Histomorphometric evaluation of ischemia-reperfusion injury and the effect of preservation solutions histidine-tryptophan-ketoglutarate and university of Wisconsin in limb transplantation

Background. The effect of cold ischemia (CI) in vascularized composite allotransplantation is unknown. We herein assess tissue-specific damage, acceptable CI time, and the effect of preservation solutions in a syngenic rat hindlimb transplant model. Methods. Lewis rat limbs were flushed and stored for 2, 10, or 30 hr CI in saline, histidine-Tryptophan-ketoglutarate or University of Wisconsin preservation solution before transplantation. Morphologic alterations, inflammation, and damage of the individual tissues were analyzed on day 10 using histomorphology, confocal, light, and transmissionelectron microscopy. Results. Two-hour CI led to mild inflammation of tissues on day 10, whereas 10-hr and 30-hr CI resulted in massive inflammation and tissue damage. Although muscle was mainly affected after prolonged CI (Q10 hr), nerve was affected in all CI groups. A perineural cell infiltrate, hypercellular appearance, pronounced vacuolization, and mucoid degeneration, appearing as Wallerian degeneration, were observed. Staining with propidium iodide and Syto 16 revealed a decrease in viable muscle cell nuclei in the anterior tibial muscle on day 10 in all groups, which was most pronounced in 10-hr and 30-hr CI animals. Transmission-electron microscopy indicated that a large number of mitochondria were degenerated in the 10-hr and 30-hr CI groups. Histidine-Tryptophan-ketoglutarate preservation solution slightly decreased inflammation and tissue damage compared to University of Wisconsin-Treated and salinetreated animals, especially in skin and muscle when CI times did not exceed 10 hr. Conclusion. Severe inflammation and tissue damage are observed after prolonged CI in muscle and nerve. Ischemia times in vascularized composite allotransplantation should be kept as short as possible and certainly below 10 hr.