Provided herein are compositions and methods useful for the expansion of hematopoietic stem and progenitor cells, such as those that have been genetically modified, for instance, to express a heterologous transgene. In accordance with the composition and methods described herein, hematopoietic stem and progenitor cells may be genetically modified, for example, to express transgenes encoding therapeutic proteins. Genetically modified hematopoietic stem and progenitor cells may be expanded, for instance, by treatment ex vivo with an aryl hydrocarbon receptor antagonist, and may be infused into a patient, such as a patient in need of hematopoietic stem cell transplant therapy. Thus, provided herein are methods for the treatment of various stem cell disorders, including hematopoietic diseases, metabolic disorders, cancers, and autoimmune diseases, among others.
