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SPARE HUMAN PARTS

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ETHICALLY SOURCED HUMAN BODIES
https://technologyreview.com/pig-kidney-transplant-thymus
https://technologyreview.com/ethically-sourced-spare-human-bodies
Ethically sourced “spare” human bodies could revolutionize medicine
by Carsten T. Charlesworth, Henry T. Greely, & Hiromitsu Nakauchi  /  March 25, 2025

“Why do we hear about medical breakthroughs in mice, but rarely see them translate into cures for human disease? Why do so few drugs that enter clinical trials receive regulatory approval? And why is the waiting list for organ transplantation so long? These challenges stem in large part from a common root cause: a severe shortage of ethically sourced human bodies. It may be disturbing to characterize human bodies in such commodifying terms, but the unavoidable reality is that human biological materials are an essential commodity in medicine, and persistent shortages of these materials create a major bottleneck to progress. This imbalance between supply and demand is the underlying cause of the organ shortage crisis, with more than 100,000 patients currently waiting for a solid organ transplant in the US alone. It also forces us to rely heavily on animals in medical research, a practice that can’t replicate major aspects of human physiology and makes it necessary to inflict harm on sentient creatures. In addition, the safety and efficacy of any experimental drug must still be confirmed in clinical trials on living human bodies. These costly trials risk harm to patients, can take a decade or longer to complete, and make it through to approval less than 15% of the time.

There might be a way to get out of this moral and scientific deadlock. Recent advances in biotechnology now provide a pathway to producing living human bodies without the neural components that allow us to think, be aware, or feel pain. Many will find this possibility disturbing, but if researchers and policymakers can find a way to pull these technologies together, we may one day be able to create “spare” bodies, both human and nonhuman. These could revolutionize medical research and drug development, greatly reducing the need for animal testing, rescuing many people from organ transplant lists, and allowing us to produce more effective drugs and treatments. All without crossing most people’s ethical lines. Although it may seem like science fiction, recent technological progress has pushed this concept into the realm of plausibility. Pluripotent stem cells, one of the earliest cell types to form during development, can give rise to every type of cell in the adult body. Recently, researchers have used these stem cells to create structures that seem to mimic the early development of actual human embryos. At the same time, artificial uterus technology is rapidly advancing, and other pathways may be opening to allow for the development of fetuses outside of the body. Such technologies, together with established genetic techniques to inhibit brain development, make it possible to envision the creation of “bodyoids”—a potentially unlimited source of human bodies, developed entirely outside of a human body from stem cells, that lack sentience or the ability to feel pain.

Embryos made from stem cells, rather than an egg and sperm, appear to generate a short-lived pregnancy-like response in monkeys. There are still many technical roadblocks to achieving this vision, but we have reason to expect that bodyoids could radically transform biomedical research by addressing critical limitations in the current models of research, drug development, and medicine. Among many other benefits, they would offer an almost unlimited source of organs, tissues, and cells for use in transplantation. It could even be possible to generate organs directly from a patient’s own cells, essentially cloning someone’s biological material to ensure that transplanted tissues are a perfect immunological match and thus eliminating the need for lifelong immunosuppression. Bodyoids developed from a patient’s cells could also allow for personalized screening of drugs, allowing physicians to directly assess the effect of different interventions in a biological model that accurately reflects a patient’s own personal genetics and physiology. We can even envision using animal bodyoids in agriculture, as a substitute for the use of sentient animal species.

Of course, exciting possibilities are not certainties. We do not know whether the embryo models recently created from stem cells could give rise to living people or, thus far, even to living mice. We do not know when, or whether, an effective technique will be found for successfully gestating human bodies entirely outside a person. We cannot be sure whether such bodyoids can survive without ever having developed brains or the parts of brains associated with consciousness, or whether they would still serve as accurate models for living people without those brain functions. Even if it all works, it may not be practical or economical to “grow” bodyoids, possibly for many years, until they can be mature enough to be useful for our ends. Each of these questions will require substantial research and time. But we believe this idea is now plausible enough to justify discussing both the technical feasibility and the ethical implications. Bodyoids could address many ethical problems in modern medicine, offering ways to avoid unnecessary pain and suffering. For example, they could offer an ethical alternative to the way we currently use nonhuman animals for research and food, providing meat or other products with no animal suffering or awareness. But when we come to human bodyoids, the issues become harder. Many will find the concept grotesque or appalling. And for good reason. We have an innate respect for human life in all its forms. We do not allow broad research on people who no longer have consciousness or, in some cases, never had it. At the same time, we know much can be gained from studying the human body. We learn much from the bodies of the dead, which these days are used for teaching and research only with consent. In laboratories, we study cells and tissues that were taken, with consent, from the bodies of the dead and the living.

Recently we have even begun using for experiments the “animated cadavers” of people who have been declared legally dead, who have lost all brain function but whose other organs continue to function with mechanical assistance. Genetically modified pig kidneys have been connected to, or transplanted into, these legally dead but physiologically active cadavers to help researchers determine whether they would work in living people. In all these cases, nothing was, legally, a living human being at the time it was used for research. Human bodyoids would also fall into that category. But there are still a number of issues worth considering. The first is consent: The cells used to make bodyoids would have to come from someone, and we’d have to make sure that this someone consented to this particular, likely controversial, use. But perhaps the deepest issue is that bodyoids might diminish the human status of real people who lack consciousness or sentience. Thus far, we have held to a standard that requires us to treat all humans born alive as people, entitled to life and respect. Would bodyoids—created without pregnancy, parental hopes, or indeed parents—blur that line? Or would we consider a bodyoid a human being, entitled to the same respect? If so, why—just because it looks like us? A sufficiently detailed mannequin can meet that test. Because it looks like us and is alive? Because it is alive and has our DNA? These are questions that will require careful thought.

Until recently, the idea of making something like a bodyoid would have been relegated to the realms of science fiction and philosophical speculation. But now it is at least plausible—and possibly revolutionary. It is time for it to be explored. The potential benefits—for both human patients and sentient animal species—are great. Governments, companies, and private foundations should start thinking about bodyoids as a possible path for investment. There is no need to start with humans—we can begin exploring the feasibility of this approach with rodents or other research animals. As we proceed, the ethical and social issues are at least as important as the scientific ones. Just because something can be done does not mean it should be done. Even if it looks possible, determining whether we should make bodyoids, nonhuman or human, will require considerable thought, discussion, and debate. Some of that will be by scientists, ethicists, and others with special interest or knowledge. But ultimately, the decisions will be made by societies and governments. The time to start those discussions is now, when a scientific pathway seems clear enough for us to avoid pure speculation but before the world is presented with a troubling surprise. The announcement of the birth of Dolly the cloned sheep back in the 1990s launched a hysterical reaction, complete with speculation about armies of cloned warrior slaves. Good decisions require more preparation. The path toward realizing the potential of bodyoids will not be without challenges; indeed, it may never be possible to get there, or even if it is possible, the path may never be taken. Caution is warranted, but so is bold vision; the opportunity is too important to ignore.”

MECHANICAL WOMBS
https://technologyreview.com/artificial-human-embryos-are-coming
https://technologyreview.com/startup-embryo-organ-harvesting
This startup wants to copy you into an embryo for organ harvesting
by Antonio Regalado  /  August 4, 2022

“In a search for novel forms of longevity medicine, a biotech company based in Israel says it intends to create embryo-stage versions of people in order to harvest tissues for use in transplant treatments. The company, Renewal Bio, is pursuing recent advances in stem-cell technology and artificial wombs demonstrated by Jacob Hanna, a biologist at the Weizmann Institute of Science in Rehovot. Earlier this week, Hanna showed that starting with mouse stem cells, his lab could form highly realistic-looking mouse embryos and keep them growing in a mechanical womb for several days until they developed beating hearts, flowing blood, and cranial folds. It’s the first time such an advanced embryo has been mimicked without sperm, eggs, or even a uterus. Hanna’s report was published in the journal Cell on Monday. “This experiment has huge implications,” says Bernard Siegel, a patient advocate and founder of the World Stem Cell Summit. “One wonders what mammal could be next in line.” The answer is humans. Hanna tells MIT Technology Review he is already working to replicate the technology starting with human cells and hopes to eventually produce artificial models of human embryos that are the equivalent of a 40- to 50-day-old pregnancy. At that stage basic organs are formed, as well as tiny limbs and fingers.

Stem cells can be coaxed to self-assemble into structures resembling human embryos“We view the embryo as the best 3D bio printer,” says Hanna. “It’s the best entity to make organs and proper tissue.” Researchers can already print or grow simple tissues, like cartilage or bone, but making more complex cell types and organs has proved difficult. An embryo, however, starts building the body naturally. “The vision of the company is ‘Can we use these organized embryo entities that have early organs to get cells that can be used for transplantation?’ We view it as perhaps a universal starting point,” says Hanna. Embryonic blood cells might be collected, multiplied, and transferred to an elderly person in order to reboot the immune system. Another concept is to grow embryonic copies of women with age-related infertility. Researchers could then collect the model embryo’s gonads, which could be further matured, either in the lab or via transplant into the woman’s body, to produce youthful eggs.

The startup, funded so far with seed capital from the venture firm NFX, has been briefing other investors, and its pitch materials state that its mission is “renewing humanity—making all of us young and healthy.” Renewal Bio’s precise technical plan remains under wraps, and the company’s website is just a calling card. “It’s very low on details for a reason. We don’t want to overpromise, and we don’t want to freak people out,” says Omri Amirav-Drory, a partner at NFX who is acting as CEO of the new company. “The imagery is sensitive here.” Some scientists say it will be difficult to grow human embryo models to an advanced stage and that it would be better to avoid the controversy raised by imitating real embryos too closely. “It’s absolutely not necessary, so why would you do it?” says Nicolas Rivron, a stem-cell scientist at the Institute of Molecular Biotechnology in Vienna. He argues that scientists should only create “the minimal embryonic structure necessary” to yield cells of interest.


“Mouse embryos in mechanical womb from the 2021 study”
AGUILERA-CASTREJON ET AL., NATURE 2021

For his part, Amirav-Drory says he hasn’t seen a technology with so much potential since CRISPR gene-editing technology first emerged. “The ability to create a synthetic embryo from cells—no egg, no sperm, no uterus—it’s really amazing,” he says. “We think it can be a massive, transformative platform technology that can be applied to both fertility and longevity.” To create the succession of breakthroughs, Hanna’s lab has been combining advanced stem-cell science with new types of bioreactors. A year ago, the stem-cell specialist first showed off a “mechanical womb” in which he managed to grow natural mouse embryos outside of a female mouse for several days. The system involves spinning jars that keep the embryos bathed in nutritious blood serum and oxygen. In the new research published this week, Hanna used the same mechanical womb, but this time to grow look-alike embryos created from stem cells. Remarkably, when stem cells are grown together in specially shaped containers, they will spontaneously join and try to assemble an embryo, producing structures that are called embryoids, blastoids, or synthetic embryo models. Many researchers insist that despite appearances, these structures have limited relation to real embryos and zero potential to develop completely. By adding these synthetic mouse embryos to his mechanical womb, however, Hanna managed to grow them further than ever before, to the point where hearts started beating, blood began moving, and there was the start of a brain and a tail. “The embryos really look great,” says Hanna, whose report this week provoked awe among other scientists. “They are really, really similar to natural embryos.”

Analyses show the synthetic versions are about 95% similar to normal mouse embryos, based on the mix of cell types inside each. Even so, techniques for growing synthetic embryos remain inefficient. Fewer than 1 in 100 attempts to mimic a mouse embryo was successful, and even the model embryos that developed for the longest time eventually suffered abnormalities, including heart problems, perhaps because they couldn’t grow any further without a proper blood supply. In a next set of experiments, Hanna is using his own blood or skin cells (and those of a few other volunteers) as the starting point for making synthetic human embryos. It means his lab could soon be swimming in hundreds or thousands of tiny mini-mes—all genetic clones of himself. Researchers are growing embryos outside the womb for longer than has ever been possible.Hanna is not troubled by the idea. Despite the startling fact that he’s able to mimic the beginnings of mammals in test tubes, he views these as entities without a future. They’re probably not viable, he says. Plus, right now there is no way to graduate from jar life to real life. Without a placenta and an umbilical cord connected to a mother, no synthetic embryo could survive if transplanted to a uterus. “We are not trying to make human beings. That is not what we are trying to do.” says Hanna. “To call a day-40 embryo a mini-me is just not true.”

Still, as this technology progresses, there could be debate as to whether synthetic embryos have any rights—or if they can ethically be used as fodder for science and medicine. In the US, the National Institutes of Health has, in some cases, declined to fund studies on synthetic embryos that it believes would be too close to the real thing. Although Hanna doesn’t think an artificial embryo made from stem cells and kept in a lab will ever count as a human being, he has a contingency plan to make sure there is no confusion. It’s possible, for instance, to genetically engineer the starting cells so the resulting model embryo never develops a head. Restricting its potential could help avoid ethical dilemmas. “We think this is important and have invested a lot in this,” says Hanna. Genetic changes can be made that lead to “no lungs, no heart, or no brain.”

The new startup, Renewal, has already hired some of Hanna’s students and licensed his technology from the Weizmann Institute. It’s going to begin spending money improving the incubators, developing sensors to track the embryoids as they develop, and coming up with ways to extend their survival time in the lab. Amirav-Drory says the company is at such an early stage that it is still learning what the technology could be used for—and which applications are the most promising. He and Hanna, who is Renewal’s scientific founder, have been approaching other scientists and doctors to learn what they would do, if they had access to large numbers of synthetic embryos developed for days, or even weeks. “We’ve been asking people, ‘Imagine if we can get to this or that milestone. What does it unlock?’ And people’s eyes light up,” he says.”

PREVIOUSLY

REGROWING BONES
https://spectrevision.net/2015/07/17/regrowing-bones/
REPROGRAMMED STEM CELLS
https://spectrevision.net/2017/03/29/reprogrammed-stem-cells/
TISSUE REPROGRAMMING
https://spectrevision.net/2017/08/10/tissue-reprogramming/