Bryan Johnson, the 48-year-old multimillionaire known for his anti-aging experiments, claims he has created a human clone that could one day provide replacement organs. Johnson has previously spent around $2m a year on experimental longevity treatments and attracted global attention for using blood plasma from his then 17-year-old son in an attempt to slow aging, although he later discontinued the practice after finding no evidence that it improved his biological markers.
Against that backdrop, his latest claim is consistent with his willingness to pursue controversial biomedical experiments. However, the technology he describes does not involve creating a cloned human embryo. Instead, it relies on induced pluripotent stem cell (iPSC) technology, a well-established field of research in which cells taken from a blood sample are reprogrammed to behave similarly to embryonic stem cells.
The technique was pioneered in the 2000s by Japanese scientist Shinya Yamanaka, whose groundbreaking work earned him the 2012 Nobel Prize in Physiology or Medicine. While iPSCs have transformed regenerative medicine research, they do not currently allow the growth of fully transplantable human organs.
Bryan Johnson's cloning claim is eerily reminiscent of the 2005 film The Island, in which wealthy clients pay to have themselves cloned, keeping their clones confined to an isolated colony unaware of their true origin. The deception begins to unravel when one of the two protagonists is selected to be sent to the "Island", only to discover that clones exist solely to supply replacement organs for their originals.
Although The Island is a work of fiction, the underlying problem it revolves around is very real: the chronic shortage of transplantable organs worldwide. Whether Johnson's vision of using cloned tissue or embryos to grow replacement organs proves scientifically feasible remains uncertain for now, but it targets one of medicine's greatest unmet needs.
Despite a record 173,727 organ transplants performed worldwide in 2024, the World Health Organization estimates that current transplantation meets only about one-tenth of global demand, leaving millions of patients without access to life-saving organs.
Frankenstein's Laboratory
What is especially eerie about Johnson's remarks is his statement: “This baby Bryan lives in a petri dish for now.” Whether he intended to or not, the phrase evokes a reality that already exists in a more limited form. Through in vitro fertilization and surrogacy, some parents have conceived so-called “savior siblings”, children selected to be compatible tissue matches for an existing brother or sister suffering from diseases such as leukemia.
Stem cells collected from the baby's umbilical cord blood, and in some cases from later bone marrow donations, have been used to save the life of the older sibling. While this differs fundamentally from growing a cloned human for replacement organs, it illustrates how reproductive technologies are already being used to create children whose biological compatibility has life-saving medical value.
Unlike adults, the child cannot consent to being conceived for that purpose. This raises profound ethical questions about bodily autonomy and whether a human being should be brought into existence, even in part, to serve as a medical resource for another.
Embryonic stem cell research remains one of the most tightly regulated areas of biomedical science because it raises profound ethical questions about the beginning of human life. The legal framework varies considerably between countries, creating areas in which practices prohibited in one jurisdiction may be permitted in another.
In many countries, with informed consent and subject to regulation, tissue from aborted fetuses or surplus embryos created through in vitro fertilization can be donated for scientific research. Such human tissue has become an important resource in regenerative medicine and human stem cell research, where scientists hope to better understand human development and develop new treatments for currently incurable diseases. However, this relies on cells taken from a deceased human.
It would also be remiss not to mention that human stem cells have already been used in experiments to create human-animal chimeras, in which human cells are introduced into animal embryos to study disease, development and the possibility of growing transplantable organs.
Scientists have also created babies with DNA from three different people through mitochondrial replacement therapy, a procedure developed to prevent mothers with mitochondrial disorders from passing those diseases on to their children. At the same time, gene-editing technologies such as CRISPR have dramatically expanded scientists' ability to alter the human genome. This is raising new ethical questions about where the boundaries of biomedical research should lie.
Whether such interventions should be carried out on living human beings remains the subject of intense debate. Although much of this research is aimed at understanding disease and developing new therapies, fetal tissue and embryonic stem cells have also become valuable tools for basic biological research, drug development and other applications beyond the treatment of individual patients.
The Search for Ethical Organs
Unlike Johnson, whose announcement only hinted at a future in which he might one day require replacement organs, hundreds of thousands of people worldwide are already waiting for life-saving transplants. Many die before a suitable donor can be found. The chronic shortage of organs has fueled black markets in organ trafficking and prompted governments to consider shifting from opt-in to opt-out organ donation systems in an effort to increase the number of available donors.
One of the major challenges in growing replacement organs from genetically engineered pigs is overcoming immune rejection. Human immune systems recognize several pig-specific molecules as foreign, most notably the carbohydrate alpha-gal (α-Gal), which can trigger rapid and severe rejection of a transplanted organ. Gene-editing technologies such as CRISPR are being used by a company called Revivicor to remove these antigens and make pig organs more compatible with the human immune system.
These pigs are bred and kept in specially designed biosecure facilities under strict health protocols to prevent contamination. Another company called eGenesis invested $75m in building a facility for its pigs to enable what is known as xenotransplantation.
Xenotransplantation has already been trialed in four critically ill human patients. Although all four later died, the procedures helped advance research and provided valuable clinical data.
Even with conventional human organ transplants, immune rejection remains a major challenge. Recipients typically require lifelong immunosuppressive drugs, including tacrolimus, to prevent their immune system from attacking the donated organ. Tacrolimus has also been used in some surrogacy and reproductive medicine cases to help modulate the maternal immune response and reduce the risk of immune rejection of the genetically distinct fetus. Researchers are now investigating cell therapies that could instead prepare the immune system to accept a transplanted organ, potentially reducing or even eliminating the need for lifelong immunosuppression.
It increasingly appears possible that replacement human organs could one day be grown without relying on embryonic stem cells, cloned human embryos or experiments on human embryos, an advance that would resolve many of the existing moral debates. Significant scientific and regulatory hurdles remain, but advances in regenerative medicine suggest these approaches are moving closer to clinical reality.
