| The aim of the present study was to investigate the proteolytic potential and localization of matrix metalloproteinase ( MMP ) 2 in relation to its regulatory protein , membrane type MMP ( MT 1 MMP ) , and tissue inhibitor of metalloproteinase 2 ( TIMP 2 ) , as well as to clarify an important step in the cascade of periprosthetic connective tissue remodeling in loose total hip prostheses . ^^^ Immunohistochemical analysis revealed increased expression of MT 1 MMP , MMP 2 , and TIMP 2 in fibroblasts , synovial lining like cells , and endothelial cells , as well as , to some extent , in monocyte / macrophage like cells in both tissues from the bone implant interface and reactive cellular tissues from regenerating capsules in loose hip joints , when compared with control fibrous tissues between bone and implants retrieved from unloosened hip joints . ^^^ In loose hip joints , reverse transcription PCR analysis showed the presence of MT 1 MMP , MMP 2 , and TIMP 2 mRNA in both the bone implant interface and regenerating capsular tissues . ^^^ Collectively , these data suggest that the MT 1 MMP / MMP 2 / TIMP 2 system participates in the extracellular matrix degradation and periprosthetic connective tissue remodeling in loose hip joints , and may thus contribute to the periprosthetic weakening , loosening , and osteolysis that can occur around implants . . ^^^ |