ALTERED LEVELS OF EXTRACELLULAR-MATRIX MOLECULE MESSENGER-RNA IN HEALING RABBIT LIGAMENTS

RT-PCR methods were used to amplify, semi-quantify, clone and sequence cDNA fragments specific for rabbit extracellular matrix molecules big lycan, collagen I, collagen III, decorin, lumican, versican, fibromodu lin, and also glyceraldehyde-3-phosphate dehydrogenase (G3PDH), using RNA isolated from rabbit ligaments. Sequence analysis of two independe nt clones of PCR products was used to verify the identity of the cDNA. Semi-quantitative RT-PCR was used to study mRNA levels for these matr ix molecules in normal and healing rabbit ligament at three, six, and fourteen weeks post-injury. The yield of RNA from the ligament scar wa s increased at three and six weeks post-injury, but it had returned to near normal levels by fourteen weeks. On a microgram RNA basis, it wa s demonstrated that biglycan, collagen I, collagen III and lumican mRN A levels are significantly elevated, versican mRNA levels significantl y depressed, and decorin and fibromodulin mRNA levels showed no signif icant change in response to tissue injury in the ligament during the c ourse of healing. These findings suggest that differential regulation of mRNA levels for these extracellular matrix molecules occurs during ligament healing.