IntroductionThe study sought evidence for apoptosis, the expression of MMP-1, MMP-3 and TIMP-2 and their effect on the mechanical and biochemical properties of rabbit fresh knee medial meniscal grafts in a 6-month follow-up.Material and methodsForty white male New Zealand rabbits were chosen for the study. The medial meniscus was excised from 28 animals and stored under tissue culture conditions for 2 weeks, following which 14 of them were implanted as autografts and 14 as allografts. When the animals were euthanized, 20 menisci were used for immunohistochemical examinations. Apoptosis (TUNEL method) and MMP-1, MMP-3 and TIMP-2 immunoexpression were estimated semiquantitatively. The other 20 menisci were subjected to biochemical analysis and their degree of elasticity was evaluated.ResultsAn increased level of apoptosis (p <0.05) was observed both in allografts (1.57 ±0.98) and autografts (0.86 ±0.69); no statistical differences existed between them. An increased level of metalloproteinases and TIMP-2 expression was observed only in the allografts (p < 0.05). The highest decrease of degree of elasticity and the most significant changes in biochemical composition were observed in allografts (p < 0.05).ConclusionsThe studies confirmed the existence of excessive apoptosis in both kinds of fresh viable medial meniscal implants: auto- and allografts. Our results suggest that apoptosis and increased MMP-1 and MMP-3 expression have an adverse effect on the biological properties of implants. The results of experimental studies on humans indicate the need to devise a method of apoptosis inhibition in transplanted menisci to improve long-term results.

IntroductionThe purpose of this study was to assess apoptosis, the expression of MMP-1, MMP-3 and TIMP-2, as well as the mechanical and biochemical properties of fresh rabbit medial meniscus after 2 weeks stored under tissue culture conditions.Material and methodsThe study material included 26 rabbit's medial menisci. Fourteen menisci were stored for 2 weeks under tissue culture conditions. Thirteen menisci were subjected to immunohistochemistry tests. Apoptosis (TUNEL method) and the expression of MMP-1 (collagenase-1), MMP-3 (stromelysin-2) and TIMP-2 (tissue inhibitor of metalloproteinases-2) were estimated semiquantitatively. The remaining menisci were tested mechanically and biochemically. The mechanical properties were assessed by the degree of elasticity. Biochemical composition was based on the content analysis of water, total collagen and glycosaminoglycans.ResultsAs in the control group, the conducted study did not reveal any apoptosis in the stored menisci. The study group showed a slight expression of MMP-1 (0.27 ±0.19), MMP-3 (0.30 ±0.20) and TIMP-2 (0.33 ±0.20) – no statistically significant difference from controls. The degree of elasticity was 28.51 ±1.53 in the study group, and this did not statistically differ from the control group. No significant biochemical differences were identified in any other monitored parameter.ConclusionsThe conducted in vitro study did not show any negative influence of a 2-week storage period under tissue culture conditions on the apoptosis and expression of MMP-1, MMP-3 and TIMP-2 in rabbit fresh menisci, nor any impact on their mechanical and biochemical properties.

BackgroundKnowledge of the impact of viable medial meniscus allograft and autograft transplantation on biochemical and mechanical properties of cartilage is needed to understand the development of joint osteoarthritis. The purpose of this study was to evaluate this relationship 6 months after viable medial meniscal autograft and allograft transplantation.MethodsTwenty rabbits were chosen for the study. The medial menisci were excised from 14 animals and stored under tissue culture conditions for 2 weeks. Seven menisci were implanted as autografts (group A) and seven as allografts (group B). The control group consisted of six animals which underwent arthrotomy. The tibial cartilage was used for mechanical and biochemical evaluation.ResultsThe respective decreases of glycosaminoglycans (GAGs) and elasticity were 13.4 and 14.8 % for group A and 30.4 and 32.6 % for group B. The differences between group A and B and between each group and the control were statistically significant. The total collagen content was significantly lower in group B.ConclusionsThe type of viable meniscal graft has an influence on the biochemical composition of the extracellular matrix (ECM) and biomechanical properties of the underlying tibial cartilage. A 1 % decrease of glycosaminoglycan content is associated with a 1.1 % decrease of cartilage elasticity. The average ratio of decrease of cartilage elasticity to that of the meniscus was 0.77 regardless of the type of meniscus graft. The viable allograft causes irreversible ECM disorder of the cartilage. Knowledge of the biochemical composition of the ECM meniscal grafts may serve as a predictor of their chondroprotective properties.