Impact of osteoblast maturation on their paracrine growth enhancing activity on cord blood progenitors.
BACKGROUND
Osteoblasts possess strong growth modulatory activity on haematopoietic stem cells and progenitors. We sought to characterise the growth and differentiation modulatory activities of human osteoblasts at distinct stages of maturation on cord blood (CB) progenitors in the context of osteoblast conditioned medium (OCM).


METHODS
OCM was produced from MSC-derived osteoblasts (M-OST) at distinct stages of maturation. The growth modulatory activities of the OCM were tested on CB CD34+cells using different functional assays.


RESULTS
OCMs raised the growth of CB cells and expansion of CD34+cells independently of the maturation status of M-OST. However, productions of immature CB cells including committed and multipotent progenitors were superior with OCM produced with immature osteoblasts. Osteogenic differentiation was accompanied by the upregulation of IGFBP-2, by several members of the Angpt-L family of growth factor, and by the Notch ligands Dll-1 and Dll-4. However, the growth activity of OCM and the in vivo engraftment properties of OCM-expanded CB cells were retained after IGFBP-2 neutralisation. Similarly, OCM-mediated expansion of CB myeloid progenitors was largely independent of Notch signalling.


CONCLUSIONS
These results demonstrate that immature osteoblasts possess greater regulatory activity over haematopoietic progenitors, and that this activity is not entirely dependent on Notch signalling.
Canadian Blood Services, Centre for Innovation, Ottawa, ON, Canada.|Biochemistry, Microbiology and Immunology Department, University of Ottawa, Ottawa, ON, Canada.
Manal
M
Alsheikh
Canadian Blood Services, Centre for Innovation, Ottawa, ON, Canada.
Ahmad
A
Abu-Khader
Canadian Blood Services, Centre for Innovation, Ottawa, ON, Canada.|Biochemistry, Microbiology and Immunology Department, University of Ottawa, Ottawa, ON, Canada.
Matthew
M
Michalicka
Canadian Blood Services, Centre for Innovation, Ottawa, ON, Canada.
Roya
R
Pasha
Canadian Blood Services, Centre for Innovation, Ottawa, ON, Canada.|Biochemistry, Microbiology and Immunology Department, University of Ottawa, Ottawa, ON, Canada.
Nicolas
http://orcid.org/0000-0002-0082-0944
N
Pineault
D048868:Adaptor Proteins, Signal Transducing; D000091304:Angiopoietin-Like Protein 1; D000075802:Angiopoietin-like Proteins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D018952:Antigens, CD34 / Q000235:genetics / Q000378:metabolism; D002135:Calcium-Binding Proteins; D002454:Cell Differentiation / Q000235:genetics*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D005312:Fetal Blood / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D016688:Mice, Inbred NOD; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D019899:Paracrine Communication / Q000235:genetics*; D061251:Primary Cell Culture; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014183:Transplantation, Heterologous; D014916:Whole-Body Irradiation
C117578:ANGPTL1 protein, human; D048868:Adaptor Proteins, Signal Transducing; D000091304:Angiopoietin-Like Protein 1; D000075802:Angiopoietin-like Proteins; D018952:Antigens, CD34; D002135:Calcium-Binding Proteins; D017077:Culture Media, Conditioned; C512941:DLK1 protein, human; C424126:DLL4 protein, human; C577903:IGFBP2 protein, human; D018971:Insulin-Like Growth Factor Binding Protein 2; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051880:Receptors, Notch
conditioned medium; cord blood; haematopoietic stem and progenitor cells; mesenchymal stromal cells; osteoblasts