A 3D-printed structure that allows nerve cells to travel independently and form new connections, offering a potential advance in the repair of severed arm or leg nerves, has been developed by researchers from Poznań and collaborating centres.
Peripheral nerve injuries are common in accidents, workplace incidents and surgical complications. Such injuries can cause loss of sensation, weakness or paralysis. While the body can partially regenerate damaged nerves, larger gaps often prevent full recovery.
Standard treatment involves taking a fragment of a less critical nerve, such as from the calf, and grafting it into the damaged site. This method works but can create additional scarring and sensory loss, and the length of available donor nerve is limited.
Artificial nerve tunnels have been explored for years, but current versions are too simple. They are typically smooth plastic or collagen tubes without the complex internal structure or chemical signals that guide nerve cells in living tissue.
The new device, called GrooveNeuroTube, combines a rigid skeleton, a soft hydrogel, growth factors and an antibacterial additive. “The best results were achieved by combining all three elements,” said Jagoda Litowczenko, PhD, from the Adam Mickiewicz University Center for Advanced Technologies in Poznań.
The skeleton is made of polycaprolactone, a bioplastic used in medical implants, which was 3D-printed as a thin mesh of fibres and rolled into a tube about 1.5 centimetres long. A hydrogel, a soft and highly hydrated material resembling delicate jelly, was applied to the scaffold. The hydrogel consisted of hyaluronic acid, a compound naturally present in skin and synovial fluid, and gelatin derived from collagen.
Researchers added a cocktail of growth factors, proteins that guide nerve cells to grow in specific directions and extend long neurites. They also incorporated lysozyme, an antibacterial enzyme, to protect the implant from potential infection.
To test the device, the team placed F11 cells into the tube. This cell line imitates sensory neurons from dorsal ganglia, which are important in conducting pain and tactile signals. Cells were suspended in collagen gel and applied to both ends of the tube using a bioprinter, creating a model of a severed nerve with two clusters of cells separated by an empty space.
Over the next 60 days, the researchers monitored cell behaviour. After four weeks, cells from both ends had penetrated about 8 millimetres each and met in the middle. After two months, most of the interior of the tunnel was filled with living cells that had formed long extensions and a network of connections resembling young nervous tissue.
The team compared several versions of the system: a tube without growth factors, a tube with growth factors, and a tube with growth factors plus stimulation with a pulsed electromagnetic field (PEMF), a weak rhythmic magnetic field applied for four hours a day. Cells in the fully combined group moved almost twice as far as those in tubes without growth factors, and the longest neurite extensions reached nearly half a millimetre. The percentage of living cells exceeded 95%.
The researchers said the technology remains a laboratory model and is not yet ready for clinical use. The printed tube allows for rapid testing of different hydrogel compositions, growth factor doses, and stimulation regimes, reducing the need for experiments on animals.
They added that in the future, a similar smart tube could be implanted in patients with severe nerve injuries, including those resulting from road accidents, hand injuries, or cancer surgery. Such implants could increase the chances of regaining sensation and function while reducing the number of treatments required.
The study involved scientists from Adam Mickiewicz University in Poznań, the Institute of Molecular Physics of the Polish Academy of Sciences, and collaborators from Germany, Spain, Switzerland and Czechia. (PAP)
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