Behavioural difference of vascularized and non-vascularized retina after subretinal implantation of cellulose acetate membrane

Abstract

Purpose: Age-related macular degeneration (ARMD) is the major reason of visual loss in elderly population. Main causes are loss of native retinal pigment epithel cells (RPE) and damaged Bruch's membrane. Resulting in subfoveal choriocapillaris atrophy [1] and loss of photoreceptors [2–4]. Pilot clinical trials have shown encouraging results transplanting cell suspensions of autologous RPE or iris PE [2, 5–9]. To assess the biocompatibility of porous cellulose acetate membrane as a substrate for transplanted cells and a replacement for Bruch's membrane, we used two distinct animal models with vascularized and non-vascularized retinae.

Methods: Porous cellulose acetate membranes (80 µm and 30 µm thickness) with a molecular weight cut-off of 100 kD were selected due to their superior support of cultured cells in vitro. Membranes were implanted into the subretinal space of rabbits and pigs using a modified Grieshaber Cannulated Extrusion Needle. After one month in vivo, biocompatibility was assessed histologically.

Results: In the non-vascularized rabbit model the membrane caused a diffuse loss of cells in overlying retina layers, while even directly adjacent parts of the the retina remained intact. In the vascularized pig model we found a loss of outer segments of the photoreceltors due to the missing RPE layer, but the overlying retina remained intact.

Conclusion: Subretinal PE transplantation is a new and promising technique. Cellulose acetate membranes show a good biocompatibility and stability. In non-vascularized model minimal fibrotic reaction occured. Our results also demonstrate the the importance of the vascularized model.

Footnotes

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