Targeted Deletion of the SPARC Gene Accelerates Disc Degeneration in the Aging Mouse (original) (raw)

2005, Journal of Histochemistry and Cytochemistry

SPARC (secreted protein, acidic, and rich in cysteine) is a matricellular protein that is present in the intervertebral disc; in man, levels of SPARC decrease with aging and degeneration. In this study, we asked whether targeted deletion of SPARC in the mouse influenced disc morphology. SPARC-null and wild-type (WT) mice were studied at 0.3–21 months of age. Radiologic examination of spines from 2-month-old SPARC-null mice revealed wedging, endplate calcification, and sclerosis, features absent in age-matched WT spines. Discs from 3-month-old SPARC-null mice had a greater number of annulus cells than those of WT animals (1884.6 ± 397.9 [mean ± SD] vs 1500.2 ± 188.2, p=0.031). By 19 months discs from SPARC-null mice contained fewer cells than WT counterparts (1383.6 ± 363.3 vs 1466.8 ± 148.0, p=0.033). Histology of midsagittal spines showed herniations of lower lumbar discs of SPARC-null mice ages 14–19 months; in contrast, no herniations were seen in WT age-matched animals. Ultrastr...