Free ureteral replacement in rats: regeneration of ureteral wall components in the acellular matrix graft.

ObjectivesTo evaluate ureteral replacement by a free homologous graft of acellular matrix in a rat model.MethodsIn 30 male Sprague-Dawley rats, a 0.3 to 0.8-cm midsegment of the left ureter was resected and replaced with an acellular matrix graft of equal length placed on a polyethylene stent. The animals were killed at varying intervals, and the grafted specimens were prepared for light and electron microscopy.ResultsIn all animals, the acellular matrix graft remained in its original position without evidence of incrustation or infection, and histologic examination showed complete epithelialization and progressive infiltration by vessels. At 10 weeks, smooth muscle fibers were observed; at 12 weeks, nerve fibers were first detected; at 4 months, smooth muscle cells had assumed regular configuration.ConclusionsThe ureteral acellular matrix graft appears to promote the regeneration of all ureteral wall components

In vitro functional properties of the rat bladder regenerated by the bladder acellular matrix graft.

PurposeTo assess the response of rat urinary bladder regenerated by the homologous bladder acellular matrix graft (BAMG) to in vitro electrical and pharmacologic stimuli.Materials and methodsIn Sprague-Dawley rats, partial cystectomy (>50%) was performed, followed by BAMG augmentation cystoplasty. After 4 months, organ bath studies of tissue strips in 10 were used to compare the contractility of the BAMG regenerates and the corresponding host detrusor smooth muscle.ResultsThe BAMG regenerates exhibited contractile activity to electrical field stimulation and a qualitatively identical pattern of response to muscarinic, purinergic, alpha- and beta-adrenergic drug administration and nitric oxide. At 4 months after surgery, the maximum forces of contraction of the BAMG regenerates to carbachol stimulation amounted to close to 80% of the host bladder response. With electrical field stimulation, they equaled 44% and 62% of the host bladder response after 2.5 and 4 months, respectively. Histological and immunohistochemical studies confirmed the presence of receptors for neurotransmitters that these functional in vitro studies implied.ConclusionsThe present study provides further evidence that augmentation cystoplasty with the BAMG leads to functional regeneration of the rat bladder detrusor smooth muscle

Bladder acellular matrix graft: in vivo functional properties of the regenerated rat bladder.

The purpose of this study was to determine whether the rat urinary bladder augmented by an acellular matrix graft can restore the bladder's low-pressure reservoir function and preserve normal micturition. After partial cystectomy (> 50%) and grafting with the bladder acellular matrix graft (BAMG), storage and voiding functions were monitored in 20 rats by means of a specially designed "micturition cage," leak-point cystography, and cystometry. After 4 months, sections (n = 6) were examined histologically to evaluate regeneration of bladder wall components within the BAMG. Bladder capacity and compliance increased progressively and were significantly higher in the grafted animals than in controls (partial cystectomy only), and volumes per void were significantly higher than in either control or normal animals. At 4 months, the regenerated urothelium, smooth muscle, blood vessels and nerves within the BAMG were qualitatively identical to normal bladder wall. Augmentation cystoplasty with the homologous BAMG leads to morphologic and functional rat bladder regeneration, thus enhancing low-pressure reservoir function and preserving normal micturition