Role of PTH in Bone Marrow Niche and HSC Regulation

Purpose of Review. The bone marrow microenvironment hosts a multicellular complex that is extraordinary in its interdependence and function. The composite machinery within the axial and long bones is involved in the homing, maintenance, differentiation, and egress of hematopoietic/ progenitors stem cells (HSCS) as well as mesenchymal/ stromal stem cells (MSCs) that dwell in specific anatomical areas inside the marrow space, described as niches. The need for more efficient hematopoietic stem cell transplantation protocols and bonemarrow manipulation techniques has motivated scientists to identify effective niche regulators such as the parathyroid hormone (PTH). Recent Findings PTH treatment is increasingly used with promising outcomes in autologous and allogeneic transplantation of HSCs, because PTH operates as a significant mediator in HSC engraftment, expansion, and mobilization. In addition to the well-established anti-osteoporotic effect of PTH, there is evidence that it may also coordinate hematopoietic stem cell activities. Summary. This report provides up-to-date information about PTH action within marrow niches and highlights the importance of this hormone in the behavior of hematopoietic elements in the bone marrow.