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Expression of bone morphogenetic protein-6 and -2 and a bone morphogenetic protein antagonist in horses with naturally acquired osteochondrosis

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  • 1 Comparative Orthopaedics Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
  • | 2 Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.
  • | 3 Comparative Orthopaedics Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
  • | 4 Comparative Orthopaedics Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Abstract

Objective—To determine the mRNA expression of bone morphogenetic protein (BMP)-6 and -2 and a BMP antagonist (Noggin) in horses with osteochondrosis.

Sample Population—Samples of articular cartilage from affected stifle or shoulder joints of 10 immature horses with naturally acquired osteochondrosis and corresponding joints of 9 clinically normal horses of similar age; additionally, samples of distal femoral growth plate cartilage and distal femoral articular cartilage were obtained from a normal equine fetus.

Procedure—Cartilage specimens were snap-frozen in liquid nitrogen, and total RNA was isolated. Adjacent specimens were fixed in 4% paraformaldehyde for histologic examination. Expression of BMP-6, BMP-2, and Noggin mRNA was evaluated by real-time quantitative polymerase chain reaction (PCR) assays. Spatial tissue mRNA expression of BMP-6 was determined by in situ hybridization.

Results—Nucleotide sequences were obtained for portions of the BMP-6 propeptide and mature peptide region, as well as the signal and mature peptide region of Noggin. Expression of BMP-6, BMP-2, and Noggin mRNA was found to be similar in cartilage from normal and osteochondrosis-affected horses. Spatial expression of BMP-6 correlated with the middle and deep layers of articular cartilage; no differences were observed in overall expression between cartilage specimens from the 2 groups of horses. No expression of BMP-6 was found in the superficial layer, subchondral bone, or osteochondrosis-affected cleft fibrous tissue.

Conclusions and Clinical Relevance—Although these signaling peptides may play important roles in cartilage differentiation, results did not provide evidence to suggest that they are involved in the disease process of osteochondrosis. (Am J Vet Res 2004;65:110–115)

Abstract

Objective—To determine the mRNA expression of bone morphogenetic protein (BMP)-6 and -2 and a BMP antagonist (Noggin) in horses with osteochondrosis.

Sample Population—Samples of articular cartilage from affected stifle or shoulder joints of 10 immature horses with naturally acquired osteochondrosis and corresponding joints of 9 clinically normal horses of similar age; additionally, samples of distal femoral growth plate cartilage and distal femoral articular cartilage were obtained from a normal equine fetus.

Procedure—Cartilage specimens were snap-frozen in liquid nitrogen, and total RNA was isolated. Adjacent specimens were fixed in 4% paraformaldehyde for histologic examination. Expression of BMP-6, BMP-2, and Noggin mRNA was evaluated by real-time quantitative polymerase chain reaction (PCR) assays. Spatial tissue mRNA expression of BMP-6 was determined by in situ hybridization.

Results—Nucleotide sequences were obtained for portions of the BMP-6 propeptide and mature peptide region, as well as the signal and mature peptide region of Noggin. Expression of BMP-6, BMP-2, and Noggin mRNA was found to be similar in cartilage from normal and osteochondrosis-affected horses. Spatial expression of BMP-6 correlated with the middle and deep layers of articular cartilage; no differences were observed in overall expression between cartilage specimens from the 2 groups of horses. No expression of BMP-6 was found in the superficial layer, subchondral bone, or osteochondrosis-affected cleft fibrous tissue.

Conclusions and Clinical Relevance—Although these signaling peptides may play important roles in cartilage differentiation, results did not provide evidence to suggest that they are involved in the disease process of osteochondrosis. (Am J Vet Res 2004;65:110–115)