Initial results from a Cosmetics Europe project to evaluate a multi-organ chip (MOC) system suggest a high level of reproducibility between labs, according to Jochen Kuehnl, who manages Beiersdorf's experimental toxicology lab in Hamburg, Germany.
The project, which focuses on characterising chemical metabolism, forms part of Cosmetics Europe's long-range science strategy (LRSS) programme. It uses a chip housing both skin and liver models, developed and supplied by external partner company TissUse in Germany. "This is the first [cosmetics project] to compare the two routes of exposure," said Martina Klaric, LRSS project manager at Cosmetics Europe. Although most cosmetics are applied to the skin, the team is also interested to see what happens when chemicals enter the body's circulation, she added.
The team applies test chemicals directly to the "skin", a reconstructed human epidermis, as well as injecting them into a liquid medium flowing through the chip. It then uses mass spectrometry to analyse metabolites produced in the MOC and compares the two exposure routes.
In a proof-of-concept phase, the project team worked on two well-documented chemicals: permethrin and hyperforin. The first is a pesticide but is also used as a topical treatment for scabies while the second is a plant chemical produced by St John's Wort, available as a supplement.
"The chemicals that we chose are not strictly cosmetic chemicals but have very good data regarding their metabolism," explained Ms Klaric. "We wanted to start with something predictable. At the beginning you really need to make sure your system works fine and that your data are comparable to what is in vivo." she said.
The MOC's "viability" over a selected time period is crucial, allowing repeat-dose exposures. In initial tests, the team successfully administered repeated doses over five days and the MOC maintained its metabolic capacity. The application route affected the concentrations of some metabolites as well induction of genes for metabolising enzymes.
"We were very pleased that we succeeded in obtaining such reproducible data," said Dr Kuehnl. This included metabolite profiles and concentrations, as well as viability data.
Collaboration and training are key to transferability, he added. "The devil is in the detail. You need good training and regular communication."
The project team is currently choosing the next two chemicals to study. These will be more related to the cosmetics field, with lower toxicity,
After the second set of test results, the team will publish the test protocols and data. "I think it will be very important to convey all of the learnings from this project, which could facilitate the transferability of the model," said Dr Kuehnl.