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.