Smart gel based sheet can form 3D Printed Conduit helping non invasive nerve repair
A new smart gel-based sheet using
three-dimensional (3D) printing technology that can self-roll into a tube
during surgery to form a nerve conduit could help reduce the complexity of
surgeries and aid rapid healing of nerve injuries.
The gold standard for the treatment of
peripheral nerve injuries is still autografts. Bioresorbable polymer-based
conduits are being explored for clinical use as alternatives. But these
treatment strategies suffer from several limitations, such as donor site
morbidity in the case of autografts and the necessity for sutures that demand
highly skilled microsurgeries, and additional complications posed by sutures.
These clinical shortcomings motivated
researchers at the Indian Institute of Science (IISc) in Bengaluru to design a
smart gel-based sheet using three-dimensional (3D) printing technology that can
self-roll into a tube during surgery to form a nerve conduit. In 3D printing, a
virtual model of the part is created using design software, and the part is
then fabricated using a 3D printer by layer-upon-layer deposition of the
material. 3D printed parts can further undergo a shape change on demand upon
activation after fabrication. Such technologies are now widely known as
four-dimensional (4D) printing, where time is the extra dimension.
In a recent study, the team at IISc, led by Prof
Kaushik Chatterjee, engineered a bilayered gel sheet by 3D printing in
pre-defined patterns from two gels. The gel formulations were selected to swell
differently. When the dried gel sheet was immersed in water, it rapidly swelled
and curled into a tube. The folding behaviour and final shape of the gel could
be programmed to generate tubes of desired dimensions, which could be predicted
by computational modeling. The gel sheets were then coated with thin
nanometer-scale fibers to enable the body’s cells to adhere to the gel
sheet.
Scheme 1: Fabrication
of 4D printed hydrogel conduit with programmed shape deformations. (i) 3D
printing of gels of defined formulation with precise patterning based on
computational design, (ii) 3D printed gel sheet, (iii) Programmed shape
deformation with moisture uptake.
The team at IISc worked closely with researchers
at the Indian Institute of Technology at Roorkee and Maharishi Markandeshwar
University to test the 4D printed conduits for repairing and regenerating a 2
mm gap in the sciatic nerve of rats. The shape-morphing sheets were placed
under the defect region of the nerve and stimulated to wrap the defect site to
form a conduit around the nerve without suturing. The nerve ends could grow
through the implanted conduit. There was a remarkable improvement in nerve
regeneration measured up to 45 days in the rats when the 4D printed nerve
conduits were used. The team consisting of Akshat Joshi, Saswat Choudhury,
Vageesh Singh Baghel, Souvik Ghosh, Sumeet Gupta, Debrupa Lahiri, GK
Ananthasuresh, Kaushik Chatterjee reported its findings in a paper published
in Advanced Healthcare Materials. This work was supported by the Science and Engineering Research Board
(SERB), a statutory body of the Department of Science
and Technology, under the Intensification of Research in High Priority Areas
(IRHPA) special call on 3D Bioprinting.
Such 4D-printed parts have not been used in the
clinic as yet. But such emerging technologies could pave the way for a new
generation of medical devices that surgeons can deploy during surgery to heal
nerves and many other tissues in coming years. They can offer benefits such as
reduced complexity of surgeries, deployment by minimally-invasive procedures,
and faster healing.
Scheme 2: Process showing the potential of the gel sheet to rapidly undergo
shape change during surgery, forming nerve conduits for peripheral nerve repair
to reduce the complexity of surgeries.
Publication link: https://onlinelibrary.wiley.com/doi/abs/10.1002/adhm.202300701