Chang Gung University Department of Medical Biotechnology Clinical Hematology RBC 2 : Erythropoesis & RBC Senescence Dr. Daniel Tsun-Yee Chiu Spring, 2012

Part I : Erythropoiesis I. Definition of erythropoiesis : Production of red cells II. Site(s) of erythropoiesis 1. Fetal period 2. After-birth III. Biological processes involved in erythropoiesis 1. Differentiation 2. Proliferation 3. Biosynthetic activities, hemoglobin synthesis in particular 4. Maturation: nuclear extrusion IV. Kinetics of erythropoiesis

Red Cell Production The Production of red cells, known as erythropoiesis, is a developmental system fundamentally under genetic control but modulated and regulated by the interaction of humoral, cellular, and molecular processes. These must be understood if there is to be full elucidation of any of the pathological processes which afflict the red cell system.

Hematopoiesis Fig.1.2 Diagrammatic representation of the bone marrow pluripotent stem cell and the cell lines that arise from it.

Hematopoiesis Fig.1.7 A diagram of the role of growth factors in normal haemppoiesis.

Part I : Erythropoiesis I. Definition of erythropoiesis : Production of red cells II. Site(s) of erythropoiesis 1. Fetal period 2. After-birth III. Biological processes involved in erythropoiesis 1. Differentiation 2. Proliferation 3. Biosynthetic activities, hemoglobin synthesis in particular 4. Maturation: nuclear extrusion IV. Kinetics of erythropoiesis

Site(s) of erythropoiesis Organ of erythropoiesis Fetal periodKinds of blood cells Yolk sac2~9 weekRBC liver9~24 weekRBC, myelocyte, platelet spleen10~24 weekRBC, myelocyte, platelet Lymph node8 week~after birthlymphocyte Bone marrow10 week~after birthRBC, myelocyte, platelet

Part I : Erythropoiesis I. Definition of erythropoiesis : Production of red cells II. Site(s) of erythropoiesis 1. Fetal period 2. After-birth III. Biological processes involved in erythropoiesis 1. Differentiation 2. Proliferation 3. Biosynthetic activities, hemoglobin synthesis in particular 4. Maturation: nuclear extrusion IV. Kinetics of erythropoiesis

Erythropoiesis The differentiation and proliferation of RBC. (erythroblast) (Basophilic erythroblast) (Orthochromatic erythroblast)

Differentiation Erythopoietin reaposiveness Globin mRNA sythesis Hgb sythesis Stem cell pool myeloblast megakaryoblast unipotential multipotential unipotential-erythopoitin responsive CFU-S BFU-E CFU-E 5 days 120 days

Regulation of erythropoiesis and the Production of erythropoietin

Kinetics of erythropoiesis

V. Regulation of erythropoiesis: Cytokines 1. Erythropoietin (EPO) 2. Burst promoting Activity (BPA) 3. Iron availability 4. Other regulatiory factors (eg. Androgenic steroids) VI. Required reading “ Essential Haematology " by Hoffbrand & Pettit. pp VII. Additional References 1. Rifkind et al. "Fundamental of Hematology" 3rd ed., pp 1-19, Jandl J. "Blood---Textbook of Hematology" pp 49-53, 1987 Part I : Erythropoiesis

Part II : Red Cell Destruction (Senescence) I. Red cell life span : about 120 days Methods of measuring RBC life span : 1. Single-age (Cohort) label 2. Mixed-age label II. Routes of Destruction and Major determinants of destruction 1. Spleenic entrapment --- Deformability 2. Monocyte/Macrophage --- Surface Antigenicity 3. Osmotic lysis --- Permeability

Red cell life span Single-age (Cohort) LabelMixed-age Label

Part II : Red Cell Destruction (Senescence) I. Red cell life span : about 120 days Methods of measuring RBC life span : 1. Single-age (Cohort) label 2. Mixed-age label II. Routes of Destruction and Major determinants of destruction 1. Spleenic entrapment --- Deformability 2. Monocyte/Macrophage --- Surface Antigenicity 3. Osmotic lysis --- Permeability

Red cell deformablity A. Factors affecting red cell deformability 1. Cytoplasmic viscosity 2. Intracellular rubbish 3. Membrane rigidity 4. Surface to volume ratio B. Techniques to measure red cell deformability 1. filtration 2. micropipette 3. ektacytometry

Part II : Red Cell Destruction (Senescence) III. Possible underlying mechanism (s) 1. Metabolic depletion theory 2. Mechanical shear stress 3. Changes in surface properties induced by endothelial cells 4. Oxidative damage theory IV. Required Reading Jandl J. “Blood---Text book of Hematology" pp 91-96, 1987 V. Additional Reference Rifkind et al. "Fundamental of Hematology" pp 1-19, 1986