Abstract Genetically modified and immunocompromised animals are the gold-standard models for investigating the molecular regulation of hematopoietic cells in the context of normal development and diseases, and for the development of novel stem cell-based therapeutic modalities for a wide variety of non-malignant hematological disorders. The future of hematology research also lies in our ability to examine hematopoietic cell function at single cell level and correlate single cell behavior with transcriptome and epigenetic profiling. The CCCEH Xenotransplant and Genome Editing Core (XGEC) is an established, productive and innovative core designed to provide specialized mouse strains, a wide variety of animal services for efficiency and standardization of cell transplantation assays, and transgenic animal services in a timely and cost effective fashion to members of the CCHSCC. The overarching hypothesis is that a centralized core service providing the myriad mouse needs of CCHSCC members will enhance the effectiveness, timeliness, cost-efficiency and overall impact of the scientific research and thereby accelerate the discovery and treatment of hematological diseases. XGEC provides specialized mouse strains in a cost effective manner compared with external vendors, including a collection of immunodeficient mouse strains (i.e., NSG, NSG-3GM3, NRG-SGM3, Rag-/-gc-/- /WvWv, and B6.BoyJ) utilized for xenotransplantation of human hematopoietic cells, for preclinical studies concerning gene transfer in humans and mouse hematopoietic stem cells, for human hematopoietic stem cell and single cell engraftment studies, and for quantitative (competitive) hematopoietic stem cell engraftment studies (Aim 1). The XGEC further provides specialized animal services allowing for population and single cell transplantation assays, including animal irradiation and cell transplantation services (Aim 2), and animal manipulation and monitoring services (Aim 3). In addition, the XGEC offers all services for the generation of transgenic and genetically–modified mouse lines (Aim 4). Since it began offering CRISPR-Cas services in March 2014, the core has already generated engineered animal models to CCHMC investigators and among Centers and within the wider research community. Lastly, XGEC provides technical support and facilitates research collaborations for comprehensive design and analysis of in vivo studies (Aim 5). These services will facilitate the sharing of expertise and promote interaction between investigators participating in the CCCEH, and will attract new core users in the future. Overall, the XGEC offers a unique combination of animal services and concentrated expertise performed by well-trained personnel under the supervision of Drs. Starczynowski and Huang in a cost effective and standardized way, thereby providing state-of-the-art investigation of non- malignant molecular hematology. These services will support the development of new therapeutic modalities (ph...