Monoclonal antibody to CD9 inhibits platelet-induced human endothelial cell proliferation.
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.
Ko
Eun-Mi
EM
Department of Microbiology and Immunology, Kangwon National University School of Medicine, Chunchon 200-701, Korea.
Lee
In Yong
IY
Cheon
In Su
IS
Kim
Jinkoo
J
Choi
Jin-Suk
JS
Hwang
Jong Yun
JY
Cho
Jun Sik
JS
Lee
Dong Heon
DH
Kang
Dongmin
D
Kim
Sang-Hyun
SH
Choe
Jongseon
J
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
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C554869:CD9 protein, human; D008562:Membrane Glycoproteins; D060245:Tetraspanin 29