MIT News looks at the new science of tissue engineering, taking lab-grown cells and training them to grow objects to order:
It takes a lot to make a wooden table. Grow a tree, cut it down, transport it, mill it … you get the point. It’s a decades-long process. Luis Fernando Velásquez-García suggests a simpler solution: “If you want a table, then you should just grow a table.”
Researchers in Velásquez-García’s group have proposed a way to grow certain plant tissues, such as wood and fiber, in a lab. Still in its early stages, the idea is akin in some ways to cultured meat — an opportunity to streamline the production of biomaterials.
The paper will be published in the Journal of Cleaner Production. Ashley Beckwith is lead author and a PhD student in mechanical engineering. Coauthors are Beckwith’s co-advisors Velásquez-García, a principal scientist in MIT’s Microsystems technology Laboratories, and Jeffrey Borenstein, a biomedical engineer at the Charles Stark Draper Laboratory.
The researchers grew wood-like plant tissue indoors, without soil or sunlight. They started with a zinnia plant, extracting live cells from its leaves. The team cultured the cells in a liquid growth medium, allowing them to metabolize and proliferate. Next, they transferred the cells into a gel and “tuned” them, explains Velásquez-García. “Plant cells are similar to stem cells in the sense that they can become anything if they are induced to.”
The researchers coaxed the cells to grow a rigid, wood-like structure using a mix of two plant hormones called auxin and cytokinin. By varying the levels of these hormones in the gel, they controlled the cells’ production of lignin, an organic polymer that lends wood its firmness. Beckwith says she assessed the cellular composition and structure of the final product using fluorescence microscopy. “You can visually evaluate which cells are becoming lignified, and you can measure enlargement and elongation of cells.” This procedure demonstrated that plant cells can be used in a controlled production process, resulting in a material optimized for a particular purpose.
Velásquez-García sees this work as an extension of his lab’s focus on microfabrication and additive manufacturing techniques like 3D printing. In this case, the plant cells themselves do the printing with the aid of the gel growth medium. Unlike an unstructured liquid medium, the gel acts as a scaffold for the cells to grow in a particular shape. “The idea is not only to tailor the properties of the material, but also to tailor the shape from conception,” says Velásquez-García.