A 3Rs approach to investigate the feto-maternal interface: visualisation of pathogen and antibody in a 3D in vitro human placental model

背景资料：怀孕期间的免疫接种现在被认为是保护胎儿和/或婴儿免受危及生命的感染的有效方法。然而，病原体传播和被动免疫从母亲转移到胎儿的机制仍然不清楚。位于母亲和胎儿环境之间的界面的结构是胎盘，这是一个由细胞和血管网络组成的复杂器官，其功能包括肾脏，肺，肠道和肝脏，以促进胎儿的生长和活力。由于与人类妊娠研究相关的伦理问题，已经开发了各种体内、离体和体外模型。然而，虽然体内动物模型不能匹配人胎盘的结构和/或功能特性，但是离体人模型是不切实际的，难以建立，能力有限，并且体外模型由于其单层和/或静态设置而缺乏生理相关性。为了解决目前人类胎盘实验模型固有的问题，我们提出开发一种新的和易于建立的体外平台，其将有助于减少和/或替代鼠和非鼠模型的使用。我们的模型将通过使用3D微流体生物工程平台分析胎盘-血液屏障功能以及病原体和抗体的跨胎盘转运来验证，即，实验方法：滋养层细胞代表胎盘的最外层，其中营养物、化学物质和气体胎儿-母体交换受到调节。在我们的工业合作伙伴的支持下，我们将开发一种前所未有的基于滋养层的微流体动态模型，模拟胎儿-母体界面。这将使用市售的和成像友好的3线OrganoPlate系统（Mimetas BV）来实现，我们将创建模拟三维准生理环境的管状培养系统，其中（胎儿）内皮细胞将在腔中暴露于生理水平的流动并与近腔滋养层共培养以形成功能性胎盘屏障。我们的平台将是独一无二的，因为它还将提供实时和高通量成像能力。

Background: Immunisation during pregnancy is now recognised as an efficient approach to protect the fetus and/or the infant from life-threatening infection. However, the mechanisms underlying the transmission of pathogens and the transfer of passive immunity from the mother to the fetus remain obscure. The structure that lies at the interface between mother and fetal environment is the placenta, an intricate organ made up of cellular and vascular networks that serve the functions of kidney, lung, gut and liver altogether in order to promote fetal growth and viability. Owing to the ethical issues associated with the study of human pregnancy, a variety of in vivo, ex vivo and in vitro models have been developed. However, while the in vivo animal models fail to match the structural and/or functional properties of the human placenta, ex vivo human models are impractical, difficult to set up, of limited capability, and in vitro models lack physiological relevance by virtue of their monolayer and/or static set-up.Proposed solution: To address the caveats inherent to current experimental models of the human placenta, we propose to develop a novel and easy-to-set-up in vitro platform that will help reduce and/or replace the use of both murine and non-murine models. Our model will be validated through the analyses of placenta-blood barrier functions and cross-placental transport of pathogens and antibodies using a 3D microfluidic bioengineered platform i.e., the Organoplate (Mimetas).Experimental approach: Trophoblasts represent the most outer layer of the placenta whereby nutrients, chemical and gas feto-maternal exchanges are regulated. With the support of our industrial partner, we will develop an unprecedented trophoblast-based microfluidic dynamic model, that mimics the feto-maternal interface. This will be achieved using the commercially available and imaging-friendly 3-line OrganoPlate system (Mimetas BV), we will create a tubular culture system that mimics the three-dimensional, quasiphysiological environment where (fetal) endothelial cells will be luminally exposed to physiological levels of flow and co-cultured with abluminal trophoblasts to form a functional placental barrier. Our platform will be unique in that it will also offer real-time and high-throughput imaging capability.