Characterization of Freeze-Thaw Induced Ultrastructure Damage to Endothelial Cells in Vitro

摘要

The pathophysiology of endothelial cells is important to a variety of vascular conditions including coagulation and hemostasis resulting from clinical frostbite. Use of an in vitro model system demonstrated that when bovine endothelial cells were frozen at 1 C/min or 20 C/min and thawed immediately (20 C/min) a variety of ultrastructure alterations occurred. Membranous structures were most extensively damaged with mitochondria the most sensitive organelle. Low amplitude mitochondrial swelling, first, evident at O C, progressed to high amplitude swelling by -10C (frozen). Scanning electron microscopy revealed perforated plasma membranes in some cells at -10 C (frozen) and in most cells by -20C. Cultures frozen at 20 C/min revealed largely the same ultrastructure damage noted at 1C/min except a higher precentage of cells exhibited alterations. Data from the recovery index and lactic dehydrogenase release correlated well with observed ultrastructure changes. Early swelling of mitochondria and dilation of rough endoplasmic reticulum was not lethal in the absence of freezing. Increased swellng in cytoplasmic organelles coupled with nuclear alterations at -15 C resulted in a decreased survival rate and release of significant quantities of LDH by -20 C. No unique morphological changes were temperature specific, but the total number of cells which displayed alterations increased as temperature decreased.