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.

Treatment of donor corneal tissue with immunomodulatory cytokines: a novel strategy to promote graft survival in high-risk corneal transplantation

“…However, using ex vivo treatment, we observed swelling of the murine corneal stroma after 4 days of incubation causing them to become unsuitable for transplantation. These results are in accord with published data showing that the mouse cornea, unlike that of the human, is subject to significant swelling soon after being maintained in culture medium due to a less developed Bowman’s and Descemet’s membranes, as well as loose stromal collagen lamellae 24 . To circumvent this limitation, we adopted an in vivo approach whereby donor buttons receive immunomodulatory cytokines in situ via subconjunctival injection in living donor animals prior to procurement.…”

Development of a Curved, Stratified, In Vitro Model to Assess Ocular Biocompatibility

“…Poloxamines are currently used in ophthalmology in contact lens cleaning solutions and eye drop formulations [32], [33], [74]. In our model, these surfactants show a negligible decrease in viability which is in accordance with recent in vitro and ex vivo corneal assays that demonstrated the safety of these surfactants for the ocular surface [75]. Poloxamers, similar to poloxamines but with a generally lower molecular weight, are also frequently used in ophthalmic preparations.…”

Very early endothelial cell loss after penetrating keratoplasty with organ-cultured corneas

“…Meanwhile, there is clearly still room for improving storage methods to improve endothelial survival and homogeneity and thus to count cells on a small sample more representative of the whole population. We already suggested replacing dextran by less toxic molecules such as poloxamers20 or poloxamines21 to reduce the negative impact of the deswelling step.…”