4: Hematopoiesis and Bone Marrow Evaluation

what makes up bone marrow microenvironment?

stroma, accessory/hematopoietic/endothelial/reticular cells

stromal elements of bone marrow

endothelium, fibroblasts, adipocytes, EXC matrix

accessory cells of bone marrow

macrophages, B/T lymphocytes

hematopoietic cells of bone marrow

HSCs, HPCs, neutrophils

what do bone marrow endothelial cells do?

regulate movement between blood and marrow extravascular space

what do reticular cells of bone marrow do?

prodive structural support

HSC

hematopoietic stem cell

HPC

hematopoietic progenitor cells

HSC self renewal

constant

HPC self reneal

limited; needs HSC help

HSC replication

slow, once every 8-10 weeks

HPC replication

rapid

marker of HSC and HPC

CD34+

lymphoid HSCs

B/T/NK cells

myeloid HSCs

non-lymphoid blood cells, macrophages, dendrites, osteoclasts, mast cells

what disappears as RBCs mature?

nucleus

how do macrophages help form RBCs?

expel nuclei/damaged RBCs, store Fe, provide regulatory factors

main function of erythropoietin

inhibits apoptosis

neutrophil development time

6-9 days

major LATE-ACTING factor stimulating granulocyte prouduction?

G-CSF

what does G-CSF do?

stimulates production of granulocytes, increases division, decreases marrow transit time

what is the late acting factor stimulating monocyte production?

M-CSF

what do monocytes become in tissues?

macrophages or inflammatory dendrites

what do monocytes become in bone marrow?

osteoclasts

osteoclasts

bone-degrading cells

what does TPO stand for?

thrombopoietin

what does TPO increase?

endomitosis, ploidy, cell size

when is bone marrow exam warranted?

unexplained cytopenia in blood, lymphoma/mast cell tumor, evaluating Fe stores, focal bone lesions, unexplained hyperproteinemia/hypercalcemia

describe aspirate smears

simple, fast, cheap, good for looking at individual cells, uses WG stain

describe core biopsies

better evaluation of overall cells, useful AFTER unsuccessful aspirate, good in myelofibrosis, IDENTIFIES FOCAL LESIONS

focal lesions that could be identified in core biopsies

metastatic neoplasia, necrosis, ganulamatous inflammation

M:E Ratio/Calculation

granulocytic cells / erythrocytic cells

average M:E ratio

around 1 (or slightly over) for most animals

M:E changes reflect changes in what IF HCT AND NEUTROPHILS ARE NORMAL?

erythroid series

M:E changes reflect changes in what if ONLY HCT IS NORMAL?

neutrophilic series

neutropenia and normal HCT, describe M:E ratio

low

diffentiation potential of HSCs

broad

differentiation potential of HPCs

restricted

erythroid late-acting factor

EPO

neutrophil/granulocytic late acting factor

G-CSF

monocytic late acting factor

M-CSF

megakaryocyte/platelet late acting factor

TPO

eosinophil late acting factor

IL-5