Why a group of scientists grew human heart tissue on spinach

Everyone knows that eating vegetables is great for maintaining heart health, but what about using leafy greens to create part of a human heart?

Although the research is still in its infancy, a group of scientists from Massachusetts’s Worcester Polytechnic Institute (WPI) has been able to successfully grow heart tissue on the leaves of spinach with the aim of one day being able to use the plant to replace diseased tissue in human hearts, such as those affected by a heart attack.

In a study published online ahead of its release in next month’s journal Biomaterials, senior author and bioengineering professor Glenn Gaudette and his team at WPI report being able to grow human heart cells that could contract or beat after five days for a total of 21 days straight.

With a chronic shortage of donor organs, researchers have resorted to engineering large-scale human tissue using techniques such as 3-D printing. One complex problem that has impeded this research, however, is how to recreate a small, intricate vascular system in order to deliver oxygen and nutrients required for proper tissue growth.

“One of the big problems in tissue engineering today is getting blood supply to the newly-created tissue,” Gaudette explained to in a phone interview from Worcester, Mass.

To overcome this problem, scientists have started looking at plants for a potential solution. Bioengineering researchers have begun experimenting with growing organs on different plants using their branching network of veins, which delivers water and nutrients to the leaves.

The University of Ottawa’s Pelling Lab has been testing plant-based biomaterials for growing tissue for the past four years. The lab’s work of cultivating a human ear on an apple slice made headlines last year and attracted international attention to the emerging field.

“It’s just funny. A few years ago I was literally presenting our work and being laughed at in conferences and now other groups are actually saying, ‘Hey it wasn’t so crazy,’” Andrew Pelling, the lab’s founder remarked during a phone interview from Ottawa.

Why spinach?

The scientists at WPI have been working in the field of cardiac research for a number of years and realized the potential in plants, and spinach in particular, just by looking at them. Joshua Gershlak, a graduate student and the study’s lead author, said they were inspired to use spinach when they noticed it looks pretty similar to a human heart’s aorta, the main artery extending from the heart.

“When you look at spinach, when you hold it up to the light, you can see the nice veins passing through the leaf. It turns out that the system of pipes, the vasculature in the leaf, is very similar to human muscle tissue,” Gaudette added.

In order to create the right conditions on the spinach for human heart cells to grow, the researchers used a process called “decellurization” to strip the plant of its cells. To do this, Gershlak said the team used detergents and soaps found in body wash, but in a much higher concentration, and pumped them through the leaf’s veins. The spinach’s plant vasculature made up of primarily cellulose is all that’s left once the stripping process is complete.

Gaudette said the nice thing about the decellurization process is that it rids the biomaterial of its natural cells, which the human body ordinarily rejects during a transplant. He cited the example of a heart transplant and how it’s the new organ’s cells that are rejected by the recipient. In the case of spinach, its cells would be stripped away, making it potentially easier for the body to accept; however, biocompatibility tests still need to be conducted.

“The material that’s left behind, the cellulose, is actually pretty compatible. It’s been used in a bunch of different applications,” Gaudette said.

More research needed

Andrew Pelling, from the University of Ottawa, cautioned against reading too much into studies in their early stages, such as the one from WPI. He said the research shows promise but that it’s still a relatively small experiment.

“I don’t want people to get their hopes up when it’s still way too early,” Pelling said.

The researcher said media coverage on plant-based biomaterials can be overblown or over-interpreted and there’s still a lot of work to be done in the field.

“If as a scientific community, we want our opinion and knowledge to be respected by decision makers then we have to make sure that what’s being put out there is the truth and not hype because that’s not much better than putting out nonsense,” he warned.

Pelling did say, however, that he’s encouraged that other groups, such as the WPI researchers, are delving into this field.

“This is how science works. Other groups reproduce your work, they extend it and they move in new directions,” he said. “That’s the cool part about science and discovery.”

Gaudette acknowledged his team has a lot of work to do before spinach is used to grow tissue for a human heart. He said the next steps for the researchers will be to conduct biocompatibility tests to understand how the body would react to this type of plant material inside it. He said they also still need to solve some issues surrounding blood flow in a plant’s vascular network.

Despite its early stages, Gaudette said he’s optimistic about the future possibilities of plant-based bioengineering.

“One of the exciting things for me about this area of research is really the dreaming,” he said. ““I think we’re just on the tip of the iceberg here and I hope we’ll see a lot more applications.”


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