Researchers strive to replace lab animals with hydrogel models

Scientists in the UK have made a synthetic surface that could replace animal tissues in liquid drug formulation tests.

‘Mucosal membranes like those in the nasal cavity, mouth, eyes, stomach, bladder and vagina are continuously being washed with biological fluids. The majority of drugs administered to these surfaces will get washed away, reducing drug absorption and efficiency of any therapy,’ explains Vitaliy Khutoryanskiy, from the University of Reading, who led the work.

Mucoadhesive formulations are designed to improve drug retention on such surfaces and are typically tested on animal tissues, even though the results can be unreliable. Sometimes these tissues are taken from an abattoir’s surplus stock, but in many cases fresh tissues can only be obtained from laboratory animals like rats, mice and rabbits.

Now, Khutoryanskiy and his co-workers have made a glycopolymer hydrogel to mimic mucosal tissues in the stomach that could be used to pre-screen drug formulations and minimise animal tests. The hydrogel, which is composed of 80 % hydroxyethylmethacrylate and 20% acryloylglucosamine, has similar levels of hydration to stomach mucosa. It also recreates the chemical environment made by acryloylglucosamine and N-acetylglucosamine residues on epithelial proteins called mucins.

Formulation scientist Joshua Boateng, from the University of Greenwich, UK, says drug transport across-, or prolonged residence on-, the body's mucosal surfaces is a key area of investigation currently occupying pharmaceutical science researchers. ‘Any model, such as proposed in this study, which allows effective simulation of drug transport and dosage form performance closely resembling and in place of animals is a welcome development.’

Hydrogels that mimic mucosal linings of the eye and bladder are next on the team’s agenda.