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

Collagen-Vicryl scaffolds for reconstruction of the diaphragm in a large animal model

Current methods for closure of congenital diaphragmatic hernia using patches are unsatisfactory, and novel collagen-based scaffolds have been developed, and successfully applied in a rat model. However, for translation to the human situation constructs must be evaluated in larger animal models. We developed collagen scaffolds enforced with Vicryl, loaded either with or without the muscle stimulatory growth factor insulin-like growth factor 1 (IGF1). We describe our steps to a surgical method to implant these scaffolds into a diaphragmatic defect in 1.5-3 week old lambs, and evaluate the scaffolds 6 months after implantation. Omentum was attached to the scaffold. At sacrifice, eventration of the implantation site was observed in all animals with a thin layer of tissue separating the abdomen from the thorax. Histologically, no scaffold remnants could be observed. Fatty tissue surrounded by fibrous tissue was seen, resembling encapsulated omentum, with collagen-rich tissue present between this tissue and the original diaphragmatic muscle. Outcomes were not different for scaffolds with or without IGF1. In conclusion, the scaffolds integrated well into the surrounding tissue, but slower degrading materials are needed to prevent eventrations. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 102B: 756-763, 2014

Urogenital function after cloacal reconstruction, two techniques evaluated

Objective: Current surgical techniques for cloacal reconstruction are posterior sagittal anorecto vagino urethroplasty (PSARVUP) and posterior sagittal anorectoplasty (PSARP) with total urogenital mobilization (TUM). The aim of this study was to explore the results of reconstructive cloaca surgery in the Netherlands and evaluate urogenital function after PSARVUP and TUM. Patients and methods: Medical records from five pediatric surgical departments in the Netherlands were studied for patients with cloacal malformations treated between 1985 and 2009. Forty-two patients were eligible, and patients with short common channels were categorized into PSARVUP and TUM groups. Groups were compared using Fisher's exact test. Results: Median age at time of surgery was 9 months (range 1-121). In 24 patients (57%) a PSARVUP was done, in 18 patients (43%) TUM. Median follow-up was 142 months (range 15-289). At follow-up spontaneous voiding was seen in 29 patients (69%). Clean intermittent catheterization (CIC) was needed in 14 patients (33%); a urinary diversion was created in 10 patients (24%). In total 32 patients (76%) were dry with no involuntary loss of urine per urethra. Recurrent urinary tract infections were seen in 23 patients (55%). When comparing PSARVUP and TUM groups in our series of patients with short common channels, there were no differences in urological outcome. Normal menstruation was present in 11 of the 20 patients who reached puberty (55%). Conclusion: Urogenital functional outcome after reconstructive surgery for cloacal malformations was similar in PSARVUP and TUMgroups in patients with short common channels. A thorough urological follow-up is needed to establish the long-term bladder function and urinary incontinence results to prevent long-term risks of recurrent UTI. Albeit without differences between PSARVUP and TUM groups, 45% of the patients present with abnormal or absent menstruations. Gynecological follow-up is mandatory in all patients with cloacal malformations 6 months after the first sign of puberty. (C) 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved

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 3.2cm 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

Genes in the Ureteric Budding Pathway: Association Study on Vesico-Ureteral Reflux Patients

Vesico-ureteral reflux (VUR) is the retrograde passage of urine from the bladder to the urinary tract and causes 8.5% of end-stage renal disease in children. It is a complex genetic developmental disorder, in which ectopic embryonal ureteric budding is implicated in the pathogenesis. VUR is part of the spectrum of Congenital Anomalies of the Kidney and Urinary Tract (CAKUT). We performed an extensive association study for primary VUR using a two-stage, case-control design, investigating 44 candidate genes in the ureteric budding pathway in 409 Dutch VUR patients. The 44 genes were selected from the literature and a set of 567 single nucleotide polymorphisms (SNPs) capturing their genetic variation was genotyped in 207 cases and 554 controls. The 14 SNPs with p<0.005 were included in a follow-up study in 202 cases and 892 controls. Of the total cohort, similar to 50% showed a clear-cut primary VUR phenotype and similar to 25% had both a duplex collecting system and VUR. We also looked for association in these two extreme phenotype groups. None of the SNPs reached a significant p-value. Common genetic variants in four genes (GREM1, EYA1, ROBO2 and UPK3A) show a trend towards association with the development of primary VUR (GREM1, EYA1, ROBO2) or duplex collecting system (EYA1 and UPK3A). SNPs in three genes (TGFB1, GNB3 and VEGFA) have been shown to be associated with VUR in other populations. Only the result of rs1800469 in TGFB1 hinted at association in our study. This is the first extensive study of common variants in the genes of the ureteric budding pathway and the genetic susceptibility to primary VUR

Fetal bladder wall regeneration with a collagen biomatrix and histological evaluation of bladder exstrophy in a fetal sheep model.

Contains fulltext : 70288.pdf (publisher's version ) (Closed access)OBJECTIVES: To evaluate histological changes in an animal model for bladder exstrophy and fetal repair of the bladder defect with a molecular-defined dual-layer collagen biomatrix to induce fetal bladder wall regeneration. METHODS: In 12 fetal lambs the abdominal wall and bladder were opened by a midline incision at 79 days' gestation. In 6 of these lambs an uncorrected bladder exstrophy was created by suturing the edges of the opened bladder to the abdominal wall (group 1). The other 6 lambs served as a repair group, where a dual-layer collagen biomatrix was sutured into the bladder wall and the abdominal wall was closed (group 2). A caesarean section was performed at 140 days' gestation, followed by macroscopic and histological examination. RESULTS: Group 1 showed inflammatory and maturational changes in the mucosa, submucosa and detrusor muscle of all the bladders. In group 2, bladder regeneration was observed, with urothelial coverage, ingrowth of fibroblasts and smooth muscle cells, deposition of collagen, neovascularization and nerve fibre formation. This tissue replaced the collagen biomatrix. No structural changes of the bladder were seen in group 2. CONCLUSIONS: The animal model, as in group 1, for bladder exstrophy shows remarkable histological resemblance with the naturally occurring anomaly in humans. This model can be used to develop new methods to salvage or regenerate bladder tissue in bladder exstrophy patients. Fetal bladder wall regeneration with a collagen biomatrix is feasible in this model, resulting in renewed formation of urothelium, blood vessels, nerve fibres, ingrowth of smooth muscle cells and salvage of the native bladder