In vitro effects of oxytetracycline on matrix metalloproteinase-1 mRNA expression and on collagen gel contraction by cultured myofibroblasts obtained from the accessory ligament of foals.
OBJECTIVE
To determine the effects of oxytetracycline on matrix metalloproteinase-1 (MMP-1) mRNA expression and collagen gel contraction by equine myofibroblasts in an effort to explain the mechanistic basis for the pharmacologic treatment of flexural deformities in foals.


METHODS
Cultured myofibroblasts from the accessory ligament (distal check ligament) of 6 foals.


METHODS
Collagen gel scaffolds seeded with equine myofibroblasts were cultured in individual culture dishes containing complete media (Dulbecco's modified Eagle medium with 10% fetal bovine serum) and oxytetracycline (0, 12.5, 25, or 75 microg/mL) for 48 hours. After 24 hours, the gels were released from the bottom of the culture plate and allowed to contract. Photographs were taken at 0, 1, 2, 4, 6, 8, and 24 hours after release to assess the degree of collagen gel contraction. Additional gels were harvested at 2 hours after release for RNA isolation and reverse transcriptase-polymerase chain reaction assessment of the degree of MMP-1 mRNA expression.


RESULTS
Oxytetracycline induced a dose-dependent inhibition of collagen gel contraction by equine myofibroblasts. Oxytetracycline also induced a dose-dependent decrease in MMP-1 mRNA expression by equine myofibroblasts.


CONCLUSIONS
Results of this study indicate that oxytetracycline inhibits tractional structuring of collagen fibrils by equine myofibroblasts through an MMP-1 mediated mechanism. In young foals, oxytetracycline administration may make the developing ligaments and tendons more susceptible to elongation during normal weight-bearing. Inhibition of normal collagen organization may provide the mechanistic explanation for the results seen following the pharmacologic treatment of flexural deformities in foals by oxytetracycline administration.
Arnoczky
Steven P
SP
Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
Lavagnino
Michael
M
Gardner
Keri L
KL
Tian
Tao
T
Vaupel
Zachary M
ZM
Stick
John A
JA
D000704:Analysis of Variance; D000818:Animals; D003094:Collagen / Q000187:drug effects* / Q000378:metabolism; D005782:Gels / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D006736:Horses; D066298:In Vitro Techniques; D020781:Matrix Metalloproteinase 1 / Q000235:genetics / Q000378:metabolism*; D010118:Oxytetracycline / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D005782:Gels; D012333:RNA, Messenger; D003094:Collagen; D020781:Matrix Metalloproteinase 1; D010118:Oxytetracycline