Construction of a three-dimensional sensory stimulus evaluation model focusing on the stimulus mechanism

<p>TRP channels are considered to play important roles in skin itch transmission and irritation. We focused on TRPV1 which is expressed in sensory neurons because our previous study showed that TRPV1 is activated by ethanol or polyols used in cosmetics. However, only water-soluble substances can be used to evaluate TRPV1 activities with a conventional method. In addition, it is necessary to design a new TRPV1 evaluation system considering epithelial barrier functions since TRPV1 are located in the lower layers of epithelial cells.</p><p>In our study, we constructed a co-culture system of HEK293 cells stably expressing human TRPV1 (TRPV1 cells) with a three-dimensional skin model (3D skin model) having a barrier function. First, we selected appropriate scaffold proteins to keep appropriate cell proliferation and function because proliferation rate of TRPV1 cells showed higher than those of the 3D skin model. Collagen-gel-embedded method for TRPV1 cells maintained an original cell proliferation and function. Next, we screened new indicators for TRPV1 activation instead of intracellular Ca2+ levels since it’s difficult to detect this conventical indicator under the co-culture system. As a result, we found that MCP protein, which is a member of the CC chemokine family proteins, is released in a TRPV1-activity-dependent manner and that MCP family proteins are also released in the excisional biopsy of human skin.</p><p>These data suggest that this new 3D TRPV1 model with barrier function enable us to evaluate TRPV1 activity for water-insoluble substances.</p>