A novel osmoprotective liposomal formulation from synthetic phospholipids to reduce in vitro hyperosmolar stress in dry eye treatments

Abstract

Dry eye disease (DED) is a worldwide, multifactorial disease mainly caused by a deficit in tear production or increased tear evaporation with an increase in tear osmolarity and inflammation. This causes discomfort and there is a therapeutic need to restore the homeostasis of the ocular surface. The aim of the present work was to develop a biodegradable and biocompatible liposomal formulation from the synthetic phospholipids 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) that is able to reduce the effects of hypertonic stress by helping to restore the lipid layer of the tear film. Liposomes were made using the lipid film hydration method with synthetic phospholipids (10 mg/mL) with and without 0.2% HPMC. They were characterised in terms of size, osmolarity, pH, surface tension, and viscosity. Additionally, the in vitro toxicity of the formulation at 1 and 4 h in human corneal epithelial cells (hTERT-HCECs) and human conjunctival cells (IM-HConEpiC) was determined. Furthermore, osmoprotective activity was tested in a corneal model of hyperosmolar stress. In vivo acute tolerance testing was also carried out in albino New Zealand rabbits by topical application of the ophthalmic formulations every 30 min for 6 h. All the assayed formulations showed suitable physicochemical characteristics for ocular surface administration. The liposomal formulations were well-tolerated in cell cultures and showed osmoprotective activity in a hyperosmolar model. No alterations or discomfort were reported when they were topically administered in rabbits. According to the results, the osmoprotective liposomal formulations developed in this work are promising candidates for the treatment of DED.

Keywords:

• DED
• osmoprotective liposomes
• synthetic phospholipids
• hyperosmolarity
• tolerance
• osmoprotection

Acknowledgments

M.A.G.-C. thanks the Spanish MECD (FPU18/03445) for a PhD fellowship. We acknowledge Rocio Arranz and Francisco Javier Chichón for their support within the access to the cryoEM CNB-CSIC facility in the context of the CRIOMECORR project (ESFRI-2019–01-CSIC-16). Figure 7 was created with BioRender (www.biorender.com).

Disclosure statement

The authors report there are no competing interests to declare.

Additional information

Funding

This work was supported by the European funding Fondo Europeo de Desarrollo Regional (FEDER-CICYT), under Grant FIS-PI17/00079 and PI17/00466, Research Group UCM 920415 ‘Innovation, Therapy and Pharmaceutical Development in Ophthalmology (InnOftal),’ and the ISCII-FEDER RETICS (OFTARED) under Grant RD16/0008/0004 and RD16/0008/0009.