Promotion and implementation of the 3Rs principle in TransCure research: creating a novel 3D cell system to explore the materno-foetal interface
Many scientists worldwide strive to find alternatives to mainstream approaches in pre-clinical research in order to reduce animal experimentation. Christiane Albrecht, NCCR TransCure PI, is one such scientist and recently received a grant from the Swiss 3R Competence Centre. This article illustrates her innovative system to study the materno-foetal interface following the 3Rs principle (Replacement, Reduction and Refinement).
In 1959, William Russel and Rex Burch formulated the 3Rs principle for more humane research involving animals. It aims to replace the use of animals with alternative methods whenever possible, reduce the use of animals, and refine experiments to minimise distress, while maintaining the validity of the scientific outcomes. Over the last 60 years, the 3Rs principle has become an integral part of animal research legislation around the world.
In Switzerland, the use of animals in research can only be approved if deemed indispensable. Based on the ethical concept of utilitarianism, indispensability is determined by carrying out a weighing of interests, in which the legitimate societal interests of the experiments should outweigh the potential constraints caused to the animals. In view of the Replacement principle, researchers are first required to assess the availability and feasibility of alternative methods for their scientific questions.
Support for 3Rs principle-oriented research
The Swiss 3R Competence Centre (3RCC) is the major Swiss funding body for 3Rs research, supporting high-quality research to advance this area. In the 2019 Open Call, three of the four awarded projects were from the University of Bern (the other was from ETH Zurich). The projects involve the establishment of an idiopathic pulmonary fibrosis model on a lung-on-chip (Olivier Guenat), the development of a platform for genitourinary cancer patient-derived organoids (Marianna Kruithof-de Julio), and the engineering of a 3D placenta drug transfer model (Christiane Albrecht). These 3RCC projects are an essential step in the development of animal-free models (Replacement) to advance our understanding of human biological processes.
In this context, the University of Bern’s commitment to the implementation and advancement of research methods grounded on the 3Rs principle resulted in the establishment of the position of Deputy 3Rs Coordinator, currently held by Dr. Homare Yamahachi. Among his duties is the support of researchers in preparing 3Rs grant applications and the implementation of validated 3Rs methods.
Finding a good model for placenta research
The above-mentioned project of Prof. Christiane Albrecht is planned as an extension of her studies within the TransCure network on the maternal-foetal transfer of iron across the placenta (link to project). The general goal of her research group is to gain insight into the mechanisms and regulation of nutrient and xenobiotic transport across the placental barrier. These are of fundamental importance for adequate intrauterine nutrition of the foetus, ensuring proper growth and development. In particular, her research team aims to elucidate the molecular mechanisms of lipid, amino acid and iron transport across the placenta, and to study the involvement of membrane transporters in placental pathology.
Applying the 3Rs principle in placental research is particularly important since the structure of the human placenta is different from that of most animal species. Thus, it has been demonstrated that the human placenta has numerous human-specific genetic features and major differences in placentation (formation and arrangement of the placenta in the uterus) occur between humans and other animals (Schmidt et al., 2015). Nevertheless, despite these differences and probably due to a lack of appropriate alternative ex vivo and in vitro models, murine and ovine placentae are still widely used animal models for studying placental function.
In the framework of Prof. Albrecht’s TransCure projects, several highly physiological ex vivo and in vitro models have been established, such as the ex vivo dual perfusion system of the human placenta (Melhem et al., 2019) and the in vitro confluent monolayer model using isolated primary trophoblasts from human placenta on a Transwell® system (Huang et al., 2016). The latter system will now be further developed and validated into a novel 3D cell culture model and applied to monitor the transfer of drugs from the mother to the foetus. Studying materno-foetal drug transfer in a physiological context is of ultimate importance, since the use of drugs during pregnancy can raise severe safety concerns for the foetus. The new model will be achieved by incorporating both trophoblasts and endothelial cells, and using constant liquid flow (Figure 1), which has important physiological effects on cell morphology (Sfriso et al., 2018) and biology (Salieb-Beugelaar et al., 2010). In this context, primary cells isolated from human placenta and umbilical veins will be used to create a functional in vitro co-culture perfusion model for simulating the in vivo situation at the maternal-foetal interface.
Achieving 3Rs with innovation
The concept is innovative in this area of research, especially as the Albrecht group aims to exclusively use primary cells in a co-culture model, an approach that is known to better represent in vivo physiology than immortalised cell lines. The combination of optimal cell isolation methods, special media containing defined growth factors and culture chambers designed for studying drug transport are a highly creative solution to a real need in our society. This model is expected to be cheap to apply and rapid, with a timeframe of just one week needed for appropriate synchronised growth of the two cell types. To achieve these goals, Prof. Albrecht will collaborate with Swiss hospital and industry partners (Ruedi Moser, Lindenhofgruppe and Chennakesava Cuddapah, CurioBiotech), and international academic expert (František Štaud, Charles University, Czech Republic).
This novel cell-based model will provide important information on the kinetics of materno-foetal drug transfer across the placental barrier. Most importantly, it will provide a safe initial screening method for new drugs, indicating whether they reach the foetal circulation and might exert embryonic toxicity. It will thereby simplify developmental and reproductive toxicology studies and hence reduce the number of animals used for preclinical studies. Moreover, this model will also be especially useful for the continuing TransCure studies related to improving our understanding of the physiology and pathophysiology of the human placenta.
NCCR TransCure PI
Deputy 3Rs Coordinator, Animal Welfare Office, University of Bern
The Swiss 3R Competence Centre (3RCC) promotes the 3Rs principle (replacement, reduction and refinement of animal experimentation) in Switzerland and facilitates its implementation in life sciences, focusing on research, education and communication.
Founded in 2018, the 3RCC is a joint initiative composed of the key 11 Swiss universities and higher education institutions, the Swiss association of the pharmaceutical industry (Interpharma), the Swiss Federal Food Safety and Veterinary Office (FSVO), and the Swiss Animal Protection (SAP).
Each year, the 3RCC publishes calls for funding high-quality research projects dedicated to the advancement of the 3Rs Principles.
Replacement: Methods, which permit a given purpose to be achieved without conducting experiments or other scientific procedures on animals.
Reduction: Methods for obtaining comparable levels of information from the use of fewer animals in scientific procedures, or for obtaining more information from the same number of animals.
Refinement: Methods, which alleviate or minimize potential pain, suffering and distress, and which enhance animal well-being.
Huang X, Lüthi M, Ontsouka EC, Kallol S, Baumann MU, Surbek DV, and Albrecht C, “Establishment of a Confluent Monolayer Model with Human Primary Trophoblast Cells: Novel Insights into Placental Glucose Transport.” Molecular Human Reproduction 22 (6): 442–56 (2016).
Melhem H, Kallol S, Huang X, Lüthi M, Ontsouka EC, Keogh A, Stroka D, Thormann W, Schneider H, and Albrecht C. 2019. “Placental Secretion of Apolipoprotein A1 and E?: The Anti- Atherogenic Impact of the Placenta,” Sci Rep 9, 6225 (2019).
Salieb-Beugelaar GB, Simone G, Arora A, and Philippi A. 2010. “Latest Developments in Microfluidic Cell Biology and Analysis Systems” Anal. Chem. 82 (12): 4848–64 (2010).
Schmidt A, Morales-Prieto DM, Pastuschek J, Fröhlich K, and Markert UR, “Only Humans Have Human Placentas?: Molecular Differences between Mice and Humans.” Journal of Reproductive Immunology 108: 65–71 (2015).
Sfriso R, Zhang S, Bichsel CA, Steck O, Despont A, Guenat OT, and Rieben R, “3D Artificial Round Section Micro-Vessels to Investigate Endothelial Cells under Physiological Flow Conditions.” Scientific Reports 8 (1): 1–13 (2018)