Introduction

Lymphatic vessels (LVs) maintain fluid homeostasis by draining excess interstitial fluid, which is accomplished by two distinct LVs: initial LVs and collecting LVs. The interstitial fluid is first drained into the initial LVs through permeable “button-like” lymphatic endothelial cell (LEC) junctions. Next, the drained fluid (“lymph”) transports to lymph nodes through the collecting LVs with less permeable “zipper-like” junctions that minimize loss of lymph. Despite the significance of LEC junctions in lymphatic drainage and transport, it remains unclear how luminal or interstitial flow affects LEC junctions in vascular endothelial growth factors A and C (VEGF-A and VEGF-C) conditions. Moreover, it remains unclear how these flow and growth factor conditions impact lymphatic sprouting.

Methods

We developed a 3D human lymphatic vessel-on-chip that can generate four different flow conditions (no flow, luminal flow, interstitial flow, both luminal and interstitial flow) to allow an engineered, rudimentary LV to experience those flows and respond to them in VEGF-A/C.

Results

We examined LEC junction discontinuities, lymphatic sprouting, LEC junction thicknesses, and cell contractility-dependent vessel diameters in the four different flow conditions in VEGF-A/C. We discovered that interstitial flow in VEGF-C generates discontinuous LEC junctions that may be similar to the button-like junctions with no lymphatic sprouting. However, interstitial flow or both luminal and interstitial flow stimulated lymphatic sprouting in VEGF-A, maintaining zipper-like LEC junctions. LEC junction thickness and cell contractility-dependent vessel diameters were not changed by those conditions.

Conclusions

In this study, we provide an engineered lymphatic vessel platform that can generate four different flow regimes and reveal the roles of interstitial flow and VEGF-A/C for lymphatic sprouting and discontinuous junction formation.

中文翻译：

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3D 人体淋巴管芯片揭示间质流和 VEGF-A/C 在淋巴萌芽和不连续连接形成中的作用

介绍

淋巴管 (LV) 通过排出多余的间质液来维持液体稳态，这是通过两个不同的 LV 完成的：初始 LV 和集合 LV。间质液首先通过可渗透的“纽扣状”淋巴内皮细胞（LEC）连接处排入初始左室。接下来，排出的液体（“淋巴”）通过具有渗透性较小的“拉链状”连接的左室集合输送至淋巴结，从而最大限度地减少淋巴损失。尽管 LEC 连接在淋巴引流和运输中具有重要意义，但仍不清楚在血管内皮生长因子 A 和 C（VEGF-A 和 VEGF-C）条件下管腔或间质流动如何影响 LEC 连接。此外，目前还不清楚这些流量和生长因子条件如何影响淋巴萌芽。

方法

我们开发了一种 3D 人体淋巴管芯片，它可以生成四种不同的流动条件（无流动、管腔流动、间质流动、管腔流动和间质流动），从而允许工程化的基本 LV 体验这些流动并在VEGF-A/C。

结果

我们检查了 VEGF-A/C 中四种不同流动条件下的 LEC 连接不连续性、淋巴出芽、LEC 连接厚度和细胞收缩性依赖性血管直径。我们发现 VEGF-C 中的间质流产生不连续的 LEC 连接，可能类似于没有淋巴芽的纽扣状连接。然而，间质流动或管腔和间质流动刺激 VEGF-A 中的淋巴管出芽，维持拉链状 LEC 连接。LEC 连接厚度和细胞收缩性依赖性血管直径并未因这些条件而改变。

结论

在这项研究中，我们提供了一个工程化的淋巴管平台，它可以产生四种不同的流动模式，并揭示间质流动和 VEGF-A/C 在淋巴管萌芽和不连续连接形成中的作用。