# Berkeley Scientific Journal
**Source**: https://bsj.studentorg.berkeley.edu/the-porcine-solution-to-organ-transplants/
**Parent**: https://bsj.studentorg.berkeley.edu/features-department/
[2025](https://bsj.studentorg.berkeley.edu/category/bsj-features/2025-bsj-features/), [BSJ Features](https://bsj.studentorg.berkeley.edu/category/bsj-features/), [Spring 2025](https://bsj.studentorg.berkeley.edu/category/bsj-features/2025-bsj-features/spring-2025-2025-bsj-features/)
## The Porcine Solution to Organ Transplants
[Emma Bi](https://bsj.studentorg.berkeley.edu/author/emmabi2021berkeley-edu/)
December 1, 2025
Transplantation is essential for end-state organ failures such as kidneys, heart, lungs, and liver. With currently 110,000 individuals in the US on the waitlist for an organ donation, the shortage of organ donors severely limits the success of transplantations.1 Many individuals die before transplantation, and quality of life is severely diminished for individuals with organ failure. Others may “list dive”, meaning they jump the waitlist line due to subjective decisions made by transplant centers, or they may even resort to organ trafficking. Xenotransplantation presents a groundbreaking solution to this severe organ donor shortage, with the potential to drastically reduce wait times and improve the quality of life for those suffering from organ failure.
**Figure 1**. Schematic flow of organ development in pigs with CRISPR-Cas9 technology for xenotransplantation in humans.
Scientists have recently used transgenes, genes artificially introduced into an animal, and CRISPR/Cas9 genome-editing, a novel technology that can directly target specific genes for modification, to alter organs in pigs for transplantation in non-primates and, most recently, human trials. One of the largest remaining challenges in transplantation is preventing organ rejection by the individual’s adaptive immune system, the system in the human body that develops targeted responses to potentially threatening pathogens.3 After organ transplantation, there are a number of potential rejection processes that could occur. They include an immediate short-term rejection called hyperacute rejection (HAR) minutes after transplantation, acute humoral xenograft rejection (AHXR) occurring days after HAR, and acute cellular rejection (ACR), which occurs days after transplantation.1,2,3,
**Figure 2**. Diagram of antigen recognition by antibody. Binding is mediated by favorable paratope-epitope interactions.\
HAR and AHXR rejections are primarily mediated by the immune system’s antibodies, which bind to the foreign cells and signal for macrophages (white blood cells that engulf microorganisms), and natural killer (NK) cells to invade the organ and eliminate the foreign cells. Antibodies in the transplant recipient bind to specific regions of the organ called epitopes, triggering lysis (programmed cell death), discolor from lack of oxygen (cyanosis), and organ failure.
In pigs, but not humans, one of the major epitopes is galactose-a-1, 3, galactose (a-Gal).2,3 Once transplantation takes place, the human antibodies recognize these a-Gal epitopes as foreign threats. To resolve this issue, scientists have mutated pigs with the gene encoding the a-Gal enzyme knocked using the CRISPR/Cas9 system, drastically reducing human antibody binding on porcine cells due to the absence of the epitope. Successful genetic modification of pigs involves the removing of porcine genes and the insertion of human genes to prevent HAR. With the correct combination of gene insertions and deletions, scientists hope to eventually be capable of minimizing the rejection of xenotransplantation in humans.3
There have been some promising xenotransplantation advances in recent years. In 2022, the first successful life-sustaining heart xenotransplant was performed at the University of Maryland, Baltimore. For over a month, the patient was performing well and in recovery. However, beginning day 45, the patient experienced infectious episodes that led to multiorgan failure and his death two months after surgery.3
While recent clinical trials have progressed, challenges like immune rejection and ethical considerations remain significant obstacles. However, given that most of these patients have no other alternative for survival, it is impressive that xenotransplantation can extend patients’ lifetimes, if only temporarily. Given the urgent need for alternative transplantation solutions, understanding xenotransplantation’s scientific and societal implications is crucial for improving the organ transplant system.
**References**
1. Kuscu, C., Kuscu, C., Bajwa, A., Eason, J. D., Maluf, D., & Mas, V. R. (2020). Applications of CRISPR technologies in transplantation. *American Journal of Transplantation*, *20*(12), 3285–3293.<https://doi.org/10.1111/ajt.16095>
2. Leonova, E. I., Reshetnikov, V. V., & Sopova, J. V. (2022). CRISPR/Cas-edited pigs for personalized medicine: More than preclinical test-system. *Research Results in Pharmacology*, *8*(3), Article 3.<https://doi.org/10.3897/rrpharmacology.8.83872>
3. Ryczek, N., Hryhorowicz, M., Zeyland, J., Lipiński, D., & Słomski, R. (2021). CRISPR/Cas Technology in Pig-to-Human Xenotransplantation Research. *International Journal of Molecular Sciences*, *22*(6), 3196.<https://doi.org/10.3390/ijms22063196>
**Image References**
1. Unsplash. (2021, March 5). *Photo by Julia Koblitz on Unsplash*.<https://unsplash.com/photos/person-holding-orange-and-white-toothbrush-RlOAwXt2fEA>
2. *CRISPR/Cas-edited pigs for personalized medicine: More than preclinical test-system | Research Results in Pharmacology*. (n.d.). Retrieved March 31, 2025, from<https://rrpharmacology.ru/index.php/journal/article/view/80>
3. Tankeshwar, A. (2021, June 1). *Epitopes: Types, Function, Epitope Spreading • Microbe Online*. Microbe Online.<https://microbeonline.com/epitope/>
December 1, 2025
Emma Bi
[2025](https://bsj.studentorg.berkeley.edu/category/bsj-features/2025-bsj-features/), [BSJ Features](https://bsj.studentorg.berkeley.edu/category/bsj-features/), [Spring 2025](https://bsj.studentorg.berkeley.edu/category/bsj-features/2025-bsj-features/spring-2025-2025-bsj-features/)
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