Organs may not grow on trees, but they can on leaves

By LifETIME CDT Student: Xally Montserrat Valencia Guerrero (She/Her) (University of Glasgow)

Have you ever thought about the similarity between an apple and a bone? Or maybe between a leaf and a human heart? It’s hard to think about what these things have in common, especially because they look nothing alike, their shape, colour, texture… everything it’s different! But what if we had a closer look? Scientists have found that under the microscope, an apple and a bone look quite similar, they have a porous microstructure. And what about a leaf and a heart? Well, both have a network of branched vessels.

And, if we think about it, vegetables and human tissues are assembled in an analogous way: they consist of a three- dimensional matrix where cells are entrapped. In the case of vegetables, this matrix is mostly made of cellulose and in human tissues, it is made of mostly proteins.

But what is the relevance of these similarities? Recently, scientists have been looking for strategies to replicate living tissues in the lab. For that, they need a material that serves as substitute of the protein matrix it can be used as a scaffold to seed cells and start growing a tissue. So, if plants have an internal structure that looks like those from human tissues, can they be used to grow human tissues?

If plants are to be used as a template for seeding human cells, we first need to condition them, so they can receive such cells. In the lab we are working with tobacco leaves, so the first stage in this process is to decellularise the leaves. This involves removing the plant cells from the cellulose matrix to provide free spaces where human cells, can adhere to the scaffold. Cells are then fed and supplemented with growth factors to enable them to grow into a tissue.

In a short- term future, these lab-grown tissues built on plant-based scaffolds can be used as research models for testing the effectiveness of new drugs and investigating how they work. This technology would circumvent the need to work with animals. Lab-grown human tissue would also provide a more relevant experimental system for human health.

In addition, these tissues could be used for regenerative therapies in the long-term to treat patients that have suffered from tissue damage either due to illness, injuries, or ageing.