In cryonics, cryoprotectant solutions are administered through the circulatory system of the patient so that cryoprotectant enters almost every cell of the body. This process is done near a temperature of O°C (32°F) over several hours, during which the cryoprotectant concentration slowly rises to more than 50%. (Isolated organs are subjected to similar protocols in organ banking research.) Amazingly, living cells can survive the replacement of more than half of the water inside them with other molecules if introduction and removal are done at low temperatures.