Transplants that pushed the boundaries of medicine

By Naveed Saleh, MD, MS, for MDLinx
Published December 19, 2018

Key Takeaways

Today, despite constant advances, transplantation medicine remains one of the most complex and challenging fields in medicine. It is still remarkable that the heart, brain, lungs, kidneys, liver, pancreas, intestine, and thymus can all be transplanted. In fact, in 2018, more than 30,000 organ transplants were performed, the most common of which were kidney, liver, and heart transplants, according to the United Network for Organ Sharing (UNOS). Transplantable tissues include the bones, tendons (musculoskeletal grafts), cornea, skin, heart valves, nerves and veins. Of these, cornea transplants and musculoskeletal grafts are by far the most common, outnumbering organ transplants more than 10 times.

Let’s take a look at six of the less common types of transplants—many of which have recently garnered a lot of attention—in which surgeons continue to push the traditional boundaries of medicine:

Toe-to-thumb transplants: Microsurgical toe-to-thumb transplant is the gold standard to fix thumb amputations and other thumb defects. In fact, this procedure was one of the first microsurgical procedures performed. Although thumbs are necessary to carry out countless functions, people don’t need toes to walk or perform other foot functions. Typically, surgeons take the person’s great or second toe from the non-dominant, or non-driving, foot (usually left) for transplant and trim it to look like a thumb.

The overall success rate of toe-to-thumb transfer is more than 95%. Although the transplanted toe doesn’t have the full range of motion of a thumb, it does exhibit a functional arc, as well as good sensation. Follow-up surgery is often required after initial transplant.

“The benefits of toe transfer are numerous,” wrote Steven L. Henry, MD, and co-authorsin a review article published in the Journal of Hand and Microsurgery. “The specialized tissue of the fingertip—with skin that is glabrous, durable, and highly sensitive; a septated pulp that balances conformability with sturdiness; and a nail that provides a sharp pincer while stabilizing and enhancing the function of the rest of the fingertip—can be replicated only by another digit. Bone, mobile joints, and tendons can also be restored. If missing tissue is to be replaced with like tissue, only a toe transfer will do.”

Uterus transplants: Just recently, a Brazilian woman became the first to successfully deliver a child following a uterus transplantation. This success followed 10 previous failed attempts at delivery after womb transplant in the United States, the Czech Republic, and Turkey. The Brazilian woman was 32 years old and born with a rare genetic disorder that resulted the absence of a uterus. Her donor was a 45-year-old woman who died from a brain hemorrhage.

The womb transplant took a team of surgeons 10.5 hours and involved anastomosing veins, arteries, ligaments, and the vaginal canal. After the surgery, the women spent a little over a week recovering in the intensive care unit, as well as a specialized transplant ward.

The woman received a bevy of immunosuppressive drugs, antibiotics, and anticoagulants. The eggs used for pregnancy were harvested by in vitro fertilization and fertilized.

Penis transplants: Chinese physicians performed the first penis transplant (one of two ever performed) in 2006 in a 44-year-old man using the penis of a 22-year-old deceased donor. The man who received the transplant lost his own penis in an accident, which left him with a stump 0.5 inches long. He couldn’t urinate standing up or engage in sexual intercourse. Although the man could urinate with his new penis, the appearance ended up shocking both he and his wife, and it was removed after 15 days.

Xenotransplantations: However strange, xenotransplantation, or cross-species transplantation, could provide an endless supply of organs that may somewhat correct the current paucity of organs for transplantation.

Here is a list of various historical xenotransplants:

  • Blood was transferred from animals to humans between the 17th and 20th centuries.
  • Skin grafts from frogs to humans were performed in the 19th century.
  • Between 1963 and 1964, before the advent of dialysis, 13 people received kidney transplants from chimpanzees. Most of these transplants failed after a few weeks, but one patient lived 9 months before dying of probable electrolyte disturbance.
  • A chimpanzee liver was transplanted to a human in 1966. In 1992, a patient survived 70 days after a baboon liver transplant.
  • In the 1920s, chimpanzee and baboon testicles were transplanted into humans to boost sexual drive and reverse the effects of aging.
  • A chimpanzee heart was transplanted into a human in 1964. The patient died 2 hours following surgery.
  • In 1983, an infant girl named “Baby Fae” received a baboon heart. She died 20 days after receiving the transplant from acute rejection.
  • In 1993, pancreatic islet cells were transplanted from pigs to humans in an attempt to treat diabetes. No clinical benefit was observed, although some patients did end up producing porcine C-peptide, indicative of endogenous insulin production.

None of these earlier attempts at cross-species transplantation resulted in prolonged improvement in clinical outcomes. Currently, genetically modified pigs seem to offer the most potential for future xenotransplantation. These pig tissues can be modified for protection against the immune response of humans.

Hand transplants: People who lose hands after amputation may be eligible for transplantation. Recipients of hand transplants receive either one or both hands, as well as portions of the forearm. Hand transplants are highly specialized and performed in only a few centers worldwide. These procedures can result in a degree of regained movement and sensation, although results are by no means guaranteed.

Face transplants: Face transplants are an option when a person’s face is disfigured beyond the benefit of plastic or restorative surgery. Face transplants can help the recipient regain functionality and a sense of identity. They can be partial or full, and involve the lower eyelids and tissue of the skin, muscles, bony structures, arteries veins, and nerves. To date, there have been around 40 face transplants performed globally, with the Cleveland Clinic being the first hospital to perform a near-total face transplant in the United States.

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