Epiretinal cell proliferation in macular pucker and vitreomacular traction syndrome: Analysis of flat-mounted internal limiting membrane specimens

Purpose. To describe new details of epiretinal cell proliferation
in flat-mounted internal limiting membrane (ILM) specimens.
Methods. One hundred and nineteen ILM specimens were removed
en-bloc with epiretinal membranes (ERMs) from 79 eyes with macular
pucker (MP) and 40 eyes with vitreomacular traction syndrome
(VMTS). Intraoperatively, posterior vitreous detachment (PVD) was
assessed as complete or incomplete. Whole specimens were
flat-mounted on glass slides, and processed for interference and
phase contrast microscopy, cell viability assay, and
immunocytochemistry. Results. Mean cell viability percentage was
higher in MP than in VMTS. Two cell distribution patterns were
found. Anti-CD163 labeling presented predominantly in MP with
complete PVD. CD45 expression was similar in all groups of
diagnosis. Anti-GFAP labeling was found in MP irrespective of the
extent of PVD. Alpha-SMA labeling mainly presented in MP with
incomplete PVD and in VMTS. Simultaneous antibody labeling included
GFAP/CD45, GFAP/CD163, CD163/CD45, and CD163/α-SMA. Conclusions.
Hyalocytes constitute a major cell type of epiretinal cell
proliferation in eyes with MP and VMTS. Glial cells, notably
retinal Müller cells, are involved as well. It appears that
transdifferentiation of cells in vitreomacular traction might be
more frequent than previously thought and that those cells possess
even more different immunocytochemical properties than expected.