Research ArticleTissue Engineering

Combined nucleus pulposus augmentation and annulus fibrosus repair prevents acute intervertebral disc degeneration after discectomy

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Science Translational Medicine  11 Mar 2020:
Vol. 12, Issue 534, eaay2380
DOI: 10.1126/scitranslmed.aay2380

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Strategic lumbar support

Discectomy is a common treatment for herniated or “slipped” intervertebral discs that can help alleviate symptoms but does not prevent reherniation or progression of disc degeneration. Sloan et al. developed a two-part, acellular tissue-engineered therapy to prevent degeneration after discectomy. Injecting hyaluronic acid into the inner region of the disc (nucleus pulposus) and applying a photocrosslinked collagen patch to the outer annulus fibrosus healed disc defects and maintained biomechanical support in the lumbar spines of sheep for 6 weeks after discectomy. Results support further investigation of this combined approach to potentially treat herniation while preventing disc degeneration after discectomy in humans.


Tissue-engineered approaches for the treatment of early-stage intervertebral disc degeneration have shown promise in preclinical studies. However, none of these therapies has been approved for clinical use, in part because each therapy targets only one aspect of the intervertebral disc’s composite structure. At present, there is no reliable method to prevent intervertebral disc degeneration after herniation and subsequent discectomy. Here, we demonstrate the prevention of degeneration and maintenance of mechanical function in the ovine lumbar spine after discectomy by combining strategies for nucleus pulposus augmentation using hyaluronic acid injection and repair of the annulus fibrosus using a photocrosslinked collagen patch. This combined approach healed annulus fibrosus defects, restored nucleus pulposus hydration, and maintained native torsional and compressive stiffness up to 6 weeks after injury. These data demonstrate the necessity of a combined strategy for arresting intervertebral disc degeneration and support further translation of combinatorial interventions to treat herniations in the human spine.

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