A Simple Method for Controlled Freezing of Human Donor Corneae

Abstract

A simple method for freezing cultured human donor material with dimethyl sulfoxide (DMSO) was developed empirically in a commercially available microcomputer-controlled apparatus allowing reproducible freezing curves to be made. The optimum cooling rate was found to be 1.0 °C/min down to –40 °C and then 5.0 °C/min to –80 °C. Total cell loss rates were 36.9 ± (SD) 19.8% of postmortem endothelial cell counts. An improved method for evaluating endothelial viability was applied, which enabled us to observe definite cell survival after a postculture period.

Quantification of Lactate-Dehydrogenase and Cell Viability in Postmortem Human Dental Pulp

“…The experimental design employed here has been widely used in organ transplant research for establishing the postmortem viability of different body organs, such as kidneys, heart, bone, and cornea (2,12,22,23). These studies were taken into consideration when choosing the different time intervals to be evaluated (6, 12, and 24 hours).…”

“…Results from this study showed that 89.9% of pulp cells remained viable 6 hours after death; cell viability had decreased to 67.8% 12-hour postmortem. From a biological point of view, pulp could be considered to be a viable tissue at this point, taking into consideration that tissue is still biologically viable when at least 50% of its cells are vital (7,22).…”

“…This drop results from endogenous peptidase action that degrades the enzyme during cell lysis (2,22,23).…”