Materials are widely used to help heal
wounds: Collagen sponges help treat burns and pressure sores, and
scaffold-like implants are used to repair bones. However, the process of
tissue repair changes over time, so scientists are developing
biomaterials that interact with tissues as healing takes place.
Nurse bandages hands (stock image).
Credit: © ctpaep / Fotolia
Now, Dr Ben Almquist and his team at Imperial College London have
created a new molecule that could change the way traditional materials
work with the body. Known as traction force-activated payloads (TrAPs),
their method lets materials talk to the body's natural repair systems to
drive healing.
The researchers say incorporating TrAPs into existing medical
materials could revolutionise the way injuries are treated. Dr Almquist,
from Imperial's Department of Bioengineering, said: "Our technology
could help launch a new generation of materials that actively work with
tissues to drive healing."
The findings are published today in Advanced Materials.
Cellular call to action
After an injury, cells 'crawl' through the collagen 'scaffolds' found
in wounds, like spiders navigating webs. As they move, they pull on the
scaffold, which activates hidden healing proteins that begin to repair
injured tissue.
The researchers designed TrAPs as a way to recreate this natural
healing method. They folded the DNA segments into three-dimensional
shapes known as aptamers that cling tightly to proteins. Then, they
attached a customisable 'handle' that cells can grab onto on one end,
before attaching the opposite end to a scaffold such as collagen.
During laboratory testing of their technique, they found that cells
pulled on the TrAPs as they crawled through the collagen scaffolds. The
pulling made the TrAPs unravel like shoelaces to reveal and activate the
healing proteins. These proteins instruct the healing cells to grow and
multiply.
The researchers also found that by changing the cellular 'handle',
they can change which type of cell can grab hold and pull, letting them
tailor TrAPs to release specific therapeutic proteins based on which
cells are present at a given point in time. In doing so, the TrAPs
produce materials that can smartly interact with the correct type of
cell at the correct time during wound repair.
This is the first time scientists have activated healing proteins
using different types of cells in human-made materials. The technique
mimics healing methods found in nature. Dr Almquist said: "Using cell
movement to activate healing is found in creatures ranging from sea
sponges to humans. Our approach mimics them and actively works with the
different varieties of cells that arrive in our damaged tissue over time
to promote healing."
From lab to humans
This approach is adaptable to different cell types, so could be used
in a variety of injuries such as fractured bones, scar tissue after
heart attacks, and damaged nerves. New techniques are also desperately
needed for patients whose wounds won't heal despite current
interventions, like diabetic foot ulcers, which are the leading cause of
non-traumatic lower leg amputations.
TrAPs are relatively straightforward to create and are fully
human-made, meaning they are easily recreated in different labs and can
be scaled up to industrial quantities. Their adaptability also means
they could help scientists create new methods for laboratory studies of
diseases, stem cells, and tissue development.
Aptamers are currently used as drugs, meaning they are already proven
safe and optimised for clinical use. Because TrAPs take advantage of
aptamers that are currently optimised for use in humans, they may be
able to take a shorter path to the clinic than methods that start from
ground zero.
Dr Almquist said: "The TrAP technology provides a flexible method to
create materials that actively communicate with the wound and provide
key instructions when and where they are needed. This sort of
intelligent, dynamic healing is useful during every phase of the healing
process, has the potential to increase the body's chance to recover,
and has far-reaching uses on many different types of wounds. This
technology has the potential to serve as a conductor of wound repair,
orchestrating different cells over time to work together to heal damaged
tissues."
The research was funded by the Engineering and Physical Sciences Research Council and Wellcome Trust.
Journal Reference:
- Anna Stejskalová, Nuria Oliva, Frances J. England, Benjamin D. Almquist. Biologically Inspired, Cell‐Selective Release of Aptamer‐Trapped Growth Factors by Traction Forces. Advanced Materials, 2018 DOI: 10.1002/adma.201806380
Courtesy: ScienceDaily
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