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.
Authors: Southwood Louise L, Kawcak Christopher E, Hidaka Chisa, McIlwraith C Wayne, Werpy Natasha, Macleay Jennifer, Frisbie David D
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Researchers investigated whether adenoviral gene therapy delivering bone morphogenetic protein-2 and -7 could enhance bone healing in horses by creating critical-size defects (1.5 cm) in the metacarpal IV bone of 15 adult horses, treating ostectomy sites with either Ad-BMP-2/-7, a control adenoviral vector (Ad-GFP), or no treatment, then monitoring healing radiographically over 16 weeks and histologically post-mortem. Unexpectedly, the BMP gene therapy group showed no significant advantage over untreated controls at any timepoint, and radiographic, histological, and dual energy X-ray absorptiometry analysis at 16 weeks revealed comparable bone healing across all groups, though the Ad-GFP control group did demonstrate reduced defect size at weeks 4 and 6 compared with untreated horses. These findings suggest that direct adenoviral vector-mediated BMP-2/-7 gene transfer—despite theoretical promise from laboratory studies—failed to accelerate or improve ossification in this clinically relevant equine model of a critical bone defect. For practitioners managing horses with significant bone loss or delayed healing, this work indicates that current gene therapy approaches using adenoviral BMP vectors may not offer the therapeutic benefit once anticipated, warranting continued exploration of alternative biological or mechanical interventions to support bone regeneration in defects of this magnitude.
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Practical Takeaways
- •Adenoviral BMP-2/-7 gene transfer did not enhance bone healing in this equine metacarpal ostectomy model, suggesting current gene therapy approach may not be clinically beneficial for this application
- •The critical-size 1.5 cm defect model shows that biological enhancement strategies require further optimization before clinical translation for equine fracture management
- •Consider alternative biologics or gene vectors if pursuing biological augmentation of bone healing in performance horses with metacarpal injuries
Key Findings
- •Ad-GFP control group showed significantly lower percentage defect ossification at 4 and 6 weeks compared to untreated controls (P < 0.05)
- •Ad-hBMP-2/-7 gene transfer did not significantly improve bone healing at 16 weeks compared to controls on radiographic, histological, or DEXA evaluation
- •No significant differences in bone healing outcomes were detected between any treatment groups at the 16-week endpoint