“Synthetic biology” is the design and construction of new
biological entities that do not exist in the natural world. Imagine a future where synthetic
jellyfish roam waterways looking for toxins to destroy, where eco-friendly
plastics and fuels are harvested from vats of yeast, where viruses are
programmed to be cancer killers, and electronic gadgets repair themselves like
living organisms. Welcome to the world of synthetic biology, or ‘synbio’, where
possibilities are limited only by the imagination. Its practitioners don’t view
life as a mystery but as a machine – one that can be designed to solve a slew
of pressing global health, energy and environmental problems.
When we think of robots the picture that comes in our
mind is of a moving gadget made of steel, metal, silicone, plastic or other
non-biodegradable synthetic materials. But robots today are both living and
bio-degradable and are called xenobots. Scientists in the University of Vermont
and Tufts have succeeded in building these living robots from stem cells of
frog embryo which can join hands and work together much like super-computers
and can perish after achieving their task once their pre-loaded nutrients get
used up. The Xenobots are named after the species of African frog – Xenopus
laevis whose embryonic cells or stem cells were used by researchers. These
cells were incubated and joined under microscope by tiny electrodes. The joined
cells came together into body forms never seen in nature!
The possibilities of using these xenobots are immense.
They can detect toxic contamination in environment, disintegrate polythene and
plastic in the oceans and then gather the micro-plastic from ocean and save our
marine life. As they are bio-degradable they will disintegrate without a trace
without polluting the oceans. They can also be injected in our blood and
targeted towards the blocks in our arteries. They can disintegrate these blocks
thus reopening our blocked arteries and then disappear as and when programmed
to do so by Artificial Intelligence!
These xenobots can be programmed to pick up payload
such as a cancer medicine that is to be carried to a specific organ in the
body, kill the cancer cells and then get self disintegrated. To target the tumor
cells, peptides that can specifically recognize a tumor were
expressed on the surfaces of a vector bacteria. So the chemotherapy
is targeted to the desired target and normal body cells are spared of its side
effects; needless to say, a much lesser dose of the drug is being used.
The immune system plays an important role in cancer
and can be harnessed to attack cancer cells. Cell-based therapies focus
on immunotherapies, mostly by engineering T cells. T cell receptors are
engineered and ‘trained’ to detect cancer epitopes. Chimeric antigen
receptors (CARs) are composed of a fragment of an antibody fused
to intracellular T cell signaling domains that can activate and trigger
proliferation of the cell. A second generation CAR-based therapy is already
approved by FDA
Scientists in UC San Diego have genetically engineered
mosquitoes and made them resistant to all strains of dengue virus. They
designed the antibody “cargo” to be synthetically expressed in female Aedes
aegypti mosquitoes which are responsible for spreading dengue. Once this female
sucks in blood the antibody is activated and expressed and starts hindering the
replication of virus in the mosquito, thus preventing its transmission to
humans even if it bites. On pairing with other infected mosquitoes the antibody
is spread throughout the mosquito population thus offering them immunity
against the virus thereby stopping the spread of dengue!
The rubber industry is all geared up to reduce its
carbon footprints. Natural rubber from the sap of rubber trees cannot meet the
world’s demands. Currently, synthetic rubber is derived entirely from
petrochemical sources. DuPont, together with The Goodyear Tire & Rubber Company,
is currently working on the development of a reliable, high-efficiency
fermentation-based process for the BioIsoprene™ monomer, and synthetic biology
has played an important role in making this undertaking a reality.
Waste management is a big headache in the agriculture sector.
The hull is the woody case that protects the soybeans, and it cannot be
digested by humans or other monogastric animals, such as pigs. Surfactants are
one of the most useful and widely sold classes of chemicals, because they
enable the stable blending of chemicals that do not usually remain associated
(like oil and water). Today, nearly all surfactants are manufactured from petrochemicals
and worldwide production of surfactants from petrochemicals annually emits
atmospheric carbon dioxide equivalent to combustion of 3.6 billion gallons of
gasoline. To address this problem microorganisms have been developed in the
laboratory that convert agricultural waste like soyabean hulls into useful new
surfactants that can be of use in personal care products and other
formulations. Similarly Yeast is being engineered to produce rose oil as
an eco-friendly and sustainable substitute for real roses that perfumers use to
make luxury scents.
In some ways, synthetic biology is similar to another
approach called "genome editing" because both involve changing an
organism's genetic code; however, some people draw a distinction between these
two approaches based on how that change is made. In synthetic biology,
scientists typically stitch together long stretches of DNA and insert them into
an organism's genome. These synthesized pieces of DNA could be genes that are
found in other organisms or they could be entirely novel. A microbe could be genetically engineered in the laboratory
to detect a particular pathogen and kill it once it is delivered inside the
human or animal body.
They
have tamed the typhoid causing Salmonella, engineered it to retain
its ability to enter the body’s immune cells but also to prevent it from
causing diseases. Thus they can use the bacteria to deliver a vaccine orally. It
enters through the gut lining, is engulfed by immune cells, and then it starts
making vaccine.....much like a bioreactor inside the animal/human body.
Alongside stemcell research and genome editing Synthetic Biology could offer
new insight into synthesizing body parts and repairing dead tissues and organs!
This harnessing of living cells has however raised several
ethical questions. What if these xenobots go out of control? Manipulating
complex biological systems may be risky and scientists may end up with a Frankenstein.
That AI designed these xenobots adds another layer of risk, the possibility of
programming them as biological weapons. Iron clad regulations are necessary to
keep the individual egos of rogue scientists and ambition of world domination
of rogue nations in check.
The ultimate scope of clinical applications for synthetic
biology remains to be seen. Today’s application in diagnostics, drug discovery,
and tissue engineering should soon grow more extensive and spawn opportunities
that are currently unimaginable. Indeed, synthetic biology has the potential to
radically change the way clinicians manage disease and to help us live, longer,
healthier lives.
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