Human epidermis organotypic cultures, a reproducible system recapitulating the epidermis in vitro.

The translatability of research is highly dependent on models that recapitulate human tissues and organs. Here, we describe a procedure for the generation of human epidermis organotypic cultures (HEOCs) from primary keratinocytes isolated from foreskin and adult skin as well as from an immortalized keratinocyte cell line (KerTr). We tested several media conditions to develop a defined HEOC growing and expansion media. We characterized the HEOCs and show that in optimal culture conditions they express the proliferation marker Ki67, the basement membrane protein collagen 17 (col17) and the epidermal differentiation markers keratin 15 (K15), keratin 14 (K14), keratin 5 (K5), keratin 10 (K10), keratin 1 (K1), transglutaminase 1 (TGM1), transglutaminase 3 (TGM3) and filaggrin (FLG). Thus, they recapitulate the human epidermis and are stratified from the basal layer to the stratum corneum. These HEOC can be generated reproducibly on a large scale, making it an invaluable model for screening therapeutic compounds and also for the study of pathologies affecting the epidermis.

Targeting the IL-17 Receptor Using Liposomal Spherical Nucleic Acids as Topical Therapy for Psoriasis.

The activation of T helper 17 signaling plays a critical role in psoriasis pathogenesis, and systemically-administered IL-17 inhibitors are highly effective therapy for moderate-to-severe disease. We generated topically-delivered gene-regulating nanoconstructs, comprised of spherically-arrayed antisense DNA (liposomal spherical nucleic acids [L-SNAs]), which are able to penetrate human skin to knock down cutaneous gene targets. Topically-applied L-SNAs targeting the gene encoding the mouse IL-17A receptor (Il17ra) reversed the development of psoriasis clinically, histologically, and transcriptionally in imiquimod-treated psoriasis-like mouse skin. Il17ra L-SNAs reduced the modified PASI by 74% versus controls and decreased epidermal thickness by 56%. Il17ra L-SNA reduced Il17ra protein expression by 75% and significantly decreased the mRNA expression of psoriasis markers, including Defb4, Il17c, S100a7, Pi3, Krt16, and Tnfa versus scrambled spherical nucleic acid (Scr SNA) controls. A human IL17RA L-SNA penetrates 3-dimensional cultures and normal human explants to knock down IL17RA mRNA by 63% and 66%, respectively. After topical application to psoriatic 3-dimensional rafts, anti-human IL17RA L-SNAs reduced the expression of IL17RA (by 72%) and the IL-17-induced genes IL17C (by 85%), DEFB4 (by 83%), TNFA (by 77%), and PI3 (by 65%) versus scrambled L-SNA and vehicle controls (all P < 0.001). Taken together, these data suggest that targeted suppression of IL17RA is a promising new topical treatment strategy for psoriasis.