Science is not always pretty, and sometimes it is downright difficult to digest. In a new study, researchers successfully transplanted a rat’s testis under the skin of a recipient rat’s neck.
Let’s understand the purpose behind such a seemingly bizarre study, before delving into the nitty-gritty of the procedure.
"Chemotherapy or radiation therapy for malignant cancers often injure the spermatogenesis of young patients," the authors write in their study. This transplantation research, therefore, could one day help to preserve fertility in cancer patients. The study is published in PLOS One.
To explore this further, the team from Tokyo Medical University were particularly interested in the testicles’ "immune privilege" status. If a certain body part is immunologically privileged, it means they are able to tolerate the introduction of antigens without an inflammatory response. In essence, these regions are not readily rejected. The testis is one such lucky organ.
The difficulties then of such a surgical procedure lie in the technical transplantation. The previous technique relied on the removal and transplantation of the organ back to its original location, known as orthotopic testis transplantation (OTT).
This study used a different approach – the team transplanted the testicle to another area of the body, in this case the neck, in a procedure called heterotopic testis transplantation (HTT). This, the scientists say, is “technically more simple and reproducible than OTT."
(A) The technique for harvesting the testis with the epididymis and a part of the vas deferens. (B) The cervical HTT technique. (C) The transplantation of the testis under the skin of the neck. (D) Comparison of the subcutaneous temperatures. Kai Yi et al.
The testis-to-neck transplant was performed on 12 rats with a success rate of 100 percent. The OTT success rate, on the other hand, was lower at 71 percent, with a total operative time of more than an hour longer.
Still, three issues must be considered in the HTT transplant: fluctuations in temperature, blood flow disturbance due to the folding of the testicular vessels under the skin of the neck, and the drainage of the donor vas deferens to the outside of the recipient body.
"Transplantation of children’s testes and epididymides to their fathers or brothers before receiving medical therapy may be helpful for obtaining mature spermatozoa from the transplanted testes at a future date," the authors note. "It is also possible that the transplanted testes in recipients are transplanted back into donors after medical treatment. Therefore, the establishment of the HTT model may contribute to this unmet clinical need."
So definitely not a glamorous study, but the possibilities for future research and application are great. The new development improves our understanding of testicular immunology and could help improve medical procedures that may disrupt the production of sperm, such as in the case of cancer patients.