Scientists at the University of Latvia (UL) are investigating how to deliver medications to cells that require treatment while minimising the impact on healthy cells. For this purpose, a special drug delivery system is being developed that could also help reduce treatment costs in the future. Evita Rostoka, a leading researcher at the Faculty of Medicine and Life Sciences of the University of Latvia, discusses the research on the Radio SWH TV programme "Latvia in Science", produced with the support of Rietumu Banka.
A Postman Who Must Find the Right Address
For a medication to reach the intended cell, simply knowing the correct address is not enough. The delivery molecule must travel through the bloodstream, enter the tissues and find the specific target, while the delivered drug must retain its ability to act. Combining all these tasks is one of the greatest challenges.
"We need to ensure that the postman can successfully travel with his 'cargo' through the circulatory system to exactly where it is needed," says Evita Rostoka.
Scientists already know the delivery molecules and medications, and the targets to which they need to be delivered are also clear. The greatest challenge is to combine these elements into a unified system that is not only effective but also affordable.
A Lock, a Key and an Opportunity to Reduce Costs
The researchers are focusing on aptamers – small nucleic acid molecules that can be made of DNA or RNA and are capable of recognising specific proteins on the surface of cells.
"They recognise each other like a lock and a key," Rostoka describes the interaction between an aptamer and a cell surface protein. The aptamer binds to the corresponding protein, and the cell can take it up together with the attached "cargo", such as a medication.
The advantages of aptamers are their small size and relatively simple production. Unlike large antibody molecules, they can be synthesised chemically, which could reduce costs. Moreover, smaller molecules may be able to penetrate deeper into tissues, where the target cells are located.
"It is cheaper. That is actually one of the main factors," says the researcher.
The researcher emphasises that high costs are one of the barriers to the wider use of targeted therapy. Therefore, the possibility of producing delivery molecules at a lower cost is significant, although it is not yet known how much treatment based on them would cost.
However, finding a suitable aptamer alone is not enough. One of the most important tasks of Rostoka's research is to develop a connector, or linker – a kind of bridge that connects the delivery molecule to the "cargo" it is intended to transport.
The researchers are experimenting with different principles of linker function, including testing whether it should break down under the influence of certain enzymes or remain stable. The aim is to create as universal a solution as possible, allowing both the aptamer and the substance attached to it to be changed.
The potential applications of such a system are not limited to oncology. In the future, a similar approach could also be used for the targeted delivery of antibiotics to act on specific bacteria while affecting the rest of the body as little as possible.
A Flashlight That Helps Track the Molecule's Path
How can scientists make sure that the system they have developed actually reaches the intended location? One method is to attach a fluorescent substance instead of a medication, which acts as a kind of flashlight. With the help of a special microscope, it is possible to observe where the molecule has ended up.
Latvian researchers are currently testing their delivery system in the laboratory using cell cultures and three-dimensional cell models, or spheroids. These help determine how deeply the molecular complex can penetrate a group of cells resembling tissue. Similar molecular complexes have already been tested worldwide in preclinical animal studies, but this approach has not yet reached the stage of testing in humans.
From One Solution to Many Possibilities
Rostoka began focusing on this area of research a few years ago, collaborating with researchers in organic synthesis at the University of Latvia. Funding is needed to launch a new research direction. "To obtain state funding, you already need to have some results, which is why the support of the UL Foundation is very important to us. We received funding through the MikroTik project competition in the fields of natural sciences, technology and medical sciences," explains the researcher. "Later, we were able to apply for funding through the biomedical and photonics innovation platform BioPhot and the FLPP funding competitions."
A doctoral student has also become involved in the work, developing and synthesising molecular compounds. During the experiments, the initial idea has evolved, opening up an increasing number of potential solutions. Rostoka explains that two or three years ago, there was one perspective, but now several development paths have been identified.
Although further research is still needed before such a system can be used in medicine, the findings obtained in the laboratory help scientists evaluate new solutions and improve the possibilities for targeted drug delivery.
