TEMPORAL AND SPATIAL EXPRESSION OF TRANSFORMING-GROWTH-FACTOR-BETA INTHE HEALING PATELLAR LIGAMENT OF THE RAT

We investigated the temporal and spatial expression of transforming gr owth factor-beta in the healing patellar ligament of the rat by immuno histochemistry. The mid-portion of the medial half of the patellar lig ament in 14-week-old male Wistar rats was cut transversely with a scal pel. On day 1 after ligament injury, diffuse staining for transforming growth factor-beta was observed in the extracellular matrix filling t he wound, and the staining in the adjacent ligament tissue was as weak as it was in the normal ligament. On day 3, the intensity of the diff use extracellular staining decreased, and the staining was observed in correspondence with the cellular distribution in the wound site and i n the adjacent uninjured ligament tissue. On day 7, the intense staini ng was widely distributed over the whole length of the ligament tissue . On day 28, the staining for transforming growth factor-beta was stil l observed at the wound site and in the adjacent uninjured ligament ti ssue, where the staining was reduced in intensity but still stronger t han it was in the normal ligament. On day 56, the expression of transf orming growth factor-beta was still detectable at the wound site; howe ver, in the adjacent uninjured ligament tissue, it had almost subsided to the normal level. The results of the present study suggest that li gament healing may be accompanied by extensive changes in the expressi on of transforming growth factor-p over the whole length of ligament t issue.