Researchers at the Indian Institute of Science (IISc) in Bengaluru have developed a new smart gel-based sheet produced through three-dimensional (3D) printing technology. It can self-roll into a tube shape during surgical procedures to form a nerve conduit. Its implementation could help reduce the complexity of surgeries and aid the rapid healing of nerve injuries.
Autografts remain the preferred method for treating peripheral nerve injuries. Autografts refer to the surgical procedure of using a patient’s own tissue for transplantation, rather than using tissue from another individual or a synthetic substitute. There is an ongoing exploration of bioresorbable polymer-based conduits as potential alternatives for clinical use. However, these treatment options have various drawbacks, such as donor site morbidity associated with autografts and the necessity for sutures that demand highly skilled microsurgeries, and additional complications posed by sutures.
The 3D printing process involves creating a virtual model of the part using design software, and the part is then fabricated using a 3D printer by layer-upon-layer deposition of the material. This technology also falls under the umbrella of “4D printing,” where time is considered the additional dimension, as the printed parts can undergo shape changes on demand following their fabrication.
The team at IISc, led by Kaushik Chatterjee, engineered a bi-layered gel sheet by 3D printing in pre-defined patterns from two gels. The gel formulations were selected to have different swelling properties. When the dried gel sheet was immersed in water, it quickly swelled and curved into a tube shape. The folding behaviour and final shape of the gel could be precisely programmed to generate tubes of specific dimensions, which could be predicted by computational modelling. Additionally, thin nanometer-scale fibres were applied to the gel sheets to enable cells in the body to attach to them.
The researchers at IISc collaborated with researchers at the Indian Institute of Technology at Roorkee and others 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 underneath the damaged section of the nerve and then stimulated to wrap around the defect site to form a conduit around the nerve without the need for sutures. The nerve endings were able to grow through the implanted conduit, leading to a significant improvement in nerve regeneration within 45 days of using the 4D-printed nerve conduits.
The team published their findings in a paper featured in Advanced Healthcare Materials. The project was supported by the Science and Engineering Research Board (SERB), a Department of Science and Technology statutory body, under the Intensification of Research in High Priority Areas (IRHPA) special call on 3D Bioprinting.
Even though 4D-printed parts have not yet been used in clinical settings, emerging technologies such as these have the potential to usher in a new era of medical devices that surgeons can utilise during procedures to repair nerves and other tissues. They offer several advantages, including reduced surgical complexity, deployment through minimally-invasive techniques, and shorter recovery periods. As a result, these new technologies could revolutionise the way that nerve injuries and other medical conditions are treated in the future.
