In the past five years, the number of people waiting for a heart transplant in the UK has doubled and continues to grow. Unfortunately, the demand for organs greatly outweighs the supply, but
scientists in the field of tissue engineering are sure this won’t always be the case. If you’ve ever
imagined a laboratory as jars of floating organs grown from scratch, you’re not far off what they’re
hoping to achieve.
Interest in tissue engineering began as early as the 1960’s in developing artificial skin which could be used for grafts to treat burn victims but has successfully expanded to cartilage, bone and even some whole organs such as bladders, though there is still work to be done before transplants.
Nevertheless, some incredible strides have already been put into practice when last year
Andemariam Teklesenbet Beyene was the first recipient of a fully synthetic trachea after suffering
from aggressive cancer.
(The replacement trachea. Source: bbc.co.uk)
But how does it work?
Tissue engineering is the process of creating functional tissues and organs by combining cells,
scaffolding and other molecules. Scaffolding in this sense refers to the molecules secreted by cells to support themselves (or the extra-cellular matrix) and not of the construction site variety. It is
possible for researchers to create artificial scaffolds using anything from proteins to plastic or use
existing ones by collecting it from the cells of a donor organ. Following this, cells and growth factors are introduced to the framework to fix damaged tissue or even develop new tissues. In the case of Mr. Beyene, his artificial trachea was constructed from glass before being coated with stem cells taken from his own bone marrow.
Importantly, because cells from the prospective patient are used the risk of rejection is avoided,
sparing them from taking immunosuppressant drugs for the rest of their lives. What’s more, there
would be no need to wait on an organ donation list.
Outside of a few incredible incidences like Mr. Beyene’s trachea, tissue engineering does not yet
play a significant role in clinical medicine but it is a promising and growing field.
(A 3D printed ear. Source: nature)
One fascinating area lies in the use of 3D printers which are being used to print structures that can
then be seeded with cells to form functioning organs. Unfortunately, the organs being printed are
still rudimentary but researchers at Harvard and Sydney have opened up the possibility of larger,
more complex printed organs by using 3D printing to produce capillaries. They were able to make
these printed blood vessels functional thereby tackling the problem of vascularisation (gaining a
supply of blood vessels) which tissues need to survive and grow.
If that wasn’t Sci-Fi enough, researchers are also looking at using live cells as ‘ink’ to directly
assemble organs and tissues. It is unlikely these would be suitable for transplant any time soon but
provide a brilliant opportunity for drug testing. A bioprinting firm, Organovo, already sells liver tissue produced this way to test for drug toxicity to liver cells. In the foreseeable future, this technique could be used for “personalised therapy routines” where tissues are created from a patient’s cells to test different drugs and therapies for their specific illness.
Clearly, tissue engineering is a fascinating field with a massive potential market from tailoring drug
treatments to, one day, replacing whole damaged organs. There are still many difficulties to
overcome, particularly materials meeting the high quality and safety standards necessary for human use, but despite this, designer organs may be on the market sooner than you think.