New York: A team of US researchers, including one of Indian-origin, has conducted a series of pre-clinical studies that provide important first steps in developing techniques of robotic bladder transplantation in humans.
Although transplantation is an accepted treatment for many types of organ failure, human urinary bladder transplantation has never been performed. That reflects, in part, the daunting technical challenges entailed in such a procedure, including the difficulty of obtaining surgical access to the deep pelvis and the complex anatomy of the blood vessels in that area.
Patients with terminal bladder conditions which render the bladder unusable may undergo surgery to remove the bladder (cystectomy). This is followed by some type of diversion procedure to restore urinary function, typically using a segment of the patient’s own bowel tissue. Although these reconstructive procedures have a high success rate, they carry a substantial risk of short and long-term complications.
“Our study is the first report of bladder auto-transplantation in heart-beating, brain-dead human research donors as a necessary preparatory step toward clinical bladder transplantation in living patients,” said Inderbir S. Gill, of Keck School of Medicine, University of Southern California, Los Angeles.
Gill and his team, including Dr Nima Nassiri, performed a series of fundamental pre-clinical studies to develop the technique of robotic bladder transplantation. Their experience included three models of auto-transplantation — removing the bladder and associated tissues, including arteries, veins, and ureters; preparing it as if from a human donor; and transplanting the prepared organ back into the donor.
In the October issue of The Journal of Urology, the team described their initial experiments performed in pigs, due to the general similarity of the urinary tract and blood vessels to human anatomy. It was done in a living animal model.
They also performed an experiment on the human cadaver model, designed to simulate blood flow in a living patient.
Similar techniques were then carried out in beating-heart, deceased donors who had been declared brain-dead. This phase included five subjects whose families had consented to organ donation but were ineligible due to other illnesses.
Techniques developed in the animal and cadaver models were successfully applied to the beating-heart donors. In all three models, operative times for robotic auto-transplantation decreased with experience. In the beating-heart donors, total surgical time decreased from 10.5 to 4.7 hours.
Three out of four attempts at robotic auto-transplantation in beating-heart donors were successful, resulting in good blood flow to the transplanted bladder. In one case, the donor was maintained on life support for 12 hours to confirm the continued viability of the transplanted bladder.
Compared to open surgery, the robotic approach was felt to significantly facilitate donor cystectomy (bladder removal) surgery because of its superior technical access into the deep pelvis and blood vessel control.
Based on this rigorous pre-clinical developmental work, Gill and colleagues are preparing for the initial feasibility clinical trial of human bladder transplantation.
If the technique of bladder transplantation can be successfully developed and refined, it could become “a viable treatment option in a minority of well-selected and well-counselled patients,” the researchers said. They emphasise the many unanswered questions that remain — including the long-term functioning of the transplanted bladder, the need for lifelong immunosuppressive therapy to prevent organ rejection, and patient acceptance of bladder transplant versus standard urinary diversion procedures.
