Bioprinting is relatively
new but has great potential to save many lives. UNOS, the United Network for
Organ Sharing, stated on their website UNOS.org, that on average someone is
added to the national transplant waiting list every ten minutes and that twenty
people die waiting every day. It’s very sad but with advances in technology
there is a solution. It’s called bioprinting.
Slide 2-4 (Table of
If computers and all the software we have today were
never thought of, we wouldn’t have all the life saving technology we do now. It’s
crazy to think about but our advances in technology wouldn’t be possible if it
weren’t for the ideas of others.
Bioprinting was born out of a process that started about
twenty years ago. Surgeon Anthony Atala and his team at Boston’s Children
Hospital started by trying to handmake tissues for regenerative medicine. They
would harvest cells from the patient then layer the cells on top of each other
to create handmade “scaffolds” then the cells would grow and multiply,
producing tissue such as skin, bladder, and cartilage. The problem with the handmade
“scaffolding” method was that it took to long and was labor intensive.
Atala thought of a new idea, bioprinting. Bioprinting is quicker and more
efficient. The “ink” for bioprinting contains cells and biomaterial such as
collagen. A computer system named CAD generates a 3-D model for the printer to
go off. When the material is deposited from the printer it must quickly form a
“gel” like substance to maintain a 3-D structure. This requires lots of
pre-planning calculations. The bio-engineer must take into count the cell
density, cell type, and proportions for the supporting biomaterial needed to make
the tissue thrive. There is not much room for error.
There are three different methods of bio-printing such as
inkjet, extrusion-based, and laser assisted bioprinting.
Ink jet bioprinting was the first method developed. This
approach is very fast and produces small droplets of the bio-ink on the receiving
tray. It has multiple nozzles that deposit at the same time making the process fast.
It has produced living tissues such as smooth muscle cells.
Extrusion based Bioprinting can construct bigger size
tissues in reasonable amount of time. It produces a continuous stream of
bio-ink through a syringe like structure. Unlike the other methods you can
numerous options of bio-ink.
Laser assisted Bioprinting is a complex process that is
sort of difficult to explain. In simple words, a laser pulse stimulates a
pressure bubble in what’s called a laser absorbing layer which propels the
bio-ink into a cell droplet on the collector slide.
Explaining these different methods can be confusing so I
found this clipart that makes it simpler by providing a visual aid to show the
three different methods.
Each method has its strengths and weaknesses, so I made this
chart to compare. The inkjet method is cheaper than the other methods and it’s
faster but can’t produce as big of tissues than the others. Extrusion based bioprinting
can produce better size products than the others, but the syringe structure
causes pressure drops when it tries to reload which can cause a deformation in
cells. Lastly, the laser assisted bioprinting method has less room for errors
because it doesn’t have a nozzle or syringe, but it is the most costly and
The brain behind the printer is the CAD (Computer Aided
Design) program. It is used by researchers, architects, artist, engineers, and
many other individuals. It can create 2-D drawings and 3-D models. This program
replaces manual drafting of blue prints and such things and replaces it with an
CAD makes the 3-D models for the printers. The model is
based off CT or MRI scans of the patient. It is then converted into STL (stereolithography)
format which allows CAD to implement its design modifications such as the
scaling, porosity, resolution, structure and function of the tissue. It provides
all the building blocks the printer needs to make functional tissue.
Printers have been made that have the CAD software built
into them. This allows more customization and control for printing parameters. Some
printers are very expensive, but Todd Goldstein, a 3D bioprinting researcher
and director of Northwell Ventures 3D Printing Laboratory, was able to modify a
printer to print his bio-material under $2,000 which is relatively low compared
to other models.
Bio-printed organs have more advantages than donor
organs. Donor organs have a high risk of rejection while bio-printed organs do
not because there tailored for the patient and made from the patient’s own
cells. Bio-printed organs can be produced in a reasonable amount of time while
patients die waiting for a match for an organ donor.
Researchers in Long Island, New York have printed body
parts such as bone, cartilage, and trachea. Also, the team of researchers at
Wake Forest University have printed skull bone, cartilage, and skeletal muscle.
Some issues with producing complex tissues such as organs
is blood supply. Todd Goldstein stated “The biggest issue on the whole right
now is blood supply, you can’t make the constructs too large without running
into the issue of having a necrotic core (an area of dead cells) in the middle.
Just like our body needs blood circulating all the time, so do these living tissues.”
The reason researchers have been successful with bone, cartilage, and tendons
is because they don’t require a blood supply. Goldstein said there is a
solution to the problem, that’s why there putting in a lot of time researching
and printing small capillaries and vascular networks.
Once these issues with blood supply are worked out,
researchers plan on printing hearts, livers, kidneys, and many other lifesaving
organs. This is expected to take several years however, if successful this
process could save millions of people’s lives.
The goal is to one day have no transplant waiting list, bioprinting
has the potential to make this goal possible.
This is a list of websites to help keep track of the
progress of bioprinting.
Slide 23 (References)
With time and hope bioprinting could make transplant
waiting list obsolete.