[Corneal cryopreservation in man: a proposal for an original technic]

Area of Science:

• Ophthalmology
• Cryobiology
• Tissue Engineering

Background:

• Human cornea cryopreservation is crucial for transplantation.
• Optimizing cryopreservation techniques is essential to maintain endothelial cell viability.
• Existing methods require refinement to minimize cellular damage.

Purpose of the Study:

• To propose and evaluate an original cryopreservation technique for human corneas.
• To investigate the effects of varying cryoprotectant concentrations, freezing phases, and thawing protocols on endothelial cell viability.

Main Methods:

• Human corneas were cryopreserved using a four-phase protocol involving cryoprotection with dimethylsulfoxide (DMSO) and human plasma, controlled-rate freezing, liquid nitrogen storage, and controlled thawing.
• Three cryobiological parameters were systematically altered: DMSO concentration (2-4-7% vs. 4-6-10%), freezing medium (dry vs. liquid phase), and thawing protocols (four variations).
• Endothelial cell viability was assessed using histological and Scanning Electron Microscopy (SEM) studies.

Main Results:

• Higher DMSO concentrations (10%) resulted in greater cellular osmotic lesions.
• Dry phase freezing induced more severe nuclear damage compared to liquid phase freezing.
• Specific thawing protocols (4 and 2) led to significant nuclear damage and cytoplasmic vacuole formation.

Conclusions:

• The human cornea endothelium is demonstrably affected by modifications in cryopreservation parameters.
• Optimal cryopreservation requires careful control of cryoprotectant concentration, freezing phase, and thawing procedures.
• Further research is needed to refine techniques for preserving corneal endothelial integrity during cryopreservation.