Osteoblastic niche |
Osteoclastogenic promoters |
RANKL[135] |
Osteoclastogenic inhibitors |
Osteoprotegerin[57, 135] |
Osteoblast promoters/Mesenchymal growth factors |
PDGF, FGF2, TGFβ, fibronectin-binding surface integrins[56, 58] |
Bone matrix proteins |
Osteocalcin, osteonectin, osteopontin, bone sialoprotein, BMP-2, -4 and -6. [56] |
Vascular niche |
Proangiogenic factors |
VEGF, PDGF, TGFβ IGF-2, b-FGF (FGF2), hepatocyte growth factor (HGF), epidermal growth factor (EGF), SDF1 (CXCL12), Lipid mediators e.g. sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) and MMPs[68, 136] |
Antiangiogenic factors |
TSPs, Endostatin, Plasminogen activator inhibitor (PAI) type 1, TGFβ, PF4 (CXCL4)[68, 136] |
Chemokines |
SDF1[64, 88] (synthesized in low amounts by megakaryocytes-largely taken up from the microenvironment), PF4[137] |