INTRODUCTION: Low‐back pain is a common disorder and has been significantly associated with degenerative disc disease (DDD). Mechanical loading is considered a major extrinsic component in the onset and progression of DDD. We have developed the Loaded Disc Culture System (LDCS), an ex‐vivo bioreactor for culture of entire intervertebral discs (IVDs) allowing for close control of loading conditions and monitoring of biomechanical properties. In recent publications we show that lumbar goat IVDs resemble human IVDs with respect to mechanical properties and cellular composition. The purpose of the current study is to investigate the feasibility of culturing caprine IVDs with maintenance cellular and extracellular properties in the LDCS over a 21day culture period.
METHODS: Lumbar IVDs with end plates (L1‐6; n=200) were harvested from goats (n=40) under sterile conditions. IVDs were cultured in the LDCS without loading, with a constant low dynamic load, or with a simulated physiological load. Cell viability was assessed in the nucleus (NP) and inner and outer annulus (iAF,oAF). Also, water, glycosaminoglycan (GAG) and total collagen content of the extracellular matrix (ECM) were measured.
RESULTS: Fresh discs (day_0) displayed a mean cell viability of 80.2%_(NP); 75.9%_(iAF) and 70.9% (oAF). Cell viability dropped within 7 days in the unloaded group in all regions. Constant low dynamic load showed a gradual decrease, while simulated physiological loading maintained cell viability in all regions (fig1). Water, GAG and collagen content in the extracellular matrix did not change significantly up to 21 days in any group, when compared to day 0 (fig 2).
DISCUSSION: We are able to maintain the native properties of goat discs in the LDCS over a 21day culture period by applying simulated physiological load. The LDCS may serve as a valuable platform to study the processes involved in degenerative disc disease (DDD). (cont'd)