以血管晶片探討剪應力對人類血管重塑的影響

Abstract

本研究透過血管晶片來研究剪應力對人類血管的影響，因剪應力為誘發動脈血管新生機制的重要機制，是在動脈阻塞後，誘導鄰近副動脈血管直徑增大，以代替原動脈輸血功能之生理機制，防止組織因動脈血管阻塞而壞死，此機制也是未來發展動脈血栓治療的重要因子。本研究透過施加週期性壓力使血管內產生剪應力誘發動脈血管新生機制，並比較以人類臍動脈及臍靜脈內皮細胞在剪應力環境下的血管重塑行為。 本研究所開發的血管晶片為單腔室之三維微組織平台，可於腔室中依序誘導Vasculogenesis及Angiogenesis步驟，形成具血管網絡之微組織，成功將人類臍動脈及靜脈內皮細胞培養出平均直徑為 23 μm 及 21 μm 之血管結構，再透過施加週期性壓力於可灌注之動脈血管組織，使血管內產生剪應力，成功誘發動脈血管新生機制 (Arteriogenesis)，促使血管直徑在 48hr 後增加 133%，血管直徑可達 69 μm，並在 72hr 後觀察到血管重塑的現象。本研究亦透過有限元素分析動脈血管內的剪 應力，發現誘發動脈血管新生機制之剪應力範圍落在 1 至 7 Pa、剪切率為 1000 至 10000 1/s的範圍，有符合人體小動脈之生理剪應力範圍。統計所有產生動脈血管新生機制的血管組織，平均直徑增加了 52%，表明此方法可用以培養出更大直徑的血管組織，將可建立出更近似人體的血管模型，以做為心血管疾病模型的基礎，助於疾病治療方法的開發。而靜脈血管組織在受到週期性低壓力時，觀察到直徑一有增加趨勢，較大直徑血管平均直徑可達 31 μm，然而，靜脈血管在受到週期性高壓力環境時，發現有血管數量減少且直徑縮小的現象。 總結，本研究以微生理的角度出發，以實驗驗證動脈及靜脈血管中的內皮細胞 對血液流動所造成的剪應力有不同的反應，是一項重要的生理環境刺激，將可作為血管晶片中培養出較大血管結構的一種微流體操控技術。

In our study, we investigate the effects of shear stress on human vessels using a vessel-on-a-chip device. Shear stress is an important physiological cue in the mechanism of arteriogenesis, which promotes vessel remodeling and prevents blockages, ensuring proper blood flow. This mechanism is also crucial for the future drug development for arterial thrombosis. In this study, cyclic pressure is applied to induce shear stress within the vessels to the effect of shear stress on arteriogenesis. The vascular remodeling of vessels formed by human umbilical arterial (HUAEC) and vein (HUVEC) endothelial cells are also investigated. The developed device is a single-chamber microfluidic device with two perfusion channels. Vasculogenesis and angiogenesis are sequentially induced using hypoxia, forming microtissues with vascular networks from both HUAECs or HUVECs. The corresponding average vessel diameters are 23 μm and 21 μm. By introducing cyclic pressure to perfused arterial vessels, arteriogenesis is successfully induced. This leads to a 133% increase in vessel diameter within 48 hours, reaching a diameter of 69 μm. Vascular remodeling is also observed after 72 hours of cyclic shear stresses. Finite element analysis reveals that the induced arteriogenesis may occur within a shear stress of 1 to 7 Pa and a shear rate of 1000 to 10,000 1/s, falling within the physiological range in human arterioles vessels. This vessel remodeling depends on vessel diameter and volumetric flow rate. The vessels exhibiting arteriogenesis show an average of 52% increase in diameter. This result suggests that this method can develop a more physiologically relevant vascular model for cardiovascular disease research and drug development. In the case of venous vascular tissue, vessel diameter increment is also observed. The average diameter of large-diameter vessels can reach 31 μm. However, vessel quantity and diameter shrinkage are observed under a high cyclic pressure. In summary, this study experimentally verified that the arterial and venous endothelial cells respond differently to the shear stress caused by blood flow. It is a new physiological stimulus that can be applied to grow larger vessels in a microfluidic model system.