EVALUATION OF CARTILAGE GROWTH FOLLOWING SUSTAINED DELIVERY OF TGF-β USING A RAT DEGENERATED DISC MODEL

摘要

The current modalities of treating symptomatic degenerative disc disease are either conservative non-surgical or surgical modalities. However, none of these modalities is a true cure for the degenerative process. Ideally, the best treatment would be preventing the progression of degeneration. The goal of our research is to identify factors that may slow or stop the degenerative process. A rat degenerative disc model induced by piercing the center of the disc was implemented. In this phase of the study, it was hypothesized that continuous sustained release of transforming growth factor (TGF-β) would reverse the loss of cellularity associated with degenerating discs. A total of eighteen rats were divided into three equal groups. Group I served as control and groups II and III were subjected to a surgery where a 21-gauge needle was used to pierce the L4/L5 disc posteriorly. Animals in group III received TGF-β over a four week period via a tricalcium phosphate sustained delivery device. After 4 weeks the animals were sacrificed and the traumatized discs were removed. Sections of 10 μm were taken and stained with hematoxylin and eosin and evaluated using light microscopy techniques. Using Image Pro software the area of the transition zone was calculated and the number of chondrocyte nuclei per area was determined. The results show that after four weeks, animals in group II (trauma only) showed evidence of disc degeneration with the largest decrease in cell number anterior to the site of trauma. Treatment with TGF-β resulted in chondrocyte numbers similar to control in posterolateral views of the disc, while lateral views and views of the site directly opposite the trauma (anterior) had approximately 45% less chondrocytes per area than the control; however, the chondrocyte numbers in the anterior views were twice as many as seen in the discs retrieved from trauma only animals.