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.
