How does cryonics work?

Added On October 9, 2015

Recently, news about Chinese writer Du Hong to use cryonics procedure after clinical death and wish to resuscitation in the future, has attracted many attentions. 

CNC interviewed Doctor Aaron Drake, who performed the cryonics for her to find out the truth behind this technology.
Ms. Du Hong was a writer for children's book. She died for pancreatic cancer this May. Her daughter and son in law contacted the Alcor Life Extension Foundation in America before her death and asked Alcor to basically freeze her brain, preserve it and hopefully to use future science and technology to bring her back to life someday. 
Ms. Du has become the very first Chinese to do so.
SOUNDBITE (ENGLISH) AARON DRAKE, Alcor Life Extension Foundation
"I was one of the two people on the surgeon team that were in Beijing in this past May. We did not really know if we were able to successfully pull this off in a different country especially in China, but we got such level support from the hospital, to the mortuary, to all the government officials, and even shipping."
When we talk about freeze the brain, it is actually freeze and preserve the head. 
On one hand, it is safer to keep the brain in the head, on the other hand, the head can provide DNA of the person to clone the body in the future. 
However, preserving a single head is of high cost.
It will cost about 75,000 dollars.
Scientists predict that the first brain transplant will happen in a very near future - 2017. As long as the future science, medicine and technology can use certain person's DNA to regenerate a body, they can transplant the brain into that body, and this person can come back to life with his/her own memories and personality, but in a healthier and younger body.
SOUNDBITE (ENGLISH) AARON DRAKE, Alcor Life Extension Foundation
"But I do not want people think we are really selling immortality, there are always things that a person could truly die from, that they can not be repair from. What we are trying to do is bridge a gap between today’s medicine and tomorrow's medicine."
What if after 50 years, the future medicine still can not wake those people up? What will happen to their brains and body at the Foundation?
SOUNDBITE (ENGLISH) AARON DRAKE, Alcor Life Extension Foundation
"There is nothing special about 50 years, that number is not something we do. More than half the money that people spend on this goes into a trust, that trust is what pays for the nitrogen cost and it does not matter it is 10 years or 50 year or 100 years or longer, the interest of that money pays for that. In theory, it should be able to stand centuries if need be."
There are several institutions around the world doing cryonics, including Alcor. Until right now, Alcor has 141 clients who have already either freezes their bodies or brains, and over 1,000 people willing to be frozen after they die. People may question, as more and more people want to do this, are we going to have a bigger population problem if all of them wake up in the future?
SOUNDBITE (ENGLISH) AARON DRAKE, Alcor Life Extension Foundation
"In theory you can say, wow all theses extra people they are dying and back to the future. But if you think about every single day on this planet where are 155,000 people who die, every single day, 155,000. In 43 years we only preserved 141. I think this is becoming more popular and a lot more people will choice it, but in terms of the vast amount people die everyday, no, I do not there will be any over population." 
If cryonics really works one day, people's dream of being immortal will come true. But, whether it will take 50 years or 100 years more, until the first one wake up, everything still remains unknown.