Evaluation of Direct In Vivo Gene Transfer in an Equine Metacarpal IV Ostectomy Model Using an Adenoviral Vector Encoding the Bone Morphogenetic Protein-2 and Protein-7 Gene

Objective
To evaluate gene transfer in an equine metacarpal IV (MCIV) ostectomy model using adenoviral vectors encoding the human bone morphogenetic protein-2 and protein-7 gene (Ad-BMP-2/-7).
Study Design
Experimental
Animals
Healthy adult horses (n = 15).
Methods
A plate stabilized, critical size 1.5 cm ostectomy was created in left and right MCIV. The ostectomy site was injected with either Ad-green fluorescent protein (Ad-GFP) or Ad-hBMP-2/-7 at completion of surgery; the same treatment was assigned to both the left and right forelimb of each horse (n = 5 horses/group). Bone healing was evaluated radiographically every 2 weeks for 16 weeks. Horses in a pilot study (n = 5) were used as untreated controls for radiographic evaluation to 8 weeks. After euthanasia at 16 weeks bone healing was evaluated using dual energy X-ray absorptiometry (DEXA) and histomorphometry. Data were analyzed using an ANOVA or Kruskal–Wallis test. Level of significance was P < .05.
Results
At 4 and 6 weeks, the Ad-GFP group had a significantly lower percentage defect ossification compared with the untreated control group. There was no significant difference between untreated and Ad-hBMP-2/-7 groups at any time point and no significant difference in bone healing radiographically, histologically, or using DEXA between any groups at 16 weeks.
Conclusions
Ad-hBMP-2/-7 did not improve bone healing in horses at 16 weeks.