A Special Tribute to Professor Shu Chien's Visionary Science
Imagine your circulatory system not just as a network of inert pipes, but as a dynamic, living landscape that actively listens and responds to its environment.
Every beat of your heart sends a wave of life-giving blood through your arteries. But this flow is more than just a delivery service for oxygen; it is a powerful physical force that speaks to your cells, telling them how to behave, when to grow, and even when to protect themselves from disease.
Understanding how blood flow impacts artery function and disease development.
Applying principles of physics to biological systems for groundbreaking discoveries.
For over six decades, the visionary scientist Professor Shu Chien has been the leading interpreter of this silent conversation between blood flow and biology. As we celebrate his 80th birthday, we honor a pioneer who bridged the worlds of engineering and medicine, unveiling the fundamental principles of how physical forces govern our health. This article delves into the heart of his work, exploring the elegant science that revealed how the simple act of blood flowing smoothly can keep us alive and well.
To understand Professor Chien's breakthroughs, we first need to learn the language of flow. Fluid dynamics, a branch of physics, gives us the key terms:
This is a smooth, orderly flow, like a slow-moving river or blood streaming straight through a healthy artery. The fluid moves in parallel layers with minimal mixing. This type of flow exerts a frictional force on the vessel wall called shear stress.
This is chaotic and disorderly flow, full of swirls and eddies. It happens when blood hits a branch in an artery or flows through a vessel narrowed by plaque. The shear stress in these areas becomes irregular and disturbed.
Professor Chien asked a revolutionary question: Do our blood vessel cells, which form the inner lining (the endothelium), actually care about the difference between these two types of flow? His work proved that they don't just care—they are exquisitely sensitive to it.
To answer this question, Professor Chien and his team designed a brilliantly simple yet powerful experiment. They needed a way to subject living cells to precisely controlled fluid flows and observe the results.
The experimental setup can be broken down into four key steps:
Human endothelial cells (the ones that line blood vessels) were carefully grown in a flat, circular Petri dish until they formed a uniform layer, mimicking the inner wall of an artery.
This cell-covered dish was placed into a device called a parallel-plate flow chamber. This chamber is designed to create a perfectly uniform layer of fluid flow across the surface of the cells when fluid is pumped through it.
The researchers connected the chamber to a pump that circulated a nutrient-rich fluid over the cells. They ran the experiment under two distinct conditions:
After a set period (e.g., 6-24 hours), the cells were analyzed to see how they responded. Scientists looked at changes in cell shape, gene expression, and protein production.
The results were striking and clear. The endothelial cells responded profoundly to the type of mechanical force they experienced.
The cells underwent a dramatic transformation. They elongated and aligned themselves parallel to the direction of the flow, creating a sleek, streamlined lining. Biochemically, they acted as guardians of vascular health, releasing substances that prevent inflammation and clotting .
The cells remained in a cobblestone-like, disorganized shape. Crucially, they switched to a "pathological" state, activating genes that promote inflammation, attract immune cells, and initiate the formation of atherosclerotic plaques—the root cause of most heart attacks and strokes .
This experiment was a landmark. It provided direct, causal evidence that atherosclerosis is not randomly located but develops precisely where disturbed flow patterns occur. Laminar flow is protective, while turbulent flow is destructive. This discovery shifted the entire paradigm of cardiovascular biology, introducing "mechanotransduction"—the process of cells converting mechanical force into biological signals—as a central player in health and disease .
| Feature Analyzed | Laminar Flow Response | Turbulent Flow Response |
|---|---|---|
| Cell Shape | Elongated and aligned with flow direction | Disorganized, cobblestone-like |
| Inflammatory Signals | Decreased (e.g., reduced NF-κB activation) | Increased (e.g., elevated ICAM-1, VCAM-1) |
| Anti-Oxidant Production | High | Low |
| Overall Effect | Protective, Anti-Atherogenic | Inflammatory, Pro-Atherogenic |
| Gene Name | Function | Change under Laminar Flow | Change under Turbulent Flow |
|---|---|---|---|
| eNOS | Produces nitric oxide, a vessel relaxant | ↑ Increased | ↓ Decreased |
| KLF2 | Master regulator of vascular health | ↑ Increased | ↓ Decreased |
| MCP-1 | Attracts inflammatory monocytes | ↓ Decreased | ↑ Increased |
| Artery Location | Typical Flow Pattern | Clinical Correlation |
|---|---|---|
| Inner curvature of aorta | Disturbed/Turbulent | High susceptibility to plaque formation |
| Straight segment of femoral artery | Stable Laminar | Low susceptibility to plaque formation |
To perform such groundbreaking experiments, Professor Chien's lab relied on a suite of essential tools and reagents. Here's a look at the key items in their toolkit.
The primary "actors" in the experiment. These cells, derived from umbilical veins, are a standard model for studying vascular biology.
The "stage." This device is engineered to create a uniform, well-defined fluid shear stress across the entire layer of cells.
The "life support." A nutrient-rich broth containing vitamins, amino acids, and growth factors needed to keep cells alive outside the body.
The "highlighters." Used to tag specific proteins of interest so they glow under a microscope, allowing visualization.
The "gene readers." Allow scientists to amplify and measure RNA messages to see how flow alters gene activity.
The "detacher." An enzyme solution used to gently release cells from the culture dish for counting and analysis.
Professor Shu Chien's work taught us that our blood vessels are not passive tubes, but intelligent, responsive tissues that thrive under the gentle, rhythmic massage of laminar flow. His research provided the mechanistic link between lifestyle factors (like exercise, which improves flow) and cardiovascular health, and it opened up entirely new avenues for therapeutic intervention .
By decoding the language of force, Professor Chien didn't just solve a biological mystery; he founded the modern field of mechanobiology, inspiring generations of scientists to explore how physical forces influence everything from bone growth to cancer metastasis . His 80th birthday is not just a milestone for a man, but a celebration of a foundational idea: that to understand life, we must understand the forces that shape it.
Pioneering research that transformed our understanding of cardiovascular biology
Years of Research
Scientific Publications
Lives Impacted