Perspective - (2022) Volume 11, Issue 5
Received: 02-May-2022, Manuscript No. JHOA-22-67388;
Editor assigned: 09-May-2022, Pre QC No. P-67388;
Reviewed: 16-May-2022, QC No. Q-67388;
Revised: 23-May-2022, Manuscript No. R-67388;
Published:
30-May-2022
, DOI: 10.37421/2167-1095.2022.11.343
Citation: Ceccanti, Marco. “Hematopoietic Stem Cell: An Overview.” J Hypertens 11 (2022): 343.
Copyright: © 2022 Ceccanti M. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The stem cells that give rise to other blood cells are known as hematopoietic stem cells (HSCs). Haematopoiesis is the name for this process. In vertebrates, the first definitive HSCs emerge from the embryonic aorta's ventral endothelium wall in the (midgestational) aorta-gonad-mesonephros area, a process known as endothelial-to-hematopoietic transition. Adults' haematopoiesis takes place in the red bone marrow, which is found in the centre of most bones. The mesoderm layer of the embryo is where the red bone marrow comes from.
All adult blood cells are created by the process of haematopoiesis. It must strike a balance between massive production demands (the average human produces more than 500 billion blood cells each day) and the requirement to control the quantity of different blood cell types in circulation. The vast bulk of hematopoiesis in vertebrates occurs in the bone marrow and is formed from a few numbers of multipotent hematopoietic stem cells capable of significant self-renewal.
Myeloid and lymphoid lines of hematopoietic stem cells give rise to different types of blood cells. Dendritic cell development involves both myeloid and lymphoid lineages. Monocytes, macrophages, neutrophils, basophils, eosinophils, erythrocytes, and megakaryocytes are all myeloid cells, as are platelets. T cells, B cells, natural killer cells, and innate lymphoid cells are all lymphoid cells. Since HSCs were initially discovered in 1961, the definition of hematopoietic stem cell has evolved. Long- and short-term regeneration cells, as well as committed multipotent, oligopotent, and unipotent progenitors, are found in the hematopoietic tissue. In myeloid tissue, hematopoietic stem cells account for 1 in 10,000 cells [1].
Structure
They're non-adherent, spherical, and have a rounded nucleus with a low cytoplasm-to-nucleus ratio. Hematopoietic stem cells resemble lymphocytes in appearance.
Location
During (mouse and human) embryonic development, the aorta-gonadmesonephros area, as well as the vitelline and umbilical arteries, contains the very first hematopoietic stem cells. HSCs are also seen in the placenta, yolk sac, embryonic skull, and foetal liver a little later. Adults' bone marrow contains hematopoietic stem cells, which are concentrated in the pelvis, femur, and sternum. They're also detected in modest amounts in umbilical cord blood and peripheral blood.
A needle and syringe can be used to extract stem and progenitor cells from the iliac crest in the pelvis. The cells can be removed as a liquid (to do a smear to examine the cell morphology) or as a core biopsy (to maintain the architecture or relationship of the cells to each other and to the bone) [2].
Function
Haematopoiesis: Hematopoietic stem cells are required for haematopoiesis, or the creation of blood cells. Hematopoietic stem cells can replenish and self-renew all types of blood cells (i.e., they are multipotent). A small number of hematopoietic stem cells can multiply to produce a large number of daughter stem cells. When a modest number of hematopoietic stem cells are transplanted into the bone marrow, this phenomenon is employed to re-establish the hematopoietic system. This procedure suggests that symmetrical cell divisions into two daughter Hematopoietic stem cells must occur after bone marrow transplantation.
Self-renewal of stem cells is assumed to occur in the bone marrow's stem cell niche, and it's plausible to suppose that critical signals present in this niche are vital in self-renewal. The environmental and molecular requirements for HSC self-renewal are of great interest, as understanding how HSC may replenish themselves will eventually allow the creation of larger populations of HSC in vitro that can be employed therapeutically.
Quiescence: Hematopoietic stem cells, like other adult stem cells, are primarily dormant or in reversible growth arrest. Quiescent HSCs' altered metabolism allows them to live in the hypoxic bone marrow environment for longer periods of time. Hematopoietic stem cells awaken from their dormancy when they are stimulated by cell death or injury. The MEK/ERK and PI3K/AKT/ mTOR pathways control the shift from dormancy to proliferation and reverse. Dysregulation of these transitions can result in stem cell exhaustion, or the loss of active Hematopoietic stem cells in the bloodstream.
Mobility: Hematopoietic stem cells have a stronger potential to pass through the bone marrow barrier than other immature blood cells, and hence may migrate in the blood from one bone's marrow to another. They may develop into T cells if they settle in the thymus. Fetuses and other extramedullary haematopoiesis cases. Hematopoietic stem cells can also settle and grow in the liver or spleen [3].
DNA damage with aging: During ageing, DNA strand breaks accumulate in long-term hematopoietic stem cells. This buildup is linked to a reduction in DNA repair and response mechanisms that are dependent on HSC quiescence. NHEJ (nonhomologous end joining) is a DNA repair process that fixes double-strand breaks. Because the break ends are directly ligated without the assistance of a homologous template, NHEJ is referred to as "nonhomologous." Several proteins are required for the NHEJ pathway, including ligase 4, DNA polymerase mu, and NHEJ factor 1.
In the repair of double-strand breaks through NHEJ, DNA ligase 4 (Lig4) plays a very particular role. Lig4 deficiency in mice results in the loss of hematopoietic stem cells as they age. In pluripotent stem cells lacking lig4, DNA double-strand breaks accumulate and apoptosis is increased. Hematopoietic cell development is faulty in multiple peripheral and bone marrow cell populations in polymerase mu mutant mice, with a 40 percent reduction in bone marrow cell number, which includes several hematopoietic lineages. Hematopoietic progenitor cell expansion potential is also diminished. These features are linked to hematopoietic tissue's ability to mend doublestrand breaks [4,5].
The transplantation of multipotent hematopoietic stem cells, usually taken from bone marrow, peripheral blood, or umbilical cord blood, is known as hematopoietic stem cell transplantation (HSCT). It can be autologous (using the patient's own stem cells), allogeneic (using stem cells from a donor), or syngeneic (using stem cells from a donor) (from an identical twin).
Patients with malignancies of the blood or bone marrow, such as multiple myeloma or leukaemia, are the most common candidates. Before the transplant, the immune system of the patient is normally weakened using radiation or chemotherapy. Allogeneic HSCT has a high risk of infection and graft-versus-host disease.
Hematopoietic stem cell transplantation is still a risky treatment with numerous risks; it is only performed on patients with life-threatening disorders. As survival rates have improved, the procedure's application has expanded to include autoimmune diseases and genetic skeletal dysplasias, including malignant infantile osteopetrosis and mucopolysaccharidosis.
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