Project Summary: This proposal details a new research plan to examine the differential effects of neuronal origin and axonal target environment on nerves from people with diabetes mellitus 2 (DM2) to understand why these nerves degenerate and have reduced plasticity compared to their heathy counterparts, especially within the epidermis. Axon growth of sensory neurons derived from human induced pluripotent stem cells (iPSCs) will be studied in the presence of skin biopsied from control subjects and patients with diabetes and varying degrees of peripheral neuropathy. We hypothesize: 1) That cellular origin matters and that sensory axons derived from iPSCs of subjects with DM2 and peripheral neuropathy will grow and regenerate more slowly than sensory neurons derived from healthy control iPSCs. 2) That the regenerative environment also plays an important role, perhaps more important than neuronal origin: that sensory axons, irrespective of their origin, will regenerate more slowly on a matrix of skin from subjects with DM2 and peripheral neuropathy compared to a matrix of skin from healthy control subjects. Understanding the role of these different potential influences on human axonal regeneration will place us in a better position in the future to identify the molecules involved and therapeutic targets for diabetic neuropathy- a condition that has defied meaningful clinical advances beyond optimizing glucose control. Sensory neurons derived from human iPSCs hold promise for advancing the field of small fiber neuropathy in general, including diabetic peripheral neuropathy (DPN). However, interactions of iPSC-derived sensory neurons with the epidermis have not been explored. Therefore, it is important to perform novel experiments, such as those proposed here, that specifically examine axons of iPSC-derived sensory neurons to determine potential factors that influence their degeneration when they are in milieu, over biopsied skin that mimics human conditions. We are addressing this knowledge gap by utilizing microfluidic chambers that separate axons from neuronal cell bodies in order to study the basic pathobiology of the distal sensory axons of diabetic patients. Through this proposal, we anticipate the development of a system derived from human cells to interrogate factors that inhibit axonal plasticity in DPN.