Immunohistochemical characterization of cells in adult human patellar tendons.
Cells in tendons are conventionally identified as elongated tenocytes and ovoid tenoblasts, but specific markers for these cells are not available. The roles and interplay of these cells in tendon growth, remodeling, and healing are not well established. Therefore, we proposed to characterize these cells with respect to cell turnover, extracellular matrix metabolism, and expression of growth factors. Here we examined 14 healthy human patellar tendon samples for the expression of various proteins in tenocytes and tenoblasts, which were identified as elongated tendon cells and ovoid tendon cells, respectively. Matrix metalloproteinase 1 (MMP1), procollagen type I (procol I), heat shock protein 47 (hsp47), bone morphogenetic protein 12 (BMP12), 13 (BMP13), and transforming growth factor beta1 (TGFbeta1) were detected by immunohistochemistry (IHC). An image analysis of the IHC staining for proliferation cell nuclear antigen (PCNA) and apoptotic cells was performed to determine the proliferation index and the apoptosis index in elongated and ovoid tendon cells. The ovoid tendon cells expressed higher levels of procol I, hsp47, MMP1, BMP12, BMP13, and TGFbeta1 than the elongated tendon cells. Both the proliferation index and the apoptosis index of ovoid tendon cells were higher than those of the elongated tendon cells. The results suggested that ovoid tendon cells, conventionally recognized as tenoblasts, were more active in matrix remodeling. The expression of BMP 12, BMP13 and TGFbeta1 might be associated with the different cellular activities of tenoblasts and tenocytes.
Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong.
Fu Sai
FS
Chuen
Cheuk Yau
CY
Chuk
Wong Yim
WY
Ping
Wong Wan
WW
Nar
Hung Leung
HL
Kim
Chan Kai
CK
Ming
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis*; D019485:Bone Morphogenetic Proteins / Q000032:analysis; D002455:Cell Division; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D010329:Patella / Q000737:chemistry* / Q000166:cytology*; D013710:Tendons / Q000737:chemistry* / Q000166:cytology*; D016212:Transforming Growth Factor beta / Q000032:analysis
D015415:Biomarkers; D019485:Bone Morphogenetic Proteins; D016212:Transforming Growth Factor beta