title: Platelet-derived growth factor enhances platelet recovery in a murine model of radiation-induced thrombocytopenia and reduces apoptosis in megakaryocytes via its receptors and the PI3-k/Akt pathway.
abstract: BACKGROUND
  Platelet-derived growth factor is involved in the regulation of hematopoiesis. Imatinib mesylate, a platelet-derived growth factor receptor inhibitor, induces thrombocytopenia in a significant proportion of patients with chronic myeloid leukemia. Although our previous studies showed that platelet-derived growth factor enhances megakaryocytopoiesis in vitro, the in vivo effect of platelet-derived growth factor in a model of radiation-induced thrombocytopenia has not been reported.
  
  
  METHODS
  In this study, we investigated the effect of platelet-derived growth factor on hematopoietic stem/progenitor cells and platelet production using an irradiated-mouse model. We also explored the potential molecular mechanisms of platelet-derived growth factor on thrombopoiesis in M-07e cells.
  
  
  RESULTS
  Platelet-derived growth factor, like thrombopoietin, significantly promoted the recovery of platelets and the formation of bone marrow colony-forming unit-megakaryocyte in irradiated mice. Histology confirmed the protective effect of platelet-derived growth factor, as shown by an increased number of hematopoietic stem/progenitor cells and a reduction of apoptosis. In a megakaryocytic apoptotic model, platelet-derived growth factor had a similar anti-apoptotic effect as thrombopoietin on megakaryocytes. We also demonstrated that platelet-derived growth factor activated the PI3-k/Akt signaling pathway, while addition of imatinib mesylate reduced p-Akt expression.
  
  
  CONCLUSIONS
  Our findings show that platelet-derived growth factor enhances platelet recovery in mice with radiation-induced thrombocytopenia. This radioprotective effect is likely to be mediated via platelet-derived growth factor receptors with subsequent activation of the PI3-k/Akt pathway. We also provide a possible explanation that blockage of platelet-derived growth factor receptors may reduce thrombopoiesis and play a role in imatinib mesylate-induced thrombocytopenia.
authors.affiliation: Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong.
authors.forename: Jie Yu
authors.initials: JY
authors.lastname: Ye
authors.forename: Godfrey Chi Fung
authors.initials: GC
authors.lastname: Chan
authors.forename: Liang
authors.initials: L
authors.lastname: Qiao
authors.forename: Qizhou
authors.initials: Q
authors.lastname: Lian
authors.forename: Fan Yi
authors.initials: FY
authors.lastname: Meng
authors.forename: Xue Qun
authors.initials: XQ
authors.lastname: Luo
authors.forename: Levon M
authors.initials: LM
authors.lastname: Khachigian
authors.forename: Ming
authors.initials: M
authors.lastname: Ma
authors.forename: Ruixia
authors.initials: R
authors.lastname: Deng
authors.forename: Jian Liang
authors.initials: JL
authors.lastname: Chen
authors.forename: Beng H
authors.initials: BH
authors.lastname: Chong
authors.forename: Mo
authors.initials: M
authors.lastname: Yang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001792:Blood Platelets / Q000187:drug effects* / Q000528:radiation effects; D008533:Megakaryocytes / Q000473:pathology*; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology* / Q000627:therapeutic use; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D013921:Thrombocytopenia / Q000188:drug therapy* / Q000209:etiology; D014916:Whole-Body Irradiation / Q000009:adverse effects
chemical_list: D010982:Platelet-Derived Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt