Response of induced bone defects in horses to collagen matrix containing the human parathyroid hormone gene.

The research examined the impact of the human parathyroid hormone gene (hPTH(1-34)) within a collagen matrix on bone defects in horses. The study found that this genetic treatment could improve bone formation in certain areas but showed detrimental effects when applied to others.

Study Design and Procedure

• The experiment involved eight clinically normal adult horses that had either diaphyseal or subchondral bone defects.
• The scientists introduced the hPTH(1-34) gene-activated matrix (GAM) into these defects and left some untreated as controls.
• Over a 13 week period, the researchers monitored the amount, speed and quality of bone healing. They employed techniques like radiography, quantitative computed tomography, and histomorphometric analysis for the evaluation.
• In addition, the joints of the horses were observed on the basis of circumference, synovial fluid analysis, pain on flexion, lameness, and gross and histological examination.

Results

• Results revealed that bone volume index was higher in cortical defects treated with the hPTH(1-34) GAM, when compared with untreated defects.
• The amount of bone produced in cortical defects treated with the hPTH(1-34) GAM was found to be positively correlated with the native bone formation in untreated defects.
• However, less bone was detected in hPTH(1-34) GAM-treated subchondral bone defects, compared with untreated defects, and histological analysis confirmed poorer healing and residual collagen sponge in these areas.

Conclusions

• It was concluded that the application of hPTH(1-34) GAM led to the production of more bone, specifically periosteal bone, after 13 weeks in the cortical defects of the horses.
• However, the hPTH(1-34) GAM hindered the healing of subchondral bone defects but was still compatible with joint tissues.
• Researchers suggested that the promotion of periosteal bone formation could be beneficial for the healing of cortical fractures in horses, but also noted that the delay in the onset of bone formation might outweigh these benefits.
• The study recommended that hPTH(1-34) GAM should not be applied in articular subchondral bone defects, but claimed that its contact with articular surfaces was unlikely to cause short-term adverse effects.