Algae Breathes Life Into 3D-Printed Tissues

Scanning electron microscope image of green algae.

(CN) — Imagine if human tissue could harness the power of plants and generate oxygen through photosynthesis. If it sounds like a creature that came out of a lab, that’s because it is. Harvard researchers published research based on 3D-printed tissue models of liver cells Wednesday that derive oxygen from Chlamydomonas reinhardtii, single-celled algae.

“The study is the first true example of symbiotic tissue engineering combining plant cells and human cells in a physiologically meaningful way, using 3-D bioprinting,” the paper’s lead author Y. Shrike Zhang said in a statement.

“Our study provides a unique example of how we can harness the symbiotic strategy, very often seen in nature, to promote our ability to engineer functional human tissues,” the Harvard Medical School bioengineer added. “A method to enable sustained release of oxygen from within the engineered tissues is in urgent demand.”

This strange but dynamic duo might provide the key to ensuring lab-grown tissues get healthy amounts of oxygen. Heart disease kills 6 million people worldwide each year and is the leading cause of death in the U.S., but the World Health Organization reports only 10% of people in need of an organ transplant get one.

“Thus, there is an increasing demand for artificial tissue substitutes to replace those that are damaged/diseased to restore tissue and organ functions,” the study authors wrote. “Tissue engineering represents a promising approach that aims at in vitro production of functional tissues for clinical transplantation to replace and restore the functions of those that are damaged.”

Besides developing actual organs for transplants, researchers can also use these tissue models to study diseases and medicine.

To begin, the team of Harvard bioengineers printed algae onto 3-D structures resembling honeycombs. The lobed shapes mimic the structure of mammal livers. Then the algae consumed the molds, leaving behind complex interconnected channels, ideal for nurturing liver cells. Not only did the structure hold up, but healthy photosynthesizing algae produced ample oxygen to feed the liver cells.

“These bioprinted unicellular microalgae represent a bionic and sustainable source of O2, promoting the development of engineered mammalian tissues,” the researchers wrote. “The exploration of C. reinhardtii as a natural, eco-friendly, cost-effective, and sustainable source of O2 would likely promote the development of engineered tissues, tissue models, and food for various applications.”

The National Institutes of Health is funding this research, but it far from being used on people anytime soon.

“This technology cannot be immediately put to human uses,” Zhang explained. “It is still proof-of-concept and will require significant follow-up studies to translate.”

Further studies will analyze “biosafety, toxicity, and immunocompatibility of algae,” for further use in the lab as well as possible “clinical translation in the future.”

The researchers published their work in the journal Matter.

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