Blake N. Johnson et al, Advanced Functional Materials, 2015

After a traumatic injury like a car crash or a severe bacterial infection, patients can often suffer from painful and sometimes even paralyzing nerve damage. This damage is long lasting, because nerves regenerate slowly, if at all. Now a team of researchers has devised a way to 3D print customized scaffolds that help nerves regenerate, according to a paper published today in the journal Advanced Functional Materials.

Given the length of time it takes for nerves to grow back, scientists have turned to other types of procedures to try to repair damaged nerves. These are often grafts, which are nerves taken from other, healthy places in the body and positioned around the damaged nerves to take their place. But these procedures aren’t ideal because the patient needs two surgeries, often feels pain at the donor site, and sometimes the patient’s body even rejects the graft. More recently, researchers have experimented with nerve guidance channels, which are cylinders made of bio-compatible materials that encourage nerve grow. Though these have more flexibility than nerve grafts, they can only help nerves grow in a straight line, which doesn’t help nerves damaged in “large, geometrically complex injuries,” the study authors write.

The 3D printed scaffold, implanted in a mouse

To conduct these experiments, the researchers took a scan of a nerve exposed by an incision using a structured light 3D scanner. Using that information, they created geometrically complex nerve guidance channels–which work as a bridge to connect the two ends of regenerating nerves together–that would fit a specific area of the body, and then used 3D printing to print the perfect fit.

They focused on nerves that split into two different nerves that extend to different places in the body and are more complex than typical linear nerves; the scaffold encourages the right kind of nerve growth because of its physical shape as well as the chemical composition of each branch of the channel. The researchers took scans of nerves in living patients, printed the scaffolds with silicone and special proteins mixed in, and tested their strength in a petri dish. The channels held up well—though not perfectly—and the proteins gradually released over three weeks to encourage nerve growth. They found similar results when they tested the scaffolds in mice.

This study is meant to be a proof of concept, the researchers note and the technology isn’t ready to be used on humans yet. But as a concept, it seems promising. In future studies the researchers plan to try a different material as the base for the scaffolds, and to alter the chemical gradients in it to improve nerve regeneration.