A two-compartment system for subfreezing temperatures preservation of large volumes of organic matter in an isochoric system

This is a technology paper on the design of and test results from an 11-liter isochoric (constant volume) chamber, for the preservation of large, organs in a supercooled state. Details of the design are given, as well as a proof that the chamber is isochoric. Five repeats show that in this large chamber, ice nucleation of steam distilled water occurs at – 2 °C within less than 12 hours, in all the repeats. An examination of the experimental results suggests that the ice nucleation starts on the inner walls of the isochoric chamber. A new two compartment isochoric chamber was designed to reduces the probability of ice nucleation on the walls of the chamber. In the two-compartment system, the biological matter and the preservation fluid are introduced in a sealed low-density polyethylene bag, and placed in the center of the isochoric chamber, in such a way that the bag does not touch the walls. The space between the inner walls of the isochoric chamber and the outer walls of the bag are filled with a fluid with a composition that does not freeze at the storage temperature. Three repeat experiments with steam distilled water and with in vitro pig liver show that with this technique, the system remained supercooled, without any ice nucleation for the duration of the experiments. Experiments were voluntary terminated at 48 hours of supercooling. This new technology may hold promise for long term preservation of large biological organs in a supercooled state, without the use of any chemical additives. ### Competing Interest Statement The authors have declared no competing interest.