749 Biomechanical forces modulate epithelial competence and regeneration patterning during wound-induced hair neogenesis

S | Tissue Regeneration u0026 Wound Healing 746 Differentiation of sensory neurons from human induced pluripotent stem cells Z Guo, C Tong, HE Abaci, EA Lumpkin and AM Christiano 1 Dermatology, Columbia University, New York, NY and 2 Genetics and Development, Columbia University, New York, NY Human skin is a complex structure containing many cell types, including sensory neurons which transduce sensations such as itch, pain, heat, cold and touch. It is very difficult to obtain human sensory neurons for regenerative applications and pharmaceutical development. Induced pluripotent stem cells (iPSCs) have enormous potential for cell therapy and disease modeling by providing unlimited number of cells, however, realization of this potential is limited by the capacity to efficiently generate desired cell lineages. Several protocols have been developed to differentiate sensory neurons from human iPSCs, but there is variability between different iPSC lines to obtain mature sensory neurons from human pluripotent stem cells. We manipulated the Wnt, transforming growth factor b (TGF-b), bone morphogenetic protein 4 (BMP 4) and Notch signaling pathways to enhance neuronal differentiation from integration-free iPSCs. Specifically, we generated iPSCs from human fibroblasts by introduction of episomal vectors containing defined transcription factors. From those iPSCs, we differentiated sensory neurons using a combination of small molecules including SB431542 (TGF-b inhibitor), LDN193189 (BMP4 inhibitor), DAPT (Notch inhibitor) and Chir-99021 (Wnt activator). The iPSC-derived neurons (iNCs) displayed neural markers by immunostaining and action potentials by electrophysiology. Calcium imaging analysis demonstrated that the iNCs responded specifically to an itch-related peptide. We also integrated these iNCs into 3D skin constructs to study the interactions between neurons and keratinocytes as well as fibroblasts, and generate an innervated 3D skin model. Availability of these iNCs will allow us to study their function and screen for small molecules that can be used for the treatment of itch. S132 Journal of Investigative Dermatology (2016), Volume 136 747 Cellular and molecular mechanisms during self-organization of mouse skin progenitor cells into reconstituted hairy skin M Lei, L Schumacher, Y Lai, C Yeh, P Murray, P Wu, T Jiang, R Baker, W Juan, R Widelitz, LYang and C Chuong 1 University of Southern California, Los Angeles, CA, 2 Chongqing University, Chongqing, China, 3 Oxford University, Oxford, United Kingdom, 4 China Medical University, Taichung, Taiwan and 5 University Dundee, Dundee, United