New Cryo Technique

Peter Passaro (ocsrazor@worldnet.att.net)
Sun, 8 Nov 1998 09:38:55 -0500

For those of you interested in cryogenics, a very interesting article from New Scientist.

http://www.newscientist.co.uk/cgi-bin/pageserver.cgi?/ns/981107/nretina.html

Putting life on hold

Jon Copley

taking a tip from tiny animals that can live for more than a century, Japanese researchers have invented a new technique for storing human organs for transplant.

The team, which has successfully revived a rat's heart after 10 days in storage, says the work may lead to organ banks similar to blood banks. These would allow doctors to avoid the frantic dash to bring suitable organs straight from donors to the operating table.

Organs can usually be stored for only 30 hours before they have to be used. For hearts and lungs, the time limit is even less--just 4 hours. The main problem with keeping organs in cold storage is that water damages cell membranes at low temperatures. Unfortunately, removing water from tissues usually causes at least as much damage.

But Kunihiro Seki and his colleagues at Kanagawa University in Hiratsuka-shi, Japan, knew that animals called tardigrades can withstand extreme conditions by losing most of the water in their bodies (In Brief, 31 October, p 26). They can survive in this state for a century or more. When water was added to a dried-out moss kept in a museum for 120 years, tardigrades were later found crawling all over it.

To achieve this feat, tardigrades use a sugar called trehalose to stabilise the structure of their cell membranes. "This suggested that the physiological mechanism for preservation and resuscitation of tardigrades could be applied to the preservation of mammalian organs," says Seki.

To test this, the team flushed rat hearts with trehalose solution before packing them in silica gel to remove the water from their cells. The hearts were then immersed in perfluorocarbon, a biologically inert compound, and stored at 4 C in airtight jars. Ten days later, the team took the hearts out of the jars and resuscitated them. Within half an hour, they were beating again. Measurements of their electrical activity suggested that the heart cells had survived intact.

Seki believes that the trehalose and perfluorocarbon replace the water in the cells, preventing tissue damage. He plans to repeat the experiment with a complete autopsy to confirm that the tissues are preserved intact. The researchers also plan to demonstrate the procedure with other animal organs and prolong their storage for up to a year. Seki hopes that within a few years the technique could be used to preserve human organs.

"The implications for transplant patients would be huge," comments Vanessa Morgan, who chairs the UK Transplant Co-ordinators Association. "It could lead to planned, elective operations rather than emergency surgery." She adds that recipients could have a greater choice of donor organs, improving their chances of a good match. But she cautions that the quality of transplant organs must be maintained during long-term storage. "The condition of organs is crucial and I wouldn't want to compromise condition for time."

>From New Scientist, 7 November 1998