Spinal discs made of engineered living tissue implanted in large animal model.

Approximately half the adult population in the United States is suffering from back or neck pain whose treatment and care costs result in an estimated 195 billion USD a year.  Current treatments include spinal fusion surgery and mechanical replacement devices, however, while these treatments provide symptomatic relief, they do not restore native disc structure, range of motion, or offer limited long-term efficacy.  Therefore, new therapies are highly desired.  Now, a study from researchers at Penn Medicine develops personalized spinal discs capable of providing long-term function when implanted into the largest animal model ever evaluated for tissue-engineered disc replacement.  The team states their results provide translational evidence the cells of patients suffering from neck and back pain could be used to build a new spinal disc in the lab to replace a deteriorated one.  The study is published in the journal Science Translational Medicine.

Previous studies show tissue engineering involves combining the patient’s or animal’s own stem cells with biomaterial scaffolds in the lab to generate a composite structure implanted into the spine to act as a replacement disc. Past studies from the lab developed tissue-engineered replacement discs, known as disc-like angle ply structures (DAPS), implanted sucessfully in rat tails for five weeks.  The current study extends the time period in the rat model up to 20 weeks and up to 8 weeks in vivo in the goat cervical disc space, with revamped engineered discs, known as endplate-modified DAPS, or eDAPS.

The current study sandwiches hydrogel and polymer materials seeded with cartilage or mesenchymal stem cells between acellular polymer endplates to simulate the mechanics and biochemistry of intervertebral discs. The discs were implanted into the tail spines of 14 rats, and larger versions into the necks of seven goats.  Results show the disks are stable, well-integrated into the native tissue of the animals’ spinal columns several weeks post-surgery, and were able to withstand stress forces just as effectively as the animals’ native discs.

The lab states they demonstrated successful total disc replacement in the goat cervical spine, with the matrix distribution either retained or improved within the large-scale eDAPS after four weeks.  They go on to add MRI results also suggest disc composition at eight weeks was maintained or improved, with mechanical properties either matching or exceeding those of the native goat cervical disc.

The team surmises they have used tissue engineering to grow healthy disc-like structures in the lab that were then successfully implanted into a large animal model.  For the future, the researchers state the next step will be to conduct longer-term studies to further characterize the function of the eDAPS in the goat model, as well as model the degeneration of spinal discs in humans.

Source: Penn Medicine

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