What is hematopoiesis regulated by?
Regulation occurs at the level of the structured microenvironment (stroma), via cell-cell interactions and by way of the generation of specific hormones and cytokines: erythropoietin, interleukin 3, granulocyte-monocyte colony-stimulating factor (GM-CSF), monocyte-macrophage colony-stimulating factor (M-CSF).
Which tissue is responsible for hematopoiesis?
In adults, hematopoiesis of red blood cells and platelets occurs primarily in the bone marrow. In infants and children, it may also continue in the spleen and liver.
What maintains the hematopoietic stem cell?
Bone marrow macrophages maintain hematopoietic stem cell (HSC) niches and their depletion mobilizes HSCs. Blood.
Do cytokines inhibit hematopoiesis?
Hematopoietic cytokines are large family of extracellular ligands that stimulate hematopoietic cells to differentiate into eight principle types of blood cells. Numerous cytokines are involved in the regulation of hematopoiesis within a complex network of positive and negative regulators.
How is hematopoiesis maintained?
Normal hematopoiesis is maintained by activated bone marrow CD4+ T cells. Blood.
What does hematopoietic tissue do?
The hematopoietic and lymphoid tissues give rise to and house erythrocytes (red blood cells), leukocytes (white blood cells), and platelets. The hematopoietic tissues arise from hematopoietic stem cells (HSCs) (Fig. 19.1), and include bone marrow, peripheral blood, and certain lymphoid tissue.
What is the hematopoietic system?
The haematopoietic system is the system of organs and tissues, including the bone marrow, spleen, thymus and lymph nodes, involved in the production of cellular blood components.
Are macrophages hematopoietic cells?
Macrophages are sources of inflammatory molecules and also respond to specific inflammatory factors, such as G-CSF (109), suggesting their potential to influence HSC function and hematopoietic output during aging. In the bone marrow, macrophage dysfunction induced platelet-biased HSCs in aged mice (185).
Which cytokine has a role in promoting hematopoiesis?
Thrombopoietin. TPO is the primary cytokine that regulates megakaryocyte and platelet development. TPO and its receptor Mpl also exert profound effects on primitive hematopoietic cells.
What is the transcription factor for all hematopoietic cells?
Hematopoietic differentiation is controlled by key transcription factors, which regulate stem cell functions and differentiation. TAL1 is a central transcription factor for hematopoietic stem cell development in the embryo and for gene regulation during erythroid/megakaryocytic differentiation.
How does Angiopoietin-1 interact with Tie2?
The interaction of Tie2 with its ligand Angiopoietin-1 (Ang-1) induced cobblestone formation of HSCs in vitro and maintained in vivo long-term repopulating activity of HSCs. Furthermore, Ang-1 enhanced the ability of HSCs to become quiescent and induced adhesion to bone, resulting in protection of the HSC compartment from myelosuppressive stress.
Which is a ligand for the tyrosine kinase Tie2?
Ang1 and Ang2 are factors that act as ligands for Tie2, a receptor tyrosine kinase. Ang1 binds to and induces the phosphorylation of Tie2 whereas Ang2 usually behaves as an antagonist of Ang1 and Tie2 (reviewed by Eklund and Olsen 38 ).
Which is endogenously expressed angiopoietin 1 or Ang2?
Angiopoietin-1 (Ang1), which is mainly produced by pericytes, induces vessel remodeling and maturation through activation of the receptor tyrosine kinase Tie2. Angiopoietin-2 (Ang2), on the other hand, is endogenously expressed in ECs and appears to mainly act as an antagonistic ligand to Tie2 in an autocrine manner.
How does Ang-1 signaling affect the HSC compartment?
Furthermore, Ang-1 enhanced the ability of HSCs to become quiescent and induced adhesion to bone, resulting in protection of the HSC compartment from myelosuppressive stress. These data suggest that the Tie2/Ang-1 signaling pathway plays a critical role in the maintenance of HSCs in a quiescent state in the BM niche.