Factors that improve the preservation of nephron morphology during cold storage

Light and electron microscopy were used to evaluate the nephron morphology of rat kidneys that were perfused and stored at 0 to 2 degrees C. for up to 48 hours in preservation solutions which (1) contained different osmotic agents, (2) were adjusted to different levels of osmolality, and (3) which had different ionic compositions (e.g., intracellular-like, extracellular-like). Storage in an enriched phosphate-buffered isotonic culture medium that contained very little effective osmotic agent (i.e., medium 199) results in significant necrosis of glomeruli and uriniferous tubules with 12 to 24 hours. Storage in Collins solution that has an intracellular-like ionic composition and that contains dextrose as an osmotic agent results in significantly better preservation of kidney nephrons. When the dextrose in Collins solution is replaced with mannitol or sucrose, there is dramatic improvement in the preservation of glomeruli and uriniferous tubules. Overall, sucrose appears to be the most effective osmotic agent in preventing degeneration of the nephron during cold storage. Further improvement in nephron preservation is seen when the osmolality of Collins solution is raised (i.e., 400 to 600 mOsmoles) by adding more of the osmotic agents. Finally, storage in simple sodium phosphate-buffered solutions containing either dextrose, mannitol, or sucrose results in the same quality of morphologic preservation as seen with Collins intracellular-like solutions containing similar amounts of these osmotic agents. It appears, therefore, that the selection of an effective osmotic agent (e.g., sucrose) and making the preservation solution hypertonic with this osmotic agent are of primary importance in preserving nephron morphologic integrity during cold storage. The presence of an intracellular-like ionic composition in the preservation solution, however, does not appear to influence morphologic preservation. The effects of the above variables on the ultrastructural morphology of different segments of the uriniferous tubules and the renal corpuscles are described and illustrated.