This press article on the history of cryonics and the work of the Cryonics Institute skips over a lot of the important technical details, such as the fact that patients are vitrified these days rather than frozen, a technique that minimizes ice crystal formation in tissues, but is still worth reading:
Inside the brick-fronted warehouse in Clinton Township, the body count has topped 100. Nestled inside Wal-Mart sleeping bags, the bodies stand upside-down within 10-foot-high tanks resembling immense white thermos bottles. This is the Cryonics Institute, and the people in those tanks - "cryostats," they're called - after being declared dead, have had their bodies frozen in perpetuity in the belief that future science may be able to thaw them, cure their ills, and, just maybe, return them to youthful vigor. They've made a bet: that in a time yet to come, they'll rise again, with "death" only a temporary and reversible embarrassment easily remedied by medical know-how.
Death is a gray line and it's always moving. What might have been terminal 150, 15, even five years ago is treatable today. Something as simple as CPR has saved countless lives; cardiac defibrillation - the "shock paddles" used to jump-start a stopped heart - has revived patients previously considered dead. What's "dead" mean to medicine, other than a challenge? From that perspective a storehouse of frozen bodies is no more macabre than a heart transplant, a now-common medical procedure once considered grotesque.
Right now, though, cryonics is more like an in-progress medical trial. Advances in stem-cell research, nanotechnology, and therapeutic cloning give cryonicists hope, but there are no guarantees. Today's frozen people are already dead, or "deanimated," as some prefer; tomorrow's helpful scientists will not only have to successfully thaw their "patients," but return them to life. That's assuming, fingers crossed, that they've been frozen in a recoverable way, without too much tissue damage, and that they've been carefully maintained. Once thawed, they'll have to be treated for being "dead," by whatever methods would make that possible. And who wants to wake up alone in the future in a body already ravaged by time? Better to hope that a new, youthful body is waiting for you.