title: Making Blood: The Haematopoietic Niche throughout Ontogeny.
abstract: Approximately one-quarter of all cells in the adult human body are blood cells. The haematopoietic system is therefore massive in scale and requires exquisite regulation to be maintained under homeostatic conditions. It must also be able to respond when needed, such as during infection or following blood loss, to produce more blood cells. Supporting cells serve to maintain haematopoietic stem and progenitor cells during homeostatic and pathological conditions. This coalition of supportive cell types, organised in specific tissues, is termed the haematopoietic niche. Haematopoietic stem and progenitor cells are generated in a number of distinct locations during mammalian embryogenesis. These stem and progenitor cells migrate to a variety of anatomical locations through the conceptus until finally homing to the bone marrow shortly before birth. Under stress, extramedullary haematopoiesis can take place in regions that are typically lacking in blood-producing activity. Our aim in this review is to examine blood production throughout the embryo and adult, under normal and pathological conditions, to identify commonalities and distinctions between each niche. A clearer understanding of the mechanism underlying each haematopoietic niche can be applied to improving ex vivo cultures of haematopoietic stem cells and potentially lead to new directions for transplantation medicine.
authors.affiliation: Discipline of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, NSW 2050, Australia ; Laboratory of Bone Marrow and Stem Cell Processing, Department of Medical Oncology, Medical Oncology and Stem Cell Transplant Center, Al-Sabah Medical Area, Kuwait.
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Al-Drees
authors.affiliation: Discipline of Anatomy & Histology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, NSW 2050, Australia.
authors.forename: Jia Hao
authors.initials: JH
authors.lastname: Yeo
authors.affiliation: Discipline of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, NSW 2050, Australia.
authors.forename: Badwi B
authors.initials: BB
authors.lastname: Boumelhem
authors.affiliation: Discipline of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, NSW 2050, Australia.
authors.forename: Veronica I
authors.initials: VI
authors.lastname: Antas
authors.affiliation: Discipline of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, NSW 2050, Australia.
authors.forename: Kurt W L
authors.initials: KW
authors.lastname: Brigden
authors.affiliation: Discipline of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, NSW 2050, Australia.
authors.forename: Chanukya K
authors.initials: CK
authors.lastname: Colonne
authors.affiliation: Discipline of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, NSW 2050, Australia ; Discipline of Anatomy & Histology, School of Medical Sciences, Bosch Institute, University of Sydney, Camperdown, NSW 2050, Australia.
authors.forename: Stuart T
authors.initials: ST
authors.lastname: Fraser