Platelet factor 4 enhances the adhesion of normal and leukemic hematopoietic stem/progenitor cells to endothelial cells.
Platelet factor 4 (PF4) is a growth regulator of hematopoietic stem/progenitor cells (HSPCs), but its role in modulating the adhesive property of normal and leukemic cells remains unclear. We used CD34(+) cord blood cells, KG1a cell line, human umbilical vein endothelial cells (HUVECs) and a transformed HUVECs ECV-304 cells to study the effect of PF4 on cell adhesion. When CD34(+) cord blood cells were cultured either in fibronectin-coated (FN) culture plate or over the layer of HUVECs for 2h, a concentration-dependent increase of the number of adhered cells was observed in the culture containing PF4. FACS analysis revealed that the treatment of PF4 resulted in an increased expression of CD49d and CXCR-4 on CD34(+) cells. Moreover, when CD34(+) cells were expanded in the presence of PF4, the adhesive ability to culture plate of CD34(+) cells was significantly increased. To elucidate the mechanism of action of PF4, KG1a cells were incubated with or without PF4 for 2h on pre-established layer of ECV-304 cells. The percentage of CD49d(+) KG1a cells increased about 1.56 +/- 0.4 fold, and that of CD54(+) ECV-304 increased about 1.7 +/- 0.6 fold. Furthermore, the mRNA expression of CD49d and CD54 was upregulated when KG1a or ECV-304 cells were incubated with PF4. The adhesion capacity of KG1a cells was reduced after incubation with the blocking monoclonal antibodies against CD49d and CD54, respectively. Our data demonstrate that PF4 is able to enhance the adhesive ability of normal and leukemia HSPCs.
Zhang
Jing
J
State Key Laboratory of Experimental Hematology, National Research Center of Stem Cell Engineering & Technology, Institute of Hematology, Chinese Academy of Medical Sciences & Peking Union Medical University, Tianjin 300020, China.
Lu
Shi Hong
SH
Liu
Yong Jun
YJ
Feng
Yi
Y
Han
Zhong Chao
ZC
D018952:Antigens, CD34 / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D003029:Coagulants / Q000494:pharmacology*; D042783:Endothelial Cells / Q000166:cytology*; D005312:Fetal Blood / Q000166:cytology; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D039441:Integrin alpha4 / Q000235:genetics / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D015470:Leukemia, Myeloid, Acute / Q000276:immunology / Q000473:pathology*; D010978:Platelet Factor 4 / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014471:Umbilical Veins / Q000166:cytology
D018952:Antigens, CD34; D003029:Coagulants; D012333:RNA, Messenger; D011994:Recombinant Proteins; D018799:Intercellular Adhesion Molecule-1; D039441:Integrin alpha4; D010978:Platelet Factor 4