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Photoactivated drug delivery could help to cure eye diseases

31 Aug 2016

An efficient and safe new drug administration method could help to cure diseases of the back of the eye, while saving on health care costs. Research led by Leena-Stiina Kontturi, a researcher at the University of Helsinki, and risk-funded by the Academy of Finland involves developing better dispensing methods for medicines targeted at the back of the eye.

Diseases affecting this part of the eye are the most common cause of visual impairment and blindness in industrialised countries. For example, it is estimated that 196 million patients will suffer from age-related macular degeneration in 2020 and 288 million in 2040.

"Nowadays, the only effective way of delivering medicine to the back of the eye is repeated injections into the eye once or twice a month. Since such injections are uncomfortable for the patient and costly for the health care services, we are seeking better solutions," explains Kontturi.

Light releases drug into the eye

The research involves the development of photoactivated liposomes, which can effectively and safely deliver the drug to the rear of the eye. A liposome is a bubble composed of fatty lipid molecules, which has two lipid molecule layers on its surface.

"The drug is administered using a nanoparticle – composed of lipids and photoactivated molecules – as the carrier in which the drug is encapsulated. The idea is to enable the effective and safe dosage of various drug molecules at a controlled time and location at the back of the eye," explains Kontturi.

Kontturi adds that the controlled release of the drug from the carrier is based on release activated by external and internal stimuli. Light exposure acts as an external stimulus, while intracellular pH change acts as an internal one. Targeting molecules can also be used to target the carrier at specific eye cells.

"The importance and use of biological medicinal products, such as RNA and DNA-based medicines, are continuously growing but they need efficient carriers. The development of new dispensing methods is essential to the introduction of such medicines into patient care."

The research results can be applied to various tissues

Designing and creating a photoactivated carrier is difficult. Kontturi comments that combining targeting molecules and a range of properties, such as light and pH sensitivity, into the same nanoparticle is not easy.

"This time-consuming research covers the testing of a range of possible solutions and the development of new techniques and methods. In addition, tissue at the back of the eye is difficult to target, because the body protects it in a number of ways. Photoactivatable carriers of this kind, intended for intracellular drug delivery, have barely been studied, which makes the research difficult due to the lack of background knowledge."

Kontturi believes that the risks associated with the project will be eliminated by consulting expert partners and bringing in a range of specialisms. The research is being carried out in collaboration with the University of Helsinki, the University of Eastern Finland, the University of Utrecht and the University of Ghent. The company Modulight, which specialises in the development and manufacture of lasers used in medicine, is also participating in the project.

In addition to the actual research objective, the study will provide valuable findings on the impact of photoactivation on cells and tissue, and on nanoparticle drug delivery into the eye.

"The use of photoactivated drug delivery as a dispensing system may be suitable for tissues of all kinds that can be subjected to targeted light simulation. For example, such tissues might include the skin, gastrointestinal tract, lungs and many tumours. The technology therefore has a broad range of potential applications in medicine," says Kontturi.

Major results achieved on the basis of risk funding

Kontturi freely admits that ambition attracted her to this challenging research.

"Our goal is to develop a versatile and customisable delivery system which is suitable for various types of medicine, administration routes and target cells at the back of the eye. If successful, the study will have a major impact since it can be used to treat large groups of patients."

Promising results have already been achieved in the study. Among other issues, the research team has proven that the technique works and that the carrier's characteristics can be finely controlled. Tests have also been carried out to ensure that neither the photoactivated liposomes or the required light exposure are harmful to cells at the back of the eye.

"We have already filed a patent application related to photoactivatable liposomes," says Kontturi.

Kontturi stresses that major scientific research is seldom achievable without taking risks.

"It's great that risk funding is being used to support new kinds of research ideas and younger researchers, and to promote an experimental approach and daring research. The funding has also enabled me to attend Utrecht University as a visiting researcher, which is highly useful and rewarding not only for this risk project, but also in terms of developing my own scientific perspective and understanding," says Kontturi.

Text and photo: Anna-Riikka Oravakangas

Last modified 31 Aug 2016
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