The study investigates the role of bone marrow adipocytes in regulating hematopoietic microenvironment. Adipocytes, which are present in adult bone marrow, correlate negatively with hematopoietic activity. The researchers compared hematopoietic activity in different regions of the mouse skeleton, finding that adipocyte-rich vertebrae in the tail have reduced hematopoietic stem cells and short-term progenitors compared to adipocyte-free vertebrae in the thorax. In genetically adipocyte-deficient mice and those treated with a PPARγ inhibitor, post-irradiation marrow engraftment was accelerated. These findings suggest that adipocytes negatively regulate hematopoiesis and that antagonizing adipogenesis may enhance hematopoietic recovery in clinical bone marrow transplantation. The study also demonstrates that adipocyte-rich marrow is associated with reduced cycling of hematopoietic progenitors and that blocking adipogenesis pharmacologically can improve bone marrow engraftment.The study investigates the role of bone marrow adipocytes in regulating hematopoietic microenvironment. Adipocytes, which are present in adult bone marrow, correlate negatively with hematopoietic activity. The researchers compared hematopoietic activity in different regions of the mouse skeleton, finding that adipocyte-rich vertebrae in the tail have reduced hematopoietic stem cells and short-term progenitors compared to adipocyte-free vertebrae in the thorax. In genetically adipocyte-deficient mice and those treated with a PPARγ inhibitor, post-irradiation marrow engraftment was accelerated. These findings suggest that adipocytes negatively regulate hematopoiesis and that antagonizing adipogenesis may enhance hematopoietic recovery in clinical bone marrow transplantation. The study also demonstrates that adipocyte-rich marrow is associated with reduced cycling of hematopoietic progenitors and that blocking adipogenesis pharmacologically can improve bone marrow engraftment.