Advance in printing human organs using inkjet printers
28 October 2013
Scientists at the Fraunhofer Institute for Interfacial Engineering
and Biotechnology (IGB) in Stuttgart have developed components of human
tissue that can be used as inks for inkjet printing of human organs.
The transparent liquids consist of components from the natural
tissue matrix and living cells. The substance is based on a well
known biological material gelatin, which is derived from collagen,
the main constituent of native tissue.
The researchers have chemically modified the gelling behaviour of
the gelatin so that it remains fluid during printing. After
irradiating with UV light, the molecules crosslink and cure to form
hydrogels. These are polymers containing a huge amount of water
(just like native tissue), but which are stable in aqueous
environments and when being warmed up to physiological 37°C. The
researchers can control the chemical modification of the biological
molecules so that the resulting gels have differing strengths and
swelling characteristics. The properties of natural tissue can
therefore be imitated — from solid cartilage to soft adipose tissue.
Inkjet printers print cell suspensions onto
hydrogel pads, which prevent desiccation. ©
In Stuttgart synthetic raw materials are printed as well that can
serve as substitutes for the extracellular matrix. For example a
system that cures to a hydrogel devoid of by-products, and can be
immediately populated with genuine cells.
“We are concentrating at the moment on the ‘natural’ variant.
That way we remain very close to the original material. Even if the
potential for synthetic hydrogels is big, we still need to learn a
fair amount about the interactions between the artificial substances
and cells or natural tissue. Our biomolecule-based variants provide
the cells with a natural environment instead, and therefore can
promote the self-organizing behavior of the printed cells to form a
functional tissue model,” explains Dr. Kirsten Borchers in
describing the approach at IGB.
The printers at the labs in
Stuttgart have a lot in common with conventional office printers:
the ink reservoirs and jets are all the same. The differences are
discovered only under close inspection. For example, the heater on
the ink container with which the right temperature of the bio-inks
is set. The number of jets and tanks is smaller than in the office
counterpart as well.
“We would like to increase the number of these in cooperation
with industry and other Fraunhofer Institutes in order to
simultaneously print using various inks with different cells and
matrices. This way we can come closer to replicating complex
structures and different types of tissue,” says Borchers.
big challenge at the moment is to produce vascularized tissue. This
means tissue that has its own system of blood vessels through which
the tissue can be provided with nutrients. IGB is working on this
jointly with other partners under Project ArtiVasc 3D, supported by
the European Union. The core of this project is a technology
platform to generate fine blood vessels from synthetic materials and
thereby create for the first time artificial skin with its
subcutaneous adipose tissue.
“This step is very important for printing tissue or entire organs
in the future. Only once we are successful in producing tissue that
can be nourished through a system of blood vessels can printing
larger tissue structures become feasible,” said Borchers.