Introduction and Objectives: meniscal lesions in the avascular zone are difficult to heal because of the poor biological potential of the avascular tissue. Little is known about the molecular mechanisms that develop after a meniscal lesion in this low activity zone. The purpouse of this study is to determine the levels of gene expression of five different growth factors (IGF, IL-1β; TGF-β, PDGF-β and VEGF) in the first three weeks after a meniscal lesion in the avascular zone of rabbit menisci.

Materials and Methods: 28 white female New Zealand rabbits were used in this study. Through a small arthrotomy a 5mm longitudinal lesion was performed in the avascular zone of the anterior horn of the medial meniscus of each rabbit. The rabbits were sacrificed after 0, 1, 3, 7, 14 and 21 days (4 rabbits each). After sacrifice, the zone in which the meniscal lesion was performed was disected from the rest of the mensicus. It was then divided in two parts: a peripheric vascular zone and a central avascular zone. After ARNm extraction cuantitative PRC anaylisis with Sybergreen technology was performed using specific primers for each gene.

Results: There were significant expression increases of IGF, TGF-β and PDGF-β, in the vascular zone at two weeks but no variations of note in these genes in the avasacular zone. The expression of IL-1β is increased in the first day after injury in both zones but only last up to the thrid day in the vascular zone. There is an increase in VEGF expresion in the avascular zone at two weeks that is related to a symetric decrease in the vascular zone.