The osteoblastic niche in hematopoiesis and hematological myeloid malignancies.

Purpose of review: This review focuses on evidence highlighting the bidirectional crosstalk between the hematopoietic stem cell (HSC) and their surrounding stromal cells, with a particular emphasis on cells of the osteoblast lineage. The role and molecular functions of osteoblasts in normal hematopoiesis and in myeloid hematological malignancies is discussed.

Recent findings: Cells of the osteoblast lineage have emerged as potent regulators of HSC expansion that regulate their recruitment and, depending on their stage of differentiation, their activity, proliferation and differentiation along the lymphoid, myeloid and erythroid lineages. In addition, mutations in mature osteoblasts or their progenitors induce myeloid malignancies. Conversely, signals from myelodysplastic cells can remodel the osteoblastic niche to favor self-perpetuation.

Summary: Understanding cellular crosstalk between osteoblastic cells and HSCs in the bone marrow microenvironment is of fundamental importance for developing therapies against benign and malignant hematological diseases.