Hyalocytes in idiopathic epiretinal membranes: a correlative light and electron microscopic study.
OBJECTIVE
To describe characteristics of epiretinal cells at the vitreoretinal interface by correlative light and electron microscopy (CLEM).


METHODS
Epiretinal membrane (ERM) specimens and internal limiting membrane (ILM) specimens were harvested by sequential peeling during vitrectomy from 27 eyes with idiopathic epiretinal gliosis, and processed for CLEM. Intraoperatively, the presence of posterior vitreous detachment (PVD) was documented. We used anti-vimentin, anti-α-smooth muscle actin (α-SMA), and anti-CD45 as primary antibodies. A fluorescein-tagged immunonanogold cluster was used as secondary antibody and visualized under the fluorescence and transmission electron microscope.


RESULTS
We demonstrated CD45-positive cells specifically labelled at their plasma membranes with ultrastructural features known for hyalocytes, such as oval nucleus with marginal chromatin, vacuoles, dense granules, and thin cytoplasmic protrusions. CD45-positive cells were mostly located on a thick layer of native vitreous collagen. They were covered by newly formed collagen strands with multilayered proliferation of myofibroblasts. We also demonstrated immunoreactivity for vimentin and alpha-SMA. Cell fragments with positive labelling for α-SMA and vimentin were not only found on the vitreal side of the ILM, but also on the retinal side.


CONCLUSIONS
By CLEM, the majority of CD45-positive cells in epiretinal cell proliferation were characterized as hyalocytes. In the context of anomalous PVD and vitreoschisis, ultrastructural features and topographic localization of hyalocytes suggest that these cells play a significant role in ERM formation. CLEM enables a more accurate characterization of epiretinal cell proliferation, and therefore, contributes to a better understanding of the pathogenesis of diseases at the vitreoretinal interface.
Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany, ricarda.schumann@med.uni-muenchen.de.
Ricarda G
RG
Schumann
Arnd
A
Gandorfer
Jean
J
Ziada
Renate
R
Scheler
Markus M
MM
Schaumberger
Armin
A
Wolf
Anselm
A
Kampik
Christos
C
Haritoglou
D000199:Actins / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D001485:Basement Membrane / Q000648:ultrastructure*; D015415:Biomarkers / Q000378:metabolism; D049109:Cell Proliferation; D019773:Epiretinal Membrane / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D014746:Vimentin / Q000378:metabolism; D014821:Vitrectomy; D014822:Vitreous Body / Q000166:cytology*; D020255:Vitreous Detachment / Q000175:diagnosis
C541116:ACTA2 protein, human; D000199:Actins; D015415:Biomarkers; D014746:Vimentin; D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human