Genetic and environmental factors driving congenital solitary functioning kidney

BACKGROUND

Congenital solitary functioning kidney (CSFK) is an anomaly predisposing to hypertension, albuminuria and chronic kidney disease. Its aetiology is complex and includes genetic and environmental factors. The role of gene-environment interactions (G×E), although relevant for other congenital anomalies, has not yet been investigated. Therefore, we performed a genome-wide G×E analysis with six preselected environmental factors to explore the role of these interactions in the aetiology of CSFK.

METHODS

In the AGORA (Aetiologic research into Genetic and Occupational/environmental Risk factors for Anomalies in children) data- and biobank, genome-wide single-nucleotide variant (SNV) data and questionnaire data on prenatal exposure to environmental risk factors were available for 381 CSFK patients and 598 healthy controls. Using a two-step strategy, we first selected independent significant SNVs associated with one of the six environmental risk factors. These SNVs were subsequently tested in G×E analyses using logistic regression models, with Bonferroni-corrected P-value thresholds based on the number of SNVs selected in step one.

RESULTS

In step one, 7-40 SNVs were selected per environmental factor, of which only rs3098698 reached statistical significance (P = .0016, Bonferroni-corrected threshold 0.0045) for interaction in step two. The interaction between maternal overweight and this SNV, which results in lower expression of the Arylsulfatase B (ARSB) gene, could be explained by lower insulin receptor activity in children heterozygous for rs3098698. Eight other G×E interactions had a P-value <.05, of which two were biologically plausible and warrant further study.

CONCLUSIONS

Interactions between genetic and environmental factors may contribute to the aetiology of CSFK. To better determine their role, large studies combining data on genetic and environmental risk factors are warranted.

Transitional Care for Patients with Congenital Colorectal Diseases: An EUPSA Network Office, ERNICA, and eUROGEN Joint Venture

BACKGROUND

Transition of care (TOC; from childhood into adulthood) of patients with anorectal malformations (ARM) and Hirschsprung disease (HD) ensures continuation of care for these patients. The aim of this international study was to assess the current status of TOC and adult care (AC) programs for patients with ARM and HD.

METHODS

A survey was developed by members of EUPSA, ERN eUROGEN, and ERNICA, including patient representatives (ePAGs), comprising of four domains: general information, general questions about transition to adulthood, and disease-specific questions regarding TOC and AC programs. Recruitment of centres was done by the ERNs and EUPSA, using mailing lists and social media accounts. Only descriptive statistics were reported.

RESULTS

In total, 82 centres from 21 different countries entered the survey. Approximately half of them were ERN network members. Seventy-two centres (87.8%) had a self-reported area of expertise for both ARM and HD. Specific TOC programs were installed in 44% of the centres and AC programs in 31% of these centres. When comparing centres, wide variation was observed in the content of the programs.

CONCLUSION

Despite the awareness of the importance of TOC and AC programs, these programs were installed in less than 50% of the participating centres. Various transition and AC programs were applied, with considerable heterogeneity in implementation, content and responsible caregivers involved. Sharing best practice examples and taking into account local and National Health Care Programs might lead to a better continuation of care in the future.

LEVEL OF EVIDENCE

III.

A pre-transplantation risk assessment tool for graft survival in Dutch pediatric kidney recipients

Background

A prediction model for graft survival including donor and recipient characteristics could help clinical decision-making and optimize outcomes. The aim of this study was to develop a risk assessment tool for graft survival based on essential pre-transplantation parameters.

Methods

The data originated from the national Dutch registry (NOTR; Nederlandse OrgaanTransplantatie Registratie). A multivariable binary logistic model was used to predict graft survival, corrected for the transplantation era and time after transplantation. Subsequently, a prediction score was calculated from the β-coefficients. For internal validation, derivation (80%) and validation (20%) cohorts were defined. Model performance was assessed with the area under the curve (AUC) of the receiver operating characteristics curve, Hosmer-Lemeshow test and calibration plots.

Results

In total, 1428 transplantations were performed. Ten-year graft survival was 42% for transplantations before 1990, which has improved to the current value of 92%. Over time, significantly more living and pre-emptive transplantations have been performed and overall donor age has increased (P < .05).The prediction model included 71 829 observations of 554 transplantations between 1990 and 2021. Other variables incorporated in the model were recipient age, re-transplantation, number of human leucocyte antigen (HLA) mismatches and cause of kidney failure. The predictive capacity of this model had AUCs of 0.89, 0.79, 0.76 and 0.74 after 1, 5, 10 and 20 years, respectively (P < .01). Calibration plots showed an excellent fit.

Conclusions

This pediatric pre-transplantation risk assessment tool exhibits good performance for predicting graft survival within the Dutch pediatric population. This model might support decision-making regarding donor selection to optimize graft outcomes.

Trial registration

ClinicalTrials.gov Identifier: NCT05388955.

Maternal risk factors for posterior urethral valves

Introduction

Posterior urethral valves (PUV) is a congenital disorder causing an obstruction of the lower urinary tract that affects approximately 1 in 4,000 male live births. PUV is considered a multifactorial disorder, meaning that both genetic and environmental factors are involved in its development. We investigated maternal risk factors for PUV.

Methods

We included 407 PUV patients and 814 controls matched on year of birth from the AGORA data- and biobank and three participating hospitals. Information on potential risk factors (family history of congenital anomalies of the kidney and urinary tract (CAKUT), season of conception, gravidity, subfertility, and conception using assisted reproductive techniques (ART), plus maternal age, body mass index, diabetes, hypertension, smoking, and use of alcohol and folic acid) was derived from maternal questionnaires. After multiple imputation, adjusted odds ratios (aORs) were estimated using conditional logistic regression corrected for minimally sufficient sets of confounders determined using directed acyclic graphs.

Results

A positive family history and low maternal age (<25 years) were associated with PUV development [aORs: 3.3 and 1.7 with 95% confidence intervals (95% CI) 1.4-7.7 and 1.0-2.8, respectively], whereas higher maternal age (>35 years) was associated with a lower risk (aOR: 0.7 95% CI: 0.4-1.0). Maternal preexisting hypertension seemed to increase PUV risk (aOR: 2.1 95% CI: 0.9-5.1), while gestational hypertension seemed to decrease this risk (aOR: 0.6 95% CI: 0.3-1.0). Concerning use of ART, the aORs for the different techniques were all above one, but with very wide 95% CIs including one. None of the other factors studied were associated with PUV development.

Conclusion

Our study showed that family history of CAKUT, low maternal age, and potentially preexisting hypertension were associated with PUV development, whereas higher maternal age and gestational hypertension seemed to be associated with a lower risk. Maternal age and hypertension as well as the possible role of ART in the development of PUV require further research.

Uncovering risk factors for kidney injury in children with a solitary functioning kidney

Children with a solitary functioning kidney (SFK) have an increased risk of kidney injury. The exact risk of and risk factors for kidney injury remain unknown, which impedes personalized care. Here, we recruited a nationwide multicenter cohort of 944 patients with SFK to get more insight into this by consenting patients born in 1993-2020 and diagnosed with congenital or acquired SFK before adulthood. The median follow-up was 12.8 years and four indications of kidney injury were studied: urine protein-creatinine ratios, blood pressure, estimated glomerular filtration rate and use of anti-hypertensive/proteinuric medication. For each indicator except medication use, separate cut-off values for any injury and severe injury were used. Survival analyses indicated that at 18 years of age, any or severe kidney injury were present in 75% and 39% of patients with congenital SFK, respectively. Risk factors for kidney injury included kidney agenesis as cause of the SFK, anomalies in the SFK, and high body mass index at last follow-up. Kidney agenesis and being overweight were specifically associated with proteinuria and high blood pressure, whereas anomalies in the SFK were associated with reduced estimated glomerular filtration rates. The high prevalence of kidney injury in patients with SFK emphasizes the need for long-term follow-up, in which lifestyle is an important topic to address. More research into the etiological role of risk factors will help to translate our findings into individualized care strategies. Thus, our study shows that a significant proportion of children with SFK will develop kidney injury over time.

A Genome-Wide Association Study into the Aetiology of Congenital Solitary Functioning Kidney

Congenital solitary functioning kidney (CSFK) is a birth defect that occurs in 1:1500 children and predisposes them to kidney injury. Its aetiology is likely multifactorial. In addition to known monogenic causes and environmental risk factors, common genetic variation may contribute to susceptibility to CSFK. We performed a genome-wide association study among 452 patients with CSFK and two control groups of 669 healthy children and 5363 unaffected adults. Variants in two loci reached the genome-wide significance threshold of 5 × 10^-8, and variants in 30 loci reached the suggestive significance threshold of 1 × 10^-5. Of these, an identified locus with lead single nucleotide variant (SNV) rs140804918 (odds ratio 3.1, p-value = 1.4 × 10^-8) on chromosome 7 was most promising due to its close proximity to HGF, a gene known to be involved in kidney development. Based on their known molecular functions, both KCTD20 and STK38 could explain the suggestive significant association with lead SNV rs148413365 on chromosome 6. Our findings need replication in an independent cohort of CSFK patients before they can be established definitively. However, our analysis suggests that common variants play a role in CSFK aetiology. Future research could enhance our understanding of the molecular mechanisms involved.

The Transition of Care for Patients with Anorectal Malformations and Hirschsprung Disease: A European Survey

This study aimed at evaluating how transition of care is currently being organized in the European Reference Networks (ERNs) health care providers (HCPs) in pediatric areas and in the Anorectal Malformation Network (ARM-Net) Consortium hospitals. An online questionnaire was sent to a total of 80 surgeons, members of or affiliated members of three networks: ARM-Net Consortium, ERN eUROGEN, and ERN ERNICA. Complete information were obtained for 45 HCPs, most of which deal with transition and still see a few adult patients (ca. 10%). Gynecological, gastroenterological, urological, colorectal, and continence issues were the major problems described by adult patients to their physicians, and in line with these prevalent complaints, they are referred to the appropriate adult specialists. Forty percent of patients complain about sexual and fertility problems, but the percentage of andrologists and sexologists involved in the caring of adult patients with ARM/Hirschsprung's disease is low, just above 10.9%. Most hospitals deal with transition, but three basic criteria (i.e., presence of: [1] an official written transitional program, [2] a transitional coordinator, and [3] written information on transition to be handled to patients) are jointly met only by six HCPs. According to the responders, the most important issue requiring improvement is the lack of interest and of specific preparation by adult specialists. The overall results of this exploratory survey confirm the need for the development of comprehensive programs for transition in these rare and complex diseases, and identify the hospitals that, in collaboration with the networks, could share best practices in organizing structured transitional pathways and well follow-ups.

Common needs in uncommon conditions: a qualitative study to explore the need for care in pediatric patients with rare diseases

Background

Challenges faced by children diagnosed with a rare disease or complex condition and their family members are often characterized by disease-specific complexities, such as a prolonged diagnostic process, an uncertain prognosis, and the absence of curative treatment. The psychological burden of living with a rare disease or complex condition is often understudied and may present overarching concepts that shape the general experience of having been diagnosed with a rare condition. The present study examines common needs from a comprehensive perspective combining relevant aspects from the rare disease literature in a theoretical perspective from pediatric psychology, such as a family-centred, developmental and interdisciplinary approach. An exploratory study was designed among parents from children with a rare disease or complex condition in an Integrated University Children’s Hospital in the Netherlands. Semi-structured interviews were conducted with open-ended questions based around the experience of having a child diagnosed with a rare condition, such as the psychosocial impact on the child and it’s development, the impact on the family, and how provided care was experienced.

Results

Twelve interviews were analysed with a thematic content analysis to identify common needs. Eight themes followed from the analysis and uncovered the need for (1) family-focused care, (2) coping with uncertainty, (3) empathic communication, (4) practical support, (5) information, (6) psychological support, (7) interdisciplinary care, and (8) social support.

Conclusions

The results from our study provide directions for research and health care to support young patients with a rare disease or complex condition and their families. Moreover, our results demonstrated that there are overarching concepts across different rare diseases that may be optimally supported with interdisciplinary care.

Kidney injury rates after unilateral nephrectomy in childhood-a systematic review and meta-analysis

BACKGROUND

Unilateral nephrectomy is a relatively common procedure in children which results in a solitary functioning kidney (SFK). Living with an SFK predisposes to kidney injury, but it remains unknown which children are most at risk. We aimed to investigate kidney injury rates in patients who underwent unilateral nephrectomy in childhood and to investigate differences among nephrectomies performed for a congenital anomaly, malignancy or other condition.

METHODS

MEDLINE and EMBASE were searched for studies reporting kidney injury rates [i.e. proteinuria, hypertension and/or a decreased glomerular filtration rate (GFR)] of patients who underwent unilateral nephrectomy during childhood. Studies including five or more patients with at least 12 months of follow-up were eligible. Analyses were performed using random effects models and stratified by indication for nephrectomy. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines were used for reporting.

RESULTS

Over 5000 unique articles were screened, of which 53 studies reporting on >4000 patients were included in the analyses. Proteinuria, hypertension and a decreased GFR were present in 15.3, 14.5 and 11.9% of patients, respectively. Heterogeneity among the studies was large in several subgroups, impairing quantitative meta-analyses. However, none of our analyses indicated differences in injury rates between a congenital anomaly or malignancy as an indication for nephrectomy.

CONCLUSIONS

Unilateral nephrectomy during childhood results in signs of kidney injury in >10% of patients, with no clear difference between the indications for nephrectomy. Therefore, structured follow-up is necessary in all children who underwent nephrectomy, regardless of the indication.

Genome-wide association study in patients with posterior urethral valves

Congenital lower urinary tract obstructions (LUTO) are most often caused by posterior urethral valves (PUV), a male limited anatomical obstruction of the urethra affecting 1 in 4,000 male live births. Little is known about the genetic background of PUV. Here, we report the largest genome-wide association study (GWAS) for PUV in 4 cohorts of patients and controls. The final meta-analysis included 756 patients and 4,823 ethnicity matched controls and comprised 5,754,208 variants that were genotyped or imputed and passed quality control in all 4 cohorts. No genome-wide significant locus was identified, but 33 variants showed suggestive significance (P < 1 × 10^-5). When considering only loci with multiple variants residing within < 10 kB of each other showing suggestive significance and with the same effect direction in all 4 cohorts, 3 loci comprising a total of 9 variants remained. These loci resided on chromosomes 13, 16, and 20. The present GWAS and meta-analysis is the largest genetic study on PUV performed to date. The fact that no genome-wide significant locus was identified, can be explained by lack of power or may indicate that common variants do not play a major role in the etiology of PUV. Nevertheless, future studies are warranted to replicate and validate the 3 loci that yielded suggestive associations.

CDH12 as a Candidate Gene for Kidney Injury in Posterior Urethral Valve Cases: A Genome-wide Association Study Among Patients with Obstructive Uropathies

Background

Posterior urethral valves (PUVs) and ureteropelvic junction obstruction (UPJO) are congenital obstructive uropathies that may impair kidney development.

Objective

To identify genetic variants associated with kidney injury in patients with obstructive uropathy.

Design, setting, and participants

We included 487 patients born in 1981 or later who underwent pyeloplasty or valve resection before 18 yr of age in the discovery phase, 102 PUV patients in a first replication phase, and 102 in a second replication phase.

Outcome measurements and statistical analysis

Signs of kidney injury were defined as dialysis, nephrectomy, kidney transplantation, estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m², high blood pressure, antihypertensive medication use, proteinuria, and/or one kidney functioning at <45%. We used χ² tests to calculate p values and odds ratios for >600 000 single-nucleotide polymorphisms (SNPs) in the discovery sample comparing patients with and without signs of kidney injury within 5 yr after surgery. We performed stratified analyses for PUV and UPJO and Kaplan-Meier and Cox regression analyses in the discovery and two replication samples for the associated SNPs, and RNA and protein expression analyses for the associated gene in fetal tissues.

Results and limitations

Despite the small and nonhomogeneous sample, we observed suggestive associations for six SNPs in three loci, of which rs6874819 in the CDH12 gene was the most clear (p = 7.5 × 10^–7). This SNP also seemed to be associated with time to kidney injury in the PUV discovery and replication samples. RNA expression analyses showed clear CDH12 expression in fetal kidneys, which was confirmed by protein immunolocalization.

Conclusions

This study identified CDH12 as a candidate gene for kidney injury in PUV.

Patient summary

We found that variants of the CDH12 gene increase the risk of kidney injury in patients with extra flaps of tissue in the urethra (posterior urethral valves). This is the first report on this gene in this context. Our study provides interesting new information about the pathways involved and important leads for further research for this condition.

Rare and Complex Urology: Clinical Overview of ERN eUROGEN

BACKGROUND

In 2017, the European Commission launched 24 European Reference Networks (ERNs). ERN eUROGEN is the network for urorectogenital diseases and complex conditions, and started with 29 full member healthcare providers (HCPs) in 11 countries. It then covered 19 different disease areas distributed over three workstreams (WSs).

OBJECTIVE

To provide an overview and identify challenges in data collection at European level of the ERN eUROGEN patient population treated by HCPs in the network.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study was conducted of the 29 HCPs who were full members between 2013 and 2019.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Data were extracted from the original HCP applications and the ERN continuous monitoring system. Patient volumes, new patient numbers, and procedures were compared between different WSs, countries, and HCPs. Discrepancies between monitoring and application data were identified.

RESULTS AND LIMITATIONS

Between 2013 and 2019, 122 040 patients required long-term care within the 29 HCPs. The volume of patients treated and procedures undertaken per year increased over time. Large discrepancies were found between patient numbers contained in the application forms and those reported in the continuous monitoring system (0-1357% deviation).

CONCLUSIONS

Patient numbers and procedures increased across ERN eUROGEN HCPs. Reliable data extraction appeared challenging, illustrated by the patient volume discrepancies between application forms and the continuous monitoring data. Improved disease definitions, re-evaluation of affiliated HCPs, and valid data extraction are needed for future improvements.

PATIENT SUMMARY

We analysed the patient population with rare urorectogenital diseases or complex conditions within the ERN eUROGEN network between 2013 and 2019. Clinical activity was found to increase, but differences in patient numbers were evident between healthcare providers. In order to acquire valid patient numbers, both improved definitions of diagnostic codes and greater insight into the data-gathering process are required.

Clinical Management of Children with a Congenital Solitary Functioning Kidney: Overview and Recommendations

CONTEXT

A congenital solitary functioning kidney (cSFK) is a common developmental defect that predisposes to hypertension and chronic kidney disease (CKD) as a consequence of hyperfiltration. Every urologist takes care of patients with a cSFK, since some will need lifelong urological care or will come with clinical problems or questions to an adult urologist later in life.

OBJECTIVE

We aim to provide clear recommendations for the initial clinical management and follow-up of children with a cSFK.

EVIDENCE ACQUISITION

PubMed and EMBASE were searched to identify relevant publications, which were combined with guidelines on related topics and expert opinion.

EVIDENCE SYNTHESIS

Initially, cSFK diagnosis should be confirmed and risk factors for kidney injury should be identified using ultrasound. Although more research into early predictors of kidney injury is needed, additional congenital anomalies of the kidney or urinary tract and absence of compensatory kidney hypertrophy have repeatedly been associated with a worse prognosis. The role of voiding cystourethrography and antibiotic prophylaxis remains controversial, and is complicated by the exclusion of children with a cSFK from studies. A yearly follow-up for signs of kidney injury is recommended for children with a cSFK. As masked hypertension is prevalent, annual ambulatory blood pressure measurement should be considered. During puberty, an increasing incidence of kidney injury is seen, indicating that long-term follow-up is necessary. If signs of kidney injury are present, angiotensin converting enzyme inhibitors are the first-line drugs of choice.

CONCLUSIONS

This overview points to the urological and medical clinical aspects and long-term care guidance for children with a cSFK, who are at risk of hypertension and CKD. Monitoring for signs of kidney injury is therefore recommended throughout life. Large, prospective studies with long-term follow-up of clearly defined cohorts are still needed to facilitate more risk-based and individualized clinical management.

PATIENT SUMMARY

Many children are born with only one functioning kidney, which could lead to kidney injury later in life. Therefore, a kidney ultrasound is made soon after birth, and other investigations may be needed as well. Urologists taking care of patients with a solitary functioning kidney should realize the long-term clinical aspects, which might need medical management.

Prognostic Factors on Graft Function in Pediatric Kidney Recipients

BACKGROUND

Graft survival in pediatric kidney transplant recipients has increased in the last decades. Determining prognostic factors for graft function over time allows the identification of patients at risk for graft loss and could lead to improvement of current guidelines.

METHODS

Data were collected among pediatric kidney transplant recipients in a single center during the first 5 years after transplantation. Mixed model analysis was used to indicate possible prognostic factors for the loss of graft function.

RESULTS

A total of 100 pediatric kidney transplant recipients were analyzed. Negative prognostics of graft function are higher donor age and higher recipient age, presence of obstructive uropathology, re-transplant, and occurrence of BK viremia. The negative influence on graft function of both donor age and presence of obstructive uropathology increased over time. In this study, the factors that did not influence graft function over time were the number of HLA mismatches, pre-transplant dialysis, intra-abdominal graft placement, ischemia time, occurrence of acute rejection, presence of lower urinary tract dysfunction, occurrence of urinary tract infections, and infections with cytomegalovirus and Epstein-Barr virus.

CONCLUSIONS

This study showed that a higher donor age and higher recipient age, presence of obstructive uropathology, a re-transplant, and the occurrence of BK viremia were negative prognostic factors of graft function over time, in the first 5 years after transplant. Graft function was comparable between steroid-sparing regimens (preferable in low-risk patients) and regimens including steroids (for special reasons).

Sustained Postnatal Skin Regeneration Upon Prenatal Application of Functionalized Collagen Scaffolds

Primary closure of fetal skin in spina bifida protects the spinal cord and improves clinical outcome, but is also associated with postnatal growth malformations and spinal cord tethering. In this study, we evaluated the postnatal effects of prenatally closed full-thickness skin defects in sheep applying collagen scaffolds with and without heparin/vascular endothelial growth factor/fibroblast growth factor 2, focusing on skin regeneration and growth. At 6 months, collagen scaffold functionalized with heparin, VEGF, and FGF2 (COL-HEP/GF) resulted in a 6.9-fold increase of the surface area of the regenerated skin opposed to 1.7 × for collagen only. Epidermal thickness increased 5.7-fold at 1 month, in line with high gene expression of S100 proteins, and decreased to 2.1 at 6 months. Increased adipose tissue and reduced scaffold degradation and number of myofibroblasts were observed for COL-HEP/GF. Gene ontology terms related to extracellular matrix (ECM) organization were enriched for both scaffold treatments. In COL-HEP/GF, ECM gene expression resembled native skin. Expression of hair follicle-related genes in COL-HEP/GF was comparable to native skin, and de novo hair follicle generation was indicated. In conclusion, in utero closure of skin defects using functionalized collagen scaffolds resulted in long-term skin regeneration and growth. Functionalized collagen scaffolds that grow with the child may be useful for prenatal treatment of closure defects like spina bifida. Impact statement Prenatal closure of fetal skin in case of spina bifida prevents damage to the spinal cord. Closure of the defect is challenging and may result in postnatal growth malformations. In this study, the postnatal effects of a prenatally applied collagen scaffold functionalized with heparin and vascular endothelial growth factor (VEGF)/fibroblast growth factor (FGF) were investigated. An increase of the surface area of regenerated skin ("growing with the child") and generation of hair follicles was observed. Gene expression levels resembled those of native skin with respect to the extracellular matrix and hair follicles. Overall, in utero closure of skin defects using heparin/VEGF/FGF functionalized collagen scaffolds results in long-term skin regeneration.

Labeling of Collagen Type I Templates with a Naturally Derived Contrast Agent for Noninvasive MR Imaging in Soft Tissue Engineering

In vivo monitoring of tissue-engineered constructs is important to assess their integrity, remodeling, and degradation. However, this is challenging when the contrast with neighboring tissues is low, necessitating labeling with contrast agents (CAs), but current CAs have limitations (i.e., toxicity, negative contrast, label instability, and/or inappropriate size). Therefore, a naturally derived hemin-L-lysine (HL) complex is used as a potential CA to label collagen-based templates for magnetic resonance imaging (MRI). Labeling does not change the basic characteristics of the collagen templates. When hybrid templates composed of collagen type I reinforced with degradable polymers are subcutaneously implanted in mice, longitudinal visualization by MRI is possible with good contrast and in correlation with template remodeling. In contrast, unlabeled collagen templates are hardly detectable and the fate of these templates cannot be monitored by MRI. Interestingly, tissue remodeling and vascularization are enhanced within HL-labeled templates. Thus, HL labeling is presented as a promising universal imaging marker to label tissue-engineered implants for MRI, which additionally seems to accelerate tissue regeneration.

The Impact of γ-Irradiation and EtO Degassing on Tissue Remodeling of Collagen-based Hybrid Tubular Templates

Clinical implementation of novel products for tissue engineering and regenerative medicine requires a validated sterilization method. In this study, we investigated the effect of γ-irradiation and EtO degassing on material characteristics in vitro and the effect on template remodeling of hybrid tubular constructs in a large animal model. Hybrid tubular templates were prepared from type I collagen and Vicryl polymers and sterilized by 25 kGray of γ-irradiation or EtO degassing. The in vitro characteristics were extensively studied, including tensile strength analysis and degradation studies. For in vivo evaluation, constructs were subcutaneously implanted in goats for 1 month to form vascularized neo-tissue. Macroscopic and microscopic appearances of the γ- and EtO-sterilized constructs slightly differed due to additional processing required for the COL-Vicryl-EtO constructs. Regardless of the sterilization method, incubation in urine resulted in fast degradation of the Vicryl polymer and decreased strength (<7 days). Incubation in SBF was less invasive, and strength was maintained for at least 14 days. The difference between the two sterilization methods was otherwise limited. In contrast, subcutaneous implantation showed that the effect of sterilization was considerable. A well-vascularized tube was formed in both cases, but the γ-irradiated construct showed an organized architecture of vasculature and was mechanically more comparable to the native ureter. Moreover, the γ-irradiated construct showed advanced tissue remodeling as shown by enhanced ECM production. This study shows that the effect of sterilization on tissue remodeling cannot be predicted by in vitro analyses alone. Thus, validated sterilization methods should be incorporated early in the development of tissue engineered products, and this requires both in vitro and in vivo analyses.

Clinical protocol levels are required in laboratory animal surgery when using medical devices: experiences with ureteral replacement surgery in goats

It is common to test medical devices in large animal studies that are or could also be used in humans. In this short report we describe the use of a ureteral J-stent for the evaluation of biodegradable tubular constructs for tissue reconstruction, and the regeneration of ureters in Saanen goats. Similarly to a previous study in pigs, the ureteral J-stent was blindly inserted until some resistance was met. During evaluation of the goats after three months, perforation of the renal cortex by the stent was observed in four out of seven animals. These results indicated that blind stent placement was not possible in goats. In four new goats, clinical protocols were followed using X-ray and iodinated contrast fluids to visualize the kidney and stent during stent placement. With this adaptation the stents were successfully placed in the kidneys of these four new goats with minimal additional effort. It is likely that other groups in other fields ran into similar problems that could have been avoided by following clinical protocols. Therefore, we would like to stress the importance of following clinical protocols when using medical devices in animals to prevent unnecessary suffering and to reduce the number of animals needed.

Tissue Engineering of the Urethra: A Systematic Review and Meta-analysis of Preclinical and Clinical Studies

CONTEXT

Urethra repair by tissue engineering has been extensively studied in laboratory animals and patients, but is not routinely used in clinical practice.

OBJECTIVE

To systematically investigate preclinical and clinical evidence of the efficacy of tissue engineering for urethra repair in order to stimulate translation of preclinical studies to the clinic.

EVIDENCE ACQUISITION

A systematic search strategy was applied in PubMed and EMBASE. Studies were independently screened for relevance by two reviewers, resulting in 80 preclinical and 23 clinical studies of which 63 and 13 were selected for meta-analysis to assess side effects, functionality, and study completion. Analyses for preclinical and clinical studies were performed separately. Full circumferential and inlay procedures were assessed independently. Evaluated parameters included seeding of cells and type of biomaterial.

EVIDENCE SYNTHESIS

Meta-analysis revealed that cell seeding significantly reduced the probability of encountering side effects in preclinical studies. Remarkably though, cells were only sparsely used in the clinic (4/23 studies) and showed no significant reduction of side effects. ln 21 out of 23 clinical studies, decellularized templates were used, while in preclinical studies other biomaterials showed promising outcomes as well. No direct comparison to current clinical practice could be made due to the limited number of randomized controlled studies.

CONCLUSIONS

Due to a lack of controlled (pre)clinical studies, the efficacy of tissue engineering for urethra repair could not be determined. Meta-analysis outcome measures were similar to current treatment options described in literature. Surprisingly, it appeared that favorable preclinical results, that is inclusion of cells, were not translated to the clinic. Improved (pre)clinical study designs may enhance clinical translation.

PATIENT SUMMARY

We reviewed all available literature on urethral tissue engineering to assess the efficacy in preclinical and clinical studies. We show that improvements to (pre)clinical study design is required to improve clinical translation of tissue engineering technologies.

Tubular Constructs as Artificial Urinary Conduits

PURPOSE

A readily available artificial urinary conduit might be substituted for autologous bowel in standard urinary diversions and minimize bowel associated complications. However, the use of large constructs remains challenging as host cellular ingrowth and/or vascularization is limited. We investigated large, reinforced, collagen based tubular constructs in a urinary diversion porcine model and compared subcutaneously pre-implanted constructs to cell seeded and basic constructs.

MATERIALS AND METHODS

Reinforced tubular constructs were prepared from type I collagen and biodegradable Vicryl® meshes through standard freezing, lyophilization and cross-linking techniques. Artificial urinary conduits were created in 17 female Landrace pigs, including 7 with a basic untreated construct, 5 with a construct seeded with autologous urothelial and smooth muscle cells, and 5 with a free graft formed by subcutaneous pre-implantation of a basic construct. All pigs were evaluated after 1 month.

RESULTS

The survival rate was 94%. At evaluation 1 basic and 1 cell seeded conduit were occluded. Urinary flow was maintained in all conduits created with pre-implanted constructs. Pre-implantation of the basic construct resulted in a vascularized tissue tube, which could be used as a free graft to create an artificial conduit. The outcome was favorable compared to that of the other conduits. Urinary drainage was better, hydroureteronephrosis was limited and tissue regeneration was improved.

CONCLUSIONS

Subcutaneous pre-implantation of a basic reinforced tubular construct resulted in a vascularized autologous tube, which may potentially replace bowel in standard urinary diversions. To our knowledge we introduce a straightforward 2-step procedure to create artificial urinary conduits in a large animal model.

AGORA, a data- and biobank for birth defects and childhood cancer

BACKGROUND

Research regarding the etiology of birth defects and childhood cancer is essential to develop preventive measures, but often requires large study populations. Therefore, we established the AGORA data- and biobank in the Netherlands. In this study, we describe its rationale, design, and ongoing data collection.

METHODS

Children diagnosed with and/or treated for a structural birth defect or childhood cancer and their parents are invited to participate in the AGORA data- and biobank. Controls are recruited through random sampling from municipal registries. The parents receive questionnaires about demographics, family and pregnancy history, health status, prescribed medication, lifestyle, and occupational exposures before and during the index pregnancy. In addition, blood or saliva is collected from children and parents, while medical records are reviewed for diagnostic information.

RESULTS

So far, we have collected data from over 6,860 families (3,747 birth defects, 905 childhood cancers, and 2,208 controls). The types of birth defects vary widely and comprise malformations of the digestive, respiratory, and urogenital tracts as well as facial, cardiovascular, kidney, skeletal, and central nervous system anomalies. The most frequently occurring childhood cancer types are acute lymphatic leukemia, Hodgkin and non-Hodgkin lymphoma, Wilms' tumor, and brain and spinal cord tumors. Our genetic and/or epidemiologic studies have been focused on hypospadias, anorectal malformations, congenital anomalies of the kidney and urinary tract (CAKUT), and orofacial clefts.

CONCLUSION

The large AGORA data- and biobank offers great opportunities for investigating genetic and nongenetic risk factors for disorders in children and is open to collaborative initiatives. Birth Defects Research (Part A) 106:675-684, 2016. © 2016 Wiley Periodicals, Inc.

Moderate agreement between bladder capacity assessed by frequency volume charts and uroflowmetry, in adolescent and adult enuresis patients

AIMS

Frequency Volume Charts (FVC) are recommended for the evaluation of enuretic patients. Although this is a good instrument for the assessment of functional bladder capacity, it is known that patient compliance could introduce problems. Therefore, we assessed whether uroflowmetry and post-void residual volume could replace FVC recordings in specific cases, by comparing the bladder capacity as measured by FVC or uroflowmetry.

METHODS

We performed post-hoc analyses using data from a retrospective cohort study, in secondary/tertiary care. This included 907 patients between 2003 and 2013, aged ≥11 years, suffering from enuresis (≥1 wet night/fortnight). Data were collected from the medical files. Bland Altman plots were made to compare the two methods.

RESULTS

Agreement between uroflowmetry and FVC was reasonable only when uroflowmetry was between 200 and 450 ml.

CONCLUSIONS

For individual clinical purposes, uroflowmetry can be used if values are in this range. For future research, we recommend to keep measuring bladder capacity with an FVC. Neurourol. Urodynam. 36:745-747, 2017. © 2016 Wiley Periodicals, Inc.

Maternal risk factors involved in specific congenital anomalies of the kidney and urinary tract: A case-control study

BACKGROUND

Congenital anomalies of the kidney and urinary tract (CAKUT) comprise a heterogeneous group of birth defects with a variety of genetic and nongenetic factors suspected of involvement in the etiology. However, little is known about risk factors in specific CAKUT phenotypes. Therefore, we studied potential maternal risk factors in individual phenotypes within the CAKUT spectrum.

METHODS

Questionnaire data were collected from parents of 562 children with CAKUT and 2139 healthy controls within the AGORA data- and biobank. Potential maternal risk factors investigated included folic acid use, overweight and obesity, smoking, alcohol consumption, subfertility, and diabetes mellitus. We performed logistic regression analyses to assess associations between these potential risk factors and CAKUT phenotypes.

RESULTS

Increased risks of CAKUT were observed for folic acid use and maternal obesity, while fertility treatment by in vitro fertilization or intrauterine insemination and diabetes diagnosed during pregnancy also seem to be associated with CAKUT. Use of multivitamins reduced the risk (odds ratio [OR], 0.5; 95% confidence interval [CI], 0.2-1.0) as opposed to use of folic acid supplements only (OR, 1.3; 95% CI, 1.0-1.8). Folic acid use was associated with duplex collecting systems (OR, 1.8; 95% CI, 1.0-3.4) and vesicoureteral reflux (OR, 1.8; 95% CI, 1.1-2.9) in particular. A relatively strong association was observed between diabetes during pregnancy and posterior urethral valves (OR, 2.6; 95% CI, 1.1-5.9).

CONCLUSION

Use of folic acid only seems to be counterproductive for prevention of CAKUT, in contrast to multivitamin use. Furthermore, we observed differences in risk factor patterns among CAKUT phenotypes, which stress the importance of separate analyses for each phenotype. Birth Defects Research (Part A) 106:596-603, 2016. © 2016 Wiley Periodicals, Inc.

Interaction between MTHFR 677C>T and periconceptional folic acid supplementation in the risk of Hypospadias

BACKGROUND

Hypospadias is a congenital malformation with both environmental factors and genetic predisposition involved in the pathogenesis. The role of maternal periconceptional folic acid supplement use in the development of hypospadias is unclear. As folate levels may also be influenced by the C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene, we hypothesize that a gene-environment interaction between this polymorphism and folic acid use is involved in the etiology of hypospadias.

METHODS

We conducted a case-control study among 855 hypospadias cases and 713 population-based controls from the AGORA data- and biobank. Folic acid supplement use was derived from maternal questionnaires and infant and maternal DNA was used to determine the MTHFR C677T polymorphism using Taqman assays. We performed separate analyses for different hypospadias phenotypes (anterior/middle/posterior).

RESULTS

Hypospadias was neither associated with folic acid use or the MTHFR C677T polymorphism, nor with their interaction. However, we did find an association with middle hypospadias when no supplements were used (odds ratio = 1.6; 95% confidence interval, 1.1-2.4), especially in infants carrying the CT/TT genotype (odds ratio = 2.5; 95% confidence interval, 1.4-4.7). In addition, more infants with these genotypes seemed to have posterior hypospadias, regardless of folic acid use.

CONCLUSION

Our study does not suggest a major role for folic acid supplements or the MTHFR C677T polymorphism in the etiology of hypospadias in general, but not using folic acid and/or carrying the MTHFR C677T polymorphism may be associated with middle and posterior hypospadias. Therefore, we stress the importance of studying gene-environment interactions preferably in stratified analyses for different hypospadias phenotypes.

Reference values for frequency volume chart and uroflowmetry parameters in adolescent and adult enuresis patients

AIMS

Reference values of Frequency Volume Chart (FVC) and uroflowmetry parameters for adolescent and adult enuresis patients are lacking. In this study, we aim to describe those parameters, in order to interpret findings from FVCs and uroflowmetries in those patients.

METHODS

Retrospective, descriptive cohort study, concerning 907 patients aged 11 years and older, suffering from enuresis of at least one wet night per fortnight, treated in a secondary/tertiary centre, between 2003 and 2013. The main FVC parameters of interest were: maximum voided volume (MVV), 24 hr urine production and nocturnal urine volume (NUV) including first morning void (FMV). Nocturnal polyuria (NP) was defined based on both International Children's Continence Society (ICCS, 2014) and International Continence Society (ICS, 2002) definitions. Data of all patients were collected from the medical files.

RESULTS

Age had an impact on diurnal and nocturnal FVC parameters. Median MVV excluding FMV was 250 ml in the youngest, 11-year-old males and 363 ml in the eldest, ≥18-yr-old males. For females, these values were 230 ml and 310 ml. Median 24 hr urine production increased from 1,025 ml to 1,502 ml (males) and from 1,007 ml to 1,557 ml (females). Median NUV showed an increase from 387 ml to 519 ml (males) and from 393 ml to 525 (females). Forty-two percent of men and 30% of women had a small MVV (for age). Prevalence of NP differed when assessed by the ICS or the ICCS definition: following ICS guidelines, NP was present in 96% of our male and 93% of our female population, compared to 27% and 41%, respectively, following ICCS guidelines.

CONCLUSIONS

Both small MVV and NP were found frequently in our adolescent and adult enuresis patients, which is in line with the current thoughts on causal factors. NP prevalence is quite different when using ICS or ICCS definitions, respectively. We would like to encourage the development of an unambiguous definition of NP to use both in pediatric and adult urology. Neurourol. Urodynam. 36:463-468, 2017. © 2016 Wiley Periodicals, Inc.

Bladder Regeneration Using a Smart Acellular Collagen Scaffold with Growth Factors VEGF, FGF2 and HB-EGF

Tissue engineering may become an alternative to current bladder augmentation techniques. Large scaffolds are needed for clinically significant augmentation, but can result in fibrosis and graft shrinkage. The purpose of this study was to investigate whether smart acellular collagen-heparin scaffolds with growth factors (GFs) VEGF, FGF2, and HB-EGF enhance bladder tissue regeneration and bladder capacity in a large animal model of diseased bladder. Scaffolds of bovine type I collagen with heparin and VEGF, FGF2, and HB-EGF measuring 3.2 cm in diameter were prepared. In 23 fetal sheep, a bladder exstrophy was surgically created at 79 days of gestation. One week after birth (at full term), the bladder was reconstructed by primary closure (PC group) or using a collagen-heparin scaffold with GFs (COLGF group) and compared to a historical group reconstructed with a collagen scaffold without GFs (COL group). Functional (video urodynamics) and histological evaluation was performed 1 and 6 months after bladder repair. The overall survival rate was 57%. Cystograms were normal in all animals, except for low-grade reflux in all groups. Urodynamics showed no statistically significant differences in bladder capacity and compliance between groups. Histological evaluation at 1 month revealed increased urothelium formation, improved angiogenesis, and enhanced ingrowth of smooth muscle cells (SMCs) in the COLGF group compared to the COL group. At 6 months, improved SMC ingrowth was found in the COLGF group compared to the COL group; both scaffold groups showed normal urothelial lining and standard extracellular matrix development. Bladder regeneration using a collagen-heparin scaffold with VEGF, FGF2, and HB-EGF improved bladder tissue regeneration in a large animal model of diseased bladder. Larger GF-loaded constructs need to be tested to reach clinically significant augmentation.

Clinical outcome of cloacal exstrophy, current status, and a change in surgical management

INTRODUCTION

Cloacal exstrophy is a complex and rare congenital malformation. Because of improvements in medicine, operative techniques, and perioperative management the survival rates are now approaching 100%. Currently, treatment is focused on improving quality of life. Since 1974, we encountered 20 patients with cloacal exstrophy in our hospital. The aim of this study is to evaluate our clinical experience and outcome during the last 39 years.

PATIENTS AND METHODS

A retrospective study of the medical records was performed. We evaluated anatomical status, phenotype and genotype at birth, subsequent surgical treatment and current gastrointestinal, urinary, spinal, genital, and gender status and outcome.

RESULTS

The records of all 20 patients who were treated in our center were included in this study. Of the 20 patients, 18 were primary patients, 2 referred. Six patients died within the first year of life. Median age of the surviving 14 patients was 25 years (range, 4-39 years) at time of evaluation. At the last follow-up, 11 patients had an endileostomy or endcolostomy. Three patients had a pull-through; two of them were continent for feces. Two patients were continent for urine; one with a sinus urogenitalis and one after urethra reconstruction. Eleven patients are incontinent; six of them had an incontinent urinary deviation (Bricker deviation). Of the other five incontinent patients, two had a urethral reconstruction, one vesicovaginal anastomosis, one perineotomy, and one epispadias bladder. Urinary continence was unknown in one patient. Of the surviving patients, nine have 46 XY karyotype and five 46 XX karyotype. Initially, six XY patients underwent external genital reconstruction with reassignment to female gender; however, one died postoperatively. One declared to feel like a man at age of 15 years. Remaining four XY patients underwent male external genital reconstruction. All XX patients underwent vagina or vulva reconstruction, except for one who still has aplasia vaginae. All patients were born with varying types of spinal dysraphism.

DISCUSSION

Despite medical efforts and development in treatment and support, satisfaction in outcome of cloacal exstrophy remains a challenge. Although reconstruction may be very difficult, male genital reconstruction in 46 XY patients has been given preference for more than a decade. A specialized multidisciplinary team should provide lifelong colorectal, urological, sexual, and psychosocial support to these patients, taking into account their age and phase of life.

Recent advances in ureteral tissue engineering

Reconstruction of long ureteral defects often warrants the use of graft tissue and extensive surgical procedures to maintain the safe transport of urine from the kidneys to the urinary bladder. Complication risks, graft failure-related morbidity, and the lack of suitable tissue are major concerns. Tissue engineering might offer an alternative treatment approach in these cases, but ureteral tissue engineering is still an underreported topic in current literature. In this review, the most recent published data regarding ureteral tissue engineering are presented and evaluated, with a focus on cell sources, implantation strategies, and (bio)materials.

Tissue engineering of diseased bladder using a collagen scaffold in a bladder exstrophy model

OBJECTIVE

To compare the regenerative capacity of diseased bladder in a large animal model of bladder exstrophy with regeneration in healthy bladder using a highly porous collagen scaffold.

MATERIALS AND METHODS

Highly porous bovine type I collagen scaffolds with a diameter of 32 mm were prepared. In 12 fetal sheep a bladder exstrophy was surgically created at 79 days' gestation. Lambs were born at full term (140 days' gestation). After 1 week the bladder lesion was reconstructed and augmented with a collagen scaffold (group 1). In nine normal newborn lambs the bladder was augmented with a collagen scaffold 1 week after birth (group 2). Functional (video-urodynamics) and histological evaluation was performed at 1 and 6 months after surgery.

RESULTS

The survival rate was 58% in group 1 and 100% in group 2. Cystograms were normal in all lambs, besides low-grade reflux in both groups. Urodynamics showed comparable capacity between both groups and a trend to lower compliance in group 1. Histological evaluation at 1 month revealed a non-confluent urothelial layer, an immature submucosa, and initial ingrowth of smooth muscle cells. At 6 months both groups showed normal urothelial lining, standard extracellular matrix development, and smooth muscle cell ingrowth.

CONCLUSIONS

Bladder tissue regeneration with a collagen scaffold in a diseased bladder model and in healthy bladder resulted in comparable functional and histological outcome, with a good quality of regenerated tissue involving all tissue layers. Improvements may still be needed for larger augmentations or more severely diseased bladders.

"This bicycle gives me a headache", a congenital anomaly

Backround

The combination of a presacral mass, a sacral bone deformity, and an anorectal malformation are also known as the Currarino triad or Currarino syndrome. The syndrome is associated with a very high rate of severe and intractable constipation and urinary incontinence. However, it can also result in less common complaints and symptoms. Although the syndrome is known since 1981 and the involved genes are clarified to a great extent, the diagnosis may be delayed or missed if unrecognized.

Case presentation

A 24-year old female presented with periodical headaches. She was born with an imperforate anus, absent rectum and colon, double bladder, and sacral defect. Soon after birth she underwent several surgical procedures for anorectal and bladder reconstructions. The patient now came to her pediatric urologist for urinary incontinence and mentioned severe headaches on the side, particularly when riding a bike. Finally, she solved her headache problem by stopping to ride her bicycle.

On physical examination no abnormalities were found except the ileostomy that was present ever since soon after birth and her urinary incontinence. Blood tests showed no abnormalities. Additional MRI showed a large and previously not known anterior meningocele at the level of the sacrum. Surgical treatment consisted of closure of the dura by posterior approach.

Conclusion

In this case report we describe the late discovery with an atypical presentation of an anterior meningocele in a young adult with urinary incontinence, a sacral defect, an anorectal malformation and headaches during bicycle riding. After surgical treatment of our patient the meningocele regressed. Three months after successful surgery she had no complaints and was able to ride a bike again.

Needs of children with a chronic bladder in preparation for transfer to adult care

OBJECTIVE

Transfers to adult care can be problematic, resulting in postponement due to the protective nature of pediatric care and patient dependency. It is unknown whether these findings apply specifically to urology patients. Our department is taking part in a national general transition project. In this light, our aim was to investigate the specific needs of adolescent urologic patients, regarding their independence and transition.

PATIENTS AND METHODS

80 patients, born in 1975-1998, with a chronic bladder condition received a questionnaire. They were divided into pre- and post-transfer groups. Parents (n = 7) of post-transfer patients formed a third group. Questionnaires were based on those used in the national transition study, supplemented with urological questions. Pre-transfer patients were asked about their level of independence, what subjects were discussed during consultations, and their expectations and wishes regarding transfer. Post-transfer patients and parents were asked for their opinions on the transfer process.

RESULTS

73% (n = 58) responded (55 pre-transfer and 3 post-transfer patients plus parents). It appeared that the confidence built-up with the pediatric urologist impeded the transfer. An adequate level of disease-related knowledge was reported. Relationships, sexuality and fertility were hardly talked about (respectively n = 17, 16 and 18). Parents played an important role, which patients appreciated, confirming their dependency. Despite the 49% (n = 27) who stated they can arrange their urological care themselves, 44% (n = 24) felt ill-prepared for transfer.

CONCLUSION

Although overall self-perceived knowledge is sufficient, the trust in and personal relationship with the pediatric urologist formed the greatest obstruction to successful transition. These findings have been used to improve support during transition by creating a transition protocol.

Prenatal coverage of experimental gastroschisis with a collagen scaffold to protect the bowel

BACKGROUND/PURPOSE

In fetuses with gastroschisis, toxic products in the amniotic fluid and constriction at the defect of the abdominal wall are considered causative of damage to the eviscerated bowel. The aim of this study was to cover the eviscerated bowel in gastroschisis with a collagen scaffold to protect the bowel and induce cell growth into the scaffold, which could lead to skin or abdominal wall formation replacing the scaffold.

METHODS

In 12 fetal lambs gastroschisis was surgically created at 79 days gestation. A dual-layer type I collagen scaffold was sutured into the skin of the abdominal wall around the defect covering the eviscerated bowel. Lambs were examined after caesarean section at 140 days' gestation.

RESULTS

Survival was 67%. In 7 of 8 surviving lambs the bowel was found to be covered after birth. One scaffold had ruptured. The bowel was found repositioned in the abdominal cavity in 5 lambs. In 2 lambs it was still partially outside. Only minor adherence of bowel loops and no fibrous peel formation were seen. Connective tissue and skin tissue replaced the scaffold.

CONCLUSIONS

Prenatal coverage of the bowel in experimental gastroschisis with a collagen scaffold is feasible in fetal lambs, significantly diminished damage to the bowel wall, and skin and connective tissue replaced the scaffold. This technique may be promising in the care of fetuses with this congenital anomaly.

A new, straightforward ex vivo organoid bladder mucosal model for preclinical research

PURPOSE

We developed an experimental ex vivo organoid bladder mucosal model that can be used for experimental research purposes to create alternatives to current animal models.

MATERIALS AND METHODS

We developed an ex vivo organoid bladder mucosal model by immobilizing a type I collagen scaffold on the bottom of a Transwell® insert, creating a 2-compartment system. Mucosal biopsies from porcine bladders were placed on top of the scaffold and cultured in different mediums. We evaluated the morphological aspects of biopsy tissue. Cultured samples were assessed by scanning electron microscopy, and immunohistochemical and histochemical staining for cell identification, proliferation and morphology.

RESULTS

Cells remained viable in Dulbecco's modified Eagle's medium/F-12 and smooth muscle cell medium for up to 3 weeks. The mucosa retained normal morphological characteristics for up to 1 week. Cells (mostly urothelial cells) proliferated and fully covered the scaffold surface within 3 weeks.

CONCLUSIONS

We developed an experimental ex vivo organoid model of bladder mucosa for preclinical experimental research. This model could be used for high volume screening for pharmacology and toxicology experiments. It has the potential to replace currently used animal models.

Exploration of gene-environment interactions, maternal effects and parent of origin effects in the etiology of hypospadias

PURPOSE

Hypospadias is a common congenital malformation of the male external genitalia. Association studies for single nucleotide polymorphisms in genes encoding steroid 5alpha-reductase, estrogen receptors 1 and 2, and activating transcription factor 3 have been equivocal. We examined whether nonreplication of findings for 4 single nucleotide polymorphisms in these genes could be due to interaction with environmental exposures.

MATERIALS AND METHODS

We genotyped 712 Dutch hypospadias case-parent triads for the 4 single nucleotide polymorphisms, used questionnaire information to determine exposures and performed association tests using the log-linear approach. We studied gene-environment interactions for the 4 single nucleotide polymorphisms with exposure to estrogens, cytokines or cigarette smoke, multiple birth, being born small for gestational age, maternal hypertension or preeclampsia, high body mass index or primiparity. In addition, the presence of maternal genetic and parent of origin effects was tested.

RESULTS

Gene-environment interactions were identified for rs523349 in SRD5A2 with estrogen exposure and maternal hypertension or preeclampsia, as well as for rs11119982 in ATF3 with exposure to cytokines. Both single nucleotide polymorphisms seemed to influence hypospadias risk only in exposed cases. For rs6932902 in ESR1 only maternally derived alleles appeared to increase hypospadias risk in offspring.

CONCLUSIONS

Interactions between genetic and environmental factors may help to explain nonreplication in genetic studies of hypospadias.

Improving the cell distribution in collagen-coated poly-caprolactone knittings

Adequate cellular in-growth into biomaterials is one of the fundamental requirements of scaffolds used in regenerative medicine. Type I collagen is the most commonly used material for soft tissue engineering, because it is nonimmunogenic and a highly porous network for cellular support can be produced. However, in general, adequate cell in-growth and cell seeding has been suboptimal. In this study we prepared collagen scaffolds of different collagen densities and investigated the cellular distribution. We also prepared a hybrid polymer-collagen scaffold to achieve an optimal cellular distribution as well as sufficient mechanical strength. Collagen scaffolds [ranging from 0.3% to 0.8% (w/v)] with and without a mechanically stable polymer knitting [poly-caprolactone (PCL)] were prepared. The porous structure of collagen scaffolds was characterized using scanning electron microscopy and hematoxylin-eosin staining. The mechanical strength of hybrid scaffolds (collagen with or without PCL) was determined using tensile strength analysis. Cellular in-growth and interconnectivity were evaluated using fluorescent bead distribution and human bladder smooth muscle cells and human urothelium seeding. The lower density collagen scaffolds showed remarkably deeper cellular penetration and by combining it with PCL knitting the tensile strength was enhanced. This study indicated that a hybrid scaffold prepared from 0.4% collagen strengthened with knitting achieved the best cellular distribution.

Aetiology of hypospadias: a systematic review of genes and environment

BACKGROUND

Hypospadias is a common congenital malformation of the male external genitalia. Most cases have an unknown aetiology, which is probably a mix of monogenic and multifactorial forms, implicating both genes and environmental factors. This review summarizes current knowledge about the aetiology of hypospadias.

METHODS

Pubmed was used to identify studies on hypospadias aetiology published between January 1995 and February 2011. Reference lists of the selected manuscripts were also searched to identify additional studies, including those published before 1995.

RESULTS

The search provided 922 articles and 169 articles were selected for this review. Studies screening groups of patients with hypospadias for single gene defects found mutations in WT1, SF1, BMP4, BMP7, HOXA4, HOXB6, FGF8, FGFR2, AR, HSD3B2, SRD5A2, ATF3, MAMLD1, MID1 and BNC2. However, most investigators are convinced that single mutations do not cause the majority of isolated hypospadias cases. Indeed, associations were found with polymorphisms in FGF8, FGFR2, AR, HSD17B3, SRD5A2, ESR1, ESR2, ATF3, MAMLD1, DGKK, MID1, CYP1A1, GSTM1 and GSTT1. In addition, gene expression studies indentified CTGF, CYR61 and EGF as candidate genes. Environmental factors consistently implicated in hypospadias are low birthweight, maternal hypertension and pre-eclampsia, suggesting that placental insufficiency may play an important role in hypospadias aetiology. Exogenous endocrine-disrupting chemicals have the potential to induce hypospadias but it is unclear whether human exposure is high enough to exert this effect. Other environmental factors have also been associated with hypospadias but, for most, the results are inconsistent.

CONCLUSIONS

Although a number of contributors to the aetiology of hypospadias have been identified, the majority of risk factors remain unknown.

Urotherapy in children: quantitative measurements of daytime urinary incontinence before and after treatment according to the new definitions of the International Children's Continence Society

OBJECTIVE

To assess the effectiveness of urotherapy in children with lower urinary tract dysfunction, according to the new definitions of the International Children's Continence Society.

MATERIAL AND METHODS

We performed a retrospective review of 122 children (aged 8.8 ± 2.0 years) treated in an outpatient program for lower urinary tract dysfunction. Exclusion criteria included all neurologic abnormalities. In 98 children (80%) daytime urinary incontinence was a predominant symptom. Therapy consisted of an individually adapted drinking and voiding schedule, pelvic floor relaxation, instructions on toilet behavior, biofeedback uroflowmetry and if necessary recommendations for regulation of defecation. Before and at the end of training, patients were evaluated for number and severity of daytime wet accidents per week, using a scoring system to grade the severity of incontinence. Secondary measurements of accompanying voiding symptoms were performed.

RESULTS

Of the 90 children with daytime urinary incontinence for whom sufficient objective data were collected, 42% became completely dry during the daytime and 36% showed a 50% or greater level of response. Secondary measurements showed a significant reduction in daily voiding frequency (mean 7.0 ± .3, P<0.0001) and mean post-void residual (P<0.003), and an improvement in flow pattern (P<0.05).

CONCLUSIONS

Urotherapy is successful for the treatment of daytime urinary incontinence in children. Additional benefit was evident in improvement of accompanying voiding symptoms. A combination of the definitions of the International Children's Continence Society and a scoring system to grade severity improved the evaluation method. Further research into long-term efficacy will be performed.

Urethral reconstruction of critical defects in rabbits using molecularly defined tubular type I collagen biomatrices: key issues in growth factor addition

Tubular type I collagen biomatrices with and without growth factors (GFs) were constructed and evaluated in a rabbit model for critical urethral defects. Porous tubular biomatrices with an inner diameter of 3  mm were prepared using highly purified collagen fibrils and were crosslinked with or without heparin. Heparinized biomatrices were supplemented with the heparin-binding GFs vascular endothelial GF, fibroblast GF-2, and heparin-binding epidermal GF. Biomatrices with and without GFs were used to replace a critical 1 cm urethral segment in rabbits (n = 32). All animals showed normal urination without urinary retention. General histology and immunohistology of graft areas (2, 4, 12, and 24 weeks after implantation) indicated that all biomatrices were replaced by urethra-like structures with normal appearing cytokeratin-positive urothelium surrounded by vascularized tissue. The GF-containing biomatrices showed an increase in extracellular matrix deposition, neovascularization, urothelium, glands, granulocytes, and fibroblasts, compared with biomatrices without GF. GFs substantially improved molecular features of healing but failed to be superior in functional outcome. Retrograde urethrography indicated a normal urethral caliber in case of biomatrices without GF, but a relative narrowing of the urethra at 2 weeks postsurgery and diverticula after 4 weeks in case of biomatrices with GF. In conclusion, tubular acellular type I collagen biomatrices were successful in repairing urethral lesions in artificial urethral defects, and inclusion of GF has a profound effect on regenerative processes.

Genetics of hypospadias: are single-nucleotide polymorphisms in SRD5A2, ESR1, ESR2, and ATF3 really associated with the malformation?

CONTEXT

Hypospadias is a common congenital malformation of the male external genitalia with a multifactorial etiology. Little is known about the genes involved in hypospadias. A few genetic associations have been reported but mainly in studies of small sample size. Most of these associations have not been replicated.

OBJECTIVE

The aim of this study was to investigate whether previously reported associations for four single-nucleotide polymorphisms (SNPs) in genes involved in hormonal pathways could be replicated in a large Dutch hypospadias sample. The SNPs investigated are rs523349 in steroid-5 alpha-reductase (SRD5A2), rs6932902 in estrogen receptor 1 (ESR1), rs2987983 in ESR2, and rs11119982 in activating transcription factor 3 (ATF3).

DESIGN, PARTICIPANTS, AND METHODS

We genotyped 620 Caucasian hypospadias cases and 596 controls for these SNPs using TaqMan-based genotyping.

RESULTS

We did not replicate the associations of the SNPs in SRD5A2 and ESR1 with hypospadias. The SNPs in ESR2 and ATF3 were borderline associated with hypospadias [odds ratios 0.9 (95% confidence interval 0.7-1.0) and 1.2 (95% confidence interval 1.0-1.4), respectively] but in the opposite direction compared with earlier publications. Stratification according to localization of the urethral opening produced comparable results in the subgroups.

CONCLUSIONS

The lack of consistency between our and previously performed studies might represent spurious results or chance findings in our or the earlier studies, differences in criteria used to select the study populations, or a real difference between populations, i.e. different genes contributing to disease risk. These results once again confirm the importance of replication in genetic association approaches.

[The undescended testis: arguments in favour of early treatment, provided retractile testis and acquired non-scrotal testis have been excluded]

--Guidelines for the treatment ofundescended testis (UDT) are sparse. Often an operation in the second year of life is advised. --Recent data indicate that the normal maturation process, which will ultimately lead to a normal quantity and quality of germ cells, is impaired as early as in the first half year of a newborn's life. None of the guidelines take this into account. Spontaneous descent after the fourth month following birth, of testes that have previously not descended, hardly ever occurs. --No differences have been shown in complication numbers between surgery before and after the first birthday. Orchidopexy prior to the 13th birthday reduces the risk of testicular cancer. --Therefore, based on these data, it is advised to perform orchidopexy in the second half of the first year of a newborn's life. In older boys a UDT must be treated before the 13th birthday. --In the Netherlands a lot more orchidopexies are done despite what may be expected based on prevalence numbers of UDT: testes retaining a normal volume that would most probably have descended spontaneously come puberty. --It remains important to carry out a careful physical examination and document the position of the testes soon after birth, and later on if UDT is suspected, to avoid unnecessary operations on retractile testes and acquired UDT.

Delayed intrauterine repair of an experimental spina bifida with a collagen biomatrix

BACKGROUND/PURPOSE

The aim of the study was to evaluate whether a collagen biomatrix is useful for delayed intrauterine coverage of a surgically created spina bifida in a fetal lamb.

METHODS

In 20 fetal lambs, surgery was performed at 72 or 79 days' gestation. In 15 lambs a spina bifida was created surgically. In 8 lambs it was covered with a collagen biomatrix 2 weeks later and in 7 lambs it was left uncovered. Five lambs served as sham operated controls. Neurological examination was performed at 1 week of age and afterwards the lambs were sacrificed for further histological evaluation.

RESULTS

None of the 5 surviving lambs with the defect covered showed loss of spinal function and the architecture of the spinal cord was preserved in 4 of the 5 lambs. In the uncovered group, 1 of the 4 surviving lambs had loss of spinal function, 5 lambs were available for histological evaluation and 4 of them showed disturbance of the architecture of the spinal cord.

CONCLUSIONS

Collagen biomatrices can be used for intrauterine coverage of an experimental spina bifida and can preserve the architecture of the spinal cord. Neurological outcome is not different between fetuses with their spinal cord covered and fetuses with uncovered cords.

Histological Evaluation of Acute Covering of an Experimental Neural Tube Defect with Biomatrices in Fetal Sheep

OBJECTIVE

The aim of the study was to determine the histological effect on the neural tissue of in utero covering of an experimental neural tube defect in fetal lambs, with the use of two different biomatrices.

MATERIALS AND METHODS

In 23 fetal sheep, surgery was performed at 79 days' gestation. In 19 of these, a neural tube defect was created, while 4 fetuses served as sham-operated controls. In 7 of the 19 operated fetuses the defect was left uncovered. In the remaining 12 animals the defect was covered either with a collagen biomatrix (4 animals), skin (3 animals), or small intestinal submucosa biomatrix (5 animals). The lambs were sacrificed at 1 week of age and histological examination was performed.

RESULTS

All lambs with an uncovered neural tube defect showed histological damage of the spinal cord. In lambs in which the neural tube defect was covered, one half showed a normal architecture of the spinal cord while minor histological damage was present in the other half. Between the three groups in which the defect was covered, the histological outcome was comparable.

CONCLUSIONS

Acute covering of an experimental neural tube defect in fetal lambs prevents severe histological damage to the spinal cord independent of the two biomatrices used in this study.

Hypospadias: a transgenerational effect of diethylstilbestrol?

BACKGROUND

In 2002, an increased risk of hypospadias was reported for sons of women exposed to diethylstilbestrol (DES) in utero, suggesting transgenerational effects of DES. The aim of this study was to further assess the association between parental DES exposure and hypospadias in a case-referent study.

METHODS

Cases with hypospadias were retrieved from the hospital information system. Referents were recruited via the parents of cases. Both parents completed postal questionnaires. Associations were estimated by odds ratios (OR) with 95% confidence intervals (CI). Additionally, conditional logistic regression analyses were performed for a matched subset of parents.

RESULTS

The final database included 583 cases and 251 referents. In the initial analyses, an indication was found for an increased risk of hypospadias when mothers were exposed to DES in utero: OR=2.3 (95% CI 0.7-7.9). Conditional logistic regression resulted in a stronger risk estimate: OR=4.9 (95% CI 1.1-22.3). Paternal exposure to DES did not increase the risk.

CONCLUSIONS

The results confirm an increased risk of hypospadias when mothers were exposed to DES in utero. However, the excess risk appears to be of much smaller magnitude than in the 2002 study. Further research on the potential health risks for the third generation is of great importance.

Long-term outcome of different types of 1-stage hypospadias repair

PURPOSE

We evaluated the outcome of postpubertal patients who underwent 1-stage hypospadias repair before onset of puberty with at least 10 years of followup.

MATERIALS AND METHODS

A total of 2,053 patients underwent surgical repair of hypospadias between January 1981 and May 2004 at our hospital. We evaluated patients who are now at least 18 years old and who underwent 1-stage hypospadias repair. Data were collected in regard to familial incidence, age at operation, operative technique, complications and followup of at least 10 years. Evaluation was subdivided based on operative procedure.

RESULTS

A total of 126 patients were included in the study. The familial incidence was 7.9% of cases and an associated undescended testis was seen in 9.5%. There were 62 cases with no complications. At least 1 complication was seen in 64 cases, including infection in 3, tissue necrosis in the operative area in 3, wound dehiscence in 6, fistula in 29, meatal stenosis in 15, urethral stenosis in 10, cosmetic dissatisfaction in 16 and other in 2.

CONCLUSIONS

Even in the hands of the experienced pediatric urologists the complication rate after hypospadias repair remains high, with an average of 54% at long-term followup. Our results clearly showed that additional complications can present after long-term followup (a first complication can present after more than 5 years with the longest interval being 14 years). Therefore, final outcome of hypospadias surgery can only be evaluated once the patient has reached adulthood. The results seem to depend on the severity of the abnormality, reflected in the complication distribution rather than operative technique.

In utero Repair of an Experimental Neural Tube Defect in a Chronic Sheep Model Using Biomatrices

OBJECTIVE

Persistent exposure of the unprotected spinal cord to amniotic fluid and the uterine wall can lead to progressive damage of neural tissue in case of a myelomeningocele (two-hit hypothesis). The aim of this study was to evaluate whether in utero repair of an experimental neural tube defect in a fetal lamb could protect neural tissue from secondary injury and save neurologic functions after birth.

METHODS

In 19 fetal lambs, a neural tube defect was created at 79 days' gestation. In 12 lambs the defect was covered either with a novel, molecular defined collagen-based biocompatible and biodegradable matrix (UMC) or with a small intestinal submucosa (SIS) biomatrix (Cook) or by closing the skin over the defect.

RESULTS

All lambs with the defect covered showed no or minor neurologic morbidity in contrast to the lambs with the defect uncovered in which major neurologic morbidity was seen.

CONCLUSIONS

These results demonstrate that long-term exposure of the open spinal cord to the intrauterine environment can lead to damage of neural tissue and, consequently loss of neurologic functions and that coverage of the defect can lead to a better neurologic outcome. Furthermore, we could show that a UMC biomatrix and an SIS biomatrix are useful for in utero coverage of a surgically created neural tube defect in our model.

Renal transplant nephrectomy in children: can an aggressive approach be recommended?

BACKGROUND

A patient with a failed renal graft is generally approached conservatively, especially when graft failure occurs more than 1 month after transplantation. This approach was the cause of extensive morbidity in our institution and therefore we evaluated the correctness of our approach towards transplanted children.

PATIENTS AND METHODS

Case histories of 182 renal transplants in 145 patients, performed between 1977 and 1999 were reviewed.

RESULTS

A total of 63 renal grafts failed: 19 between 0-1 month (group 1), 22 between 1 month and 1 yr (group 2) and 22 later than 1 yr after transplantation (group 3). Fifty-three grafts (84%) were removed: 100% of group 1, 86% of group 2 and 68% of group 3. The symptoms that indicated the need for graft removal were fever without a clear infection focus (n = 12), abdominal pain in the transplant area (n = 14), macroscopic hematuria (n = 10) and severe hypertension (n = 22). After transplant nephrectomy pain, fever and macroscopic hematuria completely resolved in all and hypertension resolved in 36% of patients. Transplant nephrectomy-associated morbidity was observed in 38% of the patients with 100% recovery.

CONCLUSION

The clinical outcome confirmed the indications for transplant nephrectomy. Our future approach will be more aggressive: as soon as symptoms such as unexplained fever, local pain or macroscopic hematuria appear, graft removal will be performed without delay.