Chimeras for transplantologists

American scientists create chimeras to save people

Vyacheslav Golovanov, GeekTimes

A group of American scientists is working on the creation of chimera organisms - embryos, one part of which is taken from humans, and the other from animals. The goals of these studies are to develop new methods of combating serious human diseases (by creating genetically modified animals to study the course of diseases), and, in the future, to create animals in which human organs could be grown.

Xenotransplantation, that is, the transplantation of organs and tissues from an organism of one biological species into an organism of another biological species, is a long-standing dream of physicians. If it were possible to transplant a human heart grown in an animal, dying people would not have to wait weeks and months in the queue for the appearance of a suitable donor. But so far, all that has been achieved is the transplantation of a pig's heart to a baboon.

Some scientists see a way out in the genetic modification of animals that are already quite close to humans so that they can serve as organ suppliers. But this area of research causes so much controversy that it becomes almost impossible to find funding. The National Institutes of Health (an institution of the US Department of Health) even imposed a moratorium on funding such developments.

But scientists don't give up. Pablo Ross, a specialist in reproductive biology, claims: "We don't aim to create a chimera simply because we need some kind of monster. We are doing this for biomedical purposes." In his laboratory, Ross is trying to create a pancreas that could be transplanted, for example, to patients with diabetes.

First, he removes from pig embryos the gene that they need to create a pancreas. To do this, using a laser, a hole is made in the outer membrane of the embryo, through which a specially synthesized substance is injected that removes this gene.

Pablo Ross in his laboratory at work

Then, human pluripotent stem cells are injected through another hole in the hope that the cells will fill the absence of a pig pancreas in the embryo and grow a human gland for it. After that, the edited embryo is placed in the uterus of a pig. Since the stem cells are taken from the tissues of the person himself, in the case of successful cultivation of the pancreas, his body will not reject the organ after transplantation.

So far, scientists are waiting 28 days from the moment the embryos are placed in the uterus, when they begin to form the rudiments of organs, extract them and study them under a microscope.

The ethical problem arises due to the fact that stem cells, theoretically, can create anything. What happens if they grow a pig a human brain? Will pigs suddenly be able to detect a consciousness close to human consciousness? This is what worries Professor of cell biology and anatomy Stuart Newman (Stuart Newman) from the New York Medical College.

"We are treading on shaky ground that could damage our humanity," says Newman. – And if you get a pig with a human brain, it can develop both human consciousness and human needs. We don't know for sure. And if two chimera pigs mate, a female pig may begin to develop a human embryo in the uterus." Or, the professor worries, some kind of human-pig hybrid in general.

"Another problem that worries many is that there is something sacred about what it means to be human, expressed in our genes," says Jason Robert, a bioethicist at Arizona State University. And that the introduction of this information into the body of animals, and the possible transfer of human capabilities to them, may be some kind of violation of this sacredness. In a sense, it's even a game of God."

Ross doesn't think he's playing God. "There is nothing close to it. We are just using the technologies that we have developed to improve people's lives." He explains that he does not allow embryos to develop for more than 28 days, that if the experiment goes wrong, it can always be stopped. In addition, you can not let the chimeras mate.

Another innovative method of creating new organs for transplantation is growing them "in vitro". The laboratory has already managed to grow human hearts, which even made them beat.

Portal "Eternal youth" http://vechnayamolodost.ru  26.05.2016