2004   Volume No 8 - pages 58-64

Title: Distinction between the extracellular matrix of the nucleus pulposus and hyaline cartilage: a requisite for tissue engineering of intervertebral disc

Authors: F. Mwale, P. Roughley and J. Antoniou

Address: Lady Davis Institute for Medical Research and Department of Surgery, SMBD-Jewish General Hospital, Montreal (QC) Canada

E-mail: fmwale@ldi.jgh.mcgill.ca

Key Words: Tissue engineering, intervertebral disc, proteoglycan, collagen, glycosaminoglycan, nucleus pulposus, annulus fibrosus, disc degeneration, hyaline cartilage.

Publication date: December 15th 2004

Abstract: Tissue engineering of intervertebral discs (IVD) using mesenchymal stem cells (MSCs) induced to differentiate into a disc-cell phenotype has been considered as an alternative treatment for disc degeneration. However, since there is no unique marker characteristic of discs and since hyaline cartilage and immature nucleus pulposus (NP) possess similar macromolecules in their extracellular matrix, it is currently difficult to recognize MSC conversion to a disc cell. This study was performed to compare the proteoglycan to collagen ratio (measured as GAG to hydroxyproline ratio) in the NP of normal disc to that of the hyaline cartilage of the endplate within the same group of individuals and test the hypothesis that this ratio can be used for in vivo studies to distinguish between a normal NP and hyaline cartilage phenotype. Whole human lumbar spine specimens from fresh cadavers, ranging in age from 12 weeks to 79 years, were used to harvest the IVDs and adjacent endplates. The GAG to hydroxyproline ratio within the NP of young adults is approximately 27:1, whereas the ratio within the hyaline cartilage endplate of the same aged individuals is about 2:1. The production of an extracellular matrix with a high proteoglycan to collagen ratio can be used in vivo to distinguish NP cells from chondrocytes, and could help in identifying a NP-like phenotype in vivo as opposed to a chondrocyte when MSCs are induced to differentiate for tissue engineering of a disc.

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