Assessment of apoptosis and MMP-1, MMP-3 and TIMP-2 expression in tibial hyaline cartilage after viable medial meniscus transplantation in the rabbit

INTRODUCTION: The porpuse of this animal study was to assess chondrocyte apoptosis and MMP-1, MMP-3 and TIMP-2 expression in rabbit tibial cartilage 6 months after viable medial meniscal autografts and allografts. MATERIAL AND METHODS: Twenty white male New Zealand rabbits were chosen for the study. The medial meniscus was excised from 14 animals and stored under tissue culture conditions for 2 weeks, following which t of them were implantated as autografts and 7 as allografts. The control group consisted of 6 animals which underwent arthtrotomy. When the animals were eutanized, the tibial cartilage was used for immunohisochemical examination. Apoptosis (TUNEL method) and MMP-1, MMP-3 and TIMP-2 expression were estimated semiquantatively. RESULTS: An increased level of chodrocyte apoptosis in the tibail cartilage was observed after both kinds of transplants (p < 0.05), allografts (1.43 ±0.98) and autografts (0.86 ±0.69); no statistical diferences existed between them. An increased level of metalloproteinases and TIMP-2 expression was obreved only after allografts with statistical differences among the allograft group, the autograft group nad the control group (p < 0.05). CONCLUSIONS: Our findings suggest that the meniscal graft does not protect the hyaline cartilage against excessive apoptosis. The results of experimantal studies on humans indicate the need to device a method of apoptosis inhibition in the hyaline cartilage to improve long-term results of meniscal transplantation.