Developmental Expression of Interstitial Collagen Genes In Fetal Bladders

Functional properties and connective tissue content of pediatric human detrusor muscle

The functional properties of human pediatric detrusor smooth muscle are poorly described, in contrast to those of adult tissue. Characterization is necessary for more informed management options of bladder dysfunction in children. We therefore compared the histological, contractile, intracellular Ca2+ concentration responses and biomechanical properties of detrusor biopsy samples from pediatric (3-48 mo) and adults (40-60 yr) patients who had functionally normal bladders and were undergoing open surgery. The smooth muscle fraction of biopsies was isolated to measure proportions of smooth muscle and connective tissue (van Gieson stain); in muscle strips, isometric tension to contractile agonists or electrical field stimulation and their passive biomechanical properties; in isolated myocytes, intracellular Ca2+ concentration responses to agonists. Pediatric detrusor tissue compared with adult tissue showed several differences: a smaller smooth muscle-to-connective tissue ratio, similar contractures to carbachol or α,β-methylene ATP when corrected for smooth muscle content, and similar intracellular Ca2+ transients to carbachol, α,β-methylene ATP, raised K+ concentration or caffeine, but smaller nerve-mediated contractions and greater passive stiffness with slower stress relaxation. In particular, there were significant atropine-resistant nerve-mediated contractions in pediatric samples. Detrusor smooth muscle from functionally normal pediatric human bladders is less contractile than that from adult bladders and exhibits greater passive stiffness. Reduced bladder contractile function is not due to reduced smooth muscle contractility but to greater connective tissue deposition and to functional denervation. Significant atropine resistance in pediatric detrusor, unlike in adult tissue, demonstrates a different profile of functional neurotransmitter activation. These data have implications for the management of pediatric bladder function by therapeutic approaches.

Different bladder defects reconstructed with bladder acellular matrix grafts in a rabbit model

OBJECTIVE

To evaluate the potential use of the bladder acellular matrix graft (BAMG), two different bladder defects in the rabbit model were reconstructed.

MATERIALS AND METHODS

Two groups of rabbits underwent partial bladder wall cystectomy (group A, 30-40%; group B, 70-60%) and reconstruction of the defects with an equally sized BAMG. After 4, 12, and 24 weeks, bladder cystographs were performed. Then the rabbits were killed after uneventful postoperative periods, and the grafts were harvested for H&E staining and immunohistochemical staining.

RESULTS

Two rabbits died on the postoperative days 3 and 6 in group A due to urinary peritonitis. At 24 weeks, in group A, the reconstructed bladders reached a mean volume of 94.39±0.54% of the precystectomy bladder capacity. Histologically, complete regeneration of smooth muscle and urothelium tissue was evident. Regenerated SMCs and urothelium stained positive for α-smooth muscle actin and AE1/AE3. In group B, the mean bladder volume was 64.5±3.19% of the precystectomy volume. Histologically, group B was characterized by multilayered urothelium without organized muscle tissue.

CONCLUSION

The BAMG was an effective scaffold for bladder wall regeneration in the rabbit model. However, the use of BAMG reconstruction in larger bladder defects did not induce the same quality and quantity of bladder regeneration as the reconstruction of smaller bladder defects.

Is joint hypermobility associated with vesico-ureteral reflux? An assessment of 50 patients

OBJECTIVE

To assess whether there is an increased prevalence of joint hypermobility in patients with vesico-ureteric reflux (VUR).

MATERIALS AND METHODS

We studied 50 patients with primary VUR and matched controls drawn from a reference population. Joint mobility was assessed using the Bulbena hypermobility score.

RESULTS

We identified significantly more patients with VUR with generalized joint hypermobility than controls (24% vs 6.7%, P= 0.007).

CONCLUSION

Our findings confirm our clinical observation of an increased rate of joint hypermobility in patients with VUR. We speculate that an altered composition of the connective tissue may contribute to the severity of the (pre-existing) VUR phenotype.

Prenatal resolution of megacystis possibly caused by spontaneous rupture of posterior urethral valves

We report herein a case of resolution of severe megacystis, possibly caused by spontaneous rupture of posterior urethral valves during follow-up on a prenatal ultrasound. A 32-year-old woman presented at gestational week 15 for evaluation of fetal bladder enlargement. Prenatal ultrasonography revealed megacystis and posterior urethral dilatation. The longitudinal diameter of the bladder was 25 mm. Megacystis spontaneously resolved at gestational week 16. No association with urinary ascites was observed, and amniotic fluid volume remained normal throughout gestation. A boy was delivered vaginally at week 37. Apgar scores were 8 at 1 minute and 9 at 5 minutes. The neonate voided smoothly. Ultrasonography revealed a thickened bladder wall and normal kidneys and upper urinary tracts. Voiding cystourethrography showed dilatation of the posterior urethra but confirmed normal bladder capacity with smooth voiding and no vesicoureteral reflux. On day 57, remnant valves were incised. Postoperatively, filling cystometry showed a compliant bladder with no involuntary phasic contraction. At 7 months follow-up, the infant was asymptomatic, and ultrasonography showed some improvement of bladder wall thickness. Resolution of megacystis in utero appears to have resulted from spontaneous rupture of the posterior urethral valves. To the best of our knowledge, no similar cases have been previously reported.

Basic fibroblast growth factor modulates proliferation and collagen expression in urinary bladder smooth muscle cells

Bladder hypertrophy is a general consequence of bladder outlet obstruction (BOO) and a typical phenomenon observed in clinical urologic diseases such as benign prostatic hyperplasia and neurogenic bladder. It is characterized by smooth muscle hyperplasia, altered extracellular matrix composition, and increased contractile function. Various growth factors are likely involved in hypertrophic pathophysiology, but their functions remain unknown. In this report, the role of basic fibroblast growth factor (bFGF) was investigated using a rat bladder smooth muscle cell (BSMC) culture system and an original animal model, in which bFGF was released from a gelatin hydrogel directly onto rat bladders. bFGF treatment promoted BSMC proliferation both in vitro and in vivo. In vitro, bFGF downregulated the expression of type I collagen, but upregulated type III collagen. ERK1/2, but not p38MAPK, was activated by bFGF, whereas inhibition of ERK1/2 by PD98059 reversed bFGF-induced BSMC proliferation, type I collagen downregulation, and type III collagen upregulation. In the in vivo release model, bFGF upregulated type III collagen and increased the contractile force of treated bladders. In parallel with these findings, hypertrophied rat bladders created by urethral constriction showed increased urothelial bFGF expression, BSMC proliferation, and increased type III collagen expression compared with sham-operated rats. These data suggest that bFGF from the urothelium could act as a paracrine signal that stimulates the proliferation and matrix production of BSMC, thereby contributing to the hypertrophic remodeling of the smooth muscle layer.

Management of the valve–bladder syndrome and congenital bladder obstruction: the role of nocturnal bladder drainage

Valve-bladder syndrome often develops after the resolution of posterior urethral valves, but is also found after the resolution of congenital bladder obstruction. The features of this syndrome include the persistent dilation of the upper urinary tracts, a thick-walled, noncompliant urinary bladder, urinary incontinence, and polyuria secondary to nephrogenic diabetes insipidus. Nocturnal bladder management, which involves timed emptying of the bladder or continuous drainage, has been recommended in conjunction with diurnal timed voiding therapy as an adjunct to the treatment of valve-bladder syndrome. This treatment is derived from the hypothesis that valve-bladder syndrome is caused by congenital obstruction, and that the resultant changes in detrusor muscle are associated with a persistent bladder dysfunction characterized by chronic overdistention of the urinary bladder. Such overdistention is exacerbated by polyuria, and can be a cause of secondary hydronephrosis. Bladder dysfunction and overdistention is usually treated during waking time, but occasionally this is not effective on its own, and nocturnal therapy is used as well. To date, there are a few sets of data that suggest overnight bladder drainage can bring about profound improvements in the degree of upper-tract hydronephrosis, renal function, or bladder function. Nocturnal bladder drainage seems, in these initial reports, to be a simple and safe therapeutic maneuver. This review discusses the etiology of valve-bladder syndrome and examines each of the studies which have investigated nocturnal bladder drainage in its treatment.

Extracellular matrix gene responses in a novel ex vivo model of bladder stretch injury

PURPOSE

Congenital bladder outlet obstruction from either mechanical or functional causes often results in clinical bladder fibrosis. We tested the hypothesis that early molecular changes relevant to fibrosis occur in response to stretch injury of the bladder wall and that specific extracellular matrix receptors mediate some of these responses. Furthermore, we introduce a novel ex vivo model of bladder injury which has advantages over previously described in vivo bladder outlet obstruction models by uniquely interrogating molecular responses to bladder distention.

MATERIALS AND METHODS

The bladders of Sprague Dawley rats were hydrodistended transurethrally, the ureters and bladder neck were ligated, and the whole bladder was excised and incubated in culture medium in the distended state. At fixed time-points control and stretch bladders were snap frozen, RNA was extracted, and semiquantitative reverse transcription polymerase chain reaction for collagens I, III and XII, and RHAMM (receptor for hyaluronic acid) messenger (m) RNA was performed to establish trends in stretch related gene expression. Bladder specimens were also subjected to routine histological evaluation.

RESULTS

An average 3-fold reduction in collagen I mRNA expression was seen with 8 hours of static stretch (p <0.05). Bladder stretch increased collagen III mRNA levels approximately 2.5-fold (p <0.05). Whole bladder collagen XII and RHAMM mRNA were elevated as much as 5-fold (p <0.05) with stretch. Blocking RHAMM function significantly attenuated these matrix gene responses (p = 0.01 to 0.005).

CONCLUSIONS

The ex vivo model of whole bladder stretch is viable and easily reproducible for the study of molecular pathophysiological mechanisms contributing to maladaptive bladder disease. Furthermore, collagen gene transcription is revealed to be rapidly responsive to stretch injury of the bladder. Intact RHAMM receptor function is involved in these responses. Elucidation of the intermediate steps in this response to injury may allow for the development of novel therapeutic strategies which may prevent pathological matrix remodeling seen in clinical bladder disease.

Extracellular matrix gene responses in a novel ex vivo model of bladder stretch injury

PURPOSE

Congenital bladder outlet obstruction from either mechanical or functional causes often results in clinical bladder fibrosis. We tested the hypothesis that early molecular changes relevant to fibrosis occur in response to stretch injury of the bladder wall and that specific extracellular matrix receptors mediate some of these responses. Furthermore, we introduce a novel ex vivo model of bladder injury which has advantages over previously described in vivo bladder outlet obstruction models by uniquely interrogating molecular responses to bladder distention.

MATERIALS AND METHODS

The bladders of Sprague Dawley rats were hydrodistended transurethrally, the ureters and bladder neck were ligated, and the whole bladder was excised and incubated in culture medium in the distended state. At fixed time-points control and stretch bladders were snap frozen, RNA was extracted, and semiquantitative reverse transcription polymerase chain reaction for collagens I, III and XII, and RHAMM (receptor for hyaluronic acid) messenger (m) RNA was performed to establish trends in stretch related gene expression. Bladder specimens were also subjected to routine histological evaluation.

RESULTS

An average 3-fold reduction in collagen I mRNA expression was seen with 8 hours of static stretch (p <0.05). Bladder stretch increased collagen III mRNA levels approximately 2.5-fold (p <0.05). Whole bladder collagen XII and RHAMM mRNA were elevated as much as 5-fold (p <0.05) with stretch. Blocking RHAMM function significantly attenuated these matrix gene responses (p = 0.01 to 0.005).

CONCLUSIONS

The ex vivo model of whole bladder stretch is viable and easily reproducible for the study of molecular pathophysiological mechanisms contributing to maladaptive bladder disease. Furthermore, collagen gene transcription is revealed to be rapidly responsive to stretch injury of the bladder. Intact RHAMM receptor function is involved in these responses. Elucidation of the intermediate steps in this response to injury may allow for the development of novel therapeutic strategies which may prevent pathological matrix remodeling seen in clinical bladder disease.

Homologous bladder augmentation in dog with the bladder acellular matrix graft

OBJECTIVE

To determine the functional potential and antigenicity of the homologous bladder acellular matrix graft (BAMG) in a dog model.

MATERIALS AND METHODS

Seven mongrel dogs underwent partial cystectomy (20-50%) and grafting with an equal-sized BAMG; two control animals underwent partial cystectomy (40%) only. The dogs were killed after 30 (one), 120 (one) and 210 days (five dogs). Blood samples were obtained before and at 1, 2, 4, 7, 14, 30, 90 and 210 days after surgery. The dogs underwent cystography, intravenous pyelography and ultrasonography before and after surgery, and on the day they were killed, with cystoscopy carried out just before death. The grafted tissue was assessed using routine and immunohistochemical techniques.

RESULTS

All the dogs survived surgery; a complete blood cell count, chemical panel and white blood cell count showed no significant difference between the experimental and control animals. Cystography, cystoscopy and ultrasonography revealed no pathological changes in the upper urinary tract. After 7 months, the mean bladder capacity in the augmented dogs was significantly higher (P = 0.035) than in the controls (264 vs 172 mL). Histological evaluation showed an invasion of all bladder wall components during the first month; at 7 months, the morphological examination showed essentially complete regeneration.

CONCLUSION

In this dog model, the potential of the BAMG as a bladder augmentation graft was confirmed, having minimal antigenicity with maximal acceptance. The reconstructed bladder matched the morphological and functional properties of the normal bladder.

Ultrastructural smooth muscle ontogeny of the rat bladder

The transmission electron microscope characteristics of developing rat bladder smooth muscle are described at 14 and 18 days of gestation, birth, and adulthood. Caveolae, microfilaments, and dense bodies increase during smooth muscle development. Collagen content in the extracellular matrix also increases. These changes may reflect increased bladder emptying in the rat, and also allow for comparison of smooth muscle cells in studies of bladder wound healing and tissue substitutes.