title: Monoclonal antibody to CD9 inhibits platelet-induced human endothelial cell proliferation.
abstract: Platelets are anucleate cytoplasmic fragments derived from bone marrow megakaryocytes, and endothelial cells constitute the barrier between bloodstream and adjacent tissues. Although platelets are thought to regulate the biological functions of endothelial cells, the molecular mechanisms involved are poorly understood. With human umbilical vein endothelial cells and freshly isolated platelets, we established an in vitro model of platelet-induced endothelial cell proliferation. Platelets stimulated endothelial cell proliferation in a dose-dependent manner and transwell experiments with semi-permeable membranes suggested that direct cell-to-cell contacts were required. We developed mAbs against platelets and selected a mAb that blocks their proliferative effect. We purified the antigen by immunoprecipitation and identified it by Q-TOF MS analysis as the tetraspanin CD9. Since both platelets and endothelial cells expressed CD9 strongly on their surfaces we carried out a pre-treatment experiment that showed that CD9 molecules on the endothelial cells participate in the mitogenic effect of the platelets. The inhibitory effect of our mAb was comparable to that of a well-known functional anti-CD9 mAb. These results suggest that the tetraspanin CD9 plays an important role in endothelial regeneration.
authors.affiliation: Department of Microbiology and Immunology, Kangwon National University School of Medicine, Chunchon 200-701, Korea.
authors.forename: Eun-Mi
authors.initials: EM
authors.lastname: Ko
authors.forename: In Yong
authors.initials: IY
authors.lastname: Lee
authors.forename: In Su
authors.initials: IS
authors.lastname: Cheon
authors.forename: Jinkoo
authors.initials: J
authors.lastname: Kim
authors.forename: Jin-Suk
authors.initials: JS
authors.lastname: Choi
authors.forename: Jong Yun
authors.initials: JY
authors.lastname: Hwang
authors.forename: Jun Sik
authors.initials: JS
authors.lastname: Cho
authors.forename: Dong Heon
authors.initials: DH
authors.lastname: Lee
authors.forename: Dongmin
authors.initials: D
authors.lastname: Kang
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Jongseon
authors.initials: J
authors.lastname: Choe
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D015703:Antigens, CD / Q000276:immunology / Q000502:physiology*; D001792:Blood Platelets / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects*; D018920:Coculture Techniques; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects; D006801:Humans; D008562:Membrane Glycoproteins / Q000276:immunology / Q000502:physiology*; D060245:Tetraspanin 29
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C554869:CD9 protein, human; D008562:Membrane Glycoproteins; D060245:Tetraspanin 29