TAG: GS 3: SCIENCE AND TECHNOLOGY
THE CONTEXT: The first recipient of a genetically modified pig kidney transplant, 62-year-old Richard “Rick” Slayman, passed away on May 11, approximately two months after the surgery.
EXPLANATION:
- Both the Massachusetts General Hospital, where the procedure was performed, and Slayman’s family did not attribute his death to the transplant operation.
- This event brings attention to xenotransplantation, its potential, and its complications.
What is Xenotransplantation?
- Xenotransplantation refers to the transplantation, implantation, or infusion of live cells, tissues, or organs from a nonhuman animal source into a human recipient.
- This can also involve human body fluids, cells, tissues, or organs that have been in contact with live nonhuman animal cells, tissues, or organs.
- The goal is to use animal cells and organs to treat human diseases and conditions.
- The concept of xenotransplantation is driven by the significant gap between the number of patients needing transplants and the availability of human donor organs.
- In the United States alone, nearly 90,000 people are waiting for a kidney transplant, and over 3,000 die annually while still waiting.
- Xenotransplantation offers a potential solution to this organ shortage.
- The first attempts at xenotransplantation involving the heart were made in the 1980s.
- Over the years, advancements in genetic modification and surgical techniques have renewed interest in this field.
- The use of pig heart valves for human valve replacements has been successful for over 50 years, showcasing the anatomical and physiological similarities between pigs and humans.
The Procedure of Xenotransplantation
- The process of xenotransplantation involves several critical steps.
- Firstly, the animal organ must undergo genetic modifications to reduce the likelihood of rejection by the human immune system.
- For Slayman’s pig kidney transplant, 69 genomic edits were made using CRISPR-Cas9 technology.
- This included removing pig genes that produce sugars reactive to human antibodies and adding human genes to enhance compatibility.
- During the transplantation procedure, sewing the pig kidney into the human body is similar to a regular transplant.
- Post-surgery, standard immune-suppressing drugs are administered to prevent rejection.
- Continuous monitoring is essential to assess the body’s response to the transplanted organ.
Why Pigs are Preferred for Xenotransplantation
- Pigs are commonly used in xenotransplantation due to several factors:
- Anatomical and Physiological Similarity: Pig organs closely resemble human organs in size and function.
- Widespread Breeding: Pigs are farmed extensively, making them a readily available and cost-effective source.
- Variety of Breeds: Different pig breeds allow for matching the size of harvested organs with the specific needs of human recipients.
Notable Xenotransplantation Cases
- In January 2022, a genetically modified pig heart was transplanted into a human for the first time.
- The patient survived for two months but eventually died due to various factors, including a latent virus in the pig heart that contributed to transplant dysfunction.
Complications and Challenges in Xenotransplantation
- Xenotransplantation faces several complications:
- Organ Rejection: The human body may reject the animal organ. Techniques such as embedding the pig’s thymus gland with the kidney help mitigate immune responses.
- Infection Risks: There is a risk of infection from recognized and unrecognized infectious agents, potentially affecting not only the recipient but also close contacts and the general population.
- Cross-Species Infection: Retroviruses from animals can cross species barriers and cause diseases years after the infection, posing significant public health concerns.