Functional properties of hyalocytes under PDGF-rich conditions

Yoshihiro Noda, Yasuaki Hata, Toshio Hisatomi, Yuka Nakamura, Kumiko Hirayama, Muneki Miura, Shintaro Nakao, Kimihiko Fujisawa, Taiji Sakamoto, Tatsuro Ishibashi

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Abstract

PURPOSE. To investigate the functional properties and intracellular signaling of hyalocytes under platelet-derived growth factor (PDGF)-rich conditions. METHODS. The hyalocytes were isolated from bovine eyes and identified by immunocytochemistry and electron microscope. The expression of PDGF receptor α/β and its phosphorylation in response to PDGF-BB was analyzed by Western blot analysis. PDGF-BB-induced proliferation and migration were evaluated by thymidine uptake and Boyden's chemotaxis assay. The expression of the urokinase-type plasminogen activator (uPA) gene and the fibrinolytic activity were assessed by Northern blotting and fibrin zymography. An in vitro type I collagen gel contraction assay was performed to determine the effect of PDGF-BB on cellular contraction. RESULTS. The hyalocytes were immunocytochemically positive for S-100 and negative for glial fibrillary acidic protein (GFAP) and cytokeratin, as previously described. The electron microscope demonstrated that hyalocytes possess lysosome-like granules, mitochondria, and micropinocytotic vesicles in their cytoplasm. The hyalocytes expressed PDGF receptor α and β, both of which were immediately phosphorylated in response to PDGF-BB. PDGF-BB also activated p85 P13-kinase, p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase. PDGF-BB induced thymidine uptake and migration in a concentration-dependent (0-10 ng/mL) manner. Inhibitors of the respective kinases prohibited PDGF-BB-dependent thymidine uptake and migration with the exception of the p44/p42 MAP kinase inhibitor, which displayed no inhibitory effects on migration. PDGF-BB increased uPA gene expression and fibrinolytic activity. Collagen gel contraction observed under PDGF-BB-rich conditions was not prohibited by the respective inhibitors investigated. CONCLUSIONS. The hyalocytes demonstrated macrophage-like characteristics and may have both physiologic and pathologic roles, such as the maintenance of vitreous transparency through fibrinolytic activity and the pathogenesis of proliferative-vitreoretinal diseases through cellular proliferation and vitreous hyper-contraction.

Original languageEnglish
Pages (from-to)2107-2114
Number of pages8
JournalInvestigative Ophthalmology and Visual Science
Volume45
Issue number7
DOIs
Publication statusPublished - Jul 2004

All Science Journal Classification (ASJC) codes

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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    Noda, Y., Hata, Y., Hisatomi, T., Nakamura, Y., Hirayama, K., Miura, M., Nakao, S., Fujisawa, K., Sakamoto, T., & Ishibashi, T. (2004). Functional properties of hyalocytes under PDGF-rich conditions. Investigative Ophthalmology and Visual Science, 45(7), 2107-2114. https://doi.org/10.1167/iovs.03-1092