Bio-Engineered Spinal Disc Implants Tested in Animals

(NIH)

A team of engineers and neurosurgeons at Cornell University in Ithaca, New York and New York City have developed and tested in rats a biologically based implant to replace intervertebral discs in the spinal column. Their findings appear online in the journal Proceedings of the National Academy of Sciences (paid subscription required).

Spinal discs are made of soft, compressible tissue that separate the interlocking vertebrae that make up the spine. The discs act as shock absorbers for the spine, allowing it to flex, bend, and twist. Discs, however, can degenerate or become injured, leading to severe back and neck pain due to vertebrae rubbing together, or they can herniate and cause compression of nerves or the spinal cord.

Biomedical engineer Larry Bonassar and neurosurgeon Roger Härtl engineered artificial discs out of two polymers: collagen, which wraps around the outside, and a hydrogel called alginate in the middle. They then seeded the implants with cells that repopulate the structures with new tissue.

The researchers found the quality of the implants improve as they mature in the body, due to the growth of the tissue cells, as opposed to artificial implants today that degrade over time. “Our implants have maintained 80-90 percent of initial disc height,” says Bonassar. “In fact, the mechanical properties only get better with time.”

The FDA in 2005 approved for people with spinal disc problems a surgical procedure to remove the disc completely and replace it with an implant made of a combination of metal and plastic that aims to mimic the normal movement of the lumbar and spine. Härtl notes that the complicated metal or plastic implants run the mechanical risk of  degrading from wear and tear, causing fragments to accumulate in the body. The bio-based implants can integrate and mature with the vertebrae, says Härtl, with fewer long-term side effects.

The research was funded first by an Ithaca-Weill seed grant, and later by grants from AOSpine Foundation, and NFL Charities.

Read more: NFL Grant Funds Bioengineered Spinal Disc Research

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