LA-N5 Neuroblastoma Cell-based Assay as an Alternative Tool for Human Botulinum Neurotoxins Potency Detection

Botulinum neurotoxins (BoNTs), the most potent neurotoxins known to humankind, are a large protein family classified to several serotypes. Although lethally toxic, botulinum toxin in low doses is clinically effective in several medical conditions and cosmetic purposes. A simple and reliable protocol for assessing BoNT potency is imperative for the clinical diagnosis of botulism as well as pharmaceutical and cosmetic products, and it must include all steps of nerve intoxication. The current “gold standard” tool to detect BoNT intoxication is the in-vivo mouse bioassay, mainly due to its sensitivity and ability to detect all BoNT serotypes. However, it involves high variability and consumes numerous mice, calling for its replacement. Cell-based assays, which have gained increasing importance in determining the potency of BoNTs, can be respectable replacement. Importantly, cell-based assays in human neuroblastoma cell lines are inexpensive, easy to use and offer a long culturing life. However, previously described tests in such cell lines were all limited to assessing partial BoNT activity in human-specific intoxicated serotypes. Herein, we present that the human neuroblastoma cell line LA-N5 highly expresses all of the receptors and substrates related to BoNT human serotypes and performs cholinergic phenotype. By using a specific antibody-sandwich ELISA assay we detected dose-dependent BoNT activity at a wide concentration range. The unique ability of this cell line to detect all BoNT’s human-specific serotypes, even without differentiation, offers a simple and rapid alternative "all-in-one" for BoNTs potency determination of clinical samples as well as pharmaceutical and cosmetic BoNT’s products.