Viability studies on frozen--thawed rat islets of Langerhans.

In an attempt to determine logistical methods of curing diabetes mellitus in man, an investigation has been made on the viability, in vitro and in vivo, of deeply frozen (?150 °C) cryoprotected rat islets of Langerhans. It is found that rat islets, after recovery from a frozen bank of several syngeneic donors, secrete insulin, when thawed, cultured, and then subjected to a high glucose challenge. Cryoprotected frozen-thawed islets are also examined by electron microscopy. In vivo transplantation of recovered frozen islets has been studied for a period of 16 weeks in one streptozotocindiabetic Lewis rat. All normal tests indicated recovery. After sacrifice, staining procedures showed viable islets in the liver, the site of reimplantation, and only dead islet Beta cells in the pancreas.