Histological characteristics of the reconstructed anterior cruciate ligament with repetitive freeze-thawing allogenic Achilles tendon / 中国组织工程研究

ABSTRACT

BACKGROUND: Thawed allografts are usually discarded for various reasons. Whether these discarded allografts can be refrozen for later use and their histological changes in vivo have not been reported. OBJECTIVE: To investigate the histological characteristics of anterior cruciate ligament (ACL) reconstructed with the repetitive freeze-thawing allogenic Achilles tendon in New Zealand white rabbits. METHODS: Allogenic Achilles tendons were harvested from adult male New Zealand white rabbits, and were stored at -8 ℃ and thawed at 20 ℃ for 1, 2, 3 and 10 times, respectively, after sealed package and 60Co irradiation. Twenty-four adult male New Zealand white rabbits were enrolled the left and right knees of 12 rabbits were respectively reconstructed with 1 (control group) and 2 times of freeze-thawing allogenic Achilles tendon, and another 12 rabbits underwent reconstruction with 3 and 10 times of freeze-thawing allogenic Achilles tendon, respectively. Three specimens from each group were evaluated with modified histology grading scores at 6, 12 and 24 weeks to assess the cell morphology, cell quantity, matrix staining intensity, fibrocartilage formation, new bone formation, tendon healing and cartilage injury. RESULTS AND CONCLUSION: The cell morphology, matrix staining intensity and total scores of the 10 times group were significantly higher than those of the other groups at 6 weeks (P 0.05). ACL reconstructed with 10 times of repetitive freeze-thawing allogenic Achilles tendons had higher histological scores at 6 weeks after modeling, but no significant differences were shown at 12 and 24 weeks after modeling. To conclude, our study only testifies better histological scores on the multiple times of freezethawing Achilles tendon than the less times of freeze-thawing Achilles tendon at the early period after operation.