Sphere formation of ocular epithelial cells in the ciliary body is a reprogramming system for neural differentiation.
It is well known that neural stem/progenitor cells of the central nervous system (CNS) can proliferate to form neurospheres (CNS-neurospheres) that are positive for nestin, an intermediate filament for neural progenitors. Retinal stem/progenitor properties were also isolated from the ciliary body (CB) of the eye where, as in the CNS, such stem/progenitors also form spheres and have been considered to expand only via expansion by their proliferation even from the single-cell level (called spheres of pigment cells from the ciliary margin: PCM-spheres). We here found a new and distinct process underlying the growth of CB cell-derived spheres (CB-spheres) that is unlike the mechanism of CNS- and PCM-sphere expansion; this new process is a cell proliferation-independent incorporation of neighbor spheres and cells cultured at high density (200 cells/mul). The majority of cells in CB-spheres consisted of nestin-negative epithelia-like cells and started to express nestin during the course of their expansion by high-density cultivation. The growth of CNS-neurospheres was sensitive to a cell-cycle inhibitor, whereas the growth of CB-spheres was not seriously affected by cell proliferation; rather, the spheres grew by incorporating other CB-spheres and nestin-negative adherent cells, the latter of which started to express nestin and lost the expression of epithelial markers after being incorporated. These results indicate that CB-spheres do not form by the accumulation of neural progenitors but rather by a reprogramming system from epithelia-like cells for neural differentiation, a clearly distinct mechanism from sphere formation by single-cell expansion of retinal stem/progenitor populations.
Kohno
Ri-ichiro
R
Division of Pathophysiological and Experimental Pathology, Department of Pathology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Ikeda
Yasuhiro
Y
Yonemitsu
Yoshikazu
Y
Hisatomi
Toshio
T
Yamaguchi
Masahiro
M
Miyazaki
Masanori
M
Takeshita
Hiroko
H
Ishibashi
Tatsuro
T
Sueishi
Katsuo
K
D000818:Animals; D016590:Aphidicolin / Q000494:pharmacology; D002448:Cell Adhesion / Q000502:physiology; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002924:Ciliary Body / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D005434:Flow Cytometry; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D046529:Microscopy, Electron, Transmission; D009419:Nerve Tissue Proteins / Q000378:metabolism; D064231:Nestin; D009474:Neurons / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure
D004791:Enzyme Inhibitors; D007381:Intermediate Filament Proteins; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D016590:Aphidicolin