An important step
toward creating artificial living material has been made by EPFL researchers.
They are working on a technique that should eventually allow them to “print”
living constructs resembling human tissues in which cells can develop and
interact in a coordinated and physiological manner. Their research results have
recently been published in Advanced Materials.
“We have not yet
created tissue, strictly speaking,” explains Professor Jürgen Brügger, head of
EPFL’s Microsystems 1 Laboratory. “At this stage, we have essentially studied a
way in which to structure biological materials in three dimensions; this
research will improve cell culture and then will eventually be used as a base
for creating tissues.”
Someday this new
technology, which is the fruit of joint research between EPFL’s Engineering
School (STI) and School of Life Sciences (SV), will make it possible to print
tissues one drop at a time. Progress made in several different areas has
combined to bring the technology to this point.
First, printing
involves ink, a raw material that’s challenging to design, explains Professor
Matthias Lutolf, head of EPFL’s Stem Cell Engineering Laboratory. “Mixing the
right ingredients isn’t sufficient. The cells grow in a haphazard manner, randomly,
and won’t develop into viable tissue.”
A more malleable material
To make up a
coherent whole, the cells need an environment that provides the right kinds of
signals that induce very specific behavior in each of the cells—proliferation,
migration, differentiation, or death. In natural tissues, these signals come
from molecules that make up a complex extracellular matrix (ECM). By studying
the connections and communications taking place between cells and between cells
and ECM molecules, the scientists were able to reconstruct this matrix and thus
create a new kind of biological ink.
On a technical
level, the researchers from EPFL’s two Microsystems Laboratories—under the
leadership of professors Jürgen Brugger and Philippe Renaud—focused on developing
a gel that could be used as a base from which the tissue could be constructed,
as well as a strategy for printing droplets. Thanks to the gel, made up of
concentrated calcium, and the printing sequence they came up with, each droplet
of ink landing on the surface sticks to it and keeps its initial shape instead
of spreading out.
“The various
tissue elements don’t blend together uncontrollably,” explains Brugger. “Above
all, the material polymerizes more quickly and becomes flexible and malleable,
which allows us to assemble several layers and to envision building channels,
which are indispensable for fluid perfusion, nutrient input, and waste
elimination.”
Testing new drugs
“Thanks to the
combination of these technical and biological advances, we are working towards
the growth of a tissue in which the cells develop and live happily,” Lutolf
explains.
Even though it will still be quite some time before
tissue can be constructed, this technology could lead to very promising
applications on the medium term. “An exiting avenue would be to develop 3D
constructs that function like human tissues and could be used as models for
testing new drugs,” says Lutolf. “This is not only very interesting in a
biological sense, but could also reduce the need for animal testing.”
