Welcome to a mind-boggling possibility

Du Hong, writer of books for children, died on May 30 of cancer. She is back in the news more than three months later because journalists have found she spent $120,000 to have her brain cryopreserved with US-based Alcor Life Extension Foundation in the hope of "coming back to life" with the help of future technology, say, half a century later. Neuro-cryopreservation means keeping a person's brain in liquid nitrogen at about minus 196 degrees Centigrade.

The idea of reviving life comes from nature. Certain types of pear trees can lie dormant in winter when temperatures could drop to minus 33 C only to resume all life activities after temperatures return to normal; some apple trees can survive even minus 46 C. On some temperate beaches, certain kinds of oysters and mussels freeze in the cold night where temperatures can drop to minus 30 C and revive with daylight. These plants and animals only minimize metabolism - the process doesn't stop - which means they are still alive.

Du's case is totally different because she is dead while the above-mentioned creatures are not. Her "revival" in the future will depend on revolutionary technologies about which we have no idea now.

For such a magic to happen, two key challenges have to be met. First, the brain must be kept exactly like it was when removed from the skull with its entire cellular structure intact. That's why it must be preserved in liquid nitrogen, which ensures most chemical reactions considerably slow down or altogether cease.

With the latest technologies that lower temperature within a very short time without producing ice, modern-day doctors can preserve some human organs or cells alive for a short term: three to eight hours for the heart, five to nine hours for lungs, with 10 to 11 hours being the upper limit with the best organ care system. Single cells, like human egg cells, can be usually preserved for two years, with the world record being 22 years. Keeping a brain for 50 years or more is possible, but we still don't have the technology to ensure it remains what it is 50 years later.