Half-Man Half-Pig is No Longer a Fantasy?

Annually, a hundred of thousands of patients die, hopefully waiting for life-saving organ donors. Only in the US, in 2022, 17 people died every day waiting for a transplant, with more than 100,000 reportedly on the waiting list. The extreme lack of human donor organs has forced scientists to look for alternatives for transplantation. This barrier turned into a solution, when people searched across species, bringing xenotransplantation (the transfer of living cells, tissues, organs across species) straight out of sci-fi movies into our reality. 

Currently, among all animals tested for the highest organ suitability, pigs’ organs are the most similar to human’s. This is largely due to porcine organs like heart, and kidneys are highly alike to human organs in size, function, and metabolic anatomy. Despite those phenomenal findings, the path to successful pig-to-human transplantation has long been blocked by an immediate immunological barrier known as hyperacute rejection (HAR). 

When a pig organ is transferred into a primate, the recipient’s body recognizes the tissue as a foreign object, as the immune system lunges an attack that destroys the graft within minutes to hours (Cooper et al., 2015). For decades, scientists sought for a way to weaken or isolate that certain trigger for the recipient’s immune system. It was discovered that human antibodies primarily target a carbohydrate epitope found on pig’s endothelial cells’ surface, also known as galactose-α1,3-galactose– “alpha-Gal” (Sandrin & Mckenzie, 1994). Since human and similar primate bodies lack enzymes required in order to produce alpha-Gal, the immune system sets it as a threat and activates the complement cascade to destroy the foreign tissue (Cooper et al., 2015).

However, nowadays, modern medicine actively uses CRISPR-Cas9 gene-editing technologies to overcome HAR. After long experiments, scientists were able to engineer “fake” pigs, where genes responsible for producing alpha-Gal are deleted completely. Researchers are pushing this a few steps further, as they modified some pigs to not only suppress that alpha-Gal gene, but also produce complement-regulatory proteins like hCD55, which shields transplanted tissue from immune attacks and stops blood clotting (Huai et al., 2025).

These genetic modifications proved themselves to be unexpectedly successful. In most recent procedures, genetically modified pig organs have been transplanted into human recipients, with promising stability. The first case of real xenotransplantation occurred in the February of 2022, as David Bennett Senior, a 57-year-old man with terminal heart disease received a pig heart with 10 genetic modifications. University of Maryland Medical Center in Baltimore surgeon Dr. Bartley Griffith performed high-risk surgery for 7 hours straight. This clinical breakthrough led the way for several successful organ transplants in the next 2024, 2025. In 2024, for example, surgeons at Massachusetts General Hospital performed an extraordinary procedure, prosperously transplanting gene-edited pig kidneys and livers into human patients with post-surgical long-term stability and no immediate HAR (Zhang et al., 2024).

So, is xenotransplantation possible in the near future? Yes! While clinics across the world are busy developing  rigorous infection control protocols and complex ethical considerations to ensure long-term graft survival, the rapid progress in gene-engineering techniques suggest that the xenotransplantation is inching closer to becoming a standard surgery in clinical practice (Huai et al., 2025; Zhang et al., 2024). Over time it is expected to perfect those techniques, standardizing pig-to-human transplantations, eventually leading to end the worldwide donor shortage.