title: Chondrocyte clusters adjacent to sites of cartilage degeneration have characteristics of progenitor cells.
abstract: The purpose of this study was to investigate the site-specific characteristics and roles of chondrocyte clusters in human knee osteoarthritis. Cartilage explants were obtained from 45 knees undergoing total knee replacement surgery. The explants were taken from 4 locations in the knee: the medial femoral condyle, the medial posterior femoral condyle (MPC), the lateral femoral condyle, and the lateral posterior femoral condyle (LPC). Cartilage degeneration, cell density, and cell arrangement were compared histologically. A live/dead cell viability assay and immunohistochemical analyses using antibodies against STRO-1, FGF2, and Ki-67 were performed. Cell proliferation and cartilaginous nodule production in MPC and LPC explants in monolayer culture were compared. Finally, MPC cartilage explants were cultured to observe histological changes. The cell density of the MPC explants was higher than that of the LPC because of clustering. MPC explants contained more live cells than the LPC did, and the expression of IHC markers in MPC explants was higher than that in LPC. Chondrocytes from MPC proliferated faster and produced more nodules in monolayer culture than those from the LPC and MPC explants were repaired during organ culture. In conclusion, chondrocyte clusters adjacent to severe cartilage degeneration have specific characteristics, with progenitor and proliferative potential.
authors.affiliation: Department of Orthopedic Surgery, Osaka Medical College, 2-7 Daigakumachi, Osaka, 569-8686, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Hoshiyama
authors.forename: Shuhei
authors.initials: S
authors.lastname: Otsuki
authors.forename: Shuhei
authors.initials: S
authors.lastname: Oda
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kurokawa
authors.forename: Mikio
authors.initials: M
authors.lastname: Nakajima
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Jotoku
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Tamura
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Martin K
authors.initials: MK
authors.lastname: Lotz
authors.forename: Masashi
authors.initials: M
authors.lastname: Neo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017760:Bone Malalignment / Q000150:complications / Q000473:pathology*; D002358:Cartilage, Articular / Q000473:pathology*; D002470:Cell Survival; D002478:Cells, Cultured; D019902:Chondrocytes / Q000473:pathology*; D005260:Female; D005269:Femur / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009924:Organ Culture Techniques; D020370:Osteoarthritis, Knee / Q000209:etiology / Q000473:pathology*; D013234:Stem Cells / Q000473:pathology*
keywords: STRO-1; chondrocyte cluster; osteoarthritis