Combined Cystometrography and Electromyography of the External Urethral Sphincter Following Complete Primary Repair of Bladder Exstrophy

Human Pluripotent Stem Cell Derived Organoids Reveal a Role for WNT Signaling in Dorsal-Ventral Patterning of the Hindgut

The cloaca is a transient structure that forms in the terminal hindgut giving rise to the rectum dorsally and the urogenital sinus ventrally. Similarly, human hindgut cultures derived from human pluripotent stem cells generate human colonic organoids (HCOs) which also contain co-developing urothelial tissue. In this study, our goal was to identify pathways involved in cloacal patterning and apply this to human hindgut cultures. RNA-seq data comparing dorsal versus ventral cloaca in e10.5 mice revealed that WNT signaling was elevated in the ventral versus dorsal cloaca. Inhibition of WNT signaling in hindgut cultures biased their differentiation towards a colorectal fate. WNT activation biased differentiation towards a urothelial fate, giving rise to human urothelial organoids (HUOs). HUOs contained cell types present in human urothelial tissue. Based on our results, we propose a mechanism whereby WNT signaling patterns the ventral cloaca, prior to cloacal septation, to give rise to the urogenital sinus.

Functional, histological and molecular characteristics of human exstrophy detrusor

INTRODUCTION

Bladder exstrophy is a congenital anomaly involving foetal exposure and protrusion of the open bladder through an incomplete lower abdominal wall. Techniques to surgically correct exstrophy after birth have greatly improved, but it still presents a major challenge to achieve continence and a good quality of life for patients and their families as the pathophysiology of bladder dysfunction is unknown.

OBJECTIVES

A multimodal approach was used to characterise the histological and biomechanical properties of exstrophy detrusor. These were correlated with myocyte responses to agonists and an evaluation of developmental signalling pathways to evaluate the cause of bladder dysfunction in exstrophy.

STUDY DESIGN

Detrusor muscle specimens were obtained during corrective surgery from four exstrophy groups: neonatal (1-3 days, n = 8), younger children (7 months-5 years, n = 13) and older children (8-14 years, n = 11) undergoing secondary procedures and cloacal exstrophy (16 days-9 years, n = 9); control specimens were obtained from children (3 months-9 years, n = 14) undergoing surgery for other pathologies but with normal bladder function. Five lines of experiments were undertaken: measurement of connective tissue to detrusor muscle ratio, contractile responses to electrical and agonist stimulation; in vitro biomechanical stiffness, intracellular Ca²⁺ responses to contractile agonists and immunohistochemistry for proteins (MMP-7, cyclinD1, β-catenin and c-myc) involved in fibrosis generation. Exstrophy data were compared with those from the control group.

RESULTS

Exstrophy tissue demonstrated reduced smooth muscle compared with connective tissue, reduced contractile responses and greater mechanical stiffness. However, intracellular Ca²⁺ responses to agonists were maintained. These changes were greatest in neonatal and cloacal exstrophy samples and least in those from older paediatric bladders. Immunolabelled MMP-7, β-catenin and c-myc were reduced in exstrophy samples.

DISCUSSION

These results highlight the reality that newborns with exstrophy have significantly reduced compliance and bladder underactivity, which may persist or return to normal values with surgery and age. The primary cause of underactivity is increased connective tissue in relation to detrusor muscle; however, detrusor myocyte function remains normal. Finally, the increase of the smooth muscle content in the paediatric bladder group indicates a remodelling response of the bladder to surgical correction and time. Excess gestational fibrosis is associated with changed expression of key proteins in the Wnt-signalling pathway, a potential aetiological factor and therapeutic target.

CONCLUSION

Results point to connective tissue deposition as the primary pathological process that determines bladder function with normal myocyte function. Future research that reduces connective tissue deposition may lead to improvement in outcomes for these children.

Contemporary issues relating to transitional care in bladder exstrophy

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Short-term outcomes of the multi-institutional bladder exstrophy consortium: Successes and complications in the first two years of collaboration

INTRODUCTION/BACKGROUND

Bladder exstrophy is a rare diagnosis that presents major reconstructive challenges. To increase experience and proficiency in the care of bladder exstrophy (BE), the Multi-Institutional BE Consortium (MIBEC) was formed, with a focus on refining technical aspects of complete primary repair of bladder exstrophy (CPRE) and subsequent care.

OBJECTIVE

Outcome measures included successful CPRE (absence of dehiscence), complications, and integrated points of technique and care over the short-term.

STUDY DESIGN

Boston Children's Hospital, Children's Hospital of Philadelphia and Children's Hospital of Wisconsin alternately served as the host, with observation, commentary and critique by visiting collaborating surgeons. CPRE with bilateral iliac osteotomy was performed at 1-3 months of age. High-definition video capture of the surgery allowed local and distant broadcast to facilitate real-time observation and teaching, and recording of all procedures.

RESULTS

From February 2013 to February 2015, MIBEC participating surgeons performed CPRE on 27 consecutive patients (22 classic BE, five epispadias). There were no dehiscences in 27 patients (0%, 95% CI 0-12.5%). Thirteen girls and 14 boys underwent CPRE at a median age of 2.3 months (range 0.1-51.6). One boy had a hypospadiac urethral meatus at CPRE completion. Hydronephrosis of mild or moderate grade was present postoperatively in eight girls and two boys. Additional results, per gender, are presented in the Summary table below.

DISCUSSION

Absence of dehiscence in this cohort was comparable or compared favorably with the literature. However, several girls had significant obstructive complications following CPRE. The rate of bladder outlet obstruction (BOO) in girls was increased compared with published reports. A low complication rate was noted in the boys following CPRE, which was comparable to reports in the literature, and early signs of continence and spontaneous voiding were noted in some boys and girls. Limitations included variation in patient age at presentation, thereby introducing a wide age range at CPRE. Outcome data were limited by short follow-up regarding voiding with continence.

CONCLUSION

This collaborative effort proved beneficial regarding significantly increased surgeon exposure to CPRE, refinement of CPRE technique, surgeon learning and expertise. Technical refinement of CPRE is ongoing.

Sacral agenesis and neurogenic bladder: Long-term outcomes of bladder and kidney function

BACKGROUND

Sacral agenesis (SA) is a rare congenital condition that refers to the absence of part or all of two or more lower sacral vertebral bodies. It can be associated with neurogenic bladder dysfunction that does not necessarily correlate with the level of spinal or skeletal defect. Patients with SA should undergo urodynamic studies (UDS) to guide lower urinary tract (LUT) management.

OBJECTIVE

This review aimed to update the present institutional experience since 1981 of this rare patient population with detailed, long-term follow-up of bladder and kidney function.

STUDY DESIGN

A single institution, retrospective, IRB-approved review was performed on patients born after January 1, 1981 with an isolated diagnosis of sacral agenesis without spina bifida, and followed with urologic involvement at Boston Children's Hospital. Records were reviewed for demographics, radiologic imaging, UDS including cystometrogram (CMG) and electromyography (EMG), surgery, and blood chemistries. Comparisons were made between groups of patients based on age at diagnosis, with specific focus on renal function and stability of neurogenic bladder lesion.

RESULTS

Forty-three patients were identified: 23 female and 20 male. Thirty-seven children (86%) had a known age of diagnosis. Nineteen were diagnosed before 2 months old, including five who were diagnosed prenatally, 11 were diagnosed between 2 and 18 months, and seven were diagnosed after 18 months. All 43 had UDS, with 24 (55.8%) studied at the time of diagnosis (Summary Table). Twenty had serial full UDS, with 30% demonstrating neurourologic instability. None developed end-stage renal disease (ESRD) or required spinal cord detethering.

DISCUSSION

Many children with SA appeared to be diagnosed prenatally or early in life; SA was mostly identified during evaluation of associated anomalies. Though UDS aid in urologic management, testing was not routinely utilized at the time of diagnosis.

CONCLUSIONS

This review of long-term follow-up in SA patients showed stable LUT and renal function, with minimal risk of progression to ESRD.