Mesenchymal-epithelial interactions in the bladder

During bladder development, undifferentiated mesenchymal and epithelial cells undergo an orderly sequence of differentiation defined by the expression of smooth-muscle (alpha-actin, myosin, vinculin, desmin, vimentin, and laminin) and epithelial (cytokeratins 5, 7, 8, 14, 18 and 19) protein markers. This process requires mesenchymal-epithelial interactions with bladder epithelium (urothelium) necessary for the differentiation of bladder smooth muscle. Peptide growth factors such as keratinocyte growth factor (KGF) and transforming growth factors (TGF) alpha and beta are likely candidates as mediators of these mesenchymal-epithelial interactions. Transcripts for KGF, TGF alpha, and TGF beta are regulated during bladder development and during smooth-muscle hypertrophy secondary to bladder-outlet obstruction. Finally, two experimental bladder models--(1) partial outlet obstruction and (2) regeneration of bladder smooth muscle into an acellular tissue matrix--are described in the context of mesenchymal-epithelial interactions in the bladder.

The effect of prepubertal androgen exposure on adult penile length

PURPOSE

Recent studies in the rat suggest that early exposure to exogenous testosterone accelerates the loss of androgen receptors and compromises eventual penile length. To determine whether this is true in men we measured adult penile length of patients treated in childhood for sexual precocity.

MATERIALS AND METHODS

We examined 21 men with sexual precocity due to true precocious puberty (12) or congenital adrenal hyperplasia (9) who had been followed at our institution since childhood. Penile lengths were compared with data from normal men.

RESULTS

Mean stretched penile length plus or minus standard deviation was 12.7 +/- 2.6 cm. in all patients, 12.1 +/- 2.6 cm. in those with true precocious puberty and 13.6 +/- 1.6 cm. in those with congenital adrenal hyperplasia. These lengths were not significantly different from those of normal men (12.4 +/- 2.7 cm.).

CONCLUSIONS

In contrast to findings in rats, exposure to endogenous testosterone during gestation and/or childhood does not reduce adult penile length in men. Thus, the use of testosterone to treat childhood genitourinary anomalies would likely not compromise mature penile size.

Growth factors and receptors in bladder development and obstruction

During fetal and neonatal development and experimental obstruction, the bladder wall undergoes changes in both the amount and composition of the urothelium, extracellular matrix, and smooth muscle. We hypothesize that cell-cell signaling among the different layers of the bladder wall mediates these changes. Growth factors likely to be involved in this process are keratinocyte growth factor (KGF) and transforming growth factor (TGF)-alpha, -beta 2, and -beta 3. Whole rodent bladders were analyzed by RNase protection assays for KGF, KGF receptor, TGF alpha, epidermal growth factor receptor, and TGF beta 2 and -beta 3 transcripts at Fetal Day 14 (before smooth muscle differentiation) and Fetal Day 18 (after smooth muscle differentiation), at birth, and 60 days postnatal. Growth factor transcripts were also analyzed in partially obstructed rodent bladders and in sham-operated animals. TGF beta 2 and -beta 3 mRNA expression decreased as a function of gestational age, whereas TGF alpha mRNA increased. KGF mRNA was low before smooth muscle differentiation at 14 days' gestation, then increased. The mRNA of receptors for KGF and EGF remained essentially unchanged throughout bladder development. In bladders subjected to partial urethral outlet obstruction, there was a 2-fold increase in mRNA for TGF beta 2, a 5-fold increase in TGF beta 3, and a 10-fold increase TGF alpha mRNA. In contrast, there was no change in transcripts for either KGF or receptors for KGF and epidermal growth factor. Immunohistochemical localization of the protein for these growth factors showed selective localization to the epithelium and/or smooth muscle for TGF beta 2 and -beta 3, whereas TGF alpha and the epidermal growth factor receptor localized throughout the bladder wall. In conclusion, growth factor mRNA expression is modulated in bladder development and obstruction, which implies a possible mechanistic role of growth factors for the observed changes in the bladder wall and extracellular matrix.

Regeneration of bladder urothelium, smooth muscle, blood vessels and nerves into an acellular tissue matrix

PURPOSE

To study the cellular events occurring during bladder development and regeneration we developed an in vivo model of bladder augmentation with an acellular tissue graft. We propose that the extracellular matrix orchestrates the regenerative capacity of host bladder cells (urothelium, smooth muscle, blood vessels and nerve cells) after bladder augmentation with acellular tissue matrix.

MATERIALS AND METHODS

A total of 40 adult rats underwent partial cystectomy and augmentation with a patch of extracellular matrix representing the full thickness of rat gastric or bladder tissue. Sections were examined histologically to assess urothelial, smooth muscle and neuronal invasion of the graft.

RESULTS

A total of 32 rats was evaluated 1 day to 26 weeks after grafting. Epithelialization occurred by day 4, accompanied by granulocytic infiltration. Smooth muscle regenerated 2 weeks after grafting in juxtaposition to epithelial surfaces and it matured into normal sized bundles by 26 weeks. Neovascularity was noted 2 weeks postoperatively. Neural elements formed around developing smooth muscle bundles as early as 4 weeks after grafting.

CONCLUSIONS

We demonstrated the regeneration of urothelium, smooth muscle, blood vessels and nerves within a full thickness grafted acellular tissue matrix scaffold in the rat. The spatial orientation of these elements suggests that mesenchymal-epithelial interactions occur during phenotypic regeneration of the bladder. Urothelium appears to regulate the early forming smooth muscle. This in vivo model provides a suitable method to study cellular events during regeneration.

Lower urinary tract function in ambulatory children with spina bifida

OBJECTIVE

To investigate lower urinary tract function in ambulatory children with myelomeningocele.

PATIENTS AND METHODS

The urological course of 45 children with myelomeningocele who walked either independently (19 children) or with ankle-foot orthotics (26 children) was reviewed. Follow-up ranged from 9 months to 13.5 years (mean 4.75 years).

RESULTS

A normal pattern of voiding was observed both clinically and during urodynamic evaluation in only three of the 45 children, with the remainder displaying neurogenic lower urinary tract dysfunction. The independent walkers and those with orthotics did not differ in the spectrum of lower urinary tract dysfunction or other variables. Those patients with persistent incontinence underwent an initial urodynamic evaluation when older (mean 3.7 years versus 6.4 weeks in those who were continent).

CONCLUSION

Ambulatory children with myelomeningocele suffer the full spectrum of lower urinary tract dysfunction. Given the potential danger of untreated lower urinary tract dysfunction, ambulatory children with myelomeningocele should receive the same diagnostic and therapeutic attention as their peers with more overt neurological deficits.

Epithelial development in the rat ventral prostate, anterior prostate and seminal vesicle

The prostate and seminal vesicle (SV) are androgen-dependent secretory glands of the male genital tract. The epithelial cells of these glands produce the bulk of the seminal secretions. The objective of the present study was to examine the ontogeny of cytokeratin and androgen receptor (AR) expression in the rat SV, anterior prostate (AP) and ventral prostate (VP). The study utilized organ culture to examine the effects of androgens on the development of these markers and castration of adult rats to examine androgenic effects on their maintenance. Tissues were examined from 14 days of gestation to adulthood. The SV was a tubular organ from its inception while the prostate formed from solid epithelial cords. These prostatic buds canalized in a proximal to distal manner starting at day 1 postnatal in the VP and day 5 in the AP. The expression of cytokeratins and AR was visualized by immunocytochemistry. In all three glands keratins 5, 7, 8, 14, 18 and 19 were initially uniformly expressed in all epithelial cells. In the SV, segregation of cytokeratins between the luminal and basal cell types started at 4 days postnatally with keratin 7 localizing to basal cells. Five days after birth, keratins 5 and 14 were also localized to the basal epithelium, while keratins 8 and 18 were only expressed by luminal cells, Keratin 19 was expressed in all epithelial cells throughout development and into adulthood. In the VP and AP the same pattern of cytokeratin segregation occurred as in the SV. Epithelial differentiation occurred in a proximal to distal fashion in the prostate. In the proximal VP ducts keratins 7 and 14 were basally localized by 2 days postnatally, while keratin 5 did not clearly segregate to basal cells until day 9 after birth. In the AP keratin 14 was basally localized by 1 day postnatal but keratin 5 and 7 did not colocalize to the basal cells until days 9 and 12, respectively. AR were expressed in the epithelium of the urogenital sinus from 19 days of gestation. At 19 and 20 days of embryonic development AR-negative prostatic buds were seen emerging from the AR-positive urogenital sinus epithelium. By birth AR were detectable in the epithelium of both prostatic lobes and the SV. The role of androgens in the development of the prostatic and SV epithelium was investigated in a serum-free organ culture system. These experiments showed that differentiation of prostatic and SV luminal and basal epithelial cell types was accelerated as compared to the in vivo situation in the presence of androgens, and did not occur in their absence. Following castration of adult animals the prostate and SV regressed with preferential loss of luminal epithelium. The relative numbers of basal cells was increased, though some flattened cells expressing a luminal cell pattern of cytokeratins were still observed. AR were detected in the prostatic and SV epithelium of long-term castrated animals. In summary, the rat prostate was found to be derived from undifferentiated solid epithelial cords. Canalization occurred concurrent with the differentiation of clear epithelial subtypes. Epithelial AR were expressed from around the time of birth and expression levels increased with age. The SV was canalized from its inception but likewise was derived from an undifferentiated epithelial precursor.

Ontogeny of the rat bladder: smooth muscle and epithelial differentiation

The sequential expression of smooth muscle and epithelial markers in the rat bladder has been defined. Smooth muscle differentiation, based on cell morphology and immunohistochemical localization of smooth muscle alpha-actin, myosin, vinculin, desmin, vimentin and laminin, begins at 16 days of gestation (birth = 22 days) in the rat bladder. Smooth muscle cell differentiation begins in the periphery of the bladder mesenchyme immediately subadjacent to the serosa and continues toward the urothelium. The cytokeratins 5, 7, 8, 14, 18, and 19 are expressed in the bladder epithelium as a function of developmental age with cytokeratin 7, 8, 18, and 19 being coexpressed at 15 days' gestation followed by cytokeratin 5 at 17 days' gestation and cytokeratin 14 in the newborn bladder. An understanding of the ontogeny of both smooth muscle and epithelial differentiation markers in the normal bladder will allow us to study events that occur in the diseased bladder.

Stromal development in the ventral prostate, anterior prostate and seminal vesicle of the rat

The prostate and seminal vesicle (SV) are androgen-dependent secretory glands of the male genital tract. They produce the bulk of the seminal secretions. The object of the present study was to examine and document the ontogeny of stromal maturation in the rat anterior and ventral prostate and SV. These organs have a loosely organized cellular mesenchyme during fetal development. During prostatic development the mesenchyme condensed to form smooth muscle sheaths immediately surrounding the epithelium, with looser connective tissue between individual ducts. In the SV, a loose connective tissue layer called the lamina propria lies between the epithelium and developing muscle. Smooth muscle alpha-actin, myosin, desmin, laminin, vinculin, vimentin and androgen receptor (AR) expression were examined by immunocytochemical methods during the pre- and postnatal developmental periods. The first marker to be detected was vimentin, which was initially found throughout the mesenchyme. During development vimentin became mostly restricted to the interductal tissue of the prostate and the lamina propria of the SV. Smooth muscle markers were expressed in an orderly sequence in a proximal to distal manner along prostatic ducts, from the urethra towards the tips. Expression of alpha-actin was followed by vinculin, myosin, desmin, and laminin. These markers became localized to the developing smooth muscle sheaths and were not expressed in the interductal tissue of the prostate or the lamina propria of the SV. Organ culture experiments demonstrated that androgens were required for the differentiation of smooth muscle sheaths. Castration of adult rats demonstrated that androgens were required to maintain smooth muscle differentiation. In castrates, the stroma was relatively thicker but less dense than in intact animals. Following castration, expression of the smooth muscle markers was lost sequentially in the reverse order of their expression during development. In long-term castrates alpha-actin, vimentin and a small amount of vinculin were detected. AR were first detected in the urogenital sinus mesenchyme immediately surrounding the epithelium at 16 days of gestation. As development progressed expression of AR became more widespread, and postnatally was found throughout the mesenchyme. As maturation of smooth muscle occurred, stromal expression of AR became localized to the muscular sheath immediately surrounding the epithelium. In the prostate the interductal connective tissue displayed very low levels of AR expression. In the SV, AR were also observed in the lamina propria. In summary, stromal differentiation and dedifferentiation in the rat prostate and SV were found to be androgen-dependent processes with ordered sequential ontogenic expression of specific markers.

Contradictory renal function measured with mercaptoacetyltriglycine diuretic renography in unilateral hydronephrosis

PURPOSE

We studied apparently supranormal renal function in hydronephrotic kidneys, as measured by 99mtechnetium mercaptoacetyltriglycine renography.

MATERIALS AND METHODS

We retrospectively reviewed the clinical history, ultrasonography and renography of 29 children.

RESULTS

Of the 29 children 7 had greater than 50% relative function in the hydronephrotic kidney. This finding was independent of patient age, gender, degree of hydronephrosis or obstructive pattern. Of these 7 cases 6 occurred on the right side (p < 0.05 versus a large registry).

CONCLUSIONS

In most cases supranormal renal function is caused by a technical problem, likely the inadequate background subtraction of mercaptoacetyltriglycine in the liver.

Recurrent Staphylococcus aureus renal abscess in a child positive for the human immunodeficiency virus

A 10-year-old girl with the human immunodeficiency virus was found to have a Staphylococcus aureus renal abscess with perinephric extension. The abscess was drained first percutaneously and then surgically, and the patient received a 6-week course of intravenous antibiotics. Three months later, the abscess recurred, necessitating a nephrectomy. The extended morbidity and difficulty of eradicating S aureus suggest that, in immunocompromised patients, early aggressive surgical management is indicated.

Buccal mucosal urethral replacement

Graft substances, such as skin and bladder mucosa, have been previously used for urethral replacement when local epithelial tissue was not available. However, these substances have been associated with meatal prolapse, stricture and fistula formation. We have used buccal mucosa as a tissue for urethral substitution in these situations during the last 8 years. We review our clinical experience in 18 urethral reconstructions performed for urethral replacement in 4 cases of exstrophy/epispadias, 12 complex hypospadias repairs and 2 cases of complex bulbar urethral strictures. There have been 5 cases of meatal stenosis (2 requiring operative revision) but none of meatal eversion. There has also been 1 urethrocutaneous fistula and 1 mid graft stricture. Mean followup was 27 months and minimum followup was 6 months. Histological examination of the buccal mucosal graft compared to grafts of skin showed that the full thickness of the dermis or lamina propria is thinnest while the native vascular supply is greatest in the buccal mucosa. These 2 factors are associated with improved graft take and may explain the encouraging clinical results.

Primary dilated megaureter: long-term followup

Previously, we reported on the changing concepts in the management of 35 neonates with primary obstructive megaureters, 25 of whom were observed without surgery for a mean of 28 months while 10 were surgically treated. We report the long-term outcome of the 25 patients who were managed without surgery. This group consists of 19 male and 6 female neonates with 19 unilateral and 6 bilateral dilated ureters. Of the patients 17 presented with an antenatal diagnosis of hydronephrosis, 2 with infection and 6 with incidental findings. None of the patients had vesicoureteral reflux. Followup serial imaging (2 or more studies per case) consisted of excretory urography in 18 of the 25 cases, diethylenetriaminepentaacetic acid renal scan in 16 and/or sonogram in 10. Mean followup was 7.3 years (range 4.8 to 12.4) for 24 patients and 1 was lost to followup after 1.5 years. Excretory urography showed improvement in urinary tract dilatation in 12 cases and stable dilatation in 6. Renal scans demonstrated expected interval increases in the glomerular filtration rate with age without any deterioration in per cent of renal function in all 16 cases. None of the patients had stones, pain or pyelonephritis. We conclude that it is safe to follow a select group of patients with primary dilated megaureters in the absence of vesicoureteral reflux. We recommend antibiotic prophylaxis and serial urinary tract imaging to confirm renal growth and preservation of renal function.

Type III collagen decreases in normal fetal bovine bladder development

In normal fetal bovine bladder development we have shown that compliance increases at approximately the same time that urine production first occurs. The late first trimester fetal bladders are relatively stiff with a progressive increase in bladder compliance peaking in the newborn period. From the newborn period through adulthood, we documented a relatively modest decrease in bladder compliance, which may result from the normal aging process. To account for these changes, we have used the bovine model to perform biochemical analyses of the major structural collagens that are found in the bladder (types I and III). These results show that the per cent of type III collagen decreases in the developing bladder from the end of the first trimester until the newborn period. Comparing the newborn bladder to that of a mature adult, we documented a relatively modest increase in the amount of type III collagen. We demonstrated that the ratio of type III-to-type I collagen parallels the normal compliance changes in the developing fetal and mature bovine bladder.

Dorsal tunica albuginea plication for hypospadias curvature

A systematic approach is described to correct congenital penile curvature using intraoperative artificial erection, preservation of the urethral plate when possible, tunica albuginea plication to straighten the penis and island flap urethroplasty (onlay and tube) when needed. After many years of experience we recognize that curvature correction is not necessarily enhanced by division of a healthy urethral plate. To correct inherent congenital curvature or corporeal disproportion we use a modification of the Nesbit dorsal tunica albuginea plication.

Changing concepts of hypospadias curvature lead to more onlay island flap procedures

From 1987 through 1992, 1,109 primary hypospadias operations were performed at our hospital, of which 374 (33%) were onlay island flap procedures. In contrast, from 1982 to 1987 only 66 of 657 primary hypospadias repairs (10%) were onlay island flaps. The increase in this type of repair stems from the observation that in most cases of hypospadias the urethral plate is not the cause of penile curvature. Intraoperative artificial erection after skin take down revealed that only 50 of the 374 patients (13%) still had a significant bend. After experience demonstrated that the residual bend was not due to a fibrous urethral plate, but rather to a generally mild (20 to 30 degree) corporeal disproportion, correction was achieved by dorsal tunica albuginea plications. We conclude that better healing of the onlay flap to spongiosum supported urethral plate may account for the lower fistula rate (6%) observed with the onlay island flap hypospadias repair, and even in severe cases of hypospadias the urethral plate is usually healthy and it does not require division to produce a straight penis.

Culture of urethral fibroblasts: cell morphology, proliferation and extracellular matrix synthesis

The in vitro morphology and proliferative activity of urethral fibroblasts were characterized from primary isolates of fetal bovine urethral spongiosum. Cells were identified as fibroblastic based on their spindle-shaped morphology and lack of expression of phenotypic markers characteristic of either urethral smooth muscle or epithelial cells. Urethral fibroblasts proliferated at a steady rate and did not exhibit contact-inhibition of growth in a culture medium of Medium 199 supplemented with 10% newborn calf serum. Both immunohistochemistry and metabolic labeling analyses of extracellular matrix synthesis demonstrated the presence of collagen types I and III, and fibronectin. Quantitation of the collagenous components of the cell medium revealed that urethral fibroblasts synthesize 85% type I collagen, 14% type III collagen and < 1% type V collagen. In contrast, the urethral fibroblast cell layer matrix consisted of 98% type I collagen, < 1% type III and < 1% type V collagen.