IN VITRO CULTURE SYSTEM FOR THE MAINTENANCE OF HUMAN INTERVERTEBRAL DISC TISSUE

Abstract

Objectives and Background: This study investigated a simple, novel, in vitro culture system which enables the in situ investigation of human intervertebral disc (IVD) cell function in healthy and diseased IVD in explant culture. Studies investigating the function of cells in IVD tissue are scarce. Whilst there is a paucity of realistic animal models of human IVD disease and in vivo study of human tissue remains impracticable, the only possible approaches remain in-situ molecular biology applied to tissue sections of biopsied tissue, which suffers from lacking a dynamic dimension. Or in vitro studies, of which cell culture lacks physiological relevance and explant cultures are subject to loss of tissue integrity and altered cellular behaviour. We have investigated a system that preserves the structure of the tissue and cellular phenotype within an explant culture system.

Methods: Human IVD tissue was obtained from disc replacement surgery and separated into nucleus pulposus (NP) and annulus fibrosus (AF) tissue, which was then cultured in either a Perspex ring or unconstrained in tissue culture medium for up to 3 weeks. The effectiveness of this system to maintain tissue integrity and cell function was tested using microscopy and either tinctoral histochemistry or immunohistochemistry.

Results: Unconstrained in medium, IVD tissue expanded and structural integrity was disturbed. The number of cells expressing type I collagen increased and aggrecan decreased by comparison with directly harvested tissue. In contrast the tissue in the Perspex rings maintained its structure and at the end of 3 weeks the cellular parameters were the same as in the newly harvested tissue.

Conclusions: This is the first reported system to preserve cell function of discal explants for long periods in tissue culture. This system will be a useful tool for a wide range of investigations of IVD biology that have not hitherto been possible.