Renal differentiation of amniotic fluid stem cells.

OBJECTIVES: The role of stem cells in regenerative medicine is evolving rapidly. Here, we describe the application, for kidney regeneration, of a novel non-genetically modified stem cell, derived from human amniotic fluid. We show that these pluripotent cells can develop and differentiate into de novo kidney structures during organogenesis in vitro. MATERIALS AND METHODS: Human amniotic fluid-derived stem cells (hAFSCs) were isolated from human male amniotic fluid obtained between 12 and 18 weeks gestation. Green fluorescent protein and Lac-Z-transfected hAFSCs were microinjected into murine embryonic kidneys (12.5-18 days gestation) and were maintained in a special co-culture system in vitro for 10 days. Techniques of live microscopy, histology, chromogenic in situ hybridization and reverse transcriptase polymerase chain reaction were used to characterize the hAFSCs during their integration and differentiation in concert with the growing organ. RESULTS: Green fluorescent protein and Lac-Z-transfected hAFSCs demonstrated long-term viability in organ culture. Histological analysis of injected kidneys revealed that hAFSCs were capable of contributing to the development of primordial kidney structures including renal vesicle, C- and S-shaped bodies. Reverse transcriptase polymerase chain reaction confirmed expression of early kidney markers for: zona occludens-1, glial-derived neurotrophic factor and claudin. CONCLUSIONS: Human amniotic fluid-derived stem cells may represent a potentially limitless source of ethically neutral, unmodified pluripotential cells for kidney regeneration.

New surgical techniques in pediatric urology.

More sophisticated endoscopic instruments, combined with a better understanding of bladder and urethral pathology, have significantly improved the therapeutic approaches for both posterior urethral valves and ureteroceles. New generation lithotripters have allowed for a safe and efficient method of treating urinary calculi in children, which was once thought too injurious a process with first-generation machines. The rapidly advancing field of laparoscopy, aided by the development of more optically refined and diminutive instruments, has allowed for its application in a wide variety of surgical interventions in pediatric urology. The tubularized incised plate urethroplasty has challenged more traditional approaches to hypospadias repair and is now considered by many pediatric urologists to be the best approach for midshaft and distal hypospadias. The one-stage approach to exstrophy repair may hold the answer to improved continence without a formal bladder neck reconstruction. Finally, the field of tissue engineering leads the way to new advances in autologous biological substitutes in the surgically-challenged patient where there is a shortage of local tissues at the surgeon's disposal.

Neurogenic bladder in infants born with anorectal malformations: comparison with spinal and urologic status.

BACKGROUND/PURPOSE: Spinal dysraphism and neurovesical dysfunction (NVD) frequently are associated in children with anorectal malformations (ARM). This study compares the urodynamic data from a selected group of patients with the results of their spinal and urologic imaging studies. METHODS: Twenty-six children (20 with isolated imperforate anus and six with persistent cloacal malformations) were investigated. All patients were evaluated with leak point pressures (LPP), renal ultrasound scan, and voiding cystourethrography. Eight children had urodynamics performed before and after posterior sagittal anorectoplasty (PSARP). The spinal cord was assessed using ultrasonography or magnetic resonance imaging. Current urologic status was obtained to provide long-term follow-up. RESULTS: Twenty-one of 26 children demonstrated elevated LPPs above the established normal value of 40 cm H2O, and 15 of these children had normal spinal imaging study findings. Uroradiographic studies findings showed that 12 of 21 children with elevated LPPs had hydronephrosis or vesicoureteral reflux with seven of these patients having normal spinal cords. LPPs in the eight patients with pre- and postoperative studies were 74 +/- 14.7 cm H2O and 68 +/- 31.8 cm H2O (mean +/- SD), respectively. CONCLUSIONS: These urodynamic and radiographic data confirm that NVD (elevated LPP) is common in patients with anorectal malformations despite normal spinal cords. Bladder dysfunction does not appear to be a sequelae of a properly performed PSARP. Patients with ARM and any uroradiographic or clinical urologic abnormality should undergo urodynamic testing even though the spinal studies are normal.

An alternative ureteroileal reimplantation used in augmentation cystoplasty for neurogenic bladder with bilateral vesicoureteral reflux.

PURPOSE: We describe the use of a serous lined extramural tunnel for ureteral reimplantation during augmentation of a neurogenic bladder to prevent reflux. MATERIALS AND METHODS: A 46-year-old male C6 spinal cord injury patient presented with a high pressure bladder, detrusor-sphincter dyssynergia and bilateral grade II/III vesicoureteral reflux. Despite maximal anticholinergic therapy and intermittent catheterization, detrussor pressures were between 80 and 100 cm. water at volumes of 100 to 150 cc with consistent leakage between catheterizations. Preoperative ultrasound and voiding cystourethrogram demonstrated moderate bilateral hydronephrosis and a heavily trabeculated bladder. Augmentation cystoplasty with the formation of 3 cm. extramural ureteral tunnels as described by Ghoneim was performed. The serosa of the adjacent limbs of the ileal segment were opposed to form the back wall of a serosal lined tunnel. RESULTS: At 3 weeks postoperatively a cystogram demonstrated no extravasation or reflux. At 8 weeks an excretory urogram showed prompt function and excretion bilaterally with marked improvement of preoperative hydronephrosis. CONCLUSIONS: Subserosal ureteral tunnels can be used as an alternative antireflux technique during augmentation cystoplasty when ureteral reimplantation is required. Two advantages of this technique include the elimination of staples and avoidance of ischemic problems associated with an afferent intussuscepted nipple valve.