PROJECT SUMMARY The Stanford Alzheimer's Disease Research Center supports the National Alzheimer's Project Act by serving as a shared resource to promote research on Alzheimer's disease, cognitive impairment linked to Lewy body changes in the brain, and cognitive aging. Clearly, within the scope of the parent Stanford ADRC, this Administrative Supplement respectfully requests supplemental funding for the Stanford ADRC Neuropathology Core to take responsibility for the derivation, characterization, and banking of 20 new human induced pluripotent stem cell (iPSC) lines and to assess biomarkers in iPSC-derived neuronal and microglia cultures for AD and PD. In particular, we support and expand Aim 4 of the parent ADRC to “make available participant biospecimens and high-content biospecimen data” by generating new iPSC lines that can be differentiated into neuronal and glia cultures and recapitulate many molecular and phenotypic aspects of AD and PD. The Aims of this study are: (1) the derivation of 60 new human iPSC clones from 20 existing ADRC human skin fibroblasts lines with defined clinical phenotypes and genetic characterization within the AD spectrum (AD-dementia, AD-mild cognitive impairment) and Lewy body spectrum (Parkinson’s disease, dementia with Lewy bodies), matched with healthy controls. We use non-integrating reprogramming methods to develop these iPSC clones. All clones will undergo rigorous quality control testing in accordance with NIH guidelines. (2) AD/ADRD phenotypic characterization of iPSC neurons and microglia. We will differentiate cell lines into cortical neurons and microglia using established protocols, develop multiplex imaging phenotyping and expression panels for AD and PD-related neuropathology (Aim 2.1), and test lysates and media supernatant for established AD biomarkers, including tau, hyperphosphorylated tau, A1-40, and A1-42, alpha-synuclein aggregates and compare analyses to cerebrospinal fluid biomarkers in corresponding samples from the same donor (Aim 2.2). (3) Banking and distribution of iPSC lines to the NCRAD biobank (Aim 3a). We will collaborate across centers to innovate the development of new resources, such as directly transformed neurons and human organoids (in collaboration with UC San Diego’s iPSC Core) and the development of microglia and chimera models (in collaboration with UC Irvine’s iPSC Core) (Aim 3b). When successfully completed, the work proposed in this supplement will yield 60 new iPSC clones from 20 clinically and genetically well-characterized ADRC participants, and we will share all lines with the NCRAD repository, the research community at Stanford and beyond. This resource will expand the Stanford ADRC tissue resource repertoire and allow the scientific community to work with advanced predictive human cellular model systems.