Study design: changes in cell density of endplate (EP), nucleus pulposus (NP), and anulus fibrosus (AF) during ageing were systematically investigated in defined regions of interest in complete human motion segments.
Objectives: to elucidate cell density and total cell number in distinct anatomic regions of the intervertebral disc; to test effects of gender, level and age on cell density; and to correlate changes in cell density with histologic signs of disc degeneration.
Summary of background data: the available information on the cell density within intervertebral discs and its age-related changes is sparse. This knowledge, however, is a crucial prerequisite for cell-based tissue engineering approaches of the intervertebral disc.
Methods: in 49 complete cross-sections from lumbar motion segments (newborn to 86 years) from 22 specimens, cell density was determined by the Abercrombie method in EP, NP, and AF, and total cell number was counted per region of interest.
Results: cell density in EP, NP, and AF decreased significantly from 0 to 16 years with the main changes occuring from 0 to 3 years for NP and AF. No significant variations were observed thereafter. We found a significant correlation of cell density and histologic degeneration score between 0 and 1, but not for scores >1. Gender and disc level did not influence cell density.
Conclusion: This study provides data concerning the total number of cells in the various regions of the intervertebral disc for different age groups. This knowledge will be beneficial for cell-based treatment approaches, which may evolve in the future.