The chief physician: May also be relevant with pig hearts

Before that, many more experiments must be done, not to mention a review of possible ethical problems, according to Lars Wennberg.

- It is important that the animal rights and animal welfare perspective is reviewed carefully, he says.

The pigs used in the American project are not ordinary pigs.

- They are very carefully controlled.

First of all, they are cloned and genetically modified.

Then they are raised under strict conditions to avoid infections with viruses and bacteria, for example, says Lars Wennberg.

SVT:

- You could possibly imagine hearts.

The liver is a more complicated organ in that it is a large protein factory and many of human proteins differ from pigs, so it is more uncertain.