A team of scientists have announced the birth of piglets whose viral genetic information incorporated into DNA was deactivated using the CRISPR tool. In the same week, this same tool still allowed the historic genetic editing of human embryos, freeing them from serious but common genetic heart disease.
Thus, if this process of genetic correction in pigs becomes more widespread, the animal organs can be transplanted to humans.
Exemplifying the importance of these transplants, when a patient needs to replace the heart, lungs or kidneys, he must find a donor who is compatible. It is only in particular cases that these organs can be donated by living people, so sufficient organs are not being donated to respond to the number of people needing new hearts or lungs. Since the anatomy of pigs is very similar to that of humans, even in matters of proportion, making them organ donors could fill the lack of tissues for transplants.
Something that was not possible until now, since the genetic information of the bodies incorporates genes coming from viruses called endogenous retroviruses. Some of the microbes that pigs carry can be eliminated through chemical or vaccination, but when viral genetic information is embedded in the DNA of pigs – because it is transmitted through the sperm or the parent’s egg – it resists any medication. So that scientists tried to develop pig and human cells together in the laboratory, these viruses have been able to enter human cells. This meant that if a pig’s heart were put into the human body, the viruses would pass into our bodies and could cause diseases as serious as cancer.
Now researchers at eGenesis, a biotechnology company, have found a way around this problem. It is through a tool called CRISPR, which allows cutting out a damaged and well-identified part of DNA and replacing it with new healthy information, scientists have deactivated the genetic information embodied by retroviruses in the genetic material of pig embryos. Then they implanted these embryos in the womb of sows and waited for them to be born. They all developed: 37 were born and 15 of them are still alive, the oldest being 4 months old. These numbers still do not indicate that the mortality rate of pigs increases when DNA is changed, because it is normal for piglets to die of infection when they are still very young.
In 2002 an important step, similar to this one, was taken when a team was able to change the cell membrane of the pigs. The goal was to block a molecule that would cause the cells to be rejected after being introduced into the human body. Now that the two organisms are immunologically more similar, it is possible that after studying these processes better and knowing their side effects, it is possible to transplant organs from pigs to humans.