Mammary Epithelial Reconstitution with Gene-Modified Stem Cells Assigns Roles to Stat5 in Luminal Alveolar Cell Fate Decisions, Differentiation, Involution, and Mammary Tumor Formation

Abstract

The mammary gland represents a unique model system to study gene functions in adult stem cells. Mammary stem cells (MaSCs) can regenerate a functional epithelium on transplantation into cleared fat pads. We studied the consequences of distinct genetic modifications of MaSCs on their repopulation and differentiation ability. The reconstitution of ductal trees was used as a stem cell selection procedure and the nearly quantitative lentiviral infection efficiency of the primary mammary epithelial cells (MECs) rendered the enrichment of MaSCs before their transplantation unnecessary. The repopulation frequency of transduced MaSCs was nearly 100% in immunodeficient recipients and the resulting tr..