Twin's testicular transplant may have wider implications

A testicular transplant involving identical twin brothers may have broader implications for accident victims, soldiers, cancer patients and transgender people. 

A 36-year-old, born without testes, received the transplant from his identical twin brother, following a six-hour operation by an international team of surgeons in Belgrade, Serbia. The procedure, only the third known transplant of its type, was intended to stabilise testosterone levels and improve the brother's chances of fathering children in the future.

The operation was led by Dr Miroslav Djordjevic, a specialist in urologic reconstruction and sex reassignment surgery at Mount Sinai Hospital in New York and at the University of Belgrade, Serbia. Dr Djordjevic had been approached by the brothers, who wish to remain anonymous, after learning that he had performed a successful uterus transplant between twin sisters, enabling the recipient to give birth.

The surgical team also included Dr Dicken Ko, a transplant surgeon and urology professor at Tufts University School of Medicine in Boston, Massachusetts, and Dr Branko Bojovic, an expert in microsurgery at Harvard Medical School. Dr Ko and Dr Bojovic were both part of the surgical team that performed the first penis transplant in the USA in 2016.

The extremely complex procedure requires sewing together two arteries and two veins less than 2 millimetres wide. 'Once you remove the testicle from the donor, the clock starts ticking very fast,' Dr Bojovic told the New York Times. 'Within two to four hours, you have to have it re-perfused and working again.'

Without a blood supply, a testis is viable for only four to six hours and it can take up to one hour to make each of the four blood vessel connections, but the team managed to complete all successfully in less than two hours. The team did not connect the vas deferens, which carries sperm out of the testes, so the recipient cannot father children in the usual way, but he already has normal testosterone levels and is ready to go home, according to media reports.

The absence of testes is exceedingly rare, but this surgery may have broader applications for soldiers, accident victims and cancer patients. Dr Bojovic also said that the team has received enquiries from people undergoing gender reassignment who are interested in receiving transplants instead of undergoing the usual surgery, which creates a penis from the patient's own tissues.

However, this does raise issues regarding the ethics of non-lifesaving transplants. A transplant from any donor other than an identical twin would require immune-suppressing drugs to prevent rejection, which could have serious side effects. There is also the possibility of recipients fathering children with sperm from donors, who may not be related to them.

'Then the offspring is technically whose child?' asked Dr Ko. 'It raises much debate in the literature of medical ethics.'

Dr Djordjevic has a surgical plan for transplanting a penis onto an anatomically female body which he hoped to implement with the next year, but given the ethical dilemmas this raises has ruled out testicular transplantation as part of gender reassignment.