Be it drugs or chemicals, before being approved many active ingredients must be tested on animals to ensure they are safe. As an alternative, some of these tests may involve cell cultures grown outside of an organism. However, these extracted cells have so far only been tested in two-dimensional models, for example in Petri dishes. But in the body, human cells grow in structures and organs – which are three-dimensional, not flat. “Studies have shown that results from 3D cell culture systems are much more suitable for extrapolation to the human organism,” explains Dr Peggy Stock, head of the collaborative research project at Leipzig’s Faculty of Medicine.
Elastic silicone from a 3D printer
Two years into the project – “Conception of a 3D Silicone Structure for Mammalian Cell Culture” – the researchers have now taken a big step forward. Together with their industrial partner KET GmbH, the scientists have developed a new 3D silicone plotting technology. This involves superimposing the strands of the lattice to resemble an organic structure. Previously, the researchers tested different types of silicone until they found the most suitable one: “We work with a silicone that is highly elastic and roughly corresponds to that found in organs in the human body. The silicone needs to work well for the cells, but also of course for 3D printing,” continues Dr Peggy Stock, a member of the Applied Molecular Hepatology group headed by Professor Bruno Christ.
In order to test the advantages of the 3D system compared to 2D cell cultures, the research team isolated human stem cells from fat tissue. They sowed these on the silicone lattice before cultivating them in an incubator. The scientists differentiated the human stem cells on the 3D lattices in such a way that they would behave like organic cells in the body. They survived for up to six weeks. “We were able to show that cells colonise the 3D lattice and form their own three-dimensional cell structures. This preserves their natural properties, such as communication between the cells,” notes Stock. In addition, the function of liver cells which had been differentiated from stem cells was found to be significantly improved compared to cells differentiated in a 2D culture. Specifically, the liver-like cells were better able to synthesise the proteins that are normally synthesised in the liver . The researchers also noted more successful bone cell differentiation than in a 2D culture. “We will not abandon animal testing altogether, but with this silicone lattice we have created something that will allow us to predict the feasibility of innovations in the field of medicine and pharmaceuticals, can be used in a wide range of applications, and can thus contribute to reducing the number of experiments conducted on animals,” continues Stock.