When physicians run out of treatment options, they look to a nascent
field known as bioengineering for solutions to their patients' ailments.
Specialized scientists apply engineering principles to biological
systems, opening up the possibility of creating new human tissue,
organs, blood and even corneas such as the one shown here. Waiting lists
for organ transplants continue to be lengthy so the race to save lives
with bioengineered body parts is on. Here’s a look at some of the most
notable achievements in recent years.
Skin
Producing small amounts of artificial skin to graft onto patients and
use for toxicity testing has been possible for years. Human skin cells
are cultivated in the lab and then embedded in a collagen scaffold. In
2011, the Fraunhofer Institute for Interfacial Engineering and
Biotechnology introduced a system that can rapidly manufacture two-layer
artificial skin models. Their Tissue Factory has the capacity to make
5,000 skin sheets in a month.
Ear
Reproducing 3D biological structures, particularly the complex human
ear, presents significant challenges for bioengineers. A team at
Princeton University, led by Associate Professor of Mechanical and
Aerospace Engineering Michael McAlpine, used 3D printing technology to
make a functional ear from calf cells and electronic materials. The ear
that debuted in May 2013 is not a simple replacement — it can pick up
radio frequencies well beyond the range that human ears normally detect.
Bladder
Surgeon Anthony Atala directs the Wake Forest Institute for
Regenerative Medicine and is known for growing new human cells, tissues
and organs — particularly ones that advance urology. Atala and his
team’s bioengineered bladders succeeded in clinical trials. The bladders
were constructed from patients’ cells that were grown over two months
on a biodegradable scaffold and then implanted. Patients included
children with spina bifida who risked kidney failure. It’s been several
years since then and the results are positive. “These constructs appear
to be doing well as patients get older and grow,” Atala told
The NIH Record.
Blood Vessels
Being able to make blood vessels in the lab from a patient’s own cells
could mean better treatments for cardiovascular disease, kidney disease
and diabetes. In 2011, the head of California-based Cytograft Tissue
Engineering reported progress in a study where three end-stage kidney
disease patients were implanted with blood vessels bioengineered in the
lab. After eight months the grafts continued to work well, easing access
to dialysis. Then, this month, a team at Massachusetts General Hospital
found a way to bring mature vascular cells back to an early, stem-like
state. They generated long-lasting blood vessels in living mice.
Heart
Artificial heart devices have been surgically implanted since the 1980s,
but no device has been able to replace the human heart as effectively
as a healthy biological one. After all, a human heart pumps 35 million
times in a single year. Recently scientists have made advances in adding
more biological material to artificial heart devices. In May the French
company Carmat prepared to test an artificial device containing cow
heart tissue. At Massachusetts General Hospital, surgeon Harald C. Ott
and his team are working on a bioartificial heart scaffold while MIT
researchers recently printed functional heart tissue from rodent cells.
Liver
Bioengineers are working on it, but the liver is one of the largest,
most challenging organs to recreate. In 2010 bioengineers at Wake Forest
University Baptist Medical Center grew miniature livers in the lab
using decellularized animal livers for the structure and human cells.
This month, a team from the Yokohama City University Graduate School of
Medicine published results of a study where they reprogrammed human
adult skin cells, added other cell types, and got them to grow into
early-stage liver “buds.” Currently the scientists can produce about 100
of them, but the study’s lead author Takanori Takebe told The Wall Street Journal that even a partial liver would require tens of thousands.
Trachea
In April, after an international team of surgeons spent nine hours
operating on her at Children's Hospital of Illinois in Peoria, 32-month
old Hannah Warren became the youngest patient to ever receive a
bioengineered organ. Scientists had made a windpipe for her using her
own bone marrow cells. Born without a trachea, she needed help
breathing, eating, drinking and talking. Harvard Bioscience created the
custom scaffold and bioreactor for the experimental procedure. Sadly
Hannah died on July 7 due to complications from a more recent surgery on
her esophagus. Despite the high risks, bioengineers say they will
continue to move ahead.
Back Discs
When a ruptured or degenerating disc causes chronic back pain, treatment
is limited. At worst, patients undergo surgery to fuse vertebrae
together and then have limited flexibility. Over the past several years
artificial discs have emerged as an alternative, but they can wear out
as they work. In 2011, a research team from Cornell University
bioengineered implants using gel and collagen seeded with rat cells that
were then successfully placed into rat spines. This summer Duke
bioengineers took things further, coming up with a gel mixture they
think can help regenerate tissue when injected into the space between
discs.
Intestines
Little by little, bioengineered intestines are being grown in the lab to
diagnose digestive disorders and to help patients born without a piece
of intestine. In 2011, Cornell biological and environmental engineering
assistant professor John March began collaborating with Pittsburgh-based
pediatric surgeon David Hackam on a small artificial intestine using
collagen and stem cells. Then last year in Switzerland, EPFL professor
Martin Gijs led a project in the Laboratory of Microsystems to create a
miniature intestinal wall from cultured epithelial cells and electronics
called NutriChip to identify foods that cause inflammation. Scientists
at Harvard’s Wyss Institute also made a “gut-on-a chip” to mimic the
real thing using intestinal cells in a tiny silicon polymer device.
Kidney
One in 10 American adults will have some level of chronic kidney
disease, according to the Centers for Disease Control and Prevention.
Currently around 600,000 patients in the U.S. have chronic kidney
failure. Most rely on dialysis while a fraction of them actually get
transplants. Scientists from the University of California, San Francisco
are on a mission to create a sophisticated artificial kidney device
made with human kidney cells, silicon nanofilters and powered by blood
pressure. The project, led by UCSF nephrologist William Fissell and
bioengineering professor Shuvo Roy, aims to begin testing the kidney
device in 2017.
