Molecular and cellular studies for the understanding of flame retardants single modes-of-action and mixture effects related to their kinetics in vitro.

• Applicant: Dr. Katharina Koch, since 4/2024
• Subject Area: Toxicology, Laboratory Medicine
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 499234656

Oligodendrocytes (OL) belong to the glial cells of the central nervous system and are responsible for axon myelination thereby facilitating rapid saltatory conduction of neuronal action potentials. During development, neural stem/progenitor cells give rise to committed oligodendrocyte precursor cells (OPC) which proliferate and migrate to the final site of myelination. Subsequent terminal differentiation of OPCs into pre-myelinating OL (pre-OL), and finally myelin-producing mature OL, involves a fine-tuned interplay of hormonal signaling, transcriptional regulation and biosynthetic processes. Hence, developing OL can be concerned by a large variety of substances through a broad spectrum of modes-of-action (MoA). An impairment of oligodendrogenesis, e.g. due to exposure towards developmental neurotoxic substances, contributes to functional adverse outcomes manifesting in neurological disorders such as the Alan-Herndon-Dudley Syndrome or periventricular leukomalacia. In the toxicological context, however, oligodendrocytes, despite their high susceptibility to a large variety of stressors, are an understudied cell type as most developmental toxicity studies deal with neurons and astrocytes. Within the ‘Neurosphere Assay’, a primary in vitro cell culture model based on human neural progenitor cells, which mimics a variety of neurodevelopmental processes, like proliferation, migration and differentiation into neural effector cells (astrocytes, neurons and OL), we identified OL as the most sensitive cell type for a broad variety of substances, e.g. flame retardants (FR).Despite regulations like REACH (Registration, Evaluation, Authorization, and Restriction of Chemical substances), several FR have already been marketed without having a full toxicological profile, specifically their neurodevelopmental hazards, have not been sufficiently investigated. High concentrations of FR can be found e.g. in house dust and breast milk. Thus, children and especially toddlers are highly exposed towards FR as they frequently spend their time close to the floor and exercise children-specific mouthing behavior. The overall goal of this project is to investigate the molecular hazards of different FR classes on oligodendrogenesis and identify their MoAs by using methodologies of qRT-PCR, immunocytochemical stainings, western blots as well as detailed transcriptomic analyses. Additionally, we will investigate the consequence of FR mixed exposure on neurodevelopmental processes using the ‘Neurosphere Assay’, to address a real-life exposure scenario since humans are co-exposed to more than one chemical at a time. Moreover, we will include analytical determination of FR in vitro exposure into the studies by using chromatography techniques LC-MS/MS and GC-MS. The outcome of these studies in combination with performance of in vitro-to-in vivo extrapolations allow a neurodevelopmental risk assessment for FR.

• DFG Programme: Research Grants
• Ehemalige Antragstellerin: Professorin Dr. Ellen Fritsche, until 3/2024