Changes in genetic expression in a rabbit knee model of posttraumatic extrinsic contracture

Abstract

Objective To investigate the changes in genetic expression in a rabbit knee model of posttraumatic extrinsic contracture. Methods A model of posttraumatic extrinsic contracture was created in rabbit knees to study the differentially expressed genes. The left knees of 3 mature New Zealand rabbits (12 to 18 months old) were operated on to result in stable intra-articular fractures which were then immobilized as the trauma group while the right knees without any operation served as the control group. The gene expression profiles of joint capsule were studied with Agilent rabbit whole genome microarray technology. Differentially expressed genes were screened by comparing gene expression profiles between the trauma and control groups. Among those differentially expressed genes, matrix metalloproteinase 2 (MMP2), Actin alpha 2 (Acta2), and Keratinocyte growth factor (KGF), related to fibrosis, were selected for verification by real-time reverse transcription polymerase chain reaction (real-time RT-PCR) analysis. Results When compared to normal capsules, 90 differentially expressed genes were screened out in the contracted capsules. Of them, 21 were up-regulated and 69 down-regulated. These genes were associated with regulation of response to external stimulus, regulation of lipopolysaccharide-mediated signaling pathway, regulation of response to biotic stimu-lus, et al. The real-time RT-PCR testing showed the MMP2, Acta2 and KGF genes were all significantly up-regulated compared to the control group (P< 0.05), consistent with the results of the microarray. Conclusions There exist differentially expressed genes in the joint capsules in a rabbit knee model of posttraumatic joint extrinsic contracture compared with normal ones. Posttraumatic extrinsic contracture may be associated with MMP2 and Acta2. The function of KGF genes in human joint contracture needs further re-search. Key words: Gene expression; Stifle; Arthrogryposis; Rabbits