You are what you eat, and now bioengineers are repurposing culinary staples as “ghost bodies” – scaffolding on which human tissues can be grown. Nicknamed “biohacking”, this manipulation of vegetation has potentially meaty consequences for both regenerative medicine and cosmetic body modification.
A recent study, published in Biomaterials journal, details the innovative use of spinach leaves as vascular scaffolds. The branching network of plant vasculature is similar to our human system for transporting blood, and now this resemblance has been put to likely life-saving use. Prior to this, there have been no ways of reproducing the smallest veins in the human body, which are less than 10 micrometres in diameter.
The team of researchers responsible for desecrating Popeye’s favourite food is led by bioengineering professor Glenn Gaudette and PhD student Joshua Gershlak at the Worcester Polytechnic Institute (WPI). They were discussing the dearth of organ donors over lunch when they were inspired to use their lunch to help solve the problem.
In 2015 the NHS released figures showing that in the last decade over 6000 people, including 270 children, had died while waiting for an organ transplant. Hearts, in particular, are in short supply as it is so far impossible to perfectly recreate a human heart. After a heart attack, often there is a portion of tissue that no longer beats, and so cannot push blood around the body. A major obstacle to resolving this is the inability to engineer dense heart muscle, peppered with enough capillaries. There must be adequate flow of oxygenated blood to every cell in order to avoid tissue death.
However, the scientists had an ingenious thought – each thin, flat spinach leaf already came equipped with its own microscopic system of channels. If these leaves were stacked together, the resulting hunk of human muscle would be dense and veiny. Cautiously, the team lined the cellulose matrix with cardiac muscle cells and monitored their progress. After five days they were amazed to note that the cells had begun to contract – like a beating heart. Microbeads, roughly the same size as blood cells, were pumped through the veins successfully.
Although the leafy engineering was a success, scientists are currently unaware of how to proceed with grafting their artificial channels into a real vasculatory system, not least because of the potential for rejection. Additionally, there is the worry that the detergents used to strip the rigid protein matrix from the rest of the leaf (in order for human endothelial cells to be seeded onto this “cellulose scaffolding”) may ruin the viability of the cells. Luckily, cellulose is known to be “biocompatible”, meaning your body is unlikely to reject it if it is properly buried under your skin.
Elsa Sotiriadis, Programme Director at RebelBio & SOSventures, told me: “cellulose is a promising, widely abundant scaffolding material, as it is renewable, inexpensive and biodegradable”, adding that “once major hurdles – like heat-induced decomposition and undesirable consistency at high concentrations – are overcome, it could rapidly transform 3D-bioprinting”.
This is only the most recent instance of “bio-hacking”, the attempt to fuse plant and human biology. Last year scientists at the Pelling Laboratory for Biophysical Manipulation at the University of Ottawa used the same “scrubbing” process to separate the cellulose from a slice of Macintosh red apple and repopulate it with “HeLa” cervix cells. The human ear made from a garden variety piece of fruit and some cervix was intended as a powerful artistic statement, playing on the 1997 story of the human ear successfully grafted onto the back of a live mouse. In contrast to the WPI researchers, whose focus is on advancing regenerative medicine – the idea that artificial body parts may replace malfunctioning organic ones – Andrew Pelling, head of the Pelling Laboratory, is more interested in possible cosmetic applications and the idea of biohacking as simply an extension of existing methods of modification such as tattooing.
Speaking to WIRED, Pelling said: “If you need an implant – an ear, a nose – why should that aesthetic be dictated by the company that’s created it? Why shouldn’t you control the appearance, by doing it yourself or commissioning someone to make an organ?
The public health agency in Canada, which is unusually open to Pelling’s “augmented biology”, has supported his company selling modified body parts. Most significantly, the resources needed for this kind of biohacking – primarily physical, rather than pharmacological or genetic – are abundant and cheap. There are countless different forms of plant life to bend to our body ideals – parsley, wormwood, and peanut hairy roots have already been trialled, and the WPI team are already considering the similarities between broccoli and human lungs. As Pelling demonstrated by obtaining his equipment via dumpster-diving and then open-sourcing the instructions on how to assemble everything correctly, the hardware and recipes are also freely available.
Biohacking is gaining popularity among bioengineers, especially because of the possibility for even wackier uses. In his interview with WIRED, Pelling was excited about the possibility of using plants to make us sexier, wondering whether we could “build an erogenous interaction using materials that have textures you find pleasing [to change how our skin feels]? We’re looking at asparagus, fennel, mushroom…” If he has his way, one day soon the saying “you are what you eat” could have an entirely different meaning.