Microarray analysis of angiogenic genes in condylar cartilage

Abstract

AIM: Microarray technology allows the analysis of over 15,000 genes, some of which are expressed in the condyles involved in angiogenesis during growth. In this way, some angiogenic regulating factors involved in condylar cartilage growth could be identifi ed. The aim of this study was to investigate the angiogenic gene expression changes in mandibular condylar cartilage under mechanical strain. MATERIALS AND METHOD: Two hundred and eighty, 35 day old, female Sprague-Dawley rats randomly divided into seven experimental and seven control groups. The experimental groups were fi tted with bite-jumping appliances. Each group of rats was killed on the following experimental days: 1, 3, 7, 9, 14, 30 and 33. Immediately after sacrifi ce, the condyles were dissected and total RNA was extracted to oligonucleotide microarray gene chips containing 15,923 genes. After a series of microarray data analyses, the genes that appeared absent at all time points in both groups were excluded. All genes that were either unchanged or where the expression changed less than 2-fold in relation to the control group were excluded from further analyses. This selection resulted in a net of 1,082 genes; 666 were increased and 416 were decreased in expression, at least a 2-fold change. This group of genes was further analyzed using hierarchical clustering and selforganizing maps and resulted in the identifi cation of numerous genes not previously known to be regulated in condylar cartilage during chondrogenesis under mechanical strain. RESULTS: Ten genes were involved in angiogenesis. CONCLUSIONS: Using microarray technology to analyze the gene expression of mandibular condylar cartilage under mechanical strain, some angiogenic regulating factors involved in condylar cartilage growth were identifi ed.