A Large Animal Model of Bladder Exstrophy
While most patients who undergo bladder exstrophy closure develop sufficient bladder capacity, others do not. To discover the factors which lead to these differences, we compare bladder biopsies from normal neonatal sheep to those of sheep which have undergone creation of bladder exstrophy. We then compared these results with those of a previous study in which we compared bladder biopsies from human neonatal bladders to newborn exstrophy bladders.
Materials and Methods
In earlier work from our laboratory, bladder specimens from 9 normal neonatal human bladders were compared to 12 newborn exstrophy bladders. We demonstrated an increase in collagen and a decrease in smooth muscle in the exstrophy bladders as compare to the normal bladders. We also demonstrated a threefold increase in Type III collagen in the exstrophy bladders when compared to the controls. Now we proceed with a similar analysis between normal and exstrophic lamb bladders developed via a previously published animal model of bladder exstrophy. Bladder specimens from 10 newborn control lambs and 7 lambs with bladder exstrophy were stained with Maison trichrome as well as monoclonal antibodies to Type I and Type III collagen. Specimens were then analyzed via a color digital image analysis system.
In the sheep model, there was a significant increase in collagen versus smooth muscle in the exstrophy bladders when compared to the controls (p<0.05). This finding is similar to that seen in human exstrophy bladders. However, unlike in the human tissue, we did not find a significant difference in the ratio of Type I and Type III collagen between the two groups.
The exstrophy bladder specimens from the fetal lamb model reveal a similar increase in collagen versus smooth muscle, as do the specimens from our exstrophy patients. They do not, however, demonstrate the same increase in collagen Type III, as do the patient specimens.
KeywordsLarge Animal Model Normal Bladder Male Fetus Control Bladder Fetal Demise
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