Bone marrow stromal proteoglycans regulate megakaryocytic differentiation of human progenitor cells.
Adherence of hematopoietic progenitor cells (HPCs) to stroma is an important regulatory step in megakaryocytic differentiation. However, the mechanisms through which megakaryocytic progenitors are inhibited by stroma are poorly understood. We examined the role of sulfated glycoconjugates, such as proteoglycans (PGs), on human bone marrow stroma (hBMS). To this end, PG structure was altered by desulfation or enzymatic cleavage. PGs participated in adhesion of human HPC, as desulfation resulted in about 50% decline in adhesion to hBMS. Heparan sulfate proteoglycans (HSPGs) were found to be responsible by showing about 25% decline in adhesion after pre-incubation of HPC with heparin and about 15% decline in adhesion after enzymatic removal of HSPGs from hBMS. Furthermore, PGs were involved in binding cytokines. Both desulfation and enzymatic removal of stromal HSPGs increased release of megakaryocytopoiesis-inhibiting cytokines, that is, interleukin-8 (IL-8, 1.9-fold increase) and macrophage inflammatory protein-1alpha (MIP-1alpha, 1.4-fold increase). The megakaryocytic output of HPC grown in conditioned medium of desulfated stroma was decreased to 50% of the megakaryocytic output in CM of sulfated stroma. From these studies, it can be concluded that PGs in bone marrow, in particular HSPGs, are involved in binding HPC and megakaryocytopoiesis-inhibiting cytokines. Bone marrow stromal PGs thus reduce differentiation of HPC toward megakaryocytes.
Zweegman
Sonja
S
Department of Hematology, VU University Medical Center, 1081 HV Amsterdam, The Netherlands. s.zweegman@vumc.nl
Van Den Born
Jakob
J
Mus
Adriana M C
AM
Kessler
Floortje L
FL
Janssen
Jeroen J W M
JJ
Netelenbos
Tanja
T
Huijgens
Peter C
PC
Dräger
Angelika M
AM
D000208:Acute Disease; D018952:Antigens, CD34 / Q000378:metabolism; D001798:Blood Proteins / Q000494:pharmacology*; D001853:Bone Marrow / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation; D002478:Cells, Cultured; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D017077:Culture Media, Conditioned; D047093:Eosinophil Major Basic Protein; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology*; D006497:Heparan Sulfate / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D016209:Interleukin-8 / Q000494:pharmacology; D007951:Leukemia, Myeloid / Q000378:metabolism / Q000473:pathology; D008228:Lymphoma, Non-Hodgkin / Q000378:metabolism / Q000473:pathology; D019402:Macrophage Inflammatory Proteins / Q000494:pharmacology; D008533:Megakaryocytes / Q000166:cytology*; D011509:Proteoglycans / Q000494:pharmacology*; D017154:Stromal Cells / Q000166:cytology / Q000473:pathology*
D018952:Antigens, CD34; D001798:Blood Proteins; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D017077:Culture Media, Conditioned; D047093:Eosinophil Major Basic Protein; D006497:Heparan Sulfate; D016209:Interleukin-8; D019402:Macrophage Inflammatory Proteins; D011509:Proteoglycans; C074129:PRG2 protein, human