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Alpha‐smooth muscle actin in pathological human disc nucleus pulposus cells in vivo and in vitro
Author(s) -
Hastreiter Dawn,
Chao Jeannie,
Wang QI,
Ozuna Richard M.,
Spector Myron
Publication year - 2004
Publication title -
wound repair and regeneration
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.847
H-Index - 109
eISSN - 1524-475X
pISSN - 1067-1927
DOI - 10.1111/j.1067-1927.2004.12408.x
Subject(s) - pathology , in vivo , intervertebral disc , in vitro , nucleus , degenerative disc disease , h&e stain , immunohistochemistry , explant culture , histology , anatomy , actin , myofibroblast , chemistry , medicine , lumbar , biology , microbiology and biotechnology , biochemistry , fibrosis
That a contractile actin isoform has been found in cells of other cartilage tissues in healing and disease states prompted this investigation of the presence of α‐smooth muscle actin (α‐SMA) in pathological human intervertebral disc tissue. The presence of this isoform has been reported in human intervertebral disc specimens obtained at autopsy from subjects for whom there were no reported symptoms. An objective of this study was to evaluate the cell density and percentage of α‐SMA–containing cells in pathological nucleus pulposus tissue obtained from lumbar disc surgery from 17 patients. Additionally, explants of nucleus pulposus material were cultured to determine how α‐SMA expression changed with time in vitro. Seventy‐six 5‐mm diameter explants (approximately 2 mm thick) pooled from six lumbar surgeries were cultured for 1, 2, 4, or 6 weeks. Microtomed sections of paraffin‐embedded specimens were stained with hematoxylin and eosin or a monoclonal antibody to α‐SMA. Histologically, cells were categorized as to α‐SMA phenotype (positive or negative), and the areal cell density was determined. The evaluation of the cultured nucleus pulposus explants also included documentation of the percentage of cells that were round or elongated and the percentage of the cells that were part of a group (group: ≥ 2 cells). Every nucleus pulposus section exhibited the presence of α‐SMA–containing cells, which accounted for approximately 24 percent of the cells in vivo. In vivo, the cell density was significantly higher in older individuals ( p = 0.02). The average time for cell outgrowth from the explants was 8.6 days. Approximately 10–15 percent of the cells in the explants stained positive for α‐SMA. The time in culture had no significant effect on any of the outcome measures except the percentage of α‐SMA–containing cells that were round ( p = 0.008), with values decreasing through 4 weeks and then slightly rising at 6 weeks. The role of α‐SMA in intervertebral disc pathology warrants further investigation.