Chemicals eluting from disposable plastic syringes and syringe filters alter neurite growth, axogenesis and the microtubule cytoskeleton in cultured hippocampal neurons

Cultures of dissociated hippocampal neurons are often used to study neuronal cell biology. We report that the development of these neurons is strongly affected by chemicals leaching from commonly used disposable medical‐grade syringes and syringe filters. Contamination of culture medium by bioactive substance(s) from syringes and filters occurred with multiple manufacturing lots and filter types under normal use conditions and resulted in changes to neurite growth, axon formation and the neuronal microtubule cytoskeleton. The effects on neuronal morphology were concentration‐dependent and significant effects were detected even after substantial dilution of the contaminated medium. Gas chromatography‐mass spectrometry analyses revealed many chemicals eluting from the syringes and filters. Three of these chemicals (stearic acid, palmitic acid and 1,2‐ethanediol monoacetate) were tested but showed no effects on neurite growth. Similar changes in neuronal morphology were seen with high concentrations of bisphenol A and dibutyl phthalate, two hormonally active plasticisers. Although no such compounds were detected by gas chromatography–mass spectrometry, unknown plasticisers in leachates may affect neurites. This is the first study to show that leachates from laboratory consumables can alter the growth of cultured hippocampal neurons. We highlight important considerations to ensure leachate contamination does not compromise cell biology experiments. Cultures of dissociated hippocampal neurons are used to study many aspects of neuronal cell biology. We report that leachates from medical grade syringes and sterile syringe filters may alter neurite growth in these cultures. These consumables are commonly used in the laboratory. Our results serve as a reminder to other researchers to ensure that leachate contamination does not compromise experimental results, and that specifying details about which materials were used is crucial. The merged image shows the differences between dissociated hippocampal neurons that were cultured for 2 days in control medium (left half of image) compared to those cultured in syringe‐filtered medium (right half of image), which have a greater number of long thin neurites. Neurons were immunolabelled for Tau (green) and MAP2 (red) and nuclei labelled with DAPI (blue). Cultures of dissociated hippocampal neurons are used to study many aspects of neuronal cell biology. We report that leachates from medical grade syringes and sterile syring