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SPHERTOX is an independent ground-breaking project for young research talents (FRIPRO) funded by the Research Council of Norway.

Project period
The Research Council of Norway

About the project


Alternatives to animal testing have long been sought by implementing the 3Rs (refinement, reduction and replacement), to more efficiently assess the safety of chemicals, endorse ethical considerations and reduce costs of experimental studies. Regulatory legislations within the European Union e.g. Registration, Evaluation, Authorization and Restrictions of Chemicals (REACH) have in recent years required more chemicals to be assessed for hazard, increasing the need for toxicity and bioconcentration (BC) testing. Thus, efforts to implement (non-animal) alternative bioassays (Directive 2010/63/EU), with key focus on fish, has intensified.

Recent advances within in vitro fish acute toxicity and BC assessment has resulted in standardized tests with short exposure times (OECD TG: 249 and OECD TG 319A/B). There is currently no in vitro model for fish that is accommodating both chronic toxicity testing and/or BC assessment of chemicals with low metabolic rate.

Project Goals

The overarching goal of the SPHERTOX project is to investigate if hepatic 3D spheroids from Rainbow trout fish (RT) is a suitable bioassay for cell-based (in vitro) bioconcentration assessment and chronic toxicity testing, alone and when in co-cultures, respectively. This will be addressed by providing both basic and applied knowledge by generating theoretical and experimental data to develop and evaluate the next-generation ecotoxicological methodologies for fish, for end-users within the academic, industry and regulatory community. The interdisciplinary approach envisioned for SPHERTOX on implementing more complex and physiologically relevant test systems and computational approaches to develop a “virtual fish” will help bridging the gaps between in vitro and in vivo. 

More specifically the SPHERTOX project will: 

  • Use state-of-the-art imaging techniques to investigate the spheroids microenvironment.
  • Assess spheroids for their suitability in long-term toxicity testing. 
  • Evaluate spheroids as a complementary bioassay to standardized methods (RT-S9 and RT-hepatocytes) for assessing compounds with low biotransformation rate 
  •  Investigate spheroids potential in multi-compartment co-culturing systems to increase the biological complexity and improving in vitro-in vivo extrapolation. 
  • Use physiological computational models to improve in vivo toxicokinetic predictions. 
  • Contribute with data to a novel causal inference model to identify confounding factors in experimental toxicology.


Figure: Isolated primary hepatocytes from rainbow trout used in 3D spheroids within complex co-culturing systems with cells to predict in vivo response.