Even though it has been hyped as one of the benefits of genetic engineering, can we soon grow vaccines and other pharmaceuticals like crops in an economically viable manner?
By: Ringo Bones
If Prof. Henry Daniel has his way, we would all be soon growing our vaccines and other pharmaceuticals as easily as we crow corn and other cash crops. For some years now, Prof. Daniel of University of Pennsylvania has been growing an experimental batch of genetically modified lettuce that could eventually lower the cost of dosage of vaccines from hundreds of dollars a batch to produce to pennies per batch. A 1-acre greenhouse could produce 350 million doses of plant based vaccines using Prof. Daniel’s method.
Other benefits of genetically modified crops that are infused with oft needed pharmaceuticals – i.e. pharming – is that soon we can manufacture insulin inside a plant cell that can be viably used as orally taken insulin tablets. Orally taken insulin tablets were experimented in the mid 1980s via artificially grown protein crystals that are grown in the weightless conditions of low earth orbit during NASA’s Space Shuttle program, but with a lack of a “cheap” way to create these specialized protein crystals, orally taken insulin research was eventually abandoned as “not economically viable”.
Prof. Henry Daniel joined the faculty of the University of Pennsylvania School of Dental Medicine back in 2013 is a molecular biologist with a focus on plants, pursued basic science research after earning his biochemistry Ph.D. from Madurai Kamaraj University in his native India. Yet he began to think differently about his work upon recognizing what he perceived as a human-rights injustice: the sky-high costs of medications taken for chronic or lengthy illnesses.
“Interferon, a common anti-cancer drug, for example, costs $30,000 to $40,000 for a four-month treatment, and a third of the global population earns $2 or less a day” Daniel says. “To me, there is something morally not right about that. If you have something that saves lives, you have an obligation to make it available to everyone.”
Prof. Daniel’s outside of the box thinking has turned lettuce leaves into drug delivery systems, with results that have the potential to make disease treatment and prevention to most of the global population. Now at Penn, Prof. Daniel is working to take his plant based medicine platform from the lab to the clinic and to begin saving lives.
Prof. Daniel’s platform addresses a shortcoming in vaccine production, because vaccines contain pathogens – even if they are killed or inactivated – they must be refrigerated to ensure that the organisms don’t reproduce and pose threats to people receiving the inoculations. So if Prof. Daniel “sidesteps” the cold chain problem of vaccine production and distribution by “genetically manipulating” plants to become room temperature vaccines.
Plants have several properties that lend themselves well to producing and carrying biomedical molecules in the body. First, their cells are totipotent, in other words, all the different tissues of a plant can be grown starting from a single cell in a culture dish. This characteristic enables scientists to make modifications to one plant cell and from that grow a plant to which every cell has those modifications.
Plant cells also have fibrous walls made of cellulose which cannot be broken down by human enzymes, though they can be digested by microbes that reside inside in the gut. This feature enables therapeutic proteins produced inside plant cells to travel partway through our digestive systems before being released in the intestines, where they can disseminate into the bloodstream.
In addition, because plants are commonly consumed as foods, most people won’t be allergic to them as they might to some synthetically produced drugs that are based on egg proteins – to which a substantial number of people are sensitive to. And finally, plants can easily be grown; Prof. Daniel has reported that just an acre of genetically modified tobacco plants, for example, could produce enough anthrax vaccine / anti-toxoid to immunize every person in the United States. And it was a batch of genetically modified tobacco plants that produced the first truly effective anti-Ebola cure – ZMapp.
Since developing the concept of a plant based vaccine in the 1990s, Prof. Daniel has methodically tested each step – from introducing proteins into a plant to designating molecular tags to direct the protein from the gut into the bloodstream or immune system, to harvesting and freeze-drying the specially engineered plants in capsules. Animal studies have shown this platform’s power. In 2012, Prof. Daniel and colleagues published a paper in the Journal of Plant Biotechnology describing the creation of lettuce plants engineered to express a protein that stimulate the pancreas to produce insulin. Mice fed capsules of the freeze-dried material produced insulin and had normal sugar levels in their blood and urine, the appearance of a fundamental cure for diabetes. What’s more, the capsules could be stored at room temperature for as long as 15 months and still retain their potency. Similarly, a 2010 publication in the journal PNAS demonstrated the ability to block severe immune reaction and death in hemophilic mice. Prof. Daniel’s lab has also developed oral vaccines against cholera, malaria, anthrax and the plague.