L.A.J. Roelofs

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.

Tissue Engineered Tubular Construct for Urinary Diversion in a Preclinical Porcine Model

PURPOSE The ileal conduit has been considered the gold standard urinary diversion for patients with bladder cancer and pediatric patients. Complications are mainly related to the use of gastrointestinal tissue. Tissue engineering may be the technical platform on which to develop alternatives to gastrointestinal tissue. We developed a collagen-polymer conduit and evaluated its applicability for urinary diversion in pigs. MATERIALS AND METHODS Tubular constructs 12 cm long and 15 mm in diameter were prepared from bovine type I collagen and Vypro® II synthetic polymer mesh. Characterized tubes were sterilized, seeded with and without primary porcine bladder urothelial cells, and implanted as an incontinent urostomy using the right ureter in 10 female Landrace pigs. At 1 month the newly formed tissue structure was functionally and microscopically evaluated by loopogram and immunohistochemistry, respectively. RESULTS The survival rate was 80% with 1 related and 1 unrelated death. By 1 month the collagen was resorbed and a retroperitoneal tunnel had formed that withstood 40 cm H(2)O water pressure. In 5 cases the tunnel functioned as a urostomy. Histological analysis revealed a moderate immune response, neovascularization and urothelial cells in the construct lumen. The polymer mesh provoked fibroblast deposition and tissue contraction. No major differences were observed between cellular and acellular constructs. CONCLUSIONS After implanting the tubular constructs a retroperitoneal tunnel was formed that functioned as a urinary conduit in most cases. Improved large tubular scaffolds may generate alternatives to gastrointestinal tissue for urinary diversion.

Intra-uterine tissue engineering of full-thickness skin defects in a fetal sheep model

In spina bifida the neural tube fails to close during the embryonic period and it is thought that prolonged exposure of the unprotected spinal cord to the amniotic fluid during pregnancy causes additional neural damage. Intra-uterine repair might protect the neural tissue from exposure to amniotic fluid and might reduce additional neural damage. Biodegradable collagen scaffolds may be useful in case of fetal therapy for spina bifida, but biochemical properties need to be studied. The aim of this study was to investigate whether biodegradable collagen scaffolds can be used to treat full-thickness fetal skin defects. We hypothesized that the pro-angiogenic growth factors VEGF and FGF2 would enhance vascularization, epidermialization and lead to improved wound healing. To investigate the effect of these two growth factors, a fetal sheep model for skin defects was used. Compared to wounds treated with bare collagen scaffolds, wounds treated with growth factor-loaded scaffolds showed excessive formation of capillaries and less myofibroblasts were present in these wounds, leading to less contraction. This study has demonstrated that collagen scaffolds can be used to treat fetal skin defects and that the combination of collagen scaffolds with VEGF and FGF2 had a beneficial effect on wound healing.

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

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.

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

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.

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.

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.

Bladder regeneration using multiple scaffolds with growth factors in a bladder

INTRODUCTION 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 the use of multiple scaffolds instead of one large scaffold, to enhance bladder tissue regeneration and bladder capacity. Second, acellular collagen, collagen-heparin, and collagen-heparin scaffolds with growth factors (GFs) were used and the biological activity of the different scaffolds was compared in a large animal model. MATERIALS AND METHODS Scaffolds were made of bovine type I collagen with or without heparin (Ø = 3.2 cm). Collagen-heparin scaffolds were loaded with GFs, vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF2), and heparin-binding epidermal growth factor (HB-EGF). Three identical scaffolds prepared from collagen (COL-group), collagen with heparin (COLHEP-group), or collagen-heparin with growth factors (COLHEPGF-group) were implanted in one porcine bladder. The outcome was compared with sham-operated animals (Sham-group), in which no scaffold was used. Urodynamic evaluation was performed before surgery and 3 months after bladder reconstruction, together with histological evaluation. RESULTS Survival rate was 92%, 12 animals completed the study, 3 of every group, 1 animal developed peritonitis due to urine leakage and was sacrificed. The regenerated area was largest in the COLHEP-group, and least in the COL-group (p = 0.002). Histological evaluation revealed a normal urothelial layer and good angiogenesis in all groups, and comparable ingrowth of smooth muscle cells. Urodynamics showed no statistically significant differences in bladder capacity and compliance between groups. Bladder capacity and compliance was very high in this animal model, which made it impossible to study the increase due to augmentation. CONCLUSIONS Implantation of multiple collagen-heparin scaffolds in one bladder is feasible in a porcine model, resulting in tissue almost indistinguishable from native tissue involving all cell layers of the bladder. Collagen scaffolds with heparin incorporated resulted in a larger area of regenerated tissue. To reach clinically significant augmentation, multiple larger collagen-heparin scaffolds, with or without GFs, need to be tested to study the largest possible diameter of scaffold and number of used scaffolds still resulting in well-vascularized tissue.

Clinical and histological outcome of fetal spinal surgery in a chronic sheep model

Material and methods Study subjects were fetal lambs with an, at 79 days gestation, surgically created opening of the spinal canal. Biomatrix covering, applied immediately after creation of the spinal defect, was taken as a tool for surgery improvement. The clinical and pathological findings at full-term age were taken as outcome measures. For comparison, two procedures were used, i.e., spinal canal opening without closure; and closure using skin.