title: Role of receptor-mediated endocytosis in the antiangiogenic effects of human T lymphoblastic cell-derived microparticles.
abstract: Microparticles possess therapeutic potential regarding angiogenesis. We have demonstrated the contribution of apoptotic human CEM T lymphocyte-derived microparticles (LMPs) as inhibitors of angiogenic responses in animal models of inflammation and tumor growth. In the present study, we characterized the antivascular endothelial growth factor (VEGF) effects of LMPs on pathological angiogenesis in an animal model of oxygen-induced retinopathy and explored the role of receptor-mediated endocytosis in the effects of LMPs on human retinal endothelial cells (HRECs). LMPs dramatically inhibited cell growth of HRECs, suppressed VEGF-induced cell migration in vitro experiments, and attenuated VEGF-induced retinal vascular leakage in vivo. Intravitreal injections of fluorescently labeled LMPs revealed accumulation of LMPs in retinal tissue, with more than 60% reductions of the vascular density in retinas of rats with oxygen-induced neovascularization. LMP uptake experiments demonstrated that the interaction between LMPs and HRECs is dependent on temperature. In addition, endocytosis is partially dependent on extracellular calcium. RNAi-mediated knockdown of low-density lipoprotein receptor (LDLR) reduced the uptake of LMPs and attenuated the inhibitory effects of LMPs on VEGF-A protein expression and HRECs cell growth. Intravitreal injection of lentivirus-mediated RNA interference reduced LDLR protein expression in retina by 53% and significantly blocked the antiangiogenic effects of LMPs on pathological vascularization. In summary, the potent antiangiogenic LMPs lead to a significant reduction of pathological retinal angiogenesis through modulation of VEGF signaling, whereas LDLR-mediated endocytosis plays a partial, but pivotal, role in the uptake of LMPs in HRECs.
authors.affiliation: Departments of Pediatrics and Pharmacology, Research Center of Centre hospitalier universitaire Sainte-Justine, University of Montreal, Montreal, Quebec, Canada.
authors.forename: Chun
authors.initials: C
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Xiong
authors.forename: Qian
authors.initials: Q
authors.lastname: Qiu
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Shao
authors.forename: Zuo
authors.initials: Z
authors.lastname: Shao
authors.forename: David
authors.initials: D
authors.lastname: Hamel
authors.forename: Houda
authors.initials: H
authors.lastname: Tahiri
authors.forename: Grégoire
authors.initials: G
authors.lastname: Leclair
authors.forename: Pierre
authors.initials: P
authors.lastname: Lachapelle
authors.forename: Sylvain
authors.initials: S
authors.lastname: Chemtob
authors.forename: Pierre
authors.initials: P
authors.lastname: Hardy
mesh_terms: D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation; D055252:Cell-Derived Microparticles / Q000502:physiology*; D004705:Endocytosis / Q000502:physiology*; D042783:Endothelial Cells / Q000502:physiology; D004730:Endothelium, Vascular / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D051381:Rats; D015861:Retinal Neovascularization / Q000473:pathology / Q000503:physiopathology*; D012171:Retinal Vessels / Q000473:pathology / Q000503:physiopathology; D013601:T-Lymphocytes / Q000473:pathology / Q000502:physiology*