A group of scientists from the Salk Institute conducted a series of experiments that consisted on the implantation of human stem cells in early pig embryos. This is the first step toward the growing of human organs in other animals for them to be later transplanted into people with distinct diseases.

The study was oriented to growing human organs from patients’ skin generated stem cells. This cells would produce the specific organ to grow within the selected animal (in this case a pig), for the scientists to harvest it and transplant it to the patient. Since the generated organ had its genesis in the stem cells from the patient himself, there is very low risk for an immune rejection of the new organ.

human-pig-embryo
Injection of human iPS cells into a pig blastocyst. A laser beam (green circle with a red cross inside) was used to perforate an opening to the outer membrane (zona pellucida) of the pig blastocyst to allow easy access of an injection needle delivering human iPS cells. Image Credit: Salk Institute

This new experiment is creating creatures that are like chimeras since the animals selected had two different genomes from different species since the embryonic stage. These animals are conformed by a mix of human and pig cells, producing an unseen chimera-like specimen.

The team of biologists from the Salk Institute for Biological Studies in La Jolla, California, led by both Jun Wu and Juan Carlos Izpisua Belmonte, were able to prove that human stem cells are capable of generating pig tissue, even when both species have 90 years of different evolution processes.

Rat grown pancreases could reverse diabetes in mice

A recent study conducted by Stanford University School of Medicine and the Institute of Medical Science at the University of Tokyo showed that the pancreases grown on rats and generated from mice stem cells are capable of reversing the diabetes condition. (este link puede ir aqui http://www.pulseheadlines.com/grown-pancreases-transplanted-mice-revert-diabetes-condition/58432/ )

“Furthermore, the recipient animals only needed treatment with immunosuppressive drugs for five days after transplantation, rather than the ongoing immunosuppression that would be needed for unmatched organs,” said Hiromitsu Nakauchi, MD, Ph.D., a professor of genetics at Stanford, when explaining how the procedure worked in mice.

This study, along with the experiments done by the researchers from the Salk Institute both prove the viability of the human organ growing process in other animals as a way of reversing and treating several illnesses. However, many experiments must be conducted in order to accomplish that visionary goal.

The biologic community has spent years on understanding how the regeneration of tissue works and how to conduct valid experiments in that particular area. Scientists are not aware of what kind of chemical sequences are required to get each different tissue and organ regeneration.

“In the last 18 years, hundreds of labs, including ours, have tried to generate different cell types from human pluripotent stem cells in the culture dish with a cocktail of factors,” Dr. Izpisua Belmonte said. “But the cocktails are not identical to what the cells experience in the embryo. So I thought, ‘Why not let nature do the job?’”

There are a lot of technical and even ethical barriers that make difficult the creation of chimeras for scientific purposes. However, the tense situation regarding organs for transplants in the U.S. could enhance the respective investigations.

Currently, in the United States, there are about 80,000 patients in the wait-list to get an organ for transplant. However, the creation of chimeras with the use of stem cells in animal embryos could be very controversial.

The humanization of animals is undesirable for the scientific community, as none of them want to see a pig with human characteristics. Either way and according to Rudolf Jaenisch, a stem cell expert at the Whitehead Institute in Cambridge, Mass, this process “is a very promising work in principle.”

Current legislation regarding this kind of scientific experiments 

Back in 2005, Republican Senator Sam Brownback from the state of Kansas introduced a bill in the Senate that imposes a $1 million fine to anyone that conducts the creation of chimeras using human stem cells in the reproductive tissue system in animals.

Even when that bill didn’t pass, it raised a lot of concerns as it opened a public debate concerning this issue. In 2015, the National Institutes of Health approved a moratorium that included the use of public funds in any experiment process that would introduce human stem cells into animal embryos.

One year later, the National Institutes of Health started a request for the lifting of the ban, and instead recommended the making of legislation that includes that for any kind of human stem cells implantation processes, there must be a previous examination by a team of experts that can approve the procedure.

To this day, the ban is still valid, and it’s unknown if the Trump Administration would consider the lift of the moratorium or if any new legislations would be discussed by the Congress.

Even when the Salk Institue experiment was not affected by the N.I.H. moratorium, the study from the University of Tokyo did pass through rough times when conducting all the experiments.

According to Dr. Nakauchi, he had to move his laboratory to Stanford from Tokyo because the Japanese regulations concerning chimera research, for after being hit by the moratorium one year later. Because of this, the mice diabetes reverse discovery took nine years to be found by those researchers. “I have been in a very frustrating situation,” Nakauchi admitted.

Source: The New York Times