Establishment of a multi-center biobank of patient-specific pluripotent stem cells for pediatric sepsis research. PROJECT SUMMARY: Sepsis is the final common pathway among those with serious infections and kills more children than cancer in the U.S each year. Yet, there are no therapies available for pediatric sepsis beyond early antibiotics and organ support. Multiple levels of heterogeneity at the patient, organ, and cellular levels have significantly impeded scientific progress. Although precision medicine approaches have been used to sift through patient- level differences, we fundamentally lack a comprehensive understanding of how heterogeneous cellular responses contribute to sepsis pathogenesis. Thus, there is a crucial need for human sepsis biorepositories to unravel cell-specific mechanistic pathways and accelerate the development of novel sepsis therapeutics. We seek to bridge this gap by developing an unprecedented biobank of patient-specific induced pluripotent stem cells (iPSCs) derived from children with sepsis. Human iPSCs can be used as a renewable and expandable source of any cell type and have been used for precision modeling of numerous disease states. However, it remains unknown whether they can serve as robust in vitro models of sepsis – an acute condition with complex gene-environment interactions and driven primarily by the host response. Through this phased innovation award, we seek to establish the ability of patient-specific iPSC derived cells to capture disease phenotypes and recapitulate in vivo responses of circulating primary cell subsets in human sepsis. Milestone-driven developmental activities in the R21 phase will focus on establishment of an efficient sample enrichment process to simultaneously collect and bank peripheral blood mononuclear cells for iPSC generation, circulating primary leukocytes and endothelial cells, and serum from whole blood. We will then generate quality-controlled iPSC lines, differentiate them into monocytes and endothelial cells, and perform functional and phenotypic characterization of patient derived cells relative to those derived from healthy donors. In the R33 phase, we will use state-of-the-art multiomic sequencing to determine if patient-specific iPSC derived cells treated with risk-stratified septic serum mirror transcriptomic and epigenomic responses of respective circulating primary cells. Scale up activities will include patient recruitment across multiple centers, standardized protocols for iPSC generation and distribution, and development of a bioinformatic database that will allow us to collate and contextualize omic analyses with rich clinical data. Through the successful execution of this proposal, we seek to transform our existing pediatric sepsis biobank to meet the needs of the next generation of scientific inquiry and facilitate cell-specific mechanistic research in human sepsis.