UC San Diego medical researchers have for the first time used 3D printing technology to create a spinal cord and implant it with neural stem cells into rats with spinal cord injuries, the university announced Monday.

The implant is designed to promote nerve growth and regrowth for victims of severe spinal cord injuries, according to the researchers. For the rats in the study, the 3D printed spinal cords spurred tissue growth, the regeneration of nerve cell extensions called axons and expansion of the implanted neural stem cells into the rat’s natural spinal cord.

The research appears in Monday’s issue of the journal Nature Medicine.

“The new work puts us even closer to real thing,” said Jacob Koffler, the study’s co-first author. “The 3D scaffolding recapitulates the slender, bundled arrays of axons in the spinal cord. It helps organize regenerating axons to replicate the anatomy of the pre-injured spinal cord.”

According to the researchers, the process can be scaled to human spinal cords, shedding light on a possible solution for severe spinal cord injuries in humans. The 3D printer the researchers used generated two-millimeter-long implants in 1.6 seconds, as well, a fact which co-first author Wei Zhu said showcased the printer’s flexibility to recently diagnosed spinal cord injuries.

“We can quickly print out an implant that’s just right to match the injured site of the host spinal cord regardless of the size and shape,” Zhu said.

The spinal cord grafts generated new spinal cord tissue and reconnected the rats’ severed spinal cords over the span of a few months. According to the researchers, the rats that received the implants regained “significant functional motor improvement in their hind legs.”

The researchers’ next step will be to incorporate proteins into the implants that will help keep the stem cells alive once the graft is implanted. Eventually, Koffler and the other researchers hope to conduct a clinical trial with human subjects who have spinal cord injuries.

“The scaffolding provides a stable, physical structure that supports consistent engraftment and survival of neural stem cells,” Koffler said. “It seems to shield grafted stem cells from the often toxic, inflammatory environment of a spinal cord injury and helps guide axons through the lesion site completely.”

— City News Service

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