Frequently Asked Questions (FAQs) of
Dr. Doris A. Taylor
What college degree is required to work in the field of organ
The multidisciplinary nature of the work we do attracts
researchers from a variety of backgrounds in the biological
sciences, engineering and medicine. I have a BS degree in biology
and physical science, a PhD in Pharmacology, and post-doctoral
training in molecular biology and cardiology. But in my lab, we
have engineers (biomedical and electrical), surgeons,
cardiologists, physiologists, and cell biologists. They have PhDs,
MDs, master’s degrees, BS degrees and high school degrees.
The specific education and training requirements vary based on the
area you are interested in and the role you want to play. However,
I would say a universal requirement is the ability to think and be
passionate about the work you’re doing each and every day.
Do you see donor organs or bioengineered organs being used more
for planned transplants or in more emergency situations?
I see both situations benefiting from this science and
technology. Because these organs can be recellularized with an
individual’s own cells, the new organs will most likely be used for
planned transplantations. If a heart valve or a cardiac patch turns
out to work without cells, or if any tissue only requires bathing
in cells for a few days, then we could use the method for some
emergency transplants, too.
How will doctors choose between using a donor organ vs. a
bioengineered organ for their patients in need of a
In regenerative medicine, the plan is to grow organs for all
types of patients. If the patient is able to receive an organ from
a suitable donor in a timely fashion, then that will most likely be
the route taken. However, there are many patients who are waiting
for a suitable match or have many other factors that do not allow
them to be on a transplant list. We will be able to work with those
It is important to remember that when you get an organ
transplant today, you unfortunately are trading one problem for
another – because you now have to avoid rejection of the new organ.
This is usually managed by taking drugs that help to prevent
rejection for the rest of your life. These drugs can have
side effects like high blood pressure, diabetes, and often damage
your kidneys and vasculature.
This is why we want to build organs or tissues using your own
cells. That way you can not only have a new organ but avoid the
need to take rejection-preventing drugs that can cause other
problems. If we can succeed in this area, I suspect anyone who
needs a transplant but can wait for the time it takes to build one
will benefit. That being said, if organ donors exist, I don’t think
anyone will say no to that route, which has proven to help so many
in life-threatening, organ-failure situations. Having both options
available helps to better treat patients needing this critical
What organs are most easily bioengineered using your methods?
Can all organs be easily bioengineered?
We see this methodology being used for every organ. However, the
anatomy and physiology of some organs are much more complex than
others. A heart is more challenging and more complex than a liver,
for example. Knowing this, we suspect the liver will be the
first bioengineered organ to be transplanted, likely for patients
with acute liver failure. Still, all organ types are needed and we
hope this methodology will help to address those needs.
Have you been looking into reproducing other tissues such an
intestine or skin?
We can decellularize any tissue that gets a blood supply
including intestines, the pancreas and skin.
In our decellularization technique, the extracellular matrix
composition and architecture of the tissue we are stripping remains
intact. Since both of these components are unharmed during
decellularization, we are able to harness the perfect scaffold that
nature has already grown for us. This matrix and scaffolding
actually helps to instruct the cells that grow on it and makes sure
they organize to grow and become a functional organ.
Tissues, such as intestine and skin, are being developed by some
of my colleagues in the field. As I understand, these other tissues
work well in low pressure settings such as the right side of the
heart, but in high blood pressure settings the thin tissues like
intestine and skin tend to fail. That doesn’t mean they can’t
be helpful, though; they are being used for wounds and for breast
reconstruction. So while simple sheets of tissue like intestine and
skin can work really well to address things like burns, they won’t
work to build a heart, which is where my lab’s focus is
Do you see any possibility for making bones with the bone
marrow already in them?
This is a goal I raised a few years ago. I think it may be
possible, but not yet. We have a lot of work to do with organs
first. It’s a great question, though.
What is your opinion about using pig organs for a scaffolding
to make human organs?
Pig hearts are similar in size and anatomy to human hearts, so
they make a suitable donor tissue for building a new human heart
for patients in need. However, other pig organs may not be as
suitable. For example, we don’t think pig liver would be quite as
good. Other organs beyond a heart could still be viable options,
like pancreas, kidney, lung and gall bladder, which are being
studied in other labs.
Do you see any applications for this research outside of a
For example I was watching a documentary about growing meat—is
this the same?
As we work towards building a new organ, there are many
applications of the extracellular matrix. One example is it allows
us to develop novel structures that can be used to build “mini”
organs. These “mini” organs could be used to screen new drugs and
chemicals before moving toward pre-clinical and clinical tests.
Other potential uses could be for development of vaccines, living
energy sources, biological bioreactors for biomolecules or other
factors where cells can generate a product more efficiently, as
opposed to being synthetically made.
As for growing meat, it is possible, but as a vegetarian, I have
to admit, this is not something I think about.
Which organs are easier to make and transplant?
Each organ has its own complexity in anatomy and physiology.
Organs, such as the liver, have some regenerative capacity already
and will most likely be easier to regenerate and then transplant.
The heart has little natural regenerative capacity and requires
more work to build a truly functional heart for
As we work to build a whole heart, we are learning how the
pieces can be built, such as the aorta, valves and myocardial
patches. These individual pieces can also be grown for
transplantation and help to restore part(s) of a damaged heart or
an aging heart that has lost its ability to pump correctly.
One of the major hurdles we have to building a whole heart is to
identify the number of cells and type of cells needed. In building
the heart, we believe we will need hundreds of billions of
cells, including blood vessel cells, nerves, underlying fibroblasts
and cardiac muscle cells. These cells have to assemble into the
correct organization and then relearn to communicate with each
other appropriately and work in concert to function as one whole
Learning to create whole organs that are more complex, like the
heart, will take more time than an organ that isn’t as challenging
to produce, like a liver. However, we are making positive
What are the challenges in building an organ?
Cells are a huge hurdle. We estimate it requires hundreds of
billions of cells to build a whole heart. Another
challenge is keeping the organs alive and sterile in the lab while
they develop. The organs don’t have an immune system, so keeping
them clean, “free of microbes” or “free of microorganisms” is
a big deal.
How did you discover the right solution for stripping the
organs of cells?
There is a lot of research on how to remove the cells without
damaging the extracellular matrix. Methods include both mechanical
and chemical solutions, and the chosen method depends on the organ
For the heart, we use an anion detergent solution. We tried
several detergents (soaps) for stripping cells, and ultimately we
settled on one called sodium dodecyl sulfate (this is the main
ingredient in shampoo). We developed a protocol for decellularizing
which reduces the amount of DNA present while preserving the
glycoaminoglycans (GAGs) and mechanical and structural properties.
A review article was recently published by my
group that describes a lot of the decellularization processes being
investigated worldwide. (Also see Nature New Feature | Tissue engineering: How to
build a heart)
What are the side effects of this method of transplant, if
We are still in the research phases of our work, so we don’t yet
know what potential side effects could occur. We have to build
organs that can survive long term, function properly (i.e. do the
normal work assigned to that organ), and have the ability to
effectively respond to injury. If any of these three things are
lacking in some way, this could result in a side effect.
Our moonshot goal is to develop a heart that is made up of the
patient’s own cells. In theory, this will prevent the chance of the
patient’s body rejecting the heart. However, as more is learned
about stem cells, it may very well be that cells from young healthy
donors are the better source. If this is the case, we will
still need to address the same rejection issues we face today when
we transplant organs (i.e. the patient must take medicines to
suppress the immune system so that their body does not reject the
Until we know more and are further along in the research, it’s
too soon to tell what, if any, side effects we’ll have with this
method of transplantation.
How do you plan to test this in clinical
Before we can move to clinical trials, organs will be
investigated in pre-clinical trials with large animals to test
safety and efficacy.
Do you believe that the issues involved with organ
transplantation can be solved through stem cells and tissue
Many issues associated with organ transplantation absolutely can
be solved through stem cell and tissue engineering. For example,
cell therapy is a regenerative medicine strategy that can be used
to intervene early after an injury occurs to treat the underline
injury rather than the symptoms associated with the injury and
potentially prevent the need for organ transplantation. In
addition, tissue engineering provides an opportunity to repair or
replace injured organs and tissue. Regenerative medicine is a new
field that for the first time has the opportunity to address the
major underlying issues that cause disease rather that simple treat
What role do stem cells play in your tissue engineering
Stem cells are a major component of tissue engineering.
Basically, stem are cells that can do two things: first make more
of themselves or self-renew or second differentiate into multiple
kinds of cells. In tissue engineering we typically combine some
sort of material a scaffold if you will, or some other material
with cells to build a new structure that allows those cells to
function at a sight of injury or disease. Or we use some sort of
engineered material to deliver cells in a new way to region of
What new significant discoveries have led to breakthroughs in
Breakthroughs in my research have really come: 1) with an
understanding of how to manufacture or scale up stem cells, 2) with
the whole idea of decellularization of complex organs and tissues,
and 3) with the findings about abilities to transplant stem cells
or the chemicals or microRNAs or other compounds of stem cell
secrete without even needing the cells themselves.
How close do you think we are to being able to engineer and
transplant human organs?
Building new bioreactors, finding ways to grow enough cells
(billions of) finding how to derive stem cells from an adult
individual, and the advent new materials that can be used for
scaffolds are all significant contributions to our research. As for
how close we are to being able to engineer and transplant human
organs, well it depends on the organ, Dr. Tony Atala will tell you
that he’s already transplanted most of a bladder, a simple
balloon; but transplanting a more complex organ such as heart,
liver, lung, kidney is still several years away.
Have a question? Email Dr. Taylor and the THI Regenerative
Medicine Research team at RMR@texasheart.org.