Fig. 5: Histological characterization post-explantation.

Toluidine blue-stained histological sections 6 weeks post-explantation demonstrate preservation of the INL with planar, honeycomb and pillar (B–D; n = 4 per group) devices, compared to non-implanted RCS control (A; n = 4). A thick acellular layer (red arrows) develops in the subretinal space after explantation. A pocket (*) where the implant used to be is visible in some sections. The yellow line demarks the RPE/choroid boundary. Scale bar is 50 µm. Masson’s trichrome staining (MTS) labeled the acellular layer as collagen in blue (blue arrows). It was present after removal of all three devices (F–H; n = 4 per group), but not in the RCS control (E; n = 4). Scale bar is 70 µm. GFAP (magenta) immuno-labeling of the sections showed the Müller cell activation between an RCS control (I; n = 8) and the three device groups (J–L; n = 3 per group). Scale bar is 80 µm. Müller glial population (M–P; n = 4 per group) labeled with glutamine synthetase (green) show retracted cells and the appearance of a glial seal after photoreceptor degeneration in the RCS control. Similar Müller cells are observed after extraction of planar, honeycomb and pillar implants, with varying levels of glial seal. Scale bar is 80 µm. N numbers represent individual experiments with biological replicates, all yielding similar results. INL inner nuclear layer, GCL ganglion cell layer, RPE retinal pigment epithelium.