Blood and Bone Marrow

Question 1

What is haematopoiesis?

Answer 1

The formation of mature blood cells from stem cells in marrow.
Must be occurring constantly and is tightly regulated.

Question 2

Haematopoietic tissues?

Answer 2

Peripheral blood cells (8 lineages!)
from
Bone marrow-95% (sternum, ribs, sacrum, vertebrae. Central skeleton)
Spleen- 5%

Question 3

Haemopoietc hierachy keypoints

Answer 3

HSC: Haemopoetic stem cell, is self renewing. Lots of proliferative potential.

End up as lymphoid (CLP) (B and T lymphocytes, NK cells) or myeloid (CMP) (macrophages, neutrophils, erthryocytes, etc) progenitors

End point has increased turnover rate, limited lifetimes

Question 4

Embryology

___’s come from ____ niche and migrate to ____ niche

Cells of haemotpoietic tissue come from ____ in ____ ____ of the ___ ___ to produce ____ cells, then ____ cells from endotehlium in the ___ region.
Site of haemopoiesis shifts to fetal ___, then ____ _____

Answer 4

HSC’s come from endothelial niche and migrate to endosteal niche

Cells of haemotpoietic tissue come from mesoderm in blood islands of the yolk sac to produce primitive cells, then definitive cells from endothelium in the AGM (aorto gonad mesoonephros) region. Also placenta?
Site of haemopoiesis shifts to fetal liver, then bone marrow

Question 5

Infancy and haemotpoietic tissue

In infancy, all bone marrow is haematopoietic
During cildhood, ___replacement throughout long bones, so h. _____ confined to _____ skeleton.
Even here, 50% fat
Fatty marrow is capable of ____ to haematopoiesis, and in some disorders, _____ on long bones.
Spleen and liver can resume

Answer 5

In infancy, all bone marrow is haematopoietic
During cildhood, fatty replacement throughout long bones, so h. marrow confined to central skeleton.
Even here, 50% fat
Fatty marrow is capable of reversion to haematopoiesis, and in some disorders, expansion on long bones.
Spleen and liver can resume

Question 6

Bone marrow constituents

____ bone, ___, _______ tissue (HSC + ____)
_____ cells: _____, ______, fat cells, ______ cells.
These provide ____ and ___ environment suitable for blood cell production. Produces ____, ____ molecules, _____ factors

Answer 6

Trabecular bone, fat, haemotopoietic tissue (HSC + stromal)
Stromal cells: fibroblasts, macrophages, fat cells, endothelial cells.
These provide physical and microenvironment suitable for blood cell production. Produces ECM, adhesion molecules, growth factors

Question 7

Haematopoietic stem cells: Constitute; properties; expresses?; umbilical cord

Answer 7

Constitute a small portion of of total marrow cell population

Properties: Self renewing; generation of one or more specialised cell types

Express antigen CD34, measure of stem cell number

Umbilical: Blood in here enriched in HSC population, source of these

Question 8

What regulates haematopoiesis

Answer 8

Transcription factors, such as Runx1 and GATA-2

Cytokines (TPO, CM-CSF)