Preclinical study in a corneal bioreactor of the effectiveness of amniotic membrane of umbilical cord extract (AMUCE) for the treatment of corneal deep stromal ulcerations

Abstract

PurposeOur patented corneal bioreactor (BR) improves the long‐term survival of human corneas ex vivo by restoring intraocular pressure and renewal of storage medium.AimTo use the BR to test the efficacy of eye drops containing devitalized ground amniotic membrane of umbilical cord extract (AMUCE) to treat deep stromal ulcerations. AMUCE contains high level of proteoglycans, collagen and physiological growth factors.MethodsOnly pairs of human corneas (with ECD > 800 cells/mm2) were used to obtain best possible controls. They were first stored for 2 weeks into the BR filled with CorneaMax (Eurobio, France), with 21 mmHg in the endothelial chamber to allow regeneration of a normal epithelium. Then, an 8.0 mm diameter calibrated epithelial ulcer was made with a spatula and a 6 mm diameter × 100 µm in depth was made with Excimer laser in the stroma. Using a specific BR lid allowing sterile handling, each cornea was treated topically 4 times daily either by the AMUCE eye drops (TBF, France) or by the vehicle (0.9% NaCl). Closure of the ulceration was monitored daily using fluorescein staining quantified by image analysis (FIJI) of macro‐zoom microscopy. After wound healing corneas were fixed for histology (HES) and immunolabeling of epithelial markers.ResultsThree pairs were used. Epithelium wound healing was obtained at D3, D9, D10 with AMUCE and D3, D9, D19 with the vehicle. Histology performed in ulcerations centre showed 3‐6 epithelial layers with AMUCE and 1‐4 with the vehicle. At D21, significant epithelial detachment was observed only for 2 corneas treated with the vehicle. For one pair, immunolabelling for E‐cadherin and Cytokeratin K3/K12 showed better epithelial differentiation with AMUCE than with vehicle. No evidence of stromal regeneration was observed in the 6 corneas.ConclusionsAMUCE has potential for a faster and lasting epithelium regeneration (stratification and maturation). Nevertheless, it has no impact on stromal regeneration in this model.