Haemopoiesis

Question 1

What is present in the bone marrow microenvironment?

Answer 1

• Stromal cells (macrophages, fibroblasts, endothelial cells, fat cells, reticulum cells) secrete extracellular molecules (collagen, fibronectin, haemonecitin, laminin and proteoglycans including growth factors and adhesion molecules)

Question 2

What are clonal disorders of HSCs?

Answer 2

• Haematological malignancies/pre-malingnancies that arise from a single ancestral cell
• Most lymphoproliferative disorders carry a rearrangement of either IG or TcR gene
• Non-malignant lymphoid proliferations are all polyclonal

Question 3

What are myeloproliferative disorders?

Answer 3

• Clonal disorders of haemopoiesis leading to increased numbers of one or more mature blood progeny
• Polycythaemia rubra vera (↑RBCs)
• Essential thrombocytosis (platelets >600x10*9/L)
• Myelofibrosis (proliferation of abnormal HSCs resulting in fibrosis in bone marrow)

Question 4

What is aplastic anaemia?

Answer 4

• Under-production of one or more mature blood progeny

- Most cases of bone marrow failure caused by Fanconi anaemia (AR inheritance)

Question 5

What are the features of myelodysplastic syndromes (MDS)?

Answer 5

• Dysplasia and ineffective haematopoiesis in one or more of the myeloid series

Question 6

What is an autologous stem cell transplant?

Answer 6

• Uses patient’s own blood stem cells
• Main indications are relapsed Hodgkin’s disease, non-Hodgkin’s lymphoma and myeloma
• Patients receive G-CSF and chemotherapy

Question 7

What is an allogenic stem cell transplant?

Answer 7

• Patient receives stem cells from a donor
• Syngeneic (between identical twins)
• Allogenic sibling (HLA identical)
• Haplotype identical (half matched family member)
• Volunteer unrelated
• Umbilical cord blood
• Indications are acute/chronic leukaemias, relapsed lymphoma, aplastic anaemia and hereditary disorders