Evaluation of Histological Properties of Human Meniscal Grafts Stored in a Tissue Bank

Abstract

Objectives The present paper aims to evaluate and compare the histological features of fresh and frozen menisci stored in a tissue bank for 1 month and for 5 years. Methods The meniscal grafts were subjected to a histological study. A total of 10 menisci were evaluated; 2 were frozen for 5 years, 4 were frozen for 1 month, and 4 were fresh, recently harvested specimens. Histological properties were evaluated in sections stained with hematoxylin and eosin and Masson trichrome methods. Results The menisci frozen for 1 month showed partially preserved collagen fiber structure and no significant hydropic tissue degeneration. The menisci frozen for 5 years presented an evident dissociation of collagen fibers and multiple foci of hydropic degeneration. Discussion Degeneration was much more significant in menisci stored for 5 years, indicating that a long freezing period results in substantial progression of tissue deterioration. This may suggest that the 5-year period, considered the maximum time for graft storage before transplant, is too long. Conclusion Grafts stored for 1 month showed a slight degenerative change in collagen fibers, whereas menisci frozen for 5 years presented significant tissue degeneration.

Keywords: meniscus; tibial menisci; tissue bank; transplantation.

Fig. 1

( A ) Fresh meniscus with its usual eosinophilic color. ( B ) Meniscus preserved for 1 month presenting basophilic discoloration and collagen fibers fragmentation. ( C ) Meniscus preserved for 5 years showing more accentuated changes, extensive hyaline degeneration and interstitial accumulations due to edema. (Hematoxylin & Eosin, 10x magnification).

Fig. 2

( A ) Fresh meniscus with no fiber fragmentation. ( B ) Meniscus preserved for 1 month showing fiber discontinuity and accumulated hyaline material stained in blue. ( C ) Meniscus preserved for 5 years exhibiting severe fiber fragmentation and marked interstitial dissociation due to edema (Masson's trichrome, 10x magnification).

Fig. 1

( A ) Menisco a fresco com sua coloração habitual, eosinofílica. ( B ) Menisco conservado por 1 mês com alteração da cor para basofílica e fragmentação das fibras colágenas. ( C ) Menisco conservado por 5 anos com alterações mais acentuadas, exibindo extensa degeneração hialina formando acúmulos intersticiais por edema. (Hematoxilina & Eosina, aumento de 10x).

Fig. 2

(A) Menisco a fresco sem fragmentação da fibra. ( B ) Menisco conservado por 1 mês com descontinuidade das fibras, com acúmulos de material hialino corados em azul. ( C ) Menisco conservado por 5 anos com fragmentação severa das fibras e acentuada dissociação intersticial por edema. (Tricrômico de Masson, aumento de 10x).