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Stem cells might help repair damaged intervertebral discs

If the fibrocartilage tissue in the spine degenerates over time, an intervertebral disc – the “shock absorber” between the vertebrae of the spine – can “slip,” pinching the medulla or nerves. The consequences include intense pain or even paralysis.

Not just people, but dogs, too, are susceptible to this disease. Since intervertebral discs cannot regenerate, the affected disc material is removed in an operation that can be performed on both people and animals. The pressure on the nerves and medulla disappears, but the degeneration of the disc remains.

Frank Steffen is a neurologist at the Clinic for Small Animal Surgery at the Vetsuisse Faculty of the University of Zurich. He hopes that stem cells — multipotent cells that can be differentiated into various cell types — can form new disc cartilage once injected into a damaged disc. His study on three sick German shepherds demonstrated that a treatment with the body’s own stem cells are well tolerated – an important first step.

Gaining knowledge directly from the afflicted animal

Research on intervertebral disc regeneration is frequently performed using animal testing. At the Clinic for Small Animal Surgery in Zurich, researchers have taken another path: “Since we treat numerous dogs who spontaneously sustain a slipped disc every year, we have been able to gain important knowledge directly from animals that are actually afflicted with this disease,” Dr. Steffen explained. “Due to the similarity in pathology and the course of the illness, conclusions can presumably be drawn for the treatment of affected persons as well.”

The study for the development of stem cell therapy in dogs is being conducted in cooperation with Swiss Paraplegic Research (SPR) in Nottwil, Switzerland. It was published in Tissue Engineering Part C: Methods.

The study was organized as follows: With the permission of the dog owners, Dr. Steffen and his team removed stem cells from the marrow of the affected animals’ pelvic bones. After cleaning and preparation of the cell material in the laboratory, the stem cells were injected into the donor dog’s degenerated intervertebral disc.

“Our objective is for the stem cells to trigger cellular and molecular repair processes and, ideally, to form new intervertebral disc cells in order to contribute to the regeneration of the tissue,” Dr. Steffen said.

All three dogs well-tolerated the injections of their own stem cells and no negative effects were determined. However, later X-rays and magnetic resonance tomographies did not show clear indications that the damaged discs have already regenerated in comparison with the control group.

“Proving the tolerability of the therapy was our first important step,” Dr. Stephan said.

He is now working on the effectiveness of the stem cell injections, for example, with the targeted addition of growth factors. “If our method proves successful one day, it would be a pioneering step for human medicine as well,” he said.