Science creates man-animal hybrid organs to overcome the scarcity of transplants, but ethical dilemmas and the risk of a market for rich remain enormous
The chimera was a terrifying mythological animal. He had goat body, lion head and snake tail. This monster image comes to mind in an almost spontaneous way in learning that attempts to grow human organs in animals mark constant progress. The final objective is clearly: with the scarcity of available organs, the so-called man-animal chimeras constitute a potential provision for future transplants in the human being.
Here are the facts. A few weeks ago, Chinese researchers from the Guangzhou Institutes of Medicine and Health, led by the scientist Liangxue Lai, for the first time they managed to grow buttons containing human cells within pork embryos and gave news to the International Society for Stem Cell Research held in Hong Kong. Chinese researchers have picked up embryos pigs, have deprived them of the genes involved in heart development and have injected you human stem cells there. Stayed alive for 21 days, these embryos over time have developed hearts of size comparable to those in the embryos in humans.
Xabier Aranguren, a leading researcher at the Cima-University of Navarra in Spain, known for his research on the identification of human cells with the potential to generate organs, comments: “These experiments represent an important milestone in the field of interspecious chimerism and the generation of organs by stem cells”.
Already in 2023, chimerical embryos containing a combination of human and pork cells had been transferred to surrogate mothers pork where they had developed kidneys. The fact that these organs were not entirely human must not suggest that research did not already represent a success. In fact, those kidneys, if fully formed, could be used for a transplant in humans. What now focuses on the research is the creation of chimeras with human organs one hundred percent. “The main challenge lies in the limited ability of human cells to integrate and contribute to the development of the host embryo”, explains Aranguren. «In general, human cells introduced into pork embryos contribute in very low quantities: about a human cell every 10 thousand -00 thousand pig cells. We must understand how better to overcome the interspecies that prevent an efficient integration and differentiation of human cells “.
The National Transplant Center calculated that until last April there were about 6 thousand people on the list for a kidney, a thousand for the liver, 750 for a heart, 300 for a lung and 200 for the pancreas. Last year 4,692 transplants were made, growing more than 5 percent compared to last year, and from January to the end of April about 1,100 transplants had been made. But the crucial question is this: the average of patients waiting for a transplant every year is about 8,200; If the transplants made are around 4,700 then it means that about 3,500 patients will not be able to receive the organ within a year. Too many. This difference is mainly due to the fact that the refusal to the donation is still high, with 36.3 percent of people who, the renewal of the identity card has declared that he did not want to donate. “The global deficiency of organs continues to be a critical problem and many patients die waiting for a compatible transplant,” recalls Aranguren. “Thus, the ability to cultivate human organs in animals could one day provide a renewable and personalized source of transplainable fabrics, potentially eliminating waiting lists and improving the results. Rather than generating tailor-made organs for specific individuals-which could potentially lead to discrimination-the idea is to produce organs from a set of definite of human cellular lines that collectively cover the entire spectrum of immuno-compatibility. This approach would make the benefits of technology accessible to everyone, avoiding the creation of “first -class” patients and promoting fair access to transplant therapies “.
In 2021, a highly discussed study published on Cell, and conducted at the Salk Institute for Biological Studies in California, aimed to understand interspected cellular communication and the behavior of human cells in an monkey embryo. «Research on primates remains a topic of remarkable ethical debate and is therefore subject to rigorous regulatory checks. These studies provide for the micro -injection of human cells in monkey embryos in in vitro contexts. On the other hand, pigs are considered the most suitable model for this type of research thanks to their physiological similarities with human beings and their practical advantages in terms of reproductive biology and organ size “. To the list of chimeras made to last for a number you can add those men-pope, the quail-galline and the mouse mopes to obtain study models.
Research on chimeras puts us in front of no small ethical risks and problems. Current studies limit development in the early embryonic phases (for example, 14 or 28 days) to prevent brain maturation. But if we went on, could we create animals with improved cognitive or self -awareness?
“I believe that there is no ethical committee that would approve experiments with human cells intended for the brain,” Aranguren replies. “On the contrary, all the experiments that involve them must be conducted gradually, analyzing the embryos in the initial stages of development, in order to evaluate the degree of contribution of human cells to the different organs and avoid an unwanted widespread chimerism in the brain”.
But ethical dilemmas do not end there: what really is a man-animal chimera? A real person or something that is halfway between the human and the animal? And this new being would have or would have no rights? The question sounds even more pressing if we consider that, when and if we carry out transplants from chimeras to human beings, we will be using the first as mere tools for the improvement of our lives. The International Society for Stem Cell Research has published guidelines for the regulation of experiments on chimeras that use human stem cells. This is a positive news because international ethical standards are needed for these research, rather than laws other than country to country, as well as an open dialogue between scientists, ethics and citizens experts.
