. Scale bar, 150 µm. F Quantification of Ki-67 positive cells in (E). Each datapoint represents the count of Ki-67+ cells from a sampled image, normalized to tissue length. Data are median ± interquartile range. (n = 30 from three biological replicates, evaluated with two-tailed unpaired student’s t-test). G Immunofluorescence of keratin 10, filaggrin, and loricrin in control and SFRP1-depleted epidermal organotypic tissues. Dotted white lines denote the basement membrane. Scale bar, 150 µm. H Quantitative RT-PCR of SFRP1 (isoform SFRP1_201, and total SFRP1) and differentiation-associated genes (KRT1, KRT10, FLG, LOR) in organoid epidermis in control and SFRP1 depleted tissues. I Immunoblot of FOXM1 in shControl and shSFRP1 primary keratinocytes over time course of in vitro differentiation. For relative quantitation, FOXM1 signal was normalized to beta tubulin, and the shControl day 0 signal was set to 1. J SFRP1 mRNA expression in skin diseases. Gene expression data from studies of keratinocyte cancers, psoriasis, and eczema were compiled. Selected studies included patient-matched normal skin (NS). Two-sided t-tests were performed to compare expression in NS vs. disease states. Data are mean ± SEM. Sample sizes (n) for each group depicted in figure. NS normal skin, AK actinic keratosis, IEC intraepidermal carcinoma, SCC squamous cell cancer, Pso psoriasis. P values shown above pairwise comparisons.