3D-printed guide aids in complex nerve regeneration
Complex nerve injuries are a challenging problem for the medical fraternity,as their reattachment and regrowth is a fraught and delicate process that is very rarely successful.Overcoming these difficulties, however, would mean that a cure for debilitatingconditions like paraplegia, quadriplegia and other forms of paralysis may oneday be found. In this vein, US researchers have created thefirst-ever 3D printed guide specifically designed to assist in the regrowth ofthe sensory and motor functions of complex nerves.
Hundreds of thousands of people each year areafflicted with a crippling nerve injury or disease that leaves them partiallyor wholly paralyzed. As a result, many techniques to reattach or regrow severedor withered nerves have been tried over the years, but such things as enzymaticmodification or gene manipulation are largely ineffective at growing nervesacross large areas of damage, or are difficult to repeat with certainty.
To help solve these problems, researchers from the University of Minnesota,Virginia Tech, University of Maryland, Princeton University, and Johns HopkinsUniversity collaborated on a ground-breaking procedure to produce a3D-printed silicone support structure that is implanted into living tissue toguide and encourage nerve growth and reattachment. Replete with a range ofbiochemical "cues" designed to enhance and nurture nerve cell formation, thesedevices have been successfully tested in the bodies of living rats in a laboratory.
Specifically targeting the sciatic nerve (the largest and longest nerve inmost mammals – including humans – that generally controls the muscles of thethigh, lower leg, and foot) the researchers employed a 3D scanner to intricatelymap the arrangement of this nerve in a rat. Following this, the researchers fedthe information into the software used to control a custom-built 3D printerwhich then produced the silicone nerve guide. The sciatic nerve in the rat wasthen severed, and the guide was surgically implanted into the rat by graftingit to the sliced ends of the nerve. After a period of around 10 to 12 weeks,the rat regained much of its ability to walk again.
"This represents an important proof of concept of the 3D printing of customnerve guides for the regeneration of complex nerve injuries," said the study’slead researcher, Universityof Minnesota mechanical engineering professor Michael McAlpine. "Someday we hope that we could have a 3D scanner and printerright at the hospital to create custom nerve guides right on site to restorenerve function."
All-in-all, the scanning and printing process requires little more than anhour to achieve, say the researchers, but the nerves require several weeks togrow back. Professor McAlpine points to preceding research of a similar natureand time to regrow direct lines of nerves in the laboratory, however this isthe very first time that the creation of a bespoke support guide for the regrowthof complex, Y-shaped sensory and motor branch axon bundles found in the sciaticnerve has been achieved.
"The exciting next step would be to implant these guides in humans ratherthan rats," said Professor McAlpine.
Incircumstances where a nerve is already severed or otherwise missing, as wouldbe most cases in nerve damage patients, the researchers believe that a"library" of stored nerve scans collected from other patients orcadavers could be used as proxies to create 3D-printed guides for patientssuffering from nerve injury.
The short video below shows the 3D printing process used for the production of the silicone guides.
The results of thisresearch were recently published in the journal Advanced Functional Materials
Source: University of Maryland