Development of an ex-vivo skin explant model for hidradenitis suppurativa

Summary: Abstract Body: Hidradenitis Suppurativa (HS) is a chronic, inflammatory skin disease that is not well understood, which is partially due to the lack of an accurate, consistent, and testable model for HS. Current in-vitro experimental models of hidradenitis suppurativa (HS) do not fully capture patient variability and the multiple cell type communication networks involved in this complex disease. Ex-vivo skin explants are advantageous for HS as these models use full-thickness skin punch biopsies, which contain all of the unique architecture and cell types associated with HS skin lesions. While HS skin explants have been used in prior studies, questions arise as to how well the HS skin maintains its characteristic features and cell composition while in culture. Here, we describe a fully validated and reproducible protocol for an HS skin explant culture (n = 18) and therapeutic testing. 8-mm punch biopsies from freshly excised healthy control or HS lesional skin were cultured for 1-7 days after which they were processed for histological analyses of structure (H&E), viability (TUNEL and Ki-67 staining), differentiation (keratin expression), and immune cell composition (immunofluorescence). Explant culture media was also collected at multiple timepoints to evaluate egress of immune cells from the tissue. We found that HS skin explants can be maintained in culture for up to 5 days from severely diseased tissue (HS II/III) with no overt visible loss of viability or tissue architecture. The composition of immune cells was maintained in the tissue throughout culture. These findings establish that our protocol effectively maintains the in-vivo environment of HS skin, thus allowing its use in pre-clinical testing of novel therapeutics to determine their potential efficacy and underlying mechanisms for treating HS. Emily Manna¹, Robert Feehan¹, Mackenzie L. Sennett¹, Amanda M. Nelson¹, Stephanie Schell¹ 1. Penn State College of Medicine, Hershey, PA, United States. Epidermal Structure and Barrier Function