Haematopoietic system

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Haematopoietic system
Sites of haematopoiesis periods before and after birth.
Details
FunctionCreation of the cells of blood.
Identifiers
MeSHD006413
FMA9667
Anatomical terminology

The haematopoietic system is the system in the body involved in the creation of the cells of blood.[1]

Structure

Stem cells

Main article: Hematopoietic stem cell

myeloid and lymphoid progenitor cells) can follow any of the other differentiation pathways that lead to the production of one or more specific types of blood cell, but cannot renew themselves. The pool of progenitors is heterogeneous and can be divided into two groups; long-term self-renewing HSC and only transiently self-renewing HSC, also called short-terms.[5]
This is one of the main vital processes in the body.

Development

In developing embryos, blood formation occurs in aggregates of blood cells in the yolk sac, called blood islands. As development progresses, blood formation occurs in the spleen, liver and lymph nodes. When bone marrow develops, it eventually assumes the task of forming most of the blood cells for the entire organism.[3] However, maturation, activation, and some proliferation of lymphoid cells occurs in the spleen, thymus, and lymph nodes. In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia. In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum.[6]

Function

Main article:
Haematopoeisis

Haematopoiesis (from Greek αἷμα, "blood" and ποιεῖν "to make"; also hematopoiesis in American English; sometimes also haemopoiesis or hemopoiesis) is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cells.[3] In a healthy adult person, approximately 1011–1012 new blood cells are produced daily in order to maintain steady state levels in the peripheral circulation.[7][8]

All blood cells are divided into three lineages.[9]

Clinical significance

Stem cell transplant

Main article:
stem cell transplant

A

stem cell transplant is a transplant intended to replace the progenitor haematopoietic stem cells

Haematopoietic stem cell transplantation (HSCT) is the transplantation of

autologous (the patient's own stem cells are used), allogeneic (the stem cells come from a donor) or syngeneic (from an identical twin).[10][11]

It is most often performed for patients with certain cancers of the blood or bone marrow, such as multiple myeloma or leukemia.[11] In these cases, the recipient's immune system is usually destroyed with radiation or chemotherapy before the transplantation. Infection and graft-versus-host disease are major complications of allogeneic HSCT.[11]

Haematopoietic stem cell transplantation remains a dangerous procedure with many possible complications; it is reserved for patients with life-threatening diseases. As survival following the procedure has increased, its use has expanded beyond cancer to

skeletal dysplasias; notably malignant infantile osteopetrosis[15][16] and mucopolysaccharidosis.[17]

References

  1. ^ "hematopoietic system". Merriam-Webster. Retrieved 8 July 2019.
  2. PMID 35265979
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  3. ^
    PMID 27015419
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  4. S2CID 715049
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  5. PMID 7541305
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  6. PMID 24237971
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  7. ^ Semester 4 medical lectures at Uppsala University 2008 by Leif Jansson
  8. ISBN 978-0-8385-6278-9
    .
  9. ^ "Hematopoiesis from Pluripotent Stem Cells". ThermoFisher Scientific. Retrieved 3 February 2014.
  10. ^
    PMID 25157450
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  11. ^
    PMID 26770947
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  12. PMID 27516776
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  13. PMID 10516675
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  14. PMID 18314435
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  15. doi:10.1016/j.ejrnm.2016.12.013
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  16. S2CID 11287381
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  17. PMID 26935461
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