FIRST STEPS TOWARDS ORGAN BANKS: VITRIFICATION OF RENAL PRIMORDIAL.

BACKGROUND: Kidney transplantation from deceased or living human donors has been limited by donor availability as opposed to the increasing demand, by the risks of allograft loss rejection and immunosuppressive therapy toxicity and by limitations of organ preservation protocols, which is essential to organise staff and facilities, transport organs, and perform necessary laboratory tests. However, the cryopreservation of composite tissues poses technical challenges beyond those seen in the preservation of single tissue types or organs. OBJECTIVE: The purpose of our study was to establish a protocol for long-term storing of renal primordia, that generates new adult kidneys after transplant into a syngeneic non-immunosuppressed host. MATERIALS AND METHODS: Metanephroi from 16-days-old embryos were microdissected and vitrified following the minimum essential volume method and using Cryotop as a device and VM3 as vitrification solution. After 3 months of storage in liquid nitrogen (-196 degree C), 20 metanephroi were warmed and transplanted using minimally invasive laparoscopic surgery into retroperitoneal fat of 5-month-old immune-competent New Zealand rabbits. In the same way, 22 fresh metanephroi were transplanted. Twenty-one days after transplantation, hosts were euthanized and developed kidneys were recovered and evaluated morphologically and histologically. RESULTS: Significant growth and fully differentiated mature glomeruli and tubule were observed in all kidney graft explants recovered. In total, 5 metanephroi (25.0%) were successfully grown after vitrification. In the same way, 12 metanephroi (54.5%) were successfully grown in the fresh group. CONCLUSION: These encouraging results reported that metanephroi not only survive vitrification, but they vascularized and developed morphologically normal glomeruli after their allotransplantation. These results suggest that it's possible to create a long-term biobank of kidney precursors as an unlimited source of organs for transplantation, and open new therapeutic possibilities for the patients with chronic renal failure.

Trasplante laparoscópico de metanefros: un paso inicial al xenotrasplante renal / Laparoscopic transplantation of metanephroi: A first step to kidney xenotransplantation

Antecedentes: Una solución novedosa a la escasez de riñones para trasplante puede ser el xenotrasplante de riñones embrionarios. Objetivo: Conocer la viabilidad del trasplante alogénico laparoscópico de metanefros (M) en conejos. Material y método: Se realizó disección microscópica para obtener metanefros en embriones de 14 días de edad (24 M), 15 (20 M) y 16 (26 M). Mediante laparoscopia abdominal de un puerto se insertó percutáneamente una aguja raquídea y por ella, mediante un catéter epidural, depositamos el metanefros cerca de un vaso sanguíneo patente en la grasa retroperitoneal. Setenta metanefros se trasplantaron a 18 conejos. Tres semanas después los animales fueron explorados por cirugía abierta. Se analizó la comparación de la madurez embrionaria, las variables morfométricas de los metanefros y la tasa de desarrollo de los metanefros trasplantados. Resultados: El límite temporal inferior para la extracción de metanefros en conejos es el día 14. Tres semanas postrasplante crecieron a una mínima expresión solo 3/24 M de 14 días (12,5%). Por el contrario, 10/20 (50%) de los de 15 días y 12/26 (46,1%) de los de 16 días de edad crecieron y se diferenciaron de tal manera que se habían desarrollado normalmente los glomérulos, túbulos proximales y distales y conductos colectores. No se detectaron cambios inmunológicos relevantes en sangre periférica. Conclusiones: Describimos, por primera vez en la literatura, el trasplante laparoscópico alogénico de metanefros de embriones como una técnica factible y no invasiva. Los receptores no necesitaron inmunosupresión

Background: Embryonic kidney xenotransplantation could represent a new solution to the scarcity of kidneys for transplantation. Objective: To determine the feasibility of allogeneic laparoscopic transplantation of metanephroi (M) in rabbits. Material and method: Microscopic dissection was conducted to obtain metanephroi from 14-day-old (24 M), 15-day-old (20 M) and 16-day-old (26 M) embryos. Using single-port abdominal laparoscopy, a spinal needle was inserted percutaneously, through which the metanephroi were deposited (using an epidural catheter) close to a patent blood vessel in the retroperitoneal fat. Seventy metanephroi were transplanted to 18 rabbits. Three weeks later, the animals were examined through open surgery. We compared the embryonic maturity, the morphometric variables of the metanephroi and the development rate of the transplanted metanephroi. Results: The lower time limit for the extraction of metanephroi from the rabbits was day 14. Three weeks after transplantation, only 3/24 14-day-old metanephroi grew at minimal expression (12.5%). In contrast, 10/20 (50%) 15-day-old and 12/26 (46.1%) 16-day-old metanephroi grew. These metanephroi had differentiated sufficiently for the glomeruli, proximal and distal tubules and collecting ducts to develop normally. We detected no relevant immunological changes in the peripheral blood. Conclusions: We have described for the first time in the literature the allogeneic laparoscopic transplantation of metanephroi from embryos as a feasible and noninvasive technique. The recipients did not require immunosuppression

Laparoscopic transplantation of metanephroi: A first step to kidney xenotransplantation.

BACKGROUND: Embryonic kidney xenotransplantation could represent a new solution to the scarcity of kidneys for transplantation. OBJECTIVE: To determine the feasibility of allogeneic laparoscopic transplantation of metanephroi (M) in rabbits. MATERIAL AND METHOD: Microscopic dissection was conducted to obtain metanephroi from 14-day-old (24M), 15-day-old (20M) and 16-day-old (26M) embryos. Using single-port abdominal laparoscopy, a spinal needle was inserted percutaneously, through which the metanephroi were deposited (using an epidural catheter) close to a patent blood vessel in the retroperitoneal fat. Seventy metanephroi were transplanted to 18 rabbits. Three weeks later, the animals were examined through open surgery. We compared the embryonic maturity, the morphometric variables of the metanephroi and the development rate of the transplanted metanephroi. RESULTS: The lower time limit for the extraction of metanephroi from the rabbits was day 14. Three weeks after transplantation, only 3/24 14-day-old metanephroi grew at minimal expression (12.5%). In contrast, 10/20 (50%) 15-day-old and 12/26 (46.1%) 16-day-old metanephroi grew. These metanephroi had differentiated sufficiently for the glomeruli, proximal and distal tubules and collecting ducts to develop normally. We detected no relevant immunological changes in the peripheral blood. CONCLUSIONS: We have described for the first time in the literature the allogeneic laparoscopic transplantation of metanephroi from embryos as a feasible and noninvasive technique. The recipients did not require immunosuppression.