A team of surgeons in Japan has achieved the first successful transplant of kidney tissue into rat fetuses inside their mother’s uterus. The technique that allowed animals to obtain a new kidney represents an advance for human surgeries of the future. The intervention led by nephrologist Takashi Yokoo, from the Jikei University School of Medicine, in Tokyo, introduced a “proto kidney” to several fetuses while they were in the gestation process. The tissue from another embryo developed naturally until it formed a structure capable of producing urine.
Yokoo states that the internal and external kidney structures confirmed a mature organ. Even the fetuses’ blood vessels grew within the donated tissue. However, although the pups were born alive, their kidney never connected to the urinary system. The organ was observed for weeks while the urine it generated was extracted.
Scientists created a six-legged mouse to understand more about the “primordial structures” of embryos
The deactivation of a gene in the middle of a mouse’s embryonic development resulted in its genitals transforming into a new pair of limbs.
For the procedure, the Japanese team transplanted nine fetuses into four pregnant rats. Of all of them, only eight had a new kidney. To easily locate the tissue that came from the donor embryo, they used a genetic technique for expressing proteins with green coloring. This form of recognition is commonly used in transplant experiments, as recently occurred with the chimera monkey.
The study also revealed that organs grafted into fetuses have a lower rejection rate compared to grafts into adult rats. Therefore, surgical intervention during the early stages of embryonic development It is the most efficient way to correct organ failures, at least in mammals. Japan surgery results are available on the server bioRxiv; They are still awaiting peer review.
Xenotransplants in fetuses and adults
The technique that Yokoo now implemented will one day try to combat the Potter syndrome. This is a strange condition in which a human fetus does not develop functional kidneys, so the person dies within hours of birth. The genetic mechanism that prevents the development of the vital organ is unknown, but its early detection through ultrasound will mobilize doctors to insert tissue in the place where it is missing, experts think.
Medical science relies on xenotransplants to treat human conditions related to internal organs and the lack of donors. The most striking cases in recent years are pig heart, liver and kidney grafts. The operations have been successful, but monitoring each case reveals that there is still a long way to go.
For example, Lawrence Faucette, the second person to receive a pig heart, died six weeks after undergoing the experimental procedure. The news was a hard blow to the field of xenotransplantation since the organ was operated on with at least 10 genetic modifications to avoid the probability of rejection.
On the other hand, the first patient who received a pig kidney transplant had no complications in the process, although his monitoring will continue during the following months. Faced with the avalanche of xenotransplants, surgeons remain positive about their use in the coming decades.
