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Progressive dilation for bladder tissue expansion.

PURPOSE
The use of gastrointestinal tissue for augmentation cystoplasty is associated with numerous complications. We previously reported the development of a system in which ureters were progressively dilated and used for ureterocystoplasty. We have now applied a similar system for the progressive expansion of native bladder tissue. We investigated whether the expanded bladder tissue retained normal functional and phenotypic characteristics.


MATERIALS AND METHODS
Urodynamic studies were performed in 5 beagle dogs and the bladder was divided horizontally into a superior bladder neo-reservoir, and an intact smaller bladder inferiorly with both ureters left intact and draining. A silicone catheter was threaded into the newly formed, superiorly located neo-reservoir, and connected to an injection port which was secured subcutaneously. A saline antibiotic solution was injected daily into the palpable injection port 4 weeks after surgery, dilating the neo-reservoir through the silicone catheter. Baseline and weekly cystograms were performed. Urodynamic studies of the neo-reservoirs were done immediately before sacrifice. Animals were sacrificed 3 months after the initial intervention and the bladder was examined grossly and microscopically.


RESULTS
Within 30 days after progressive dilation, the neo-reservoir volume was expanded at least 10-fold according to radiography and cystometrograms. Urodynamic studies of the dilated neo-reservoirs showed normal compliance in all animals. Microscopic examination of the expanded neo-reservoir tissue revealed normal histology. A series of immunocytochemical studies demonstrated that the dilated bladder tissue maintained normal phenotypic characteristics.


CONCLUSIONS
The system of progressive dilation is effective in expanding bladder tissue which is able to retain normal phenotypic and functional characteristics.