JOIN USScientists have successfully cultured beating human heart cells on spinach leaves, solving the long-standing problem of delivering blood into artificially developed tissues.
Current bioengineering techniques, including 3D printing, can not fabricate the branching network of blood vessels down to the capillary scale that are required to deliver the oxygen, nutrients and essential molecules required for proper tissue growth.
Researchers, including those from Worcester Polytechnic Institute (WPI) in the US, turned to plants.
They cultured heart cells on spinach leaves that were stripped of plant cells - a process called decellularisation, using a detergent.
They flowed fluids and microbeads similar in size to human blood cells through the spinach vasculature, and they seeded the spinach veins with human cells that line blood vessels.
These proof-of-concept studies open the door to using multiple spinach leaves to grow layers of healthy heart muscle to treat heart attack patients.
Other decellularised plants could provide the framework for a wide range of tissue engineering technologies.
"Plants and animals exploit fundamentally different approaches to transporting fluids, chemicals and macromolecules, yet there are surprising similarities in their vascular network structures," researchers said.
"The development of decellularised plants for scaffolding opens up the potential for a new branch of science that investigates the mimicry between plant and animal," they said.
When the plant cells are washed away what remains is a framework made primarily of cellulose, a natural substance that is not harmful to people.
"Cellulose is biocompatible and has been used in a wide variety of regenerative medicine applications, such as cartilage tissue engineering, bone tissue engineering, and wound healing," researchers said.
Researchers developed an effective process for removing plant cells from spinach leaves by flowing or "perfusing" a detergent solution through the leaves' veins.
When the plant cells are washed away what remains is a framework made primarily of cellulose, a natural substance that is not harmful to people.
In addition to spinach leaves, the team successfully removed cells from parsley, Artemesia annua (sweet wormwood), and peanut hairy roots.
Using plants as the basis for tissue engineering also has economic and environmental benefits, researchers said.
"By exploiting the benign chemistry of plant tissue scaffolds, we could address the many limitations and high costs of synthetic, complex composite materials," they said.
"By combining environmentally friendly plant tissue with perfusion-based decellularisation, we have shown that there can be a sustainable solution for pre-vascularized tissue engineering scaffolds," they added.
The study was published in the journal Biomaterials.