767 A biopsy-sized 3D model of skin vascular plexus and appendages enables monitoring T cell trafficking

The human skin vasculature has distinct anatomy with two vascular plexuses and specialized capillary loops near appendages rete ridges, diverse functions including thermal regulation immune cell trafficking. There is currently no engineered 3D model to capture this level of complexity. goal study generate an anatomically-relevant five different types, patterned hair follicles, a perfusable microvasculature mimicking the superficial plexus skin. To achieve such complexity, we combined digital-light-processing extrusion-based 3D-bioprinting create 6 mm biopsy-sized model. design pattern allowed for capturing gradient shear-stresses relevant arterioles, venules, capillaries. microchannels populated dermal endothelial cells exhibited selective permeability 70 10 kDa-sized molecules uniformly throughout pattern. In bioprinted dermis, papilla formed spheroids interacted overlaid keratinocytes form specific layers follicle, inner outer root sheaths. epidermis was properly terminally differentiated stratum corneum. Finally, introduced fluorescently-tagged naïve T in flow captured rolling, tethering, initial extravasation events. resolution us monitor diapedesis detailed morphology, e.g., lamellipodia, real-time, confirming important function recruitment our This brings closer generating truly functional its tissue-specific appendages. addition, ability circulate immune-EC interactions context microenvironment provides opportunity better understand trafficking healthy inflammatory conditions as well during wound healing using cells.