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Leukocyte in flow (1a) Tethering (1b) Rolling (2) Activation (3) Firm adhesion
Leukocyte in tissue Chemotaxis
Hematopoietic Cell Engraftment in Bone Marrow
“Homing” of HSCs
Bone marrow - identifiable by the fat cells, clusters of developing blood cells, and the large megakaryocytes. Also, in the middle of the field is a cross section of a sinusoid filled with rbc's.
Sinusoid of bone marrow seen here in longitudinal section. There is a nucleus of a lining endothelial cell near the lower center of the field. Junctions between endothelial cells are loose so that HSCs can enter and exit the blood vessels.
Hematopoietic Stem Cell (HSC) Homing to Bone Marrow
HSC in flow
(1a) Tethering (1b) Rolling (2) Activation (3) Firm adhesion
HSC in tissue Chemotaxis
Multistep Model of Leukocyte Transendothelial Migration
von Andrian et al., NEJM, 2000.
Selectin Expression and Structure
Mature Leukocytes and Hematopoietic Progenitors
Cytoplasmic Domain C-Type Lectin Domain Transmembrane Domain EGF-Like Domain Complement Regulatory Repeat
* Ca++-dependent binding to glycans 1 Constitutive expression, with 2 shedding Also expressed on platelets 3 Induced, except in BM and skin
Parallel Plate Flow Apparatus
Vacuum Source Syringe Pump
Inverted Microscope Video Monitor
CCD Camera Outlet Vacuum Inlet
Cells fixed/grown on tissue culture plastic. Protein adsorbed/dried onto glass or plastic.
Monolayer Cell Assay
Vacuum Flow Inlet
Outlet Localization of Rolling Interactions