Structural and functional characterization of bladder smooth muscle in fetal rats with retinoic acid-induced myelomeningocele

Maternal Minocycline as Fetal Therapy in a Rat Model of Myelomeningocele

INTRODUCTION

This study aimed to investigate whether the maternal administration of minocycline, a tetracycline antibiotic known to have anti-inflammatory and neuroprotective properties in models of neural injury, reduces inflammation and neural cell death in a fetal rat model of myelomeningocele (MMC).

METHODS

E10 pregnant rats were gavaged with olive oil or olive oil + retinoic acid to induce fetal MMC. At E12, the dams were exposed to regular drinking water or water containing minocycline (range, 40-140 mg/kg/day). At E21, fetal lumbosacral spinal cords were isolated for immunohistochemistry and quantitative gene expression studies focused on microglia activity, inflammation, and apoptosis (P < 0.05).

RESULTS

There was a trend toward decreased activated Iba1+ microglial cells within the dorsal spinal cord of MMC pups following minocycline exposure when compared to water (H2O) alone (P = 0.052). Prenatal minocycline exposure was correlated with significantly reduced expression of the proinflammatory cytokine, IL-6 (minocycline: 1.75 versus H2O: 3.52, P = 0.04) and apoptosis gene, Bax (minocycline: 0.71 versus H2O: 1.04, P < 0.001) among MMC pups.

CONCLUSIONS

This study found evidence that the maternal administration of minocycline reduces selected markers of inflammation and apoptosis within the exposed dorsal spinal cords of fetal MMC rats. Further study of minocycline as a novel prenatal treatment strategy to mitigate spinal cord damage in MMC is warranted.

Folic acid supplementation rescues bladder injury in fetal rats with myelomeningocele

BACKGROUND

Bladder dysfunction has been linked to the progression of renal failure in children with neurogenic bladder (NB) dysfunction. The purpose of this study was to determine whether bladder injuries in fetal rats with myelomeningocele (MMC) may be treated with folic acid.

METHODS

Pregnant Sprague-Dawley rats were randomly divided into three groups. On the 10th day of gestation, pregnant rats were intragastrically injected with all-trans retinoic acid (ATRA) (60 mg/kg) to induce MMC fetal rats. The same amount of olive oil was put into the control group to create normal fetal rats. The rats in the rescue group were given folic acid (40 mg/kg) by gavage 0.5 and 12 hr after ATRA therapy. Bladders were obtained via cesarean section on embryonic day E20.5 and examined for MMC. The histology of the fetuses was examined using hematoxylin and eosin staining, and immunohistochemistry (IHC) was utilized to determine the expression of α-smooth muscle actin (α-SMA) and neuron-specific nuclear-binding protein (NeuN). Furthermore, the levels of neuromuscular development-related and apoptotic proteins were determined by western blotting.

RESULTS

The incidence of MMC in the model group was 60.6% (20/33) while it was much lower in the rescue group (21.4%). In comparison to the model group, the weight and crown-rump length of the fetal rats in the rescue group were significantly improved. IHC revealed that there was no significant difference in the expression of α-SMA and NeuN between the control and ATRA groups, while the expression levels decreased significantly in the MMC group. Western blot analysis showed that there was no significant difference between the model and ATRA groups, but the expression of the α-SMA protein and the β3-tubulin was much lower in the MMC group than in the control group. After the administration of folic acid, the α-SMA and β3-tubulin proteins considerably increased in the folic acid-rescued MMC group and folic acid-rescued ATRA group. Meanwhile, in the control group, the expression of cleaved caspase-3 in the bladder tissue was significantly higher, and the expression of poly (ADP-ribose) polymerase (PARP) protein was significantly lower compared to the control group. Folic acid therapy reduced cleaved caspase-3 expression while increasing PARP expression in comparison to the MMC group.

CONCLUSIONS

NB in MMC fetal rats is associated with the reduction of bladder nerve and smooth muscle-related protein synthesis. However, folic acid therapy can help improve these functional deficiencies. Folic acid also exhibits strong anti-apoptotic properties against NB in MMC fetal rats.

Neurogenic Lower Urinary Tract Dysfunction in Spinal Dysraphism: Morphological and Molecular Evidence in Children

Spinal dysraphism, most commonly myelomeningocele, is the typical cause of a neurogenic lower urinary tract dysfunction (NLUTD) in childhood. The structural changes in the bladder wall in spinal dysraphism already occur in the fetal period and affect all bladder wall compartments. The progressive decrease in smooth muscle and the gradual increase in fibrosis in the detrusor, the impairment of the barrier function of the urothelium, and the global decrease in nerve density, lead to severe functional impairment characterized by reduced compliance and increased elastic modulus. Children present a particular challenge, as their diseases and capabilities evolve with age. An increased understanding of the signaling pathways involved in lower urinary tract development and function could also fill an important knowledge gap at the interface between basic science and clinical implications, leading to new opportunities for prenatal screening, diagnosis, and therapy. In this review, we aim to summarize the evidence on structural, functional, and molecular changes in the NLUTD bladder in children with spinal dysraphism and discuss possible strategies for improved management and for the development of new therapeutic approaches for affected children.

The Mechanism of Bladder Injury in Fetal Rats With Myelomeningocele

Background

Bladder dysfunction has been implicated as a major cause of progressive renal failure in children with neurogenic bladder. However, its pathogenesis remains unclear. This study aimed to compare the expression of proliferation, apoptosis, and neuromuscular-related proteins during the development of the bladder in myelomeningocele fetal rats, and to explore the characteristics of its abnormal development.

Methods

For the myelomeningocele group, Sprague Dawley pregnant rats were intragastrically injected with retinoic acid on the 10th day of gestation to induce myelomeningocele fetal rats. For the control group, the same amount of olive oil was injected to induce normal fetal rats. Bladders were harvested at embryonic days E16, E18, E20, and E22. Real-time quantitative polymerase chain reaction and western blotting were used to detect the protein levels of proliferating cell nuclear antigen (PCNA), cleaved caspase-3, neuron-specific nuclear-binding protein (NeuN), α-smooth muscle actin (α-SMA), and mRNA at E16-E22; immunohistochemistry was used to detect the expression of cleaved caspase-3 at E22.

Results

The proliferation of bladder tissue cells was inhibited, with suppressed PCNA expression in myelomeningocele bladder tissue compared with that in control tissue at the early stage (E16). Myelomeningocele bladders showed increased tissue apoptosis in the late embryonic stage, with significantly higher cleaved caspase-3 protein expression than in the control bladders at E20 and E22. NeuN protein expression increased along with embryonic stage, although the expression at E20 and E22 was significantly lower in myelomeningocele bladders than in control bladders. α-SMA protein expression in myelomeningocele bladders increased gradually with the progression of pregnancy, although its expression was lower than that for control bladders at E22. Immunohistochemistry showed abundant positive staining for cleaved caspase-3 in the bladder mucosa and muscle layer of myelomeningocele bladders, and the expression of cleaved caspase-3 was significantly higher in myelomeningocele bladders than in control bladders.

Conclusions

Bladder dysfunction in myelomeningocele fetal rats is related to the inhibition of proliferation, promotion of apoptosis, and reduction of bladder nerve and smooth muscle-related protein synthesis.

Intra-amniotic Injection of Poly(lactic-co-glycolic Acid) Microparticles Loaded with Growth Factor: Effect on Tissue Coverage and Cellular Apoptosis in the Rat Model of Myelomeningocele

BACKGROUND

Myelomeningocele (MMC) is a devastating congenital neurologic disorder that can lead to lifelong morbidity and has limited treatment options. This study investigates the use of poly(lactic-co-glycolic acid) (PLGA) microparticles (MPs) loaded with fibroblast growth factor (FGF) as a platform for in utero treatment of MMC.

STUDY DESIGN

Intra-amniotic injections of PLGA MPs were performed on gestational day 17 (E17) in all-trans retinoic acid-induced MMC rat dams. MPs loaded with fluorescent dye (DiO) were evaluated 3 hours after injection to determine incidence of binding to the MMC defect. Fetuses were then treated with PBS or PLGA particles loaded with DiO, bovine serum albumin, or FGF and evaluated at term (E21). Fetuses with MMC defects were evaluated for gross and histologic evidence of soft tissue coverage. The effect of PLGA-FGF treatment on spinal cord cell death was evaluated using an in situ cell death kit.

RESULTS

PLGA-DiO MPs had a binding incidence of 86% and 94% 3 hours after injection at E17 for doses of 0.1 mg and 1.2 mg, respectively. Incidence of soft tissue coverage at term was 19% (4 of 21), 22% (2 of 9), and 83% (5 of 6) for PLGA-DiO, PLGA-BSA, and PLGA-FGF, respectively. At E21, the percentage of spinal cord cells positive for in situ cell death was significantly higher in MMC controls compared with wild-type controls or MMC pups treated with PLGA-FGF.

CONCLUSION

PLGA MPs are an innovative minimally invasive platform for induction of soft tissue coverage in the rat model of MMC and may reduce cellular apoptosis.

Early investigations into improving bowel and bladder function in fetal ovine myelomeningocele repair

INTRODUCTION

Fetal myelomeningocele (MMC) repair improves lower extremity motor function. We have previously demonstrated that augmentation of fetal MMC repair with placental mesenchymal stromal cells (PMSCs) seeded on extracellular matrix (PMSC-ECM) further improves motor function in the ovine model. However, little progress has been made in improving bowel and bladder function, with many patients suffering from neurogenic bowel and bladder. We hypothesized that fetal MMC repair with PMSC-ECM would also improve bowel and bladder function.

METHODS

MMC defects were surgically created in twelve ovine fetuses at median gestational age (GA) 73 days, followed by defect repair at GA101 with PMSC-ECM. Fetuses were delivered at GA141. Primary bladder function outcomes were voiding posture and void volumes. Primary bowel function outcome was anorectal manometry findings including resting anal pressure and presence of rectoanal inhibitory reflex (RAIR). Secondary outcomes were anorectal and bladder detrusor muscle thickness. PMSC-ECM lambs were compared to normal lambs (n = 3).

RESULTS

Eighty percent of PMSC-ECM lambs displayed normal voiding posture compared to 100% of normal lambs (p = 1). Void volumes were similar (PMSC-ECM 6.1 ml/kg vs. normal 8.8 ml/kg, p = 0.4). Resting mean anal pressures were similar between cohorts (27.0 mmHg PMSC-ECM vs. normal 23.5 mmHg, p = 0.57). RAIR was present in 3/5 PMSC-ECM lambs that underwent anorectal manometry and all normal lambs (p = 0.46). Thicknesses of anal sphincter complex, rectal wall muscles, and bladder detrusor muscles were similar between cohorts.

CONCLUSION

Ovine fetal MMC repair augmented with PMSC-ECM results in near-normal bowel and bladder function. Further work is needed to evaluate these outcomes in human patients.

A preliminary investigation of high retinoic acid exposure during fetal development on behavioral competency and litter characteristics in newborn rats

Myelomeningocele (MMC) is the most common and severe type of spina bifida in which the developing spine and neural tube fail to close during prenatal development. This typically results in a small portion of the lower spinal cord and meninges protruding from the back of the individual, accompanied by severe motor and sensory deficits. In rats, retinoic acid (RA) exposure in high doses during fetal development has been shown to induce morphologic and clinical symptoms similar to humans with MMC. The aim of the current study was to examine litter characteristics and sensorimotor function in MMC-affected rat pups. Pregnant rats were gavage-fed 2 ml olive oil or all-trans RA (40, 45, 50 mg/kg) on gestational day 11. Pups underwent behavioral testing on postnatal day 2. Litter characteristics and newborn sensorimotor function varied across RA doses. Pups prenatally exposed to 45 and 50 mg/kg RA weighed significantly less than olive oil and 40 mg/kg RA pups. Litters exposed to 45 mg/kg RA suffered significantly higher mortality rates compared to other groups. Additionally, bladder function was significantly impaired in pups exposed to 40 mg/kg RA. Sensorimotor function findings demonstrated that for most behavioral assessments there was not a significant difference between control and RA-exposed subjects. However, pups treated with 40 mg/kg RA showed increased facial wiping, suggesting a hyper-responsiveness to sensory stimuli. Overall, the findings of the current study provide evidence for a model to examine litter characteristics and behavioral effects as well as morphology.

State of the art in translating experimental myelomeningocele research to the bedside

Myelomeningocele (MMC), the commonest type of spina bifida (SB), occurs due to abnormal development of the neural tube and manifest as failure of the complete fusion of posterior arches of the spinal column, leading to dysplastic growth of the spinal cord and meninges. It is associated with several degrees of motor and sensory deficits below the level of the lesion, as well as skeletal deformities, bladder and bowel incontinence, and sexual dysfunction. These children might develop varying degrees of neuropsychomotor delay, partly due to the severity of the injuries that affect the nervous system before birth, partly due to the related cerebral malformations (notably hydrocephalus-which may also lead to an increase in intracranial pressure-and Chiari II deformity). Traditionally, MMC was repaired surgically just after birth; however, intrauterine correction of MMC has been shown to have several potential benefits, including better sensorimotor outcomes (since exposure to amniotic fluid and its consequent deleterious effects is shortened) and reduced rates of hydrocephalus, among others. Fetal surgery for myelomeningocele, nevertheless, would not have been made possible without the development of experimental models of this pathological condition. Hence, the aim of the current article is to provide an overview of the animal models of MMC that were used over the years and describe how this knowledge has been translated into the fetal treatment of MMC in humans.

Diffusion weighted imaging as a biomarker of retinoic acid induced myelomeningocele

Neural tube defects are a common congenital anomaly involving incomplete closure of the spinal cord. Myelomeningocele (MMC) is a severe form in which there is complete exposure of neural tissue with a lack of skin, soft tissue, or bony covering to protect the spinal cord. The all-trans retinoic acid (ATRA) induced rat model of (MMC) is a reproducible, cost-effective means of studying this disease; however, there are limited modalities to objectively quantify disease severity, or potential benefits from experimental therapies. We sought to determine the feasibility of detecting differences between MMC and wild type (WT) rat fetuses using diffusion magnetic resonance imaging techniques (MRI). Rat dams were gavage-fed ATRA to produce MMC defects in fetuses, which were surgically delivered prior to term. Average diffusion coefficient (ADC) and fractional anisotropy (FA) maps were obtained for each fetus. Brain volumes and two anatomically defined brain length measurements (D1 and D2) were significantly decreased in MMC compared to WT. Mean ADC signal was significantly increased in MMC compared to WT, but no difference was found for FA signal. In summary, ADC and brain measurements were significantly different between WT and MMC rat fetuses. ADC could be a useful complementary imaging biomarker to current histopathologic analysis of MMC models, and potentially expedite therapeutic research for this disease.

Fetal surgical intervention for myelomeningocele: lessons learned, outcomes, and future implications

Fetal myelomeningocele (fMMC) closure (spina bifida aperta) has become a care option for patients that meet inclusion criteria, but it is clear that fetal intervention, while improving outcomes, is not a cure. This review will: (1) focus on the rationale for fMMC surgery based on preclinical studies and observations that laid the foundation for human pilot studies and a randomized controlled trial; (2) summarize important clinical outcomes; (3) discuss the feasibility, efficacy, and safety of recent developments in fetal surgical techniques and approaches; and (4) highlight future research directions. Given the increased risk of maternal and fetal morbidity associated with prenatal intervention, accompanied by the increasing number of centres performing interventions worldwide, teams involved in the care of these patients need to proceed with caution to maintain technical expertise, competency, and patient safety. Ongoing assessment of durability of the benefits of fMMC surgery, as well as additional refinement of patient selection criteria and counselling, is needed to further improve outcomes and reduce the risks to the mother and fetus. WHAT THIS PAPER ADDS: High-quality prospective studies are needed to broaden the indication for fetal surgery in the general myelomeningocele population. Innovative minimally invasive approaches have had promising results, yet lack comprehensive and robust experimental or clinical evaluation. Important information to help families make informed decisions regarding fetal surgery for myelomeningocele is provided.

In Utero Amniotic Fluid Stem Cell Therapy Protects Against Myelomeningocele via Spinal Cord Coverage and Hepatocyte Growth Factor Secretion

Despite the poor prognosis associated with myelomeningocele (MMC), the options for prenatal treatments are still limited. Recently, fetal cellular therapy has become a new option for treating birth defects, although the therapeutic effects and mechanisms associated with such treatments remain unclear. The use of human amniotic fluid stem cells (hAFSCs) is ideal with respect to immunoreactivity and cell propagation. The prenatal diagnosis of MMC during early stages of pregnancy could allow for the ex vivo proliferation and modulation of autologous hAFSCs for use in utero stem cell therapy. Therefore, we investigated the therapeutic effects and mechanisms of hAFSCs‐based treatment for fetal MMC. hAFSCs were isolated as CD117‐positive cells from the amniotic fluid of 15‐ to 17‐week pregnant women who underwent amniocentesis for prenatal diagnosis and consented to this study. Rat dams were exposed to retinoic acid to induce fetal MMC and were subsequently injected with hAFSCs in each amniotic cavity. We measured the exposed area of the spinal cord and hepatocyte growth factor (HGF) levels at the lesion. The exposed spinal area of the hAFSC‐treated group was significantly smaller than that of the control group. Immunohistochemical analysis demonstrated a reduction in neuronal damage such as neurodegeneration and astrogliosis in the hAFSC‐treated group. Additionally, in lesions of the hAFSC‐treated group, HGF expression was upregulated and HGF‐positive hAFSCs were identified, suggesting that these cells migrated to the lesion and secreted HGF to suppress neuronal damage and induce neurogenesis. Therefore, in utero hAFSC therapy could become a novel strategy for fetal MMC. stem cells translational medicine2019;8:1170–1179

Validation of the Fetal Lamb Model of Spina Bifida

A randomized trial demonstrated that fetal spina bifida (SB) repair is safe and effective yet invasive. New less invasive techniques are proposed but are not supported by adequate experimental studies. A validated animal model is needed to bridge the translational gap to the clinic and should mimic the human condition. Introducing a standardized method, we comprehensively and reliably characterize the SB phenotype in two lamb surgical models with and without myelotomy as compared to normal lambs. Hindbrain herniation measured on brain magnetic resonance imaging (MRI) was the primary outcome. Secondary outcomes included gross examination with cerebrospinal fluid (CSF) leakage test, neurological examination with locomotor assessment, whole-body MRI, motor and somatosensory evoked potentials; brain, spinal cord, hindlimb muscles, bladder and rectum histology and/or immunohistochemistry. We show that the myelotomy model best phenocopies the anatomy, etiopathophysiology and symptomatology of non-cystic SB. This encompasses hindbrain herniation, ventriculomegaly, posterior fossa anomalies, loss of brain neurons; lumbar CSF leakage, hindlimb somatosensory-motor deficit with absence of motor and somatosensory evoked potentials due to loss of spinal cord neurons, astroglial cells and myelin; urinary incontinence. This model obtains the highest validity score for SB animal models and is adequate to assess the efficacy of novel fetal therapies.

Lrig2 and Hpse2, mutated in urofacial syndrome, pattern nerves in the urinary bladder

Mutations in leucine-rich-repeats and immunoglobulin-like-domains 2 (LRIG2) or in heparanase 2 (HPSE2) cause urofacial syndrome, a devastating autosomal recessive disease of functional bladder outlet obstruction. It has been speculated that urofacial syndrome has a neural basis, but it is unknown whether defects in urinary bladder innervation are present. We hypothesized that urofacial syndrome features a peripheral neuropathy of the bladder. Mice with homozygous targeted Lrig2 mutations had urinary defects resembling those found in urofacial syndrome. There was no anatomical blockage of the outflow tract, consistent with a functional bladder outlet obstruction. Transcriptome analysis revealed differential expression of 12 known transcripts in addition to Lrig2, including 8 with established roles in neurobiology. Mice with homozygous mutations in either Lrig2 or Hpse2 had increased nerve density within the body of the urinary bladder and decreased nerve density around the urinary outflow tract. In a sample of 155 children with chronic kidney disease and urinary symptoms, we discovered novel homozygous missense LRIG2 variants that were predicted to be pathogenic in 2 individuals with non-syndromic bladder outlet obstruction. These observations provide evidence that a peripheral neuropathy is central to the pathobiology of functional bladder outlet obstruction in urofacial syndrome, and emphasize the importance of LRIG2 and heparanase 2 for nerve patterning in the urinary tract.

Alginate microparticles loaded with basic fibroblast growth factor induce tissue coverage in a rat model of myelomeningocele

BACKGROUND/PURPOSE

We sought to develop a minimally invasive intra-amniotic therapy for prenatal treatment of myelomeningocele (MMC) in an established rat model.

METHODS

Time-dated pregnant rats were gavage-fed retinoic acid to induce MMC. Groups received intraamniotic injections at E17.5 with alginate particles loaded with fluorescent dye, basic fibroblast growth factor (Alg-HSA-bFGF), fluorescently tagged albumin (Alginate-BSA-TR), free bFGF, blank alginate particles (Alg-Blank), or PBS. Groups were analyzed at 3 h for specific particle binding or at term (E21) to determine MMC coverage.

RESULTS

Alginate microparticles demonstrated robust binding to the MMC defect 3 h after injection. Of those specimens analyzed at E21, 150 of 239 fetuses (62.8%) were viable. Moreover, 18 of 61 (30%) treated with Alg-HSA-bFGF showed evidence of soft tissue coverage compared to 0 of 24 noninjected (P = 0.0021), 0 of 13 PBS (P = 0.0297), and 0 of 42 free bFGF (P = P < 0.0001). Scaffolds of aggregated particles associated with disordered keratinized tissue were observed covering the defect in 2 of 18 (11%) Alg-BSA-TR and 3 of 19 (16%) Alg-Blank specimens.

CONCLUSIONS

Injection of microparticles loaded with bFGF resulted in significant soft tissue coverage of the MMC defect compared to controls. Alginate microparticles without growth factors might result in scaffold development over the fetal MMC.

TYPE OF STUDY

Basic science.

LEVEL OF EVIDENCE

N/A.

Fetal surgery for spina bifida aperta

Spina bifida aperta (SBA) is one of the most common congenital malformations. It can cause severe lifelong physical and neurodevelopmental disabilities. Experimental and clinical studies have shown that the neurological deficits associated with SBA are not simply caused by incomplete neurulation at the level of the lesion. Additional damage is caused by prolonged exposure of the spinal cord and nerves to the intrauterine environment and a suction gradient due to cerebrospinal fluid leakage, leading to progressive downward displacement of the hindbrain. This natural history can be reversed by prenatal repair. A randomised controlled trial demonstrated that mid-gestational maternal-fetal surgery for SBA decreases the need for ventriculoperitoneal shunting and hindbrain herniation at 12 months and improves neurological motor function at 30 months of age. This came at the price of maternal and fetal risks, the most relevant ones being increased prematurity and a persistent uterine corporeal scar. Recently minimally invasive fetal approaches have been introduced clinically yet they lack extensive experimental or clinical trials. We aim to provide clinicians with the essential information necessary to counsel SBA parents as the basis for considering referral of selected patients to expert fetal surgery centres. We review the reported clinical outcomes and discuss recent developments of potentially less invasive fetal SBA approaches.

Safety and efficacy of fetal surgery techniques to close a spina bifida defect in the fetal lamb model: A systematic review

OBJECTIVE

To determine the safety and efficacy of different neurosurgical techniques for closure of spina bifida (SB) in the fetal lamb model.

METHOD

Systematic review of studies reporting on fetal lambs undergoing induction and closure of SB compared with non-operated normal lambs (negative controls) and/or lambs not undergoing closure of the defect (positive controls). Primary outcomes were (1) survival at birth (safety) and/or (2) presence of Somatosensory Evoked Potentials on hind limbs and/or improvement in quantitative histological spinal cord findings and/or reversal of hindbrain herniation (efficacy).

RESULTS

Out of 1311, 36 full-text articles were eligible. Nineteen were included for quality assessment. Due to high bias, only 2 adequately powered studies were included in the final analysis. An open approach using a 2-layer closure (muscle flap or acellular-dermal-matrix patch plus skin) was the only safe (patch + skin) and effective (both techniques) technique for prenatal closure in this animal model. No comparable level of evidence was identified for other techniques.

CONCLUSION

The experimental literature on prenatal SB closure underscores the lack of standardization. At present, there is animal experimental evidence that a 2-layer closure by hysterotomy is safe and effective. This technique is currently clinically used in a subset of patients. As new clinical techniques are introduced, it would seem logic to preclinically validate them against this experimental standard.

In utero repair of fetal rat myelomeningocele affects neuromuscular development in the bladder

Fetal repair of myelomeningocele (MMC) has been proven to be beneficial for the central nervous system development; however, the effect of fetal MMC repair on bladder function remains controversial. The objective of the present study was to establish an early timepoint for in utero MMC repair using a rat model, and to investigate the changes in bladder development subsequent to that intervention. Sprague Dawley rats were divided into the MMC, MMC repair and control groups. MMC rat fetus models were created by treating pregnant rats with all-trans retinoic acid. The MMC defect was then repaired in utero at embryonic day 17 (E17) using a chitosan-gelatin membrane patch. Fetal rat bladders were removed at E19 and E21 in each group, as well as at stage E17 in the MMC and control groups. Differential expression of β-III-tubulin, α-smooth muscle actin (α-SMA), nerve growth factor (NGF) and acetylcholinesterase (AChE) mRNA, and β-III-tubulin and α-SMA protein in the bladder following fetal repair was measured and compared among the three groups. In addition, the expression of NGF mRNA was significantly elevated at E21 in the MMC group compared with that of the control group, however, the level decreased in the repair group at stage E21. The expression of α-SMA mRNA significantly increased at E19 and then decreased at E21 in the repair group compared with that of the MMC group; however, there were no significant changes in α-SMA protein following the repair. Furthermore, the repair enhanced β-III-tubulin mRNA expression at E19, but ameliorated the decrease of β-III-tubulin protein at E21. The expression of AChE mRNA increased in the MMC group at E19 and E21 compared with that of the control group, although it was not significantly altered following repair as compared with that of the MMC group. In conclusion, in the current study, abnormal neuromuscular development was observed in the MMC bladder, which enabled a certain degree of improvement in the in utero MMC repair.

Distribution of interstitial cells of Cajal in the bladders of fetal rats with retinoic acid induced myelomeningocele

OBJECTIVE

Myelomeningocele (MMC) is one of the most common reason of neurogenic bladder dysfunction in children. Although neurogenic bladder dysfunction occurrence is related with bladder innervation, also there are some changes seen in the smooth muscle and neural cells of the bladder. Interstitial cells of Cajal (ICC) are the pacemaker cells found in organs with peristaltic activity. Although it has been shown that ICC are diminished in the rat urinary bladder with traumatic spinal cord injury, there is no data about ICC in fetal rat bladders with MMC. This study has been conducted to investigate the ICC in the bladders of fetal rats with retinoic acid induced MMC.

MATERIALS AND METHODS

Time dated pregnant Wistar albino rats were divided into 3 groups. In MMC group, dams were fed with gavage solution containing 60 mg/kg all-trans retinoic acid dissolved in olive oil on 10. embryologic day. Sham group animals were fed only olive oil. Control group dams were fed with standard rat chow. Fetuses were delivered by cesarean section and harvested on 22. embryologic day. MMC was identified by observing MMC sacs at the back of the fetuses. Distribution of ICCs were evaluated using immunohistochemical staining.

RESULTS

ICCs were found in all groups, which have the same morphological features that had been described earlier in the gastrointestinal tract and the bladder. The density of the ICC in the MMC group was found to be significantly decreased when compared with the control and the sham groups (p<0.05).

CONCLUSION

The density of the ICC in the urinary bladder decreased in the neurogenic bladder developed in MMC.

Bladder wall thickness in the assessment of neurogenic bladder: a translational discussion of current clinical applications

The prospective trial by Kim et al. "Can Bladder Wall Thickness Predict Videourodynamic Findings in Children with Spina Bifida?" published in Journal of Urology investigated the measurement of bladder wall thickness (BWT) as a non-invasive assessment tool for lower urinary tract changes in neurogenic bladder (NGB). In this study, no significant association was observed between BWT and high-risk urodynamic parameters. This editorial discusses the basic science of bladder wall thickening as well as prior studies relating wall thickness to clinical parameters. Although Kim et al. provide a unique literature contribution in terms of assessment of BWT at defined percent cystometric capacity, specific aspects of study methodology and population may have contributed to a lack of correlation with high-risk urodynamic findings. The application of non-invasive modalities to lower urinary tract assessment of NGB remains a promising and relevant area of future research to prevent progression to end stage lower urinary tract changes for all individuals with spina bifida.

Urinary tract effects of HPSE2 mutations

Urofacial syndrome (UFS) is an autosomal recessive congenital disease featuring grimacing and incomplete bladder emptying. Mutations of HPSE2, encoding heparanase 2, a heparanase 1 inhibitor, occur in UFS, but knowledge about the HPSE2 mutation spectrum is limited. Here, seven UFS kindreds with HPSE2 mutations are presented, including one with deleted asparagine 254, suggesting a role for this amino acid, which is conserved in vertebrate orthologs. HPSE2 mutations were absent in 23 non-neurogenic neurogenic bladder probands and, of 439 families with nonsyndromic vesicoureteric reflux, only one carried a putative pathogenic HPSE2 variant. Homozygous Hpse2 mutant mouse bladders contained urine more often than did wild-type organs, phenocopying human UFS. Pelvic ganglia neural cell bodies contained heparanase 1, heparanase 2, and leucine-rich repeats and immunoglobulin-like domains-2 (LRIG2), which is mutated in certain UFS families. In conclusion, heparanase 2 is an autonomic neural protein implicated in bladder emptying, but HPSE2 variants are uncommon in urinary diseases resembling UFS.

Fetal surgery for myelomeningocele is effective: a critical look at the whys

Formerly, the disastrous cluster of neurologic deficits and associated neurogenic problems in patients with myelomeningocele (MMC) was generally thought to solely result from the primary malformation, i.e., failure of neurulation. Today, however, there is no doubt that a dimensional additional pathogenic mechanism exists. Most likely, it contributes much more to loss of neurologic function than non-neurulation does. Today, there is a large body of compelling experimental and clinical evidence confirming that the exposed part of the non-neurulated spinal cord is progressively destroyed during gestation, particularly so in the third trimester. These considerations gave rise to the two-hit-pathogenesis of MMC with non-neurulation being the first and consecutive in utero acquired neural tissue destruction being the second hit. This novel pathophysiologic understanding has obviously triggered the question whether the serious and irreversible functional loss caused by the second hit could not be prevented or, at least, significantly alleviated by timely protecting the exposed spinal cord segments, i.e., by early in utero repair of the MMC lesion. Based on this intriguing hypothesis and the above-mentioned data, human fetal surgery for MMC was born in the late nineties of the last century and has made its way to become a novel standard of care, particularly after the so-called "MOMS Trial". This trial, published in the New England Journal of Medicine, has indisputably shown that overall, open prenatal repair is distinctly better than postnatal care alone. Finally, a number of important other topics deserve being mentioned, including the necessity to work on the up till now immature endoscopic fetal repair technique and the need for concentration of these extremely challenging cases to a small number of really qualified fetal surgery centers worldwide. In conclusion, despite the fact that in utero repair of MMC is not a complete cure and not free of risk for both mother and fetus, current data clearly demonstrate that open fetal-maternal surgery is to be recommended as novel standard of care when pregnancy is to be continued and when respective criteria for the intervention before birth are met. Undoubtedly, it is imperative to inform expecting mothers about the option of prenatal surgery once their fetus is diagnosed with open spina bifida.

Bladder changes after several coverage modalities in the surgically induced model of myelomeningocele in lambs

OBJECTIVE

To assess the presence of early bladder abnormalities in a prenatally corrected and uncorrected animal model of Myelomeningocele (MMC).

METHOD

A MMC-like lesion was surgically created in 18 fetal lambs between the 60th and the 80th day of gestation. Eight of them did not undergo fetal repair (group A), three were repaired with an open two-layer closure (group B), three using BioGlue® (groupC) and four fetoscopically (group D). At term, bladders were examined macroscopically and histopathological changes were assessed using H-E and Masson Trichrome.

RESULTS

Five animals in group A (5/8, 62%), two in group B (2/3, 66%), one in group C (1/3, 33%) and one in group D (1/4, 25%) survived. Macroscopically bladders in group A were severely dilated and showed thinner walls. Microscopically they showed a thin layer of colagenous tissue (Blue layer. BL) lying immediately subjacent to the urothelium. The muscular layers were thinner. Non compliant pattern with thick wall and low capacity was also found in the non corrected model. Group B and the control showed preservation of muscular layers and absence of BL. Groups C and D presented BL but also preservation of muscular layers.

CONCLUSION

Bladder changes in a surgically-induced model of MMC can be described using histopathological data. Both extremes of bladder changes can be observed in the model. These changes were completely prevented with open fetal surgery and partially with other coverage modalities.

Morphology of nervous lesion in the spinal cord and bladder of fetal rats with myelomeningocele at different gestational age

OBJECTIVE

To analyze the development and innervation of bladder smooth muscle and lesions of the spinal cord in fetal rats with meningomyelocele (MMC) at different gestational ages and to investigate interactions between spinal cord lesions and bladder.

METHOD

Each fetus was assigned to the MMC group or the normal group. Each group was further divided into three subgroups by gestational age: E16, E18, and E20 (embryonic days 16, 18, and 20, respectively). α-Actin and neurotubulin-β-III were analyzed in the bladder, and GFAP and VAChT were analyzed in the lumbosacral spinal cord by immunohistochemistry. Photographs were taken to determine the integrated optical density of each sample.

RESULTS

Neurotubulin-β-III was significantly lower in the MMC group than in the normal group at all fetal ages. Abundant α-actin was detected in both groups at all fetal ages. No significant difference was found between the MMC group and the normal group at any fetal age. At E16 and E18, no GFAP-positive astrocyte was detected in the MMC group or the normal group. At E20, numerous GFAP-positive astrocytes were detected in the MMC group, with significant difference from the normal group. VAChT was detected less in the MMC group than in the normal group at all fetal ages with significant differences.

CONCLUSION

Bladder smooth muscle of fetal MMC rat seems morphologically normal in development, while the innervation of the bladder smooth muscle is markedly decreased centrally and peripherally. Astrocytosis appears at a later embryonic stage, which could be a concern in the nerve repair of the spinal cord.

THE PRENATAL MANAGEMENT OF NEURAL TUBE DEFECTS: TIME FOR A RE-APPRAISAL

The prevalence of neural tube defects (NTD) in Europe is around 9 per 10,000 births making it one of the most frequent congential anomalies affecting the central nervous system. NTD encompass all anomalies that are secondary to failure of closure of the neural tube. In this review, we will first summarize the embryology and some epidemiologic aspects related to NTDs. The review focuses on myelomeningocele (MMC), which is the most common distal closure defect. We will describe the secondary pathologic changes in the central and peripheral nervous system that appear later on in pregnancy and contribute to the condition's morbidity. The postnatal impact of MMC mainly depends on the upper level of the lesion. In Europe, the vast majority of parents with a fetus with prenatally diagnosed NTDs, including MMC, opt for termination of pregnancy, as they are apparently perceived as very debilitating conditions. Animal experiments have shown that prenatal surgery can reverse this sequence. This paved the way for clinical fetal surgery resulting in an apparent improvement in outcome. The results of a recent randomized trial confirmed better outcomes after fetal repair compared to postnatal repair; with follow up for 30 months. This should prompt fetal medicine specialists to reconsider their position towards this condition as well as its prenatal repair. The fetal surgery centre in Leuven did not have a clinical programme for fetal NTD repair until the publication of the MOMS trial. In order to offer this procedure safely and effectively, we allied to a high volume centre willing to share its expertise and assist us in the first procedures. Given the maternal side effects of current open fetal surgical techniques, we have intensified our research programmes to explore minimally invasive alternatives. Below we will describe how we are implementing this.

Fetal surgery for myelomeningocele: trials and tribulations. Isabella Forshall Lecture

The rationale for in utero repair of myelomeningocele (MMC) in the context of pathologic observations, animal models, and outcomes from the initial experience with human fetal MMC repair is presented. This has now culminated in a randomized trial, Management of Myelomeningocele Study, the findings of which are listed. The story is focused on the milestone contributions of members of the Center for Fetal Diagnosis and Treatment at the Children's Hospital of Philadelphia on the road to successful fetal surgery for spina bifida. This is now performed in selected patients and presents an additional therapeutic alternative for expectant mothers carrying a fetus with MMC.

Fetal surgery for myelomeningocele: progress and perspectives

Myelomeningocele (MMC), one of the most common congenital malformations, can result in severe lifelong disabilities, including paraplegia, hydrocephalus, Chiari II malformation, bowel and bladder dysfunction, skeletal deformations, and neurocognitive impairment. Experimental studies provide compelling evidence that the neurological deficits associated with MMC are not simply caused by incomplete neurulation but rather by the prolonged exposure of the vulnerable neural elements to the intrauterine environment. MMC is the first non-lethal anomaly considered for fetal surgical intervention, necessitating a careful analysis of risks and benefits. Retrospective and prospective randomized studies suggest that fetal surgery of MMC before 26 weeks of gestation may preserve neuromotor function, reverse hindbrain herniation, and reduce the need for ventriculoperitoneal shunting. However, these studies also demonstrate that fetal surgery is associated with significant maternal and fetal risks. Consequently, additional research is necessary to further elucidate the pathophysiology of MMC, to define the ideal timing and technique of fetal closure, and to evaluate the long-term implications of prenatal intervention.

Open fetal surgery for myelomeningocele

Despite efforts at prevention through the use of preconception folic acid, spina bifida remains one of the most common congenital anomalies of the central nervous system that is compatible with life. It is, however, associated with a significant degree of lifelong morbidity. The development of open fetal surgery for myelomeningocele (MMC) has been a long process but one that serves as a model for how new procedures and technologies need to be properly evaluated before being brought into mainstream medical practice. Even so, risks and benefits need to be evaluated for each patient. The currently available studies have been carried out on a highly selected patient population where the fetal findings provided the maximum opportunity for benefit from prenatal closure of the MMC defect. There is the potential that as the surgery becomes more widely available, pressure will be brought to bear to perform surgery in cases where the likelihood for benefit is decreased and yet the risks are not. The only way to duplicate the results of the current studies is to follow the methodology and criteria that were used in the studies. This will mean that not every fetus with an MMC will be a candidate for in utero surgery. The balance of risk to benefit will continue to evolve as further technological advances are evaluated and more follow-up information is obtained.

Amniotic fluid levels of glial fibrillary acidic protein in fetal rats with retinoic acid induced myelomeningocele: a potential marker for spinal cord injury

OBJECTIVE

The objective of this study was to determine whether amniotic fluid levels of glial acidic fibrillary protein (GFAP) would reflect myelomeningocele-related neurodegeneration in the rat model of retinoic acid-induced myelomeningocele, which is a model that is very similar to human myelomeningocele and develops the entire spectrum of disease severity including features of the Chiari II malformation.

STUDY DESIGN

Time-dated (embryonic day 10) pregnant Sprague-Dawley rats were gavage fed 60 mg/kg/bodyweight retinoic acid that had been dissolved in olive oil or olive oil alone. Myelomeningocele, retinoic acid-exposed no myelomeningocele, and control fetuses were harvested at specific time points throughout gestation. A standard set of pinching tests was performed to interrogate the sensorimotor reflex arc of hindpaws and tails. Amniotic fluid-GFAP levels were analyzed by standard enzyme-linked immunosorbent assay techniques.

RESULTS

Amniotic fluid-GFAP levels were similar between groups at embryonic days 14, 16, and 18, respectively. Compared with control fetuses, amniotic fluid GFAP levels were significantly increased in myelomeningocele fetuses at embryonic days 20 and 22 (P < .001). Defect size (P < .001), presence of clubfoot deformity (P = .0004), and absence of sensorimotor function (P < .01) at embryonic day 22 correlated with amniotic fluid-GFAP levels.

CONCLUSION

Amniotic fluid-GFAP levels appear to correlate with spinal cord injury as gestation proceeds in fetal rats with myelomeningocele.

Early stages of in situ bladder regeneration in a rodent model

Surgical removal of approximately 70% of the bladder (subtotal cystectomy [STC]) was used as a model system to gain insight into the normal regenerative process in adult mammals in vivo. Female F344 rats underwent STC, and at 2, 4, and 8 weeks post-STC, bladder regeneration was monitored via microcomputed tomography scans, urodynamic (bladder function studies) pharmacologic studies, and immunohistochemistry. Computed tomography imaging revealed a time-dependent increase in bladder size at 2, 4, and 8 weeks post-STC, which positively correlated with restoration of bladder function. Bladders emptied completely at all time points studied. The maximal contractile response to pharmacological activation and electrical field stimulation increased over time in isolated tissue strips from regenerating bladders, but remained lower at all time points compared with strips from age-matched control bladders. Immunostaining of the bladder wall of STC rats suggested a role for progenitor cells and cellular proliferation in the regenerative response. Immunostaining and the presence of electrical field stimulation-induced contractile responses verified innervation of the regenerated bladder. These initial studies establish the utility of the present model system for studying de novo tissue regeneration in vivo and may provide guidance with respect to optimization of intrinsic regenerative capacity for clinical applications.

Gastroschisis in mice lacking aortic carboxypeptidase-like protein is associated with a defect in neuromuscular development of the eviscerated intestine

Mice lacking aortic carboxypeptidase-like protein (ACLP) exhibit a gastroschisis (GS) like abdominal wall defect. The objectives of this study were to evaluate the pathophysiological features of GS in ACLP mice and to characterize the neuromuscular development of the eviscerated intestine (EI). ACLP mice were created by heterozygous mating from previously generated mice with targeted disruption of ACLP. Specimens were processed for H&E, and immunohistochemistry for smooth muscle cells [SMC, alpha-smooth muscle actin (alpha-SMA) antibody], interstitial cells of Cajal (ICC, c-kit-antibody), neural crest cells (NCC, Hox-b5-antibody), and enteric neurons (EN, PGP9.5-, alpha-internexin, and synaptophysin antibody). From 47 fetuses genotyped, 13 (27.7%) were wild type, 20 (42.5%) were heterozygous, and 14 (29.8%) were ACLP homozygous. In GS mice, expression of c-kit, Hox-b5, PGP-9.5, alpha-internexin, and synaptophysin were almost completely absent and only faint alpha-SMA expression was seen in the EI. In contrast, c-kit, Hox-b5, PGP9.5, alpha-internexin, synaptophysin, and alpha-SMA expression in intra-abdominal intestine in GS fetuses was the same as control intestine. The defect observed in ACLP mice closely resembles GS. Absence of ICC, NCC, EN, and immature differentiation of SMC supports an associated defect in neuromuscular development that is restricted to the EI.

Fetal spina bifida repair--current trends and prospects of intrauterine neurosurgery

Myelomeningocele is a common dysraphic defect leading to severe impairment throughout the patient's lifetime. Although surgical closure of this anomaly is usually performed in the early postnatal period, an estimated 330 cases of intrauterine repair have been performed in a few specialized centers worldwide. It was hoped prenatal intervention would improve the prognosis of affected patients, and preliminary findings suggest a reduced incidence of shunt-dependent hydrocephalus, as well as an improvement in hindbrain herniation. However, the expectations for improved neurological outcome have not been fulfilled and not all patients benefit from fetal surgery in the same way. Therefore, a multicenter randomized controlled trial was initiated in the USA to compare intrauterine with conventional postnatal care, in order to establish the procedure-related benefits and risks. The primary study endpoints include the need for shunt at 1 year of age, and fetal and infant mortality. No data from the trial will be published before the final analysis has been completed in 2008, and until then, the number of centers offering intrauterine MMC repair in the USA is limited to 3 in order to prevent the uncontrolled proliferation of new centers offering this procedure. In future, refined, risk-reduced surgical techniques and new treatment options for preterm labor and preterm rupture of the membranes are likely to reduce associated maternal and fetal risks and improve outcome, but further research will be needed.

In utero Repair of Myelomeningocele: Rationale, Initial Clinical Experience and a Randomized Controlled Prospective Clinical Trial

Myelomeningocele (MMC), one of the most common congenital malformations, can result in severe lifelong disabilities, including paraplegia, hydrocephalus, Arnold-Chiari II malformation, incontinence, sexual dysfunction, skeletal deformations, and mental impairment. MMC was the first nonlethal anomaly to be treated by fetal surgery. Studies in animals provide compelling evidence that the primary cause of the neurological deficit associated with MMC is not simply incomplete neurulation but rather chronic mechanical injury and amniotic-fluid-induced chemical trauma that progressively damage the exposed neural tissue during gestation. Initial results suggest that the surgical repair of MMC before 25 weeks of gestation may preserve neurological function, reverse the hindbrain herniation of the Arnold-Chiari II malformation, and obviate the need for postnatal placement of a ventriculoperitoneal shunt. As it is currently unknown whether fetal surgery for MMC is truly beneficial compared to standard postnatal care, a randomized, controlled clinical trial has been initiated within the United States.

Morphologic analysis of the neuromuscular development of the anorectal unit in fetal rats with retinoic acid induced myelomeningocele

To investigate whether myelomeningocele (MMC) is associated with a global neuromuscular maldevelopment of the lower gastrointestinal (GI) tract and anorectum, the distribution and staining intensity of non-neuronal (alpha-smooth-muscle-actin), neural crest cell (NCC, [Hoxb5]), and neuronal markers (PGP-9.5, synaptophysin, neurotubulin-beta-III) within the distal colon, rectum, and anal sphincters were analyzed by immunohistochemistry and Western blot in rat fetuses with retinoic acid (RA) induced MMC. At term (E22), no gross-morphological differences of the anorectal unit of OIL (n=21) MMC (n=31), and RA-exposed-non MMC (RA, n=19) fetuses were found. Smooth muscle cells were evenly distributed within the muscle layers of the rectum and the internal anal sphincter in OIL, MMC, and RA fetuses. Density and staining intensity of NCC and mature enteric neurons within the myenteric plexus of the distal colon and rectum and innervation pattern within anal sphincters in MMC fetuses were analogous to RA and OIL controls. Normal smooth muscle and myenteric plexus development of the rectum and normal innervation of the anal sphincters and pelvic floor suggests that MMC is not associated with a global neuromuscular maldevelopment of lower GI structures in this short-gestational model.