Abstract:
Introduction: Corneal preservation methods with the preservation of a maximum number of viable
endothelial cells has been and remains one of the challenges of Eye Banks worldwide. There are three
main approaches to the preservation and storage of corneas: the viable method, i.e. the culture medium,
and non-viable – hypothermia, cryopreservation and lyophilization. Corneal preservation methods
used in the Human Tissue Bank of the Republic of Moldova, such as lyophilization, being a non-viable
method, in which cell viability is lost, only the architectural shell of the transplanted collagen fibers
are preserved, which can be recellularized, only the epithelial layer. They are used in tectonic
keratoplasties to restore the integrity of the sclera or some portion of the cornea. The most used
preservation method is the tissue culture medium "C", Eussol "C" and Cary "C" with storage
temperatures of 31° C and a duration of one month. During 11 years of activity, 435 corneas were
transplanted, of which 4.5% (20 corneas) were lyophilized and transplanted through keratoplasty with
tectonic purpose.
Material and methods. Morphological evaluation of non-viable cornea in culture media, lyophilized
and preserved in glycerol in 20 rabbits and humans.
Results. Rabbit corneas preserved in 30, 50 and 80% glycerol at pH 7.4 and subsequently frozen at
80o C histologically by immunohistochemical staining with AE1/AE3 show disorganization of
connective tissue architecture with fragmentation. Microelectronic scanning of freeze-dried human
corneas determines the structural integrity of the connective tissue shell with layer persistence. Nonviable
corneas from histological culture media by hematoxylin-eosin staining show intense edema of
all layers predominantly in the stroma.
Conclusion. (1). The most preferred non-viable method of preserving the cornea is lyophilization with
the maintenance of structural integrity, sterility and validity up to 2 years; (2). The glycerol
preservation method at temperatures of - 800 C shows a destruction of the connective tissue casing due
to the formation of ice crystals. (3). The non-viable preservation of the cornea shows a deep swelling
of the layers and for its elimination, the Carry "C" detumescence medium is needed, which maintains
the validity period of 2 months, being an expensive method.
