Medicine matters.
Whether you’re getting a flu shot or just
taking an aspirin, the medical field is vital
to the way you live your life.
New treatments are coming out nearly every
day, all because of the hard work of scientists
and engineers.
Together they’re creating breakthrough medicines
and figuring out how to get them where they need to go.
These efforts are known as drug discovery
and drug delivery, and they’re what you need if
you want to engineer a healthier world.
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In today’s world, it’s pretty easy to
get things with a personalized touch.
Everyone’s different, and people want a
lifestyle that reflects those differences.
Custom cars, tailored clothes, personalized
electronics – the list goes on.
But what about medicine?
What if you could walk into a hospital and
get a completely personalized treatment for
whatever you had going on?
That’s the dream of biomedical engineering:
a world where doctors can diagnose and treat a
person based on their individual differences.
This concept is called personalized medicine
and it’s the healthcare of the future.
It’s the idea that you could combine a person’s
genetic information with clinical data to best tailor
a treatment to meet their specific and unique needs.
Medicine is the field where all our knowledge
comes together.
You’ll need biology to understand the problem,
chemistry to figure out the solution, and physics to
deliver that solution in a safe and targeted way.
As an engineer, it’s your job to bring all this together using concepts like biocompatibility and fluid flow to create one easy-to-use package that could save someone’s life.
Lucky enough, there’s already some places
where this kind of personalized approach is
being used!
For instance, genetic tests can reveal how likely
someone is to get breast cancer and guide them
onto an appropriate monitoring path early in life.
Hopefully this leads to detecting the
disease early on, when treatment options are
less invasive and more successful.
But there are still many challenges to overcome
before personalized medicine becomes widespread.
You need to develop better systems to quickly
assess a patient’s genetic profile,
create inexpensive diagnostic devices using
that information, and find the best way to deliver
a drug if anything comes up.
And that’s all after your come up with a
good treatment in the first place!
Drug discovery is all about finding that new
treatment.
It’s the process through which you discover and
create new medications based on what you know
about your ingredients and how they’ll interact
with the human body.
Even before modern healthcare, people found
natural remedies, often by chance, that improved their
health or helped them get over an illness.
The early days of drug discovery were all about
finding the active ingredients inside those remedies –
the part that was actually affecting the body – and
learning how to replicate or improve on the outcome.
Hot peppers, for instance, were used for centuries
to relieve the pain of things like toothaches,
but today we know it’s only the substance
capsaicin that matters.
You can now buy it to treat conditions such as
arthritis and shingles – all without the burning
sensation created by other parts of the pepper!
These days we have large chemical libraries of synthetic
molecules, natural products, and chemical extracts that
|have been tested to determine their effects.
This is called classical pharmacology.
A new tool is genome analysis, the study of
a complete set of an organism’s DNA, including
all of its genes.
It’s the result of the Human Genome Project,
which successfully sequenced our DNA.
Sequencing your genome is like mapping out
all the genes in your body.
It’s about figuring out the order of all
the DNA nucleotides, or bases, in your genome.
For the Human Genome Project, researchers were
able to sequence all of our 3.2 billion base pairs,
which allowed for the rapid cloning and
synthesis of large quantities of purified proteins.
Genome analysis is the foundation of the
modern approach to developing drugs, called
reverse pharmacology.
Reverse pharmacology starts by identifying
which of those proteins is related to the
condition you want to treat.
You can compare that protein to a list of
chemical reactions to find a molecule known
to interact with it.
If you find a match, you can test the
substance on living cells to see if the reaction
has any positive impact.
From single cells, you can move up to simple
animals and – if all goes well – eventually
to human trials.
By starting with the “problem area” and working
backwards, reverse pharmacology is the more educated
– and often faster – way to discover a new medicine.
Regardless of which way you got it, once you
have a treatment, it’s on to drug delivery:
getting the medicine to move through the body,
find the site of the problem, and even attach to
right parts of the cells.
Syringes are the classic solution to this
problem.
Just draw up some medicine and inject it right
where it’s needed.
But those syringes used to need a lubricant
to help the plunger – that thing you press
down on – well, go down.
This usually meant using silicon oil, which
could be a problem.
Silicon oil can react with the medicine inside and,
as medicines have become more and more specialized,
the worse and worse the reactions can be.
Many drugs also can’t be delivered straight
to the bloodstream, but have to be metabolized
in the stomach or intestines first.
So it’s a good idea to have other options
for delivering your drugs.
We’ve talked about some possibilities before,
such as nanomaterials or biomaterials.
Researchers are currently exploring ways to
engineer nanoparticles that could deliver a drug
to its target in the body while evading your
immune system’s normal defenses.
You’ve heard about smartphones and smart
cars, but what about smart medical devices?
The idea is to design something that’s sensitive
to the body’s internal conditions, letting the drugs
react in the right way at the right times.
Take someone with diabetes, for example.
You could design smarter devices with better
materials so that insulin was only released into their
system when their blood glucose levels were too high.
In the new field of tissue engineering, researchers
are combining the principles of biology
with the applications of engineering to create
novel biomaterials that could aid in the repair of
damaged body tissues – maybe even replace them!
One goal is a type of “medical scaffold” that
can attract stem cells and guide their growth into
specific types of tissue using biological signals.
Stem cells are the building blocks of the body.
And, in the future, mastery of synthetic tissue
engineering could make it possible to regenerate
tissues and even entire organs.
That’s about as personalized as it gets!
Even that doesn’t cover the full spectrum
of what we want medicine to do.
Sometimes the problem isn't that you’re
trying to repair or regenerate the body,
but rather that you’re trying to stop something
from spreading or growing in the first place.
Cancer is the second leading cause of death
worldwide, and it’s responsible for millions
of deaths every year.
Conventional treatments generally rely on
a combination of surgery, radiation, and chemotherapy.
Chemo is often the first choice for treating many types
of cancer, but it’s basically a poison that you hope kills
the cancerous cells faster than the healthy ones.
It’s a similar story with radiation – it’s
hard to limit its effects to just the bad cells.
With conditions like these, a drug delivery
system that only gets the treatment generally
where it needs to go isn’t good enough.
You need to have a targeted drug delivery
and not hurt anything else along the way.
This enables you to maximize the positive
effect at a specific place in the body with
few negative side effects elsewhere.
It would also allow you to treat hard-to-reach
places while also using smaller doses.
The idea of this “magic bullet” approach has
led to a number of new drug carrier systems.
A great example of these are direct local
delivery systems, like the skin patch.
These patches can slowly release medicine
into the body over a period of days.
They’re commonly used to administer birth
control or help smokers with nicotine withdrawal.
A drug-eluting stent, which is a mesh tube
that delivers time-released medicine, can do
the same thing from within the body.
They’re often implanted into patients with
coronary artery disease to prevent dangerous
blockages.
Another promising tool is microparticles.
They’re small enough to travel through the
heart as part of the bloodstream, yet big enough
that they can’t enter capillaries.
A number of researchers have taken this unique
property and prepared biodegradable drugs
made of things like starch.
They can deliver a large dose of chemotherapy
directly to a targeted site, a process that’s also
called chemo-embolization.
The particles accumulate at designated spots
in the body, kind of like a storage depot.
As they break down, the drugs release slowly,
but continuously into the targeted area.
Want to speed up or slow down the release
rate of the medicine?
Try using a different material – one that
degrades at a different speed – or design the
particles to have bigger or smaller pores.
But let’s say you do want something that
can enter the capillaries so that it can keep
on circulating through your body.
Then nanoparticles are the way to go.
Particles around 110-140 nm in size seem to
be ideal for most applications
because they’re large enough to avoid being
cleaned out by the liver or kidneys, but small enough
not to be attacked by white blood cells.
The goal is for them to stay in the body’s
circulation long enough to be removed by the target
tissue rather than something like your immune system.
This approach might be especially well suited
to treat cancer.
Since the blood vessels connected to tumors
are often quite large, the medicine is less likely
to leak into surrounding tissue,
resulting in something called the enhanced
permeability and retention, or EPR, effect.
Basically, you’re increasing how much
medicine gets to where you want, while
reducing it where you don’t.
Future techniques could be even more accurate.
An idea currently being developed is microbubbles,
which are super small bubbles filled with gas.
Someday they could hold a chemotherapy drug
that would only be released when the bubbles
experience the waves of an ultrasound.
The ultrasound would target a specific part
of the body and burst only the microbubbles
at the site of the tumor,
which would activate the drug only where
it’s needed most.
Targeted carriers like these, along with good
disease detection systems and a wealth of drug
discoveries, will add up to that promised world
of personalized medicine.
Today we learned about drug discovery and
drug delivery.
We covered classical and reverse pharmacology,
as well as the new field of synthetic biology and what
people have been able to accomplish with it.
Finally, we saw how important good disease
detection is and why we need more targeted
drug delivery systems.
I’ll see you next time, when we’ll go
one step further and talk about biodevices.
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Crash Course Engineering is produced in association
with PBS Digital Studios, which also produces
Global Weirding,
a show that explores the intersection among
climate, politics, and more, hosted by climate
scientist Katharine Hayhoe.
Check it out at the link in the description.
Crash Course is a Complexly production and this
episode was filmed in the Doctor Cheryl C. Kinney
Studio with the help of these wonderful people.
And our amazing graphics team is Thought Cafe.
