Haematopoiesis and haematological malignancies Flashcards
What is haematopoiesis?
Process which regulates the proliferation of stem cells and their differentiation into mature blood cells
Which cells are found in the bone marrow?
Nucleated embryonic red blood cells
Which process happens in the bone marrow?
Site of white cell production
Which ways are there to study the health of the bone marrow?
Venesection
Lymph node aspirates and excision
Bone marrow aspirate and trephine bodies
What is venesection used for?
Assess mature blood cells
What are lymph node aspirates used for?
Assess lymphopoiesis
What are bone marrow aspirate and trephine biopsies used for?
Stem cells
Hematopoiesis
Early lymphopoiesis
What is the difference between bone marrow and trephine biopsies?
Bone marrow uses blood cells stained in suspension
Trephine views the structure of the bone marrow. Carries significant risk so is only carrried out in certain circumstances
Which haematopoietic lineages do haematopoietic stem cells give rise to?
Lymphoid
Myeloid
How are stem cells differentiated to the target cellls?
Stem cells -> progenitor cells -> precursor cells -> end cells
How often to stem cells divide in humans?
Once a year
How many times do stem cells divide before they apoptose?
70 times before apoptosis
20 of these divisions occur before the birth of a man
What happens to the properties of stem cells as they differentiate?
Properties are lost as the cells differentiate in expense of their specialisation
How can stem cells be identified?
In vivo assays
Expression of CD34+
How can progenitor cells be identified?
In vitro assays
Which assays are used to identify progenitor cells?
Colony forming assays
Placed in semi-solid medium and allowed to differentiate to blood cell types in 2-3 weeks
How can precursor cells be identified?
Morphologically recognisable
How can end cells be identified?
Fully differentiated
Have short lifespans
Negative for CD34 marker
Describe the structure of neutrophils
Lobed nuclei
Large structure
Describe the structure of lymphocytes
Large, granulated nuclei
How do stem cells divide?
Mostly asymetrically, by making one stem cell and one differentiated cell
Sometimes symetrically, by making either two differentiated cells or two new stem cells
Which factors affect the differentiation of progenitors into the differentiated cell types
ECM components
Growth factors
Mechanical forces
How do growth factors increase cell populations?
Inducing cells into the cell cycle
Shortening the cell cycle time
Instructing the lineages
Increasing mature cell survival
Inhibiting progenitor cell apoptosis
When progenitors differentiate into a cell type, they can go back to their progenitor state
TRUE or FALSE
FALSE
Differentiated cell types can’t go back to their progenitor state
Examples of early growth factors
IL-1
IL-6
EPO
Examples of intermediate growth factors
IL-3
IL-5
EPO
GM-CSF
Examples of late growth factors
G-CSF
M-CSF
What is an important function of growth factors?
Enable a rapid response to stress
Allow us to differentiate stem cells to the cell types we need
Example of growth factors affecting the differentiation of stem cells in response to stress
Bleeding results in release of the GF EPO which increases red blood cell production by increasing stem cell differentiation
Explain the TPO production feedback loop
Stimulated when clotting is needed in response to cut
Growth factors respond to stress
TPO induces stem cells to differentiate to megakaryocytes
Megakaryocytes give rise to platelets expressing sialic acid
Sialic acid receptor is lost with age
Platelets then bind to hepatic cells -> increases TPO production -> increases platelet formation
What are the 3 main types of haematological malignancies?
Leukemia
Lymphoma
Multiple myeloma
What happens in lymphoma?
Excess lymphocytes in lymph node and bone marrow
What happens in multiple myeloma?
Excess plasma cells in blood and bone marrow
What happens in leukemia?
Excess white cells in the blood and bone marrow
What are the two types of leukemia?
Acute
Chronic
What can acute and chronic leukemia be further differentiated into?
Myeloid
Lymphoid
Characteristics of acute leukemia
Disease progresses quickly
Often presents with bone marrow failure
Malignant cells have undifferentiated phenotype
Characteristics of malignant cells in acute leukemia
Malignant cells have undifferentiated phenotypes
How do patients with chronic leukemia present?
Present with features caused by cellular burden - organomegaly and gout
Bone marrow failure is late feature
Behaves more indolently so normally diagnosed incidentally
Characteristics of malignant cells in chronic leukemia
Malignant cells are mature
What differentiates chronic and acute leukemia?
Progression of the condition
Bone marrow failure presentation
Phenotype of the cells
Which 3 techniques are used to classify and diagnose leukemia?
Microscopy
Cytogenetics
Molecular genetics
Which samples are used to diagnose leukemia?
Blood
Bone marrow aspirate
Trephine
Examples of cytogenetic techniques used to diagnose a patient with leukemia
G-banding
FISH
Why is cytogenetics important?
Reveals genetic mutations that can affect the prognosis for the good or bad
Monosomy 7 = poor diagnosis
APML = good prognosis
Examples of molecular genetic techniques to diagnose patient with leukemia
PCR
Sequencing
Clinical features of acute leukemia
Bone marrow failure
Organ infiltration
Metabolic
Coagulopathy
Pancytopenia
How does bone marrow failure present?
Anaemia
Bleeding
Infection
Complications of pancytopenia
Infections
Blood loss
Brain fungal infection
Examples of organ infiltration observed in acute leukemia
Hepatosplenomegaly
CNS
Gums
Skin
Examples of pancytopenia
Thrombocytopenia
Leucopenia
What are the three main types of treatment of acute leukemia?
Supportive
Specific
Support for psychological and social impacts of disease/treatment
Examples of supportive treatments
Keep RBC, platelet and infection under control
Examples of specific treatments
Remission induction via cytotoxic chemotherapy
Consolidation chemotherapy
Maintenance chemotherapy
Allogenic SCT
Is outcome of acute leukemia treatment age-dependant?
Yes
Outcomes in childhood ALL are better than adult ALL