Differential expression of proteoglycan epitopes and growth characteristics of intervertebral disc cells grown in alginate bead culture

This study assessed the growth characteristics and proteoglycan (PG) produc tion in vitro of cells isolated from various zones; annulus fibrosus (AF), the transitional zone (TZ, an opalescent region situated between the AF and nucleus pulposus, NP) and the NP of the ovine intervertebral disc. The iso lated cells were subsequently cultured in calcium alginate microspheres. Ce llular metabolic activity was assessed over the 10 days of culture by the b ioreduction of a tetrazolium dye substrate to a coloured formazan chromopho re which could be measured colorimetrically at 490 nm. These data were corr elated with the DNA content of beads measured using the fluorescent dye Hoe chst 33258. Viable and non-viable cells in alginate beads were also assesse d histochemically using the fluorescent dyes 5-chloromethylfluorescein diac etate and ethidium homodimer-l. PGs synthesised in culture were examined im munohistologically using monoclonal antibodies to defined glycosamino- glyc an side chain PG epitopes. The results obtained clearly showed that AF and TZ cells differed from NP cells in the measured indices of cellular metabol ism and in the extent of matrix deposition. In contrast to cells from the N P the cells from the AF and TZ were more metabolically active and programme d more to cellular proliferation than to matrix production. Copyright (C) 2 001 S. KargerAG. Basel.