By Steve Weakley

Scientists have moved a step closer to being able to replace degenerated spinal discs with new ones grown in a laboratory from a patient’s own stem cells.

Spinal discs are soft tissues that cushion the vertebrae and enable our backs to conform and perform the tasks of everyday movement. Over time, the discs can wear out and cause the bones of the spine to rub together and pinch nerves. This disc degeneration is one of the leading causes of back pain.

University of Pennsylvania researchers reported in the journal Science Translational Medicine that they have successfully grown and implanted replacement discs made from the stem cells of goats. The cells were grown in a laboratory in a disc shaped form and then implanted into the necks of goats.

After 8 weeks, MRI’s showed that the replacement discs functioned just as well or better than the goats’ original cervical discs. The implanted discs were left in for 20 weeks and became part of the animals’ own tissue.

Researchers told Medical News Today that this was a major step forward from previous experiments in which they implanted discs into rat tails. Goat discs are more comparable to humans in size, structure and function.

"I think it's really exciting that we have come this far, from the rat tail all the way up to human-sized implants," said co-senior author Harvey Smith, MD, a professor of Orthopaedic Surgery at the Hospital of the University of Pennsylvania.  

"Using a true tissue-engineered motion-preserving replacement device is not something we have yet done in orthopaedics. I think it would be a paradigm shift for how we really treat these spinal diseases and how we approach motion sparing reconstruction of joints.”

Current treatments for degenerative discs include spinal fusion or artificial implants.  Both have limited benefits and usually cannot restore full functionality. Artificial implants also break down and have be replaced.

"The current standard of care does not actually restore the disc, so our hope with this engineered device is to replace it in a biological, functional way and regain full range of motion," said co-senior author Robert Mauck, PhD, a professor for Education and Research in Orthopaedic Surgery.

"This is a major step, to grow such a large disc in the lab, to get it into the disc space, and then to have it to start integrating with the surrounding native tissue. That's very promising."

The researchers say the next step is longer and more extensive tests on goats, before working on a bioengineered human model.  If those tests are successful, they eventually hope to test the implants in human trials.

"We have every reason to be optimistic, and if it works, we can change the way we think about treating some of these disc diseases," said Smith.