To disseminate and colonise tissues in the mammalian host, Trypanosoma cruzi trypomastogotes should cross several biological barriers. How this process occurs or its impact in the outcome of the disease is largely speculative. We examined the in vitro transmigration of trypomastigotes through three‐dimensional cultures (spheroids) to understand the tissular dissemination of different T. cruzi strains. Virulent strains were highly invasive: trypomastigotes deeply transmigrate up to 50 μm inside spheroids and were evenly distributed at the spheroid surface. Parasites inside spheroids were systematically observed in the space between cells suggesting a paracellular route of transmigration. On the contrary, poorly virulent strains presented a weak migratory capacity and remained in the external layers of spheroids with a patch‐like distribution pattern. The invasiveness—understood as the ability to transmigrate deep into spheroids—was not a transferable feature between strains, neither by soluble or secreted factors nor by co‐cultivation of trypomastigotes from invasive and non‐invasive strains. Besides, we demonstrated that T. cruzi isolates from children that were born congenitally infected presented a highly migrant phenotype while an isolate from an infected mother (that never transmitted the infection to any of her children) presented significantly less migration. In brief, we demonstrated that in a 3D microenvironment each strain presents a characteristic migration pattern that can be associated to their in vivo behaviour. Altogether, data presented here repositionate spheroids as a valuable tool to study host–pathogen interactions.

中文翻译：

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克氏锥虫通过类似生理环境的 3D 培养物的轮回。

为了在哺乳动物宿主中传播和定殖组织，克氏锥虫应该跨越几个生物障碍。这个过程如何发生或其对疾病结果的影响在很大程度上是推测性的。我们通过三维培养（球体）检查了锥鞭毛体的体外迁移，以了解不同T. cruzi的组织传播菌株。毒力菌株具有高度侵袭性：锥鞭毛体在球体内部深入迁移达 50 μm，并均匀分布在球体表面。在细胞之间的空间中系统地观察到球体内的寄生虫，表明存在一种细胞旁的轮回途径。相反，弱毒株的迁移能力较弱，并以斑片状分布模式留在球体的外层。侵入性——被理解为深入到球体中的能力——不是菌株之间可转移的特征，既不是通过可溶性或分泌因子，也不是通过来自侵入性和非侵入性菌株的锥鞭毛体的共培养。此外，我们证明了T. cruzi来自先天性感染儿童的分离株表现出高度迁移的表型，而来自受感染母亲的分离株（从未将感染传染给她的任何孩子）表现出明显较少的迁移。简而言之，我们证明了在 3D 微环境中，每个菌株都呈现出与其体内行为相关的特征迁移模式。总之，此处提供的数据将球体重新定位为研究宿主-病原体相互作用的宝贵工具。