Why Did Scientists Turn Spinach Leaves Into Beating Human Heart Tissue?

Have you ever noticed that the veins in a leaf look a bit like the veins in your own body? So did researchers at the Worcester Polytechnic Institute. In a study published in 2017, they announced that they successfully grew human heart tissue on spinach leaves, which may unveil the possibility of one day replacing damaged heart tissue with the help of plants.

Related: Science Is Thiiis Close To Growing Human Hearts In A Lab

Pump It Up

In all the talk of growing artificial tissue and organs in the lab, there's an elephant in the room: we're not that good at growing blood vessels, and tissues need blood vessels to, well, stay alive. The blood vessels in your own body range from the aorta's whopping 3 centimeter diameter to capillaries as thin as 5 microns15 times thinner than a human hair. Our current techniques aren't refined enough to create fluid channels that tiny, so bioengineers are hard at work finding other ways to make it happen.

Related: Why A Cotton Candy Machine May Hold The Future Of Artificial Organs

One thing we can do is start with an actual organ, like a heart, and stripping it of its existing cells so that all you have left is its underlying structure. It already has blood vessels, after all. From there, the hope is that you could use stem cells to create human heart tissue that matches that of a transplant recipient. There's just one problem: you need a heart first. It would be great if you could do the same thing with something easier to come by—spinach leaves, for example. "I had done decellularization work on human hearts before," the study's lead author Joshua Gershlak said in a press release, "and when I looked at the spinach leaf its stem reminded me of an aorta."

Related: Most Heart And Lung Donations Never Make It To A Patient, But Science May Have A Fix

He figured out a way to remove the plant cells by sending a detergent solution straight through the spinach leaf's stem into its veins. After that, he had a framework made of harmless cellulose. The team bathed that framework in live human cells, which soon began growing inside of the tiny veins and beating on the surface of the now-skeletonized leaf. Once it was colonized by human heart cells, the researchers sent fluids and blood-cell-sized microbeads through the veins, demonstrating that blood could flow through the system.

Comparison of animal and plant vascular network pattern branching and structures. A rat heart was decellularized, as previously described [6], and was perfused with a Ponceau Red stain to visualize the vasculature. A Buddleja davidii leaf was perfused with fluorescein-labeled PEGDA to visualize the leaf vasculature.

What This Means For The Future Of Medicine

Even though their beating spinach leaf looks like a miniature heart, the researchers don't plan on replacing entire human hearts with stuff from the salad bar. Instead, they hope to use the technique to grow layers of human heart muscle, which could replace the portions damaged by heart attacks. The technique doesn't just work with spinach—in fact, this very study also tried it with parsley, Artemesia annua (sweet wormwood), and peanut hairy roots. Different plants could be handy for different purposes. "The spinach leaf might be better suited for a highly vascularized tissue, like cardiac tissue, whereas the cylindrical hollow structure of the stem of Impatiens capensis (jewelweed) might better suit an arterial graft. Conversely, the vascular columns of wood might be useful in bone engineering due to their relative strength and geometries," the authors wrote. We all knew greens were good for us, but we didn't realize they were this good.

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Written by Curiosity Staff April 7, 2017

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