Sunday, October 17, 2010

Loose chondrocytes

Do loose and disorganized chondrocytes have potential to become growth plates?

Comparison between normal and loose fragment chondrocytes in proliferation and redifferentiation potential.

"Loose fragments in osteochondritis dissecans (OCD) of the knee require internal fixation. On the other hand, loose fragments derived from spontaneous osteonecrosis of the knee (SONK) are usually removed. We investigated proliferative activity and redifferentiation potential of normal cartilage-derived and loose fragment-derived chondrocytes.
Cells were prepared from normal articular cartilages and loose fragment cartilages derived from knee OCD and SONK. Cellular proliferation was compared. Redifferentiation ability of pellet-cultured chondrocytes was assessed by real-time PCR analyses. Mesenchymal differentiation potential was investigated by histological analyses. Positive ratio of a stem cell marker CD166 was evaluated in each cartilaginous tissue.
Normal and OCD chondrocytes showed a higher proliferative activity than SONK chondrocytes. Chondrogenic pellets derived from normal and OCD chondrocytes produced a larger amount of safranin O-stained proteoglycans compared with SONK-derived pellets. Expression of chondrogenic marker genes was inferior in SONK pellets. The CD166-positive ratio was higher in normal cartilages and OCD loose fragments than in SONK loose fragments.
The OCD chondrocytes maintained higher proliferative activity and redifferentiation potential compared with SONK chondrocytes. Chondrogenic properties of loose fragment-derived cells and the amount of CD166-positive cells may affect the repair process of osteochondral defects."

Loose fragment cartilage can have high proliferative and redifferentiation capality which bodes well for micro-growth plates.

OCD usually occurs in younger patients whereas SONK occurs in old patients.

"Human chondrocytes isolated from detached OCD fragments maintain similar cell viability to those from healthy normal cartilages. On the other hand, the chondrogenic redifferentiation potential of horse OCD-derived chondrocytes seems to be inferior to that of normal chondrocytes because OCD chondrocytes show lower expression of a chondrogenic transcription factor, Sry-type high-mobility-group box (SOX) 9"

"COL2A1 expression was not detected in monolayer-cultured (dedifferentiated) SONK chondrocytes, whereas type II collagen deposition and COL2A1 expression were observed in tissue samples of SONK loose fragment cartilages"

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