Introduction: The most commonly performed treatments for degenerative disc disease, anterior cervical decompression and fusion and prosthetic total disc replacement devices (TDR), despite being effective still pose risks of pseudoarthrosis, implant dislodgement, and adjacent segment disease. Tissue engineered intervertebral disc (TE-IVD), an alternative treatment option, has been previously developed by our group as a biological TDR device [1]. Presently, we evaluate the in-vivo efficacy of our TE-IVD in a canine cervical spine.

Methods: TE-IVD components were constructed in vitro using either AF or NP cultivated canine disc cells; the collagen gel based composite AF enclosed an alginate gel based composite NP. 12 skeletally mature beagles underwent discectomy with whole IVD resection and were divided into two groups: solely discectomized control and TE-IVD implanted group(Fig 1A,B). All beagles were imaged post-operatively at 2 and 4 weeks. Quantitative analysis using X rays and MRIs as well as qualitative histological assessments were performed.

Results: 2-week MRIs of implanted TE-IVDs revealed T2 high intensity with acute outer inflammation due to surgical breach, which faded by 4-weeks. At 4 weeks, TE-IVD sustained position in disc space with relatively increased T2 intensity, resulting in over 70% of NP hydration as that of adjacent healthy discs.(Fig 1,2) Conversely, discectomized disc segments were void of hydration. Disc height indices of TE-IVDs and discectomized discs were 71% and 49%, respectively, of that of healthy control discs. Further, TE-IVD histological sections exhibited chondrocyte-like cell viability, abundant proteoglycan content in the extracellular matrices, and substantial integration into the host tissues without signs of immune reaction.(Fig 1,2)

Conclusions: Despite significant biomechanical demands of the beagle cervical milieu, our in vivo TE-IVDs maintained structure and hydration in addition to disc height of the treated segment at up to 4 weeks. Discs displayed dynamic adaptation to the host environment, with extracellular matrix production, and cell proliferation.

Patient Care: Total disc replacement (TDR) using biological implant can be an alternative treatment for fusion surgery or prosthetic TDR in patients with degenerative disc disease. Although longer-term follow up with sufficient sample size and biomechanical analysis is necessary, this motion-preserving treatment aiming at biological repair can overcome the issues such as peudoarthrodesis and adjacent segment disease as seen in current treatments.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of using a biological tissue-engineered disc in total disc replacement , 2) Discuss, in small groups the regenerative capacity of the TE-IVD treatment in the canine cervical spine 3) Identify an effective treatment to disc degenerative disease that circumvents peudoarthrodesis and adjacent segment disease.

References: 1) Tissue-engineered intervertebral discs produce new matrix, maintain disc height, and restore biomechanical function to the rodent spine. Bowles RD, Gebhard HH, Härtl R, Bonassar LJ. Proc Natl Acad Sci U S A. 2011 Aug 9;108(32):13106-11.