Never replicate a successful experiment? Standardization, heterogenization and reproducibility in animal experiments

重复性是任何科学方法的基石，特别是在动物研究中，动物的生命是非常有价值的。传统上，动物、畜牧和测试程序在动物实验中是标准化的，以最大限度地提高测试灵敏度并最大限度地减少动物使用，假设这也将保证重复性。然而，通过减少实验内的变异，标准化可能会将推断限制在特定的实验条件下。事实上，我们最近在老鼠身上表明，标准化可能会在行为测试中产生虚假结果，这是重复性差的原因。然而，尽管人们普遍认识到这些问题，但如何在单个实验室内进行实验，从而在不同的研究中产生更稳定的结果，仍然不清楚。为了使研究群体更具代表性，研究内部的系统变异(即异质性)而不是严格的标准化被认为是提高动物实验研究结果的重复性和翻译价值的有力工具。因此，本项目的总体目标是开发和验证可行和有效的异质性策略，以帮助提高动物实验研究结果的重复性和翻译价值。在一系列预实验中，将调查三种不同的异质策略，并就其有效性进行比较，然后在真实的多实验室环境中测试最佳策略。将用于系统异质性的因素有(I)批次、(Ii)白天时间和(Iii)实验者，因为所有这三个因素都被认为对实验结果有很大影响。为了模拟基因效应，三个常用的近交系小鼠(C57BL/6，DBA/2，Balb/c)将在一系列六种不同的行为测试中进行检测。由于有限的重复性和翻译失败在行为表型研究的背景下得到了特别的讨论，我们将把我们的分析限制在行为结果衡量标准上。根据以前的发现，我们假设异质实验将产生比标准化实验更稳定的结果。

Reproducibility is a cornerstone of any scientific method, especially in animal research where the lives of the animals are highly valuable. Traditionally, animals, husbandry and test procedures are standardized in animal experimentation to maximize test sensitivity and minimize animal use, assuming that this will also guarantee reproducibility. However, by reducing within-experiment variation, standardization may limit inference to the specific experimental conditions. Indeed, we have recently shown in mice that standardization may generate spurious results in behavioural tests, accounting for poor reproducibility. However, despite the widespread recognition of these problems, it is still not clear how to conduct an experiment within a single lab that may result in more stable results across studies. With the aim of making study populations more representative, systematic variation within studies (i.e. heterogenization) rather than rigorous standardization has been proposed to be a powerful tool to improve the reproducibility and the translational value of research findings from animal experiments Thus, the overall aim of the present project is to develop and validate practicable and effective heterogenization strategies that may serve to improve the reproducibility and translational value of research findings from animal experiments. In a series of pre-experiments, three different heterogenization strategies will be investigated and compared with respect to their effectiveness before testing the best strategy in a real multi-laboratory-setting. Factors that will be used for systematic heterogenization are (i) batch, (ii) day time, and (iii) experimenter, since all three factors are known to greatly influence the outcome of an experiment. To mimic a genotype effect, three commonly used inbred strains of mice (C57BL/6, DBA/2, Balb/c) will be examined in a battery of six different behavioural tests. Since limited reproducibility and translational failures has been particularly discussed in the context of behavioural phenotyping studies, we will restrict our analysis to behavioural outcome measures. Based on previous findings, we hypothesize that heterogenized experiments will yield more stable results across experiments than standardized ones.