EXPRESSION ANALYSES OF DIFFERENT GROWTH FACTORS, CYTOKINES AND PROTEINS IN HUMAN FIBROCHONDROCYTES OF THE KNEE MENISCUS

Abstract

The meniscus of the human knee joint has an outstanding function for stability, shock absorption and power transmission of the thigh on the shank. After a meniscus trauma so far often only the partial or complete removal of the meniscus has to be performed. Only with injuries in the outside third a primary suture of a tear leads to the healing due to the existing vascularisation in a high number of cases in younger patients. After partial or total meniscektomie cartilage degeneration and resulting osteoarthrosis of the knee joint often is the consequence.

A goal of our investigations was the establishment of meniscus cell cultures as well as their characterisation regarding the expression of different growth factors, cytokines and proteins and the influence by adding different recombinant growth factors. We are able to cultivate human fibrochondrocytes, which originate from menisci of the knee from patient undergoing total knee replacement. Investigations were performed by immune-histochemistry and RT PCR. We could show the expression of collagen I, II, III and VI, the matrix-metalloproteinases 1, -2, -3 and -8 in the human meniscus. In Addition the expression of TGFβ1, BMP II, AS.02, Thy 1, TGFβ1, iNOS and interleukin (IL) -1, -6 and -18, ECGF and VEGF was proved. PDGF-1 and collagen X could not be found in the meniscus investigated. Same expression analysis was performed in same patients’ synovial cells and chondrocytes from knee joint. Differences were found in the collagen expression. Synovial cells do not synthesise collagen II but collagen I. Investigated chon-drocytes show a high level of collagen I an II expression, but fibrochondrocytes a low level of collagen II and high of collagen I, too. After stimulation of meniscus cells with IL-1, TGFβ1 and TNF-α no difference was found in the expression of TGFβ1, BMP II and IL-18, but a total inhibition of IL-6. TGFβ1 suppressed IL-1 expression totally compared to not stimulated fibrochondrocytes.

We were able to cultivate, characterize and stimulate human fibrochondrocytes from meniscus of the knee. We could show that meniscus cells express a huge amount of different growth factors, cytokines and proteins and can be distinguished from synovial cells and joint chondrocytes by the low level expression of collagen II. We also investigated first time the reaction of human meniscus cells after stimulation by recombinant growth factors. These results are a basis for the tissue engineering of meniscus tissue.