June 30, 2014
Scientists at Harvard Medical School have discovered how to supercool organs so that they can be transplanted four days after being harvested from a donor in a breakthrough which could globalize transplantation.
Thousands of people waiting for organ transplants have been offered new hope after scientists discovered a way to keep organs healthy for up to four days. The new technique would enable the world-wide allocation of hearts, livers, corneas, skin and kidneys from as far away as Australia and could save hundreds of lives each year.
This study was conducted on rats and if it succeeds in humans, it would enable a world-wide allocation of donor organs, saving more lives.
A rat’s liver which scientists at Harvard Medical School stored for four days with a new supercooling technique was successfully transplanted. Experiments on rats suggest that time could be extended to several days if the liver is pumped full of antifreeze and cooled to below freezing.
Keeping organs healthy for longer than 24 hours has proved tricky until now because the freezing process damages tissue irreversibly.But scientists found that by pumping anti-freeze and a glucose compound into livers, they could be ‘super-cooled’ to 21F (-6C) and preserved without actually being frozen.
Although the technique has so far only been demonstrated in rats, scientists are hopeful that the effect will be reproduced in larger animals and eventually humans.
“To our knowledge, this is the longest preservation time with subsequent successful transplantation achieved to date,” said Korkut Uygun, Professor of Bioengineering at Harvard Medical School.”If we can do this with human organs, we could share organs globally, helping to alleviate the worldwide organ shortage.”
All the rats who had supercooled livers which has been stored for three days survived for at least three months but none of the rats who had transplants using current methods did.
And the survival rate for animals receiving livers stored for four days was 58 percent.
There are 17,000 people waiting for a liver to become available for transplant in the US alone. Some may have to wait months because there are not enough livers for transplant.
When organs are removed from the donor they are stored on ice in a cooler for a maximum for 12 hours. If the organ hasn’t been transplanted within that window, perhaps because the donor and recipient live in different states, the delicate tissue can freeze and become damaged, making the organ useless for transplant.
“Extending the time limit to even a day would dramatically increase the geographical range over which a liver transplant might be possible and allow time to properly prepare an organ for the recipient,” says Bote Bruinsma at the Massachusetts General Hospital and Harvard Medical School. “That goal now looks like it should be possible.”
Bruinsma and his colleagues have developed a preservation technique that uses two cryoprotectant chemicals that together act as an antifreeze, preventing the formation of ice crystals in the organ. The first chemical fills the space between cells and protects the fragile cell membranes. The second accumulates in the cell and lowers the freezing point of water inside the cell, keeping it liquid even at subzero temperatures.
The research was published in the journal Nature Medicine.