The Hematopoietic System

Hematopoiesis

development or maturation of RBCs, WBCs, and platelets from blood stem cells

Components of the Blood

Plasma 55% total volume, Buffy Coat 1%, Erythrocytes 45% total volume

Plasma Cells

Water, Proteins, Nutrients and metabolic waste, and electrolytes

Buffy coat

Neutrophils, Eosinophils, Basophils, Monocytes, Lymphocytes, Platelets

Hematocrit

% of RBC in blood sample

STEM Cells

Relatively undifferentiated cells that retain the ability to divide throughout life to provide progenitor cells that can differentiate into specialized cells; CLOGENIC

undifferentiated cells

not specialized in their function

Allogenic STEM Cells Transplantation

Donor, collection of stem cells, processing and cryopreservation, chemotherapy, infusion of stem cells, patient

Clogenic

the ability to expand from a single cell

Key features of STEM Cells

• self-renewing capacity

• Proliferation (expansion)

• Differentiation (lineage commitment)

What two subsets of STEM cells

long term and short term

Long term subset

capable of indefinite self renewal

What marker marks the hematopoietic stem cells

CD34

Stem Cell Cycle

Long term stem cells, short-term cells, multipotent progenitors, oligolinage progenitors, differentiated progeny

Totipotent Stem Cell

Can form extraembryonic membranes, tissues, embryo, and all postembryonic tissues and organs

Totipotent Stem Cell Example

Embryo

Pluripotent stem cell

capable of giving rise to most but not all tissues of an organism

Pluripotent stem cell example

inner mass cell

Multipotent stem cell

give rise to cells that have a specific function

multipotent stem cell example

blood stem cells

What do we lose with age

telomeres

Telomeres

terminal section of a chromosome which has a specialized structure which is involved in chromosomal replication and stability

Where is bone marrow found

stroma

What does stroma support

yellow pulp and red pulp

Yellow pulp

major marrow constituent in long tubular bones is comprised of aggregated fate cells

Red pulp

in adults found in flat bones (hip, ribs, and vertebrae); major source of hemopoietic stem cells

In bone marrow HSC can differentiate into

lymphoid progenitor and myeloid progenitor cells

Lymphoid progenitor cells

Leukocytes (T lymphocytes, B lymphocytes, NK)

Myeloid progenitor cells Leukocytes

eosinophil, basophil, and neutrophil

Myeloid progenitor cells reticulocytes

erythrocytes (RBCs)

Myeloid progenitor cells megakaryocyte

thrombocytes (platelets)

Which type of cell the HSCs and progenitor cells divide into is largely decided by the specific signaling factors

endogenous factors repurposed as therapeutics: epotein and filgratism

Epotein

mimics the actions of erythropoietin (RBCs)

Filgratism

mimics the actions of colony granulocyte stimulating factor (C-GSF)—> neutrophils