Cryonics depends upon advancements in molecular and nanotechnology. Scientists have concluded that the mid to late 21st century will bring an explosion of amazing capabilities for analyzing and repairing injured cells and tissues, similar to the information processing revolution that is now occurring. These capabilities will include means for repairing and regenerating tissue after almost any injury provided that certain basic information remains intact.
A cryoprotectant is a small molecule that easily penetrates inside cells and that depresses the freezing point of water. These 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 over several hours. Living cells can survive replacement of more than 50% of the water inside them with other molecules -- if introduction and removal are done at low temperature. When tissue is cooled slowly, the formation of ice takes place between cells. The growing ice crystals increase the concentration of solutes in the remaining liquid around them. If cryoprotectants are present, the freezing point of the unfrozen solution drops sooner and faster, limiting the total amount of ice that forms. As the temperature drops below -40°C, the cryoprotectant concentration becomes so high in the remaining unfrozen solution that ice stops growing. Cells survive suspended in the residual unfrozen liquid between ice crystals. During ordinary freezing, the cryoprotectant concentration between ice crystals becomes so high that ice growth eventually stops. Here is where vitrification comes in. It’s the combination of rapid cooling and high cryoprotectant concentration to completely avoid ice formation between cells.
The biggest downside of Cryonics is that there no method of verifying the outcome. It is also not included in mainstream medical sciences, and hence receives limited support. Few scientists who are willing to do cryonics-related research live in fear of being excluded from the scientific specialty that is most relevant to their work. Cryonics is not explicitly recognized in the laws of any state in the United States.
However, Cryonics holds a lot of possibilities that are yet to be discovered. No matter what, humans haven’t understood all the aspects of death. Cryonics isn’t another name for humans wishing to chase immortality. It’s a science and not a religion. Cryonics, if it works, is a stepping-stone to a future where aging and now-terminal illnesses will be treatable in ways not possible today.
References: http://www.alcor.org/FAQs/index.html; http://www.cryonics.org/about-us/faqs; http://knappily.com/article.php/582fd17202236cd46ff0ccee