Ever Heard of an Earful of Apples?

Farina Afrin Malik

Sophomore

School of Life Sciences

Independent University, Bangladesh

September 29th, 2017

The humble apple, to most of us is simply a fruit: edible, juicy, and brightly colored. Well one particular scientist named Andrew E. Pelling didn’t seem to think so. To him, the slice of an apple represented something more. To him, it looked like a human ear and so he decided to go one step further and actually make one from it. At this point you’re probably wondering if this is a joke or not but bear with me a minute and I’ll explain to you how this came to be within the realm of possibility.

To understand this accomplishment, we need to go back to how Pelling started to work in this direction. Let's begin by thinking about what living organisms are made of. Cells are the basic building blocks of all organisms. In multicellular organisms, cells are organized into 3D structures to become tissues. Aiming to ultimately be able to artificially create mammalian tissues and organs in the lab, the scientists at Pelling lab first decided to see whether the 3D structure of an apple could be used to assemble animal cells. An article published on May 2014 in PLOS One entitled Apple-Derived Scaffolds for 3D Cell Culture [1] report the results of these early investigations.

The basic procedure carried out to answer their question began with the removal of all cellular components within slices of apple to reveal a purified non-cellular framework or scaffold made of a sturdy substance called cellulose. Multiple mouse and human cell lines were cultured (separately) within these scaffolds. Cell lines are fully characterized, laboratory-adapted lineages of specific cell types that are used as model systems for research. The researchers wanted to see whether the cells would grow or take on different properties when grown in this 3D environment. To that end, they used various techniques to characterize the growth patterns of the cells. For instance, they used several types of microscopy to generate high-resolution images of cells, and immunofluorescence staining to detect the presence of multiple proteins at different stages. 

Pelling and co showed that by the end of twelve weeks, the cells had not only grown on, but also invaded the empty cavities within the scaffolds. In addition, they showed the scaffold could be chemically modified to mimic the elasticity of mammalian tissues. The invading cells remained viable throughout the time of the experiment, largely because the porous nature of the cellulose scaffold allowed efficient nutrient and gas exchange. Note that at this stage, they had not actually grown ears, but only shown that the scaffolding could work.
  

The fruits of their labors so far. TED Ideas

With advancements in stem cell (cells that can grow into many other cell types) research and cell culture techniques, the prospect of growing tissues and organs in the lab for transplantation seems increasingly within reach. To that end, cellulose scaffolds, which have the required porousness and 3D structure for growing mammalian tissues, offer several advantages. While synthetic scaffolds are also being looked at, the approach described in this study could lead to the production of much less expensive transplants. Biomaterials such as cellulose are also easier to manipulate based on our needs than synthetic alternatives. Subsequent work from the Pelling Lab showed that tissues grown using this approach could be implanted into mice without rejection [2]. More recently, they used this scaffolding technology to (finally) develop human ears by growing specific types of cells within the scaffolds [3]. While these are yet to be perfected or tested on organisms, the possibilities are stunning.

Andrew Pelling, in a TED Talk in 2016, stated that they would like to develop kits in their lab to make it easier for anyone to make their own body parts using only tools that can be found within the kitchen. While that's quite far out, and still in very early stages, how amazing would that be? Pelling lab has recently begun to explore whether asparagus, a green stalk-like vegetable, may be used to create a neuron network. If it works, this technology could be used for repairing damaged nerves or even recreating connections within the spinal cord.

So, are we going to end up with fruits and vegetables as body parts? It’s too early to say, but at this point, it certainly seems possible.

Bibliography:

[1] D. J. Modulevsky, C. Lefebvre, K. Haase, Z. Al-Rekabi, and A. E. Pelling, “Apple derived cellulose scaffolds for 3D mammalian cell culture,” PloS One, vol. 9, no. 5, pp. e97835–e97835, May 2014.
[2] D. J. Modulevsky, C. M. Cuerrier, and A. E. Pelling, “Biocompatibility of Subcutaneously Implanted Plant-Derived Cellulose Biomaterials,” PloS One, vol. 11, no. 6, pp. e0157894–e0157894, Jun. 2016.
[3] R. J. Hickey, D. J. Modulevsky, C. M. Cuerrier, and A. E. Pelling, “Customizing the Shape and Microenvironment Biochemistry of Biocompatible Macroscopic Plant-Derived Cellulose Scaffolds,” ACS Biomater. Sci. Eng., vol. 4, no. 11, pp. 3726–3736, Nov. 2018.

Farina is a sophomore at IUB who aspires to be a biomedical scientist. In her free time, she enjoys delving into the sciences of baking and imaginative fiction.