Poloxamines for Deswelling of Organ-Cultured Corneas

Abstract

Background: Poloxamines are amphiphilic tetrofunctional block copolymers composed of four polyoxyethylene-polyoxypropylene arms joined to a central ethylene diamine bridge. Their safe profile allows diverse pharmaceutical and biomedical applications. Aim: To assess their use for corneal deswelling using a porcine model of organ culture (OC). Methods: Five poloxamines (T90R4, T904, T908, T1107 and T1307) were dissolved in a standard commercial OC medium (control) to reach 350 mosm kg^–1. In vitro cytotoxicity was tested using MTT assay on human corneal epithelial and endothelial cell (EC) lines and on primary human corneal fibroblasts. Paired porcine corneas stored in OC for 3 days were assigned for 48 h to a poloxamine medium or to a standard deswelling medium containing 5% dextran T500. Corneal EC density, morphometry, mortality, stromal thickness and transparency were evaluated before and after deswelling. Post-deswelling, EC viability/mortality was determined using a fluorescent live/dead assay. Results: Besides similar corneal thickness reduction and transparency improvement, T908, T1107 and T1307 decreased EC loss (5.4 ± 1.7% vs. 9.9 ± 2.6% in controls (p < 0.001)) and mortality, improved EC morphometry and reduced endothelial lesions compared to dextran. Conclusion: On this porcine model, poloxamines T908, T1107 and T1307 appear as good candidates to replace dextran for the deswelling. Experiments on human corneas are now necessary to confirm their efficiency and safety profile in OC.