Scientists have developed a new method of stopping or reversing disability and pain caused by degenerative disc disease in the spine using cell therapies, according to a proof-of-concept study published in the journal Biomaterials.

Researchers from the Duke Pratt School of Engineering at Duke University in Durham, North Carolina, have developed new biomaterials capable of delivering a booster shot of reparative cells to the nucleus pulposus (NP), effectively stopping pain caused by degenerative disc disease.

The NP is the "jelly-like" cushioning found between the spinal discs. According to the researchers, the NP tissue distributes pressure and provides spine mobility, helping to soothe back pain.

Degenerative disc disease is a common spinal condition caused by the breakdown of intervertebral discs. It is more likely to occur as a person ages, where the discs begin to wear thin and lose their ability to cushion the spine. This can lead to further complications, such as arthritis.

Improving existing methods

Previous laboratory research has proven that re-implanting NP cells can delay disc degeneration, the researchers say.

But Aubrey Francisco of the Department of Biomedical Engineering at Duke says that although many companies offer cell delivery strategies in a attempt to stop disc degeneration, the methods are poor, ineffective and "allow cells to quickly migrate out of and away from the injection site."

Lori Setton of the Department of Biomedical Engineering and the Department of Orthopaedic Surgery at Duke, says:

"Our primary goal was to create a material that would be liquid at the start, gel after injection in the disc space, and keep the cells in the location where they're needed. Our second goal was to create a material that would provide the delivered cells with the environmental cues to promote their persistence and biosynthesis."

How the biomaterials work

The way the new biomaterials work are by keeping the cells in place and triggering a process which mimics laminin, a protein found in native NP tissue.

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Setton explains that laminin is usually found in juvenile but not degenerated discs. The protein allows injected cells to attach and remain in place with the delivered biomaterial.

Setton adds that laminin could also enable the cells to survive for a longer period, as well as producing more of the "appropriate extracellular matrix or structural underpinning of the discs that help stop degeneration."

With this in mind, the scientists developed a "gel mix" designed to reintroduce NP cells to the intervertebral disc (IVD) area.

The gel is made up of three components; protein laminin-111 - which has been chemically modified - and two polyethylene glycol (PEG) hydrogels which can attach to the modified laminin. Once injected, the gel holds the cells in place.

This gel was injected into rats' tails, the same way the cells would be delivered to a patient. The needle was held in place in the thin outer layer of the tails for one minute while the gel entered the rat's IVD area.

Positive preliminary results

Results show that the gel began to solidify after 5 minutes, and by 20 minutes it was set.

Using a luciferase biomarker to monitor the progress of the biomaterials, the researchers were able to see that more cells remained in place 14 days after the injection when conducted with the new biomaterial carrier, compared to cells delivered via methods requiring a liquid suspension, in which cells usually remain in place for 3 to 4 days.

Setton says the preliminary results from this study could have a positive impact on the future of cell therapy. She adds:

"The concept is that these cells will be promoted to produce matrix that can support tissue regeneration or arrest degeneration. Additional studies that evaluate disc height or matrix hydration following cell delivery would be important to achieve this goal. There's definitely interest and certainly real potential there."