Discogenic pain has long been treated in the most aggressive manner, with entire disc removal. This surgery eradicates the disc's function, however, impacting a patient's range of motion and ability to absorb shock.
That's where cell-based therapy presents an opportunity in spinal disc regeneration.
"It's a non-bridge burning alternative," explains Domagoj Coric, MD, of Carolina Neurosurgery & Spine Associates in Charlotte, N.C. "With this procedure, if [patients] don't get better, they usually aren't any worse for the wear, because you haven't altered the function of the disc."
The science behind using biologics for spinal disc repair involves injecting cells with the same behavior characteristics of native cells. The minimally invasive outpatient procedure takes less than one minute to inject the cells, and requires only local anesthesia.
"This is not to replace surgery; this is to potentially help people who have failed initial non-surgical management," says Dr. Coric. "It's an exciting technology, but there's still a ways to go."
So far, researchers have only studied cell-based therapy in patients with isolated (one-level) degenerative disc disease, typically presenting clinically with mechanical low back pain. Since their native disc cells are not able to effectively produce the extracellular matrix, the regenerative cells are intended to promote repair. The ideal candidate is early in the degenerative process, with mild to moderate disc disease.
"If you inject [patients with the cells] into the harsh environment of advanced disc degeneration, [the cells] won't be able to survive and function," explains Dr. Coric.
When injecting cells with the intent to repair, investigators may choose between three cell lines: stem cells, chondrocyte cells (juvenile cartilage cells) or disc cells. The cell lines are then expanded in a cell culture and batched into several millions of cells per cc and combined with a carrier prior to injection.
Dr. Coric has been involved in trials testing various versions of cell-based therapy. He served as principal investigator for St. Louis, Mo.-based ISTO Technologies' NuQu study. The company recently completed Phase II of the trial, which evaluated the safety and efficacy of treating degenerative lumbar disc disease with allogeneic cultured chondrocytes. The second phase of the trial involved 46 patients.
Salt Lake City-based DiscGenics is taking a different approach, injecting allogenic disc cells. Dr. Coric says this study is on track to be the first U.S. Investigational New Drug study involving injection of actual disc cells, and he believes the technology will move into clinical trial in 2017.
And Australia-based Mesoblast's approach involves injecting allogeneic mesenchymal stem cells into the disc space. Mesoblast is furthest down the regulatory IND process, currently actively enrolling a Phase III/IV trial.
"The idea is that these cells will morph into disc cells and take on characteristics of the environment. They will produce extracellular matrix, which is the cushion of the disc," he says.
Despite advancements made so far in this therapy, Dr. Coric notes the technology is still relatively early in the regulatory process. He predicts the technology will not be introduced to the market until 2020 or so, best-case scenario.
"We've come a long way. It would have been more like flying cars and spaceships kind of stuff as late as 5 to 10 years ago," says Dr. Coric. "The fact [is] that we've been in advanced clinical trials, where you're comparing this to placebo. The science is good, and if it works, you know it really works."
Technology must also advance for more accurate diagnoses of degenerative disc disease, Dr. Coric says. Although he is able to identify an abnormal disc on an MRI, no reliable clinical correlate exists.
"We don't have a consistent way to verify if a radiographic abnormality is actually causing a clinical problem," says Dr. Coric. "So if you're not good at diagnosing a disease process, you're going to have more difficulty in treating it."