A microfluidic Artery-on-a-Chip using Fluigent’s Microfluidic Flow Control System, the MFCS

Artery-on-a-chip to investigate cardiovascular diseases and therapeutic targets 

Investigating etiopathogenetic mechanisms underlying cardiovascular diseases (CVD) and the study of disease progression and novel therapies have been made possible through in-vivo animal models. However, translating these findings across species can be challenging due to the unique nature of the human circulatory system.  

In response, the development of organ-on-a-chip (OOC) models has emerged to bridge the gap between animal and human models by mimicking key aspects of human physiology. 

OOC models are micro-engineered in vitro replicas of human organs, allowing for pathophysiological studies. These models consist of microfluidic cell culture devices with continuously perfused chambers, housing living cells arranged to mimic tissue geometry. The integration of patient-derived cells and precise environmental control enhances our ability to discover novel targets and conduct drug testing. 

In a recent study, artery-on-a-chip technology was applied to investigate two types of cardiovascular diseases: carotid artery disease (CAD) and abdominal aortic aneurysms (AAA).  

CAD involves atherosclerosis, which narrows arterial lumens and reduces blood flow to the brain, potentially causing transient ischemic attacks or strokes. Most CAD lesions occur at the carotid bifurcation, where complex wall shear stress distributions are present. AAA, on the other hand, results from the pathological widening of the aortic lumen and can lead to rupture with high mortality rates. Most AAA cases develop in the infrarenal segment of the aorta. 

Despite their differences, carotid artery disease and abdominal aortic aneurysms share common characteristics, including pathological remodeling of the vessel wall and alterations in hemodynamic shear stresses. The endothelial layer, at the interface with blood flow, plays a critical role in both diseases. Subsequent remodeling of the medial layer, populated by smooth muscle cells (SMC), leads to disease progression. CAD is marked by plaque buildup, intima layer disappearance, and increased inflammation. In aneurysms, the vessel wall becomes dysfunctional due to the loss of vascular SMC and the destruction of elastic matrix fibers. 

Figure 1. Summary of the study. AoC: Artery-on-a-chip. CAD: carotid artery disease, AAA: abdominal aortic aneurysm, scRNA-seq: single cell RNA sequencing. 

The study introduces the artery-on-a-chip (AoC) model, which mimics the arterial wall structure and explores interactions between vascular endothelial cells (EC) subjected to shear stress and underlying SMC cultured on a layer of extracellular matrix. The AoC serves as a valuable tool for molecular target discovery in cardiovascular disease research, and the findings have the potential to translate into the context of human diseases. Additionally, the artery-on-a-chip can be used for drug testing, allowing researchers to evaluate the effects of therapeutic agents on cellular and molecular pathophysiology, potentially advancing the development of treatments for CAD and AAA. 

This table of content summarizes the entire study and its major findings.   

The artery-on-a-chip in vitro model is capable of mimicking important physiological aspects of human arteries, such as the response to shear stress, and can further shed light on the mechanism of action of potential therapeutics before they enter the clinical stage. 

Partial results  

The robustness of this study relies on their human vascular biobank. The outcomes derived from the Artery-on-a-Chip (AoC) system were further authenticated through validation in samples obtained from vascular tissues of individuals afflicted by carotid atherosclerosis and abdominal aortic aneurysms (AAA).

The AoC: An In Vitro Model of the Arterial Wall

The artery-on-a-chip model comprises a resealable glass chip with two flow channels separated by an intermediate layer that contains a porous culture membrane. This membrane facilitates the circulation of different fluids on either side, allowing for co-culture at an interface (Figure 1.A). Primary aortic endothelial cells (EC) are grown on one side of the membrane on a collagen layer, while primary aortic smooth muscle cells (SMC) are cultured on the other side on a fibronectin layer (Figure 1.B). Immunofluorescence staining using specific antibodies validated the quality of the co-culture, confirming the attachment of EC and SMC at opposing sides of the membrane (Figure 1.C). 

Once cells reach confluence, the glass chip is assembled, sealed, and connected to Fluigent’s MFCS, microfluidic pressure controller, enabling perfusion with cell-specific culture medium. The AoC is integrated into an incubator and perfused for 24 hours at a steady flow rate, maintaining a constant wall shear stress (WSS) of 10 dyne/cm² on the EC channel. The flow rate in the SMC channel, designed to mimic physiological conditions, remains minimal (10 μL/min), generating a negligible shear stress (0.0021 dyne/cm²) necessary for nutrient turnover and waste removal. Flow sensors and specific valves ensure a constant flow rate and unidirectional recirculation of EC medium between reservoirs connected to the EC channel, establishing a controlled and stable microenvironment within the AoC model (Figure 1.D). 

Figure 2. The Artery-on-Chip model. A) Cross-sectional design showing the layers of the AoC.  B) The membrane for co-culturing endothelial cells EC and smooth muscle cells SMC at opposite sides is inserted between the top and bottom layer. C) Immunofluorescence membrane staining showing EC and SMC, labeled by the respective cell markers (PECAM for EC and SM22 for SMC). D) Connection of the AoC to the Fluigent microfluidic pressure controller (MFSC-EZ).

Full article

Paloschi V, Pauli J, Winski G, Wu Z, Li Z, Botti L, Meucci S, Conti P, Rogowitz F, Glukha N, Hummel N, Busch A, Chernogubova E, Jin H, Sachs N, Eckstein HH, Dueck A, Boon RA, Bausch AR, Maegdefessel L. Utilization of an Artery-on-a-Chip to Unravel Novel Regulators and Therapeutic Targets in Vascular Diseases. Adv Healthc Mater. 2023 Oct 5:e2302907.

doi: 10.1002/adhm.202302907.