Drugs that are used to treat conditions of the eyes, or ones that simply use the eyes as a route into the rest of the body, can be very difficult to test in pre-clinical trials. Rabbits are often utilized for this, as they lack tear ducts and so don’t blink very often, allowing substances to penetrate the eye without being washed away first. But humans blink all the time, and our blinking is more complex, has greater consequences, and is more important than may first meet the eye, if you will forgive the pun.
To study what impact all this blinking has on the eyes, and to study how blinking will affect trial drugs that are delivered through the eyes, researchers at Kyoto University in Japan have developed a device that mimics blinking using living corneal cells and microfluidics. The new device will hopefully help not only to test new drugs, but also to study the impact of blinking on the cornea.
The device has four upper chambers within which corneal cells are allowed to grow. These are linked up to four lower chambers via a porous polyester membrane. As the cells grow in the upper chamber, they create a corneal barrier to block off the lower chamber. Pushing liquid up into the upper chambers and over the corneal cells simulates the forces that the cornea experiences when we blink. The four identical parallel channels within the device allow four different compounds or scenarios to be tested under similar conditions in a single experiment.
The device has already led to some new discoveries, including the fact blinking seems to affect the overall shape of corneal cells. Moreover, it looks like blinking also promotes the growth of filaments that provide flexibility and elasticity to the cornea.
Study in Lab on a Chip: Multi-corneal barrier-on-a-chip to recapitulate eye blinking shear stress forces
Source: Kyoto University