The Matrix
Loboa, a materials engineer has developed a ‘self-destructing
super-bandage’ that is capable of ‘healing infected wounds quickly, without
scarring or standard antibiotics’. It is essentially a material that degrades
until only your own regenerated, healthy cells remain; allowing for the concept
to eventually heal damaged muscle, destroyed digestive tissue and even broken
bone.
Loboa’s work relies on the research into the
extracellular matrix. This is the framework that ‘gives the various parts of
our body their detailed shape and solidarity’, supporting and structuring the
cells of a blood vessel or organ. However this isn’t its only function.
Although the matrix chiefly consists of inanimate structural proteins, for
instance collagen and elastin, it also comprises of proteins that essentially
coax specific cells to be in a certain place. Once such animate proteins have
induced the correct cells, the matrix then determines whether they become bone,
muscle or fat cells, depending on the tension they experience once inside the
matrix.
In your
body this tension is the consequence of the stresses of every-day muscle
movement; high tension persuades stem cells to become muscle or bone whilst a
matrix with a lower tension promotes fat cells. Another role of the matrix is
to nourish the cells in order for them to mature into larger structures. This
is the result of the matrix containing powerful growth factors that aids in
the formation of blood vessels which subsequently provide oxygen for the
developing organs.
It is the exploitation of these properties
that have revolutionised the way in which both tissue and organs can be regenerated. The natural human extracellular matrix has
allowed for the world’s first artificial kidney to be built courtesy of Harald
Ott. Rather than using various stem cell types, only two cell types were
essential in forming the organ. Blood-like stem cells were placed
in the blood vessels of the decullularised kidney matrix whilst endothelial
cells were positioned into the various sections of the filtering system - this ultimately caused the other kinds of cells to form in the sites they were
supposed to.
In terms of using the matrix to attract
and grow muscle from a person’s own cells, this technique has already been successfully
performed, primarily through the use of decullularised tracheas from corpses to
create new fully functional tracheas. In
spite of this, its application hasn’t truly extended far beyond said method,
and so a study has involved the matrix from a pig bladder being used to grow
muscle in people who had lost more than half of a muscle in several types of
trauma. Residual scar tissue was surgically cleared, and then a strip of the
matrix was placed into the exposed void, made taut enough to indicate to the
body that it should become muscle. Eventually the pig matrix becomes completely
replaced by the natural matrix of the patient as well as healthy muscle. The natural matrix can also be used to repair
shattered bone. Research has suggested that a matrix made from human blood is
the most effective mechanism, as it is essentially a highly concentrated
blood clot which contains large amounts of growth factors that promotes bone repair.
Nonetheless there are drawbacks to
natural matrices. The issue of them not being naturally antimicrobial is a
particular concern due to the risk of the wound being infected by the ever
increasing number of drug-resistant superbugs. It is thus clear of the
importance of a synthetic matrix that could ‘turn slowly into the patient’s own
tissue without ever exposing the flesh beneath to microbes’.
Loboa developed a biodegradable material
using polylactic acid (often used in medical implants) and shaped it into
fibres that mimicked the structure of skin. Such fibres can be made solid,
porous of hollow; however a porous construction is preferred as it can be
permeated with a variety of anti-inflammatory drugs and Silvadur – a substance
that contains small amounts of silver ions lethal to most drug-resistant
bacteria including MRSA. The material works in two phases: the first release
overcomes all present bugs, and the second guard ‘leaks out’ slowly to destroy
any other interlopers. Soon the scaffold or plaster disappears too, leaving
only a small scar where the wound once was.
Another benefit of a synthetic matrix
is that it ‘can be used as a template to build body parts far stronger than
those nature provides’. A treatment where this would be especially beneficial
would be for kidney dialysis. A fast-decaying biodegradable polymer can be
constructed into a tube exactly the same dimensions of a vein, but with a thicker
vessel wall, and coated in human muscle cells. Within days the cells replace
the tube with a matrix of natural collagen which is thicker and thus better
able to withstand extra pressures of dialysis. After decellularisation, the
tubes can be surgically implanted into the patient, serving as the vein for
dialysis; thus eradicating the risk of the natural veins from collapsing.
The potential for synthetic matrices
is seemingly endless; nevertheless an artificial matrix does not have the countless
properties of natural matrix, which will forever be crucial for building organs
as ‘it retains so many factors to bind and differentiate cells’. However, for some applications, hybrids are a possibility; a mechanism that incorporates both the artificial and natural matrices.
For example, a synthetic matrix can provide a stronger scaffold, that can be
tailored to requirements, i.e. providing extra ‘niches’ for cells, whilst a natural
matrix can then aid wound healing through fibrinogen – to encourage the body to
accept the component, the hybrid can then be coated with surface cells derived
from the patient’s fat.
There are other future possibilities
for the matrix too. A multi-layered version could ‘simultaneously regenerate
multiple kinds of tissues damaged in severe accidents ‘, and be potentially used
by the military to treat war wounds on site at a lower cost. It even has
potential for repairing brain damage; a signalling molecule released from the
brain matrix that has been damaged by stroke, called DV, promotes the growth of
new blood vessels. This molecule, once injected into mice who had suffered
strokes, had entirely repaired the brain damage within only a couple of weeks.
The promises of these discoveries appear infinite, and I hope it won’t be long
before they become a reality.
