Honey, I shrunk a heart attack: New microchip model creates mini heart attacks

If you had a shrink ray that could condense any object to miniature size, what would you shrink?

Though shrink rays only exist in science fiction, researchers Megan McCain and Megan Rexius-Hall at the University of Southern California found a way to “shrink” heart attacks. Their newly engineered microchip model creates mini heart attacks, aiding researchers in studying how the heart repairs itself after the event.

They call their model “heart attack on a chip”.

Most people are likely familiar with the term heart attack. And most people probably know someone who has suffered a heart attack – in fact, every 40 seconds someone in the U.S. has a heart attack. However, people might not know what happens to the heart.

The heart is a central organ that pumps oxygen-rich blood to the rest of your organs via arteries. Yet the heart also needs its own supply of oxygen-rich blood. Heart attacks occur when the arteries of the heart become blocked, reducing blood supply to the heart. The heart arteries can be blocked by several things, including blood clots and a buildup of cholesterol.

Importantly, this blockage causes a lack of blood flow, damage and massive cell death.

Clearly, heart attacks themselves are bad. But because heart tissue is difficult to repair, having a heart attack increases a person’s risk for heart failure and other life-threatening events. 

"The “heart attack on a chip” is a promising new model that assists researchers in studying how the heart repairs itself after heart attacks."

-- Amber Hazzard

Other tissues in the body, like skin, can quickly replace lost or injured cells with new healthy cells. This repair process is called regeneration. Instead of regenerating, most heart cells are replaced by stiff scar tissue called collagen. The problem with collagen is that it doesn’t behave like normal heart tissue.

Normal heart tissue is strong yet flexible. This flexibility allows the heart to contract in three different directions, enabling the heart to pump blood to the rest of the body. Conversely, collagen is very stiff. If too much collagen is deposited it can cause the heart to become so stiff that it cannot effectively pump blood.

Still, there is a lot of mystery surrounding how and why the heart repairs itself this way. Scientists need to research how communication between heart cells changes after heart attacks.

In order to study what happens after heart attacks, first, researchers must create heart attacks. But who in their right mind would sign up to have a heart attack? Nobody, that’s who.

Instead, scientists simulate heart attacks in animals, cells and other models. Unfortunately, these models have limitations that make them less applicable to humans.

To overcome these limitations, McCain and Rexius-Hall created a microchip, roughly the size of a quarter, that can simulate human heart attacks.

The base of this chip has two channels on opposite sides that allow gases and liquids to flow. On top of that, the researchers grow heart cells from rats on a thin layer of protein. This protein helps the cells organize in the same pattern they form in the heart.

Once the heart cells have grown, the researchers mimic a heart attack by pumping varying amounts of oxygen through the microchip. Exposing the cells to a gradient of oxygen imitates the conditions of a real heart attack.

Traditional cell models are not able to reproduce this oxygen gradient; the cells can only be exposed to set amounts. This makes it hard to study what happens to damaged cells that live in the area surrounding the heavily damaged regions, called the border zone. The oxygen gradient on the heart attack on a chip model better recreates this border zone.

After the researchers create a heart attack, they can easily observe functional changes in real time using a microscope. These functional changes include an irregular heartbeat or a weakened heartbeat. Being able to see changes in real time is an advantage the heart attack on a chip has over animal models.

While McCain and Rexius-Hall don’t have fancy sci-fi shrink rays, they are using cutting edge technology to shrink heart attacks. Their “heart attack on a chip” is a promising new model that assists researchers in studying how the heart repairs itself after heart attacks. A better understanding of the heart’s repair process will lead to more effective treatments and improved outcomes for heart attack victims.