Immunohistochemical Study of the Expression of Transglutaminase Isoenzymes in the Healing Process of Rat's Articular Cartilage Defect

Seong, In Ho; Lee, Myung Chul; Seong, Sang Cheol

Abstract

Injury to the articular cartilage is clinically troublesome because its regeneration is limited, but until now no treatment method was proved to be satisfactory. Transglutaminases(TGase) are a group of enzymes which catalyze intermolecular crosslinking reaction to contribute to the structural stability of the tissue, and several authors suggested their use as potential biological glue. However there have been few studies on the expression of TGase and the roles of any specific subtype in the healing process of cartilge injury. So the authors observed the expression of tissue TGase(TGase C) and prostate TGase(TGase P) in the healing process of rat's articular cartilge defect. Into the knee articular cartilage of 5 month-old Sprague-Dawley rat, a defect was made with diameter 1.2mm drill bit. At 1, 3, 5, 7 days and 2, 4, 6, 8 weeks after the operation, the animals were sacrificed and their distal femurs were harvested for the histological studies. The sections were stained with HandE, alcian-blue and Safranin-O. Immunohistochemical study for the expression of TGase C and TGase P was done with the sections. Between 4 and 6 weeks after the operation, the articular cartilage defect was regenerated to the level of intact portion, but histologically it was regenerated not with hyaline catilage but with fibrocartilage. TGase C was expressed in fibroblasts, osteoblasts and fibrous matrix in the early healing phase, but after 4 weeks, it was expressed in chondrocytes and chondroid matrix. TGase P was not expressed in any of the normal articular cartilage, subchondral bone and reparative cells and tissue of the defect. As one of the new methods for the treatment of articular cartilage defect, chondrocytes were incorporated with biodegradable carriers and grafted into the injured site. To maximize the condition of the graft, addition of any specific material into these chondrocyte-carrier composite graft can be considered. In this study, TGase was found to be expressed in the healing process of articular cartilage defect. So, TGase might be supposed to play an important role in the healing process of cartilage injury, and could be tried as one of the additives for the chondrocyte graft.