- Existing tissue engineering platforms to mend damaged or injured
hearts involve invasive open heart surgery to implant regenerative cells
- Current research team has developed lab grown biocompatible tissue
that can be injected, and unfolds into a patch within the body to repair
damaged tissues and organs.
or diseased heart or other organs could be fixed by injectable lab engineered
tissue, overcoming the need for painful, invasive open surgery, according to a
biomedical engineering research team at the University of Toronto
Faculty of Applied Science & Engineering.
Injectable Lab Grown Tissue Patch - Game Changer In
Tissue Repair Technology
last couple of decades have seen a huge expansion in stem cell and tissue
engineering research and development.
‘Lab grown injectable tissue that unfolds in vivo into a patch may revolutionize repair of damaged organs non-surgically’
Generally lab generated tissue
used for repair and regeneration of injured or damaged organs (eg: heart attack
) has involved implantation of the tissue at the site of injury through an invasive surgical procedure such as open heart surgery and required general anesthesia.
authors of the study however felt that given the patient's serious illness and
delicate state of health following a heart attack, surgery under general
anesthesia might actually be dangerous. The
team therefore, wanted to develop an injectable biomaterial that could be
delivered via catheter directly into the infarcted area, avoiding invasive
and general anesthesia.
engineering Professor Milica Radisic at the University of Toronto
Faculty of Applied Science & Engineering and her colleagues are experts in developing polymer scaffolds
on which realistic 3D
tissue resembling native tissue can be grown in the lab setting. AngioChip,
one of their innovations, is a tiny patch of heart tissue having its own blood
supply. These heart cells are able to beat with a regular rhythm. Yet another
of their novel creation snaps together like sheets of Velcro™.
The team hoped to translate their expertise in the field of polymer science to
create an injectable biocompatible material
that could be used to repair
injured tissues and organs.
An Injectable Biocompatible Material - A Herculean Task
- Miles Montgomery, a PhD candidate in
Radisic's lab, spent nearly three years just experimenting in order to
produce a tissue patch that could be injected, rather than implanted.
"At the beginning it was a real
challenge; there was no template to base my design on and nothing I tried was
working," says Montgomery. "But I took these failures as an
indication that I was working on a problem worth solving."
several gut wrenching failures, Montgomery finally managed to produce what
he was looking for - a scaffold material
that matched the mechanical properties of the target tissue and possessed
the necessary shape-memory behaviour. Thus, the patch would unfold
itself into a bandage-like shape as it is delivered into the target area
refer to a type of active polymers becoming
increasingly popular due to their dual-shape
. They can alter their shape in a pre-programmed manner from
shape A to shape B when given an appropriate stimulus.
According to Radisic, the shape-memory effect depends on physical
properties, not chemical ones
. This essentially means that the unfolding
process does not further injections, and local tissue reactions or conditions
will not affect the process. Testing
The Lab Grown Injectable Tissue Patch
- The next step was growing (seeding)
heart cells on the above scaffold, and the created tissue was injected
into rats and pigs.
- The injected tissue unfolded into a
postage stamp sized patch (nearly the same size as implanted tissue) as it
emerged from the needle. The heart thankfully withstood the procedure very
"When we saw that the lab-grown
cardiac tissue was functional and not affected by the injection process, that
was very exciting," says Montgomery. "Heart cells are extremely
sensitive, so if we can do it with them, we can likely do it with other tissues
- The scaffold made of biodegradable
material would disintegrate over time leaving behind only the heart tissue
- It was found that following the procedure,
the heart function also improved and the ventricles were able to pump
better than before injection of the patch.
For Future Research
- Whether the improved cardiac function is sustained over a long period of
- The team has also applied for
patents on the invention and are planning
to test the use of the patch in other organs, such as the liver.
- Prof Radisic opines that this platform could be customized
as per requirements by, for instance the addition of growth factors to
encourage tissue regeneration.
In conclusion, though this innovation
still has to undergo further testing and modifications before it is ready for clinical trials,
it nevertheless opens up exciting possibilities in the realm of tissue
regeneration and repair.
- Materials Science and Tissue Engineering: Repairing the Heart - (https:www.ncbi.nlm.nih.gov/pmc/articles/PMC3786696/)