Abstract

Intervertebral disc (IVD) degeneration is a prevalent health problem that is highly linked to back pain. To understand the disease and tissue response to therapies, ex-vivo whole IVD organ culture systems have recently been introduced. The goal of this study was to develop and validate a whole spinal segment culturing system that loads the disc in complex loading similar to the in-vivo condition, while preserving the adjacent endplates and vertebral bodies. The complex loading applied to the spinal segment was achieved with three pneumatic cylinders. The pneumatic cylinders were rigidly attached to two triangular alumni plates at each corner, comprising the loading mechanism. By extending or compressing the pneumatic cylinders, three modes of loading were achieved: flexion-extension, bi-lateral bending, and cyclic compression. The cylinders were controlled via microcontroller, and the entire system was fully automated. The culture container, which housed the spinal segment during culturing, was a flexible silicone container with an aluminum base and lid. The culture container attached to the loading mechanism allows for loading of the spinal segment. It had a vent attached to the aluminum lid that allowed for gas exchange in the system. The dynamic bioreactor was able to achieve physiologic loading conditions with 100 N of applied compression and approximately 2-4 N-m of applied torque. The function of the bioreactor was validated through testing of bovine caudal IVDs with intact endplates and vertebral bodies that were isolated within 2 hours of death and cultured for 14 days under a diurnal cycle. The resulting IVD cell viability following 14 days of loading was approximately 43% and 20% for the nucleus pulposus and annulus fibrosus respectively, which was significantly higher than the unloaded controls. The loading system accurately mimicked flexion-extension, bi-lateral bending, and compression motions seen during daily activities. Results indicate that this complex dynamic bioreactor may be appropriate for extended pre-clinical testing of vertebral mounted spinal devices and therapies.

Degree

College and Department

Ira A. Fulton College of Engineering and Technology; Mechanical Engineering

Rights

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