Institute of Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada.
Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, M5S 3G8, Canada.
Lab Chip. 2023 Aug 8;23(16):3671-3682. doi: 10.1039/d3lc00259d.
Organ-on-a-chip systems are rapidly advancing as a viable alternative to existing experimental models in respiratory research. To date, however, epithelial cell cultures within lung airway-on-a-chip devices have yet to demonstrate the presence of an epithelial glycocalyx, a thin layer of proteoglycans, glycoproteins, and glycolipids known to play an important role in regulating epithelial function. Here, we demonstrate that an airway-on-a-chip device that incorporates bidirectional flow mimicking breathing cycles in combination with an ultra-thin matrix-derived membrane (UMM) layer can generate a glycocalyx layer comprised of heparan sulfate. Results with this device and airflow system showed dramatic differences of airway epithelial cell viability and expression of tight junctions, cilia, and mucus over a wide range of flow rates when cultured under oscillatory flow. More importantly, for the first time in a microfluidic organ-on-a-chip setting, we achieved the visualization of an airflow-induced epithelial glycocalyx layer. Our experiments highlight the importance of physiological mimicry in developing models, as bidirectional airflow showed more representative mucociliary differentiation compared to continuous unidirectional airflow. Thus, the lung airway-on-a-chip platform demonstrated in this study holds great potential as a lung epithelial barrier model for studying the mechanisms of various respiratory diseases and for testing the efficacy of therapeutic candidates in the presence of bidirectional airflow and the glycocalyx.
器官芯片系统作为现有呼吸研究实验模型的可行替代品正在迅速发展。然而，迄今为止，肺气道芯片设备中的上皮细胞培养尚未证明存在上皮糖萼，上皮糖萼是一层由糖胺聚糖、糖蛋白和糖脂组成的薄涂层，已知其在调节上皮功能方面发挥着重要作用。在这里，我们证明了一种气道芯片设备，它结合了模拟呼吸循环的双向流动和超薄基质衍生膜 (UMM) 层，可以生成由硫酸乙酰肝素组成的糖萼层。该设备和气流系统的结果表明，在振荡流培养下，在广泛的流速范围内，气道上皮细胞的活力和紧密连接、纤毛和粘液的表达有明显差异。更重要的是，这是首次在微流控器官芯片环境中实现了气流诱导的上皮糖萼层的可视化。我们的实验强调了在开发模型中进行生理模拟的重要性，因为与连续单向气流相比，双向气流显示出更具代表性的黏液纤毛分化。因此，本研究中展示的肺气道芯片平台具有很大的潜力，可以作为肺上皮屏障模型，用于研究各种呼吸道疾病的机制，并在存在双向气流和糖萼的情况下测试治疗候选物的疗效。
