Abstract 33: Transcriptomic Identification of Functionally Potent Umbilical Cord Blood Units

Abstract Introduction Umbilical cord blood (UCB) is an important donor source for standard of care cellular therapies as well as innovative new treatments. Universal potency criteria for cord blood unit (CBU) selection for different cellular therapy applications are still desired and efficient methods to elucidate these criteria remain elusive. Objectives Our goal is to find molecular markers that identify potent CBUs for use in cellular therapies. Here, we utilized transcriptomics to reveal genes associated with hematopoietic stem and progenitor cell (HSC/HPC) potency in hematopoietic cell transplantation. Methods We performed three separate transcriptomic analyses of human UCB used in mouse models of transplantation. This included bulk RNA-sequencing of HSCs/HPCs from CBUs with known engraftment capacities (n=9 CBUs), bulk RNA-sequencing of homed/early engrafted CD34+ cells (n=3 CBUs), and single cell RNA-sequencing of CD34+ cells expanded in varying oxygen tensions, which affects their transplantation potency (n=4 CBUs). Results HSCs/HPCs enriched for dehydrogenase and cell cycle associated genes yield better repopulating cell frequency. Early homed CD34+ cells have enriched expression of immune activation and cell cycle genes compared to input transplanted cells. Distinct clusters of UCB cells marked by genes such as PRSS2 and AVP are enriched in oxygenation conditions that drive increased potency. Dehydrogenase and stress response genes are enriched in populations predicted to be more functional regardless of HSC/HPC subpopulation. Integration of all three studies reveals genes that may define highly potent CBUs, including DDIT4, a stress response gene. Indeed, DDIT4 independently predicts engraftment outcomes in mouse models of transplantation. Future work will examine a qPCR based gene panel potency assay to predict outcomes in patient transplantations. Discussion We have identified genes associated with HSC/HPC potency using transcriptomic approaches. These findings have immediate translational implications for CBU selection for transplantation, but also provides a blueprint for finding CBUs best suited for use in developing off-the-shelf immune effector therapies or those that are best for treating non-hematologic central nervous system disorders such as cerebral palsy, among other applications. Importantly, this study highlights the importance for omics technology as a valuable tool to define potency criteria for UCB as a donor source for cellular therapies.