Quantitative analysis of the toxicity of human amniotic fluid to cultured rat spinal cord

Systematic classification and comparison of maternal and obstetrical complications following 2 different methods of fetal surgery for the repair of open neural tube defects

BACKGROUND

In utero repair of open neural tube defects using an open hysterotomy approach (hereafter referred to as "open") has been shown to reduce the need for ventriculoperitoneal shunting and to improve motor outcomes for affected infants. Laparotomy-assisted fetoscopic repair (hereafter referred to as "hybrid") is an alternative approach that may confer similar neurologic benefits while reducing the incidence of hysterotomy-related complications.

OBJECTIVE

This study aimed to analyze procedure-related maternal and fetal complications of in utero repair using the Clavien-Dindo classification, and to compare the outcomes of the hybrid and open approaches.

STUDY DESIGN

This was a retrospective cohort study conducted in a single center between September 2011 and July 2021. All patients who met the Management of Myelomeningocele Study criteria and who underwent either hybrid or open fetal surgery were included. Maternal complications were classified using a unique adaptation of the Clavien-Dindo scoring system, allowing the development of a comprehensive complication index score specific to fetal surgery. Primary fetal outcome was defined as gestational age at delivery and summarized according to the World Health Organization definitions of preterm delivery.

RESULTS

There were 146 fetuses with open neural tube defects who were eligible for, and underwent, in utero repair during the study period. Of these, 102 underwent hybrid fetoscopic repair and 44 underwent open hysterotomy repair. Gestational age at the time of surgery was higher in the hybrid group than in the open group (25.1 vs 24.8 weeks; P=.004). Maternal body mass index was lower in the hybrid than in the open group (25.4 vs 27.1 kg/m2; P=.02). The duration of hybrid fetoscopic surgery was significantly longer in the hybrid than in the open group (250 vs 164 minutes; P<.001). There was a significantly lower Clavien-Dindo Grade III complication rate (4.9% vs 43.2%; P<.001) and a significantly lower overall comprehensive maternal complication index (8.7 vs 22.6; P=.021) in the hybrid group than in the open group. Gestational age at delivery was significantly higher in the hybrid group than in the open group (38.1 vs 35.8 weeks; P<.001), and this finding persisted when gestational age at delivery was analyzed using the World Health Organization definitions of preterm delivery.

CONCLUSION

Use of our adaptation of the standardized Clavien-Dindo classification to assess the maternal complications associated with in utero open neural tube defect repair provides a new method for objectively assessing different fetal surgical approaches. It also provides a much-needed standardized tool to allow objective comparisons between methods, which can be used when counseling patients. The hybrid open neural tube defect repair was associated with lower rates of maternal adverse events , and later gestational age at delivery compared with the open approach.

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.

Severe and progressive neuronal loss in myelomeningocele begins before 16 weeks of pregnancy

BACKGROUND

Despite undisputable benefits, midtrimester prenatal surgery is not a cure for myelomeningocele (MMC): residual intracranial and motor deficits leading to lifelong handicap question the timing of prenatal surgery. Indeed, the timing and intensity of intrauterine spinal cord injury remains ill defined.

OBJECTIVE

We aimed to describe the natural history of neuronal loss in MMC in utero based on postmortem pathology.

STUDY DESIGN

Pathology findings were analyzed in 186 cases of myelomeningocele with lesion level between S1 and T1. Using a case-control, cross-sectional design, we investigated the timewise progression and topographic extension of neuronal loss between 13 and 39 weeks. Motor neurons were counted on histology at several spinal levels in 54 isolated MMC meeting quality criteria for cell counting. These were expressed as observed-to-expected ratios, after matching for gestational age and spinal level with 41 controls.

RESULTS

Chiari II malformation increased from 30.7% to 91.6% after 16 weeks. The exposed spinal cord displayed early, severe, and progressive neuronal loss: the observed-to-expected count dropped from 17% to ≤2% after 16 weeks. Neuronal loss extended beyond the lesion to the upper levels: in cases <16 weeks, the observed-to-expected motor neuron count was 60% in the adjacent spinal cord, decreasing at a rate of 16% per week. Progressive loss was also found in the upper thoracic cord, but in much smaller proportions. The observed-over-expected ratio of motor neurons was not correlated with the level of myelomeningocele.

CONCLUSIONS

Significant neuronal loss is present ≤16 weeks in the exposed cord and progressively extends cranially. Earlier prenatal repair (<16 weeks) could prevent Chiari II malformation in 69.3% of cases, rescue the 17% remaining motor neurons in the exposed cord, and prevent the extension to the upper spinal cord.

Hydrogel and neural progenitor cell delivery supports organotypic fetal spinal cord development in an ex vivo model of prenatal spina bifida repair

Studying how the fetal spinal cord regenerates in an ex vivo model of spina bifida repair may provide insights into the development of new tissue engineering treatment strategies to better optimize neurologic function in affected patients. Here, we developed hydrogel surgical patches designed for prenatal repair of myelomeningocele defects and demonstrated viability of both human and rat neural progenitor donor cells within this three-dimensional scaffold microenvironment. We then established an organotypic slice culture model using transverse lumbar spinal cord slices harvested from retinoic acid–exposed fetal rats to study the effect of fibrin hydrogel patches ex vivo. Based on histology, immunohistochemistry, gene expression, and enzyme-linked immunoabsorbent assays, these experiments demonstrate the biocompatibility of fibrin hydrogel patches on the fetal spinal cord and suggest this organotypic slice culture system as a useful platform for evaluating mechanisms of damage and repair in children with neural tube defects.

Spinal Cord Injury in Myelomeningocele: Prospects for Therapy

Myelomeningocele (MMC) is the most common congenital defect of the central nervous system and results in devastating and lifelong disability. In MMC, the initial failure of neural tube closure early in gestation is followed by a progressive prenatal injury to the exposed spinal cord, which contributes to the deterioration of neurological function in fetuses. Prenatal strategies to control the spinal cord injury offer an appealing therapeutic approach to improve neurological function, although the definitive pathophysiological mechanisms of injury remain to be fully elucidated. A better understanding of these mechanisms at the cellular and molecular level is of paramount importance for the development of targeted prenatal MMC therapies to minimize or eliminate the effects of the injury and improve neurological function. In this review article, we discuss the pathological development of MMC with a focus on in utero injury to the exposed spinal cord. We emphasize the need for a better understanding of the causative factors in MMC spinal cord injury, pathophysiological alterations associated with the injury, and cellular and molecular mechanisms by which these alterations are induced.

Amylase concentration and activity in the amniotic fluid of fetal rats with retinoic acid induced myelomeningocele. J Matern Fetal Neonatal Med 2020;35:147-154. [PMID: 31910702 DOI: 10.1080/14767058.2020.1713082]

Background: In utero neurologic injury in myelomeningocele (MMC) occurs via a two-hit process: failed neural tube closure followed by neurodegeneration in utero. Meconium in the amniotic fluid contains pancreatic digestive enzymes and is neurotoxic in rat models of MMC.Objectives: The objectives of this study were to demonstrate the neurotoxicity of α-amylase and to compare the enzyme concentration and activity in the amniotic fluid of rats with retinoic acid induced MMC to a healthy control population.Study design: Timed pregnant Sprague Dawley rats were gavage fed all-trans retinoic acid (60 mg/kg) in olive oil on gestational day E10 to induce a MMC defect. Control rats received olive oil. Amniotic fluid was collected on embryonic days E15, E17, E19, and E21. The amniotic fluid amylase concentration and relative activity were measured at each gestational age, and levels were compared between the MMC and control groups using Wilcoxon Rank Sum and Kruskal-Wallis tests. In a subset of dams sacrificed on E10.5, neuroepithelial cells were isolated from control embryos and exposed to α-amylase in increasing concentrations. Percentage of cell survival was assessed with CellProfiler software.Results: Amniotic fluid amylase activity for embryonic days E15, E17, E19, and E21 was determined for MMC and control pups. Amylase activity increased significantly from E15 to E21 in both control (p = 3.0 × 10^-5) and MMC (p = 1.5 × 10^-5) groups. Relative amylase activity was significantly increased in MMC pups compared to controls on E19 (247,792.8 versus 106,263.6; p = .0019) and E21 (772,645.8 versus 481,975.3; p = .021); no difference was detected on E15 (36,646.8 versus 40,179.3; p = .645) or E17 (121,617.5 versus 71,750; p = 1.000). In vitro, amylase demonstrated dose-dependent toxicity to fetal rat neuroepithelial cells.Conclusion: Amylase concentration and activity level were higher in the amniotic fluid of rats with retinoic acid induced MMC compared to controls with advancing gestational age. As amylase is toxic to neural epithelial cells, the higher activity of this digestive enzyme in fetuses with MMC may be a contributor to neural tube damage in utero. Future research should focus on amylase and other digestive enzymes in human MMC, as they may serve as potential targets of in utero therapy.

Altered Amniotic Fluid Levels of Hyaluronic Acid in Fetal Rats with Myelomeningocele: Understanding Spinal Cord Injury

Myelomeningocele (MMC) is a devastating congenital neural tube defect that results in the exposure of spinal cord to the intrauterine environment, leading to secondary spinal cord injury and severe impairment. Although the mechanisms underlying the secondary pathogenesis are clinically relevant, the exact cause of in utero-acquired spinal cord damage remains unclear. The objective of this study was to determine whether the hyaluronic acid (HA) concentration in amniotic fluid (AF) in the retinoic acid-induced model of MMC is different from that in normal controls and whether these differences could have an impact on the viscosity of AF. Our data shows that the concentration of HA in AF samples from fetuses with MMC (MMC-AF) and normal control samples (Norm-AF) were not significantly different at embryonic day 18 (E18) and E20. Thereafter, the HA concentration significantly increased in Norm-AF but not in MMC-AF. Compared with Norm-AF, the concentration of HA in MMC-AF and the viscosity of MMC-AF were significantly lower at E21. Agarose gel electrophoresis confirmed a significant reduction in the HA level of MMC-AF compared with Norm-AF at E21. No HA-degrading activity was detected in MMC-AF. In summary, we identified a deficiency in the AF level of HA and the viscosity of AF in fetal rats with MMC. These data are discussed in relation to a potential role the reduction in the AF viscosity due to the low level of HA may play in the exacerbating effects of mechanical trauma on spinal cord damage at the MMC lesion site.

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.

Amniotic fluid levels of phospholipase A2 in fetal rats with retinoic acid induced myelomeningocele: the potential "second hit" in neurologic damage

OBJECTIVES

There is growing evidence of ongoing, in utero neurological damage in fetuses with myelomeningocele (MMC). Phospholipase A2 (PLA2) has known neurotoxic properties and is predominantly present in its secretory isoform (sPLA2) in meconium, the passage of which is increased in MMC fetuses. The objective of this study was to determine if amniotic fluid (AF) levels of PLA2 are elevated in a rat model of MMC.

METHODS

Timed pregnant Sprague-Dawley rats were gavage fed 60 mg/kg/bodyweight retinoic acid (RA) in olive oil at embryonic day 10 (E10). Amniocentesis was performed at multiple gestational time points on MMC fetuses, RA-exposed fetuses without MMC and control fetuses. AF PLA2 levels were analyzed by a fluorescent enzyme activity assay. PLA2 isoforms were determined by measuring activity in the presence of specific inhibitors.

RESULTS

There was no difference in AF PLA2 activity between groups on E15. PLA2 activity was significantly increased in MMC fetuses on E17, E19 and E21 (p < 0.001). Secretory PLA2 primarily accounted for the overall greater activity.

CONCLUSIONS

PLA2 levels are elevated in the AF of fetal rats with MMC and may contribute to ongoing neural injury. This pathway may be a useful drug target to limit ongoing damage and better preserve neurologic function.

Spina bifida

Spina bifida is a birth defect in which the vertebral column is open, often with spinal cord involvement. The most clinically significant subtype is myelomeningocele (open spina bifida), which is a condition characterized by failure of the lumbosacral spinal neural tube to close during embryonic development. The exposed neural tissue degenerates in utero, resulting in neurological deficit that varies with the level of the lesion. Occurring in approximately 1 per 1,000 births worldwide, myelomeningocele is one of the most common congenital malformations, but its cause is largely unknown. The genetic component is estimated at 60-70%, but few causative genes have been identified to date, despite much information from mouse models. Non-genetic maternal risk factors include reduced folate intake, anticonvulsant therapy, diabetes mellitus and obesity. Primary prevention by periconceptional supplementation with folic acid has been demonstrated in clinical trials, leading to food fortification programmes in many countries. Prenatal diagnosis is achieved by ultrasonography, enabling women to seek termination of pregnancy. Individuals who survive to birth have their lesions closed surgically, with subsequent management of associated defects, including the Chiari II brain malformation, hydrocephalus, and urological and orthopaedic sequelae. Fetal surgical repair of myelomeningocele has been associated with improved early neurological outcome compared with postnatal operation. Myelomeningocele affects quality of life during childhood, adolescence and adulthood, posing a challenge for individuals, families and society as a whole. For an illustrated summary of this Primer, visit: http://go.nature.com/fK9XNa.

Neural tube defects: from a proteomic standpoint

Neural tube defects (NTDs) are congenital birth defects classified according to their resulting morphological characteristics in newborn patients. Current diagnosis of NTDs relies largely on the structural evaluation of fetuses using ultrasound imaging, with biochemical characterization used as secondary screening tools. The multigene etiology of NTDs has been aided by genetic studies, which have discovered panels of genes mutated in these diseases that encode receptors and cytoplasmic signaling molecules with poorly defined functions. Animal models ranging from flies to mice have been used to determine the function of these genes and identify their associated molecular cascades. More emphasis is now being placed on the identification of biochemical markers from clinical samples and model systems based on mass spectrometry, which open novel avenues in the understanding of NTDs at protein, metabolic and molecular levels. This article reviews how the use of proteomics can push forward the identification of novel biomarkers and molecular networks implicated in NTDs, an indispensable step in the improvement of patient management.

Prenatal Diagnosis and Patient Preferences in Patients with Neural Tube Defects around the Advent of Fetal Surgery in Belgium and Holland

Introduction: We review the characteristics and prenatal choices of patients recently evaluated for neural tube defects (NTD) at two tertiary units. The prenatal diagnosis of NTD allows parents to consider all prenatal options. In selected cases of spina bifida aperta this also includes fetal surgery, which we started offering after combined ‘in-house' and ‘exported' training. Material and Methods: This is a retrospective review of prospectively collected data on NTD diagnosed over the last 8 years and recent fetal surgery referrals. Results: A total of 167 patients were referred for assessment at a median of 19 weeks. Cranial lesions were diagnosed significantly earlier than spinal lesions. Of the open spinal lesions, 77% were isolated. Of these, 22% were managed expectantly and 1 (1%) had fetal surgery. There was no correlation between parental decisions on prenatal management with disease-specific severity markers. We had 14 fetal surgery referrals, all but 1 from beyond our typical referral area; 6 of the assessed patients were operated on, 4 were expectantly managed and 4 requested termination of pregnancy (TOP). These pregnancy outcomes were in the expected range. Discussion: Open spina bifida is mainly diagnosed in the second trimester and 76% of subjects request TOP, irrespective of the severity indicators. The number of local patients considering fetal surgery is low.

Intraoperative neurophysiological monitoring in patients undergoing tethered cord surgery after fetal myelomeningocele repair

OBJECT

Fetal myelomeningocele closure has been shown to be advantageous in a number of areas. In this study, the authors report on neural function in patients who had previously undergone fetal myelomeningocele repair and returned to the authors' institution for further surgery that included intraoperative neurophysiological monitoring.

METHODS

The authors retrospectively reviewed data obtained in 6 cases involving patients who underwent fetal myelomeningocele repair and later returned to their institution for spinal cord untethering. (In 4 of the 6 cases, the patients also underwent removal of a dermoid cyst [3 cases] or removal of an epidermoid cyst [1 case] during the untethering procedure.) Records and imaging studies were reviewed to identify the anatomical level of the myelomeningocele as well as the functional status of each patient. Stimulated electromyography (EMG) and transcranial motor evoked potential (tcMEP) recordings obtained during surgery were reviewed to assess the functional integrity of the nerve roots and spinal cord.

RESULTS

During reexploration, all patients had reproducible signals at or below their anatomical level on stimulated EMG and tcMEP recordings. Corresponding to these findings, prior to tethering, all patients had antigravity muscle function below their anatomical level.

CONCLUSIONS

All 6 patients had lower-extremity function and neurophysiological monitoring recording signals at or below their anatomical level. These cases provide direct evidence of spinal cord and nerve root conductivity and functionality below the anatomical level of the myelomeningocele, further supporting that neurological status improves with fetal repair.

Reduction in neural injury with earlier delivery in a mouse model of congenital myelomeningocele: laboratory investigation

OBJECT

The authors undertook this study to assess the effect of preterm delivery with respect to neural protection in a congenital myelomeningocele (MMC) mouse model.

METHODS

After confirmation of pregnancy in 15 female mice, a congenital MMC model was produced by administration of retinoic acid on the 7th day of gestation. The pregnant mice underwent cesarean sections on Days 15 (n = 5, Group E15), 17 (n = 5, Group E17), and 19 (n = 5, Group E19). Histological analyses were conducted on the lumbar defect and on the craniocervical junction in all fetuses with MMC.

RESULTS

Fetuses in Group E19 showed the most significant injury to neural tissue of the spinal cord at the MMC area followed by those in Group E17, with Group E15 being the least affected. All groups exhibited a degree of Chiari malformation; Group E19 was the most affected, followed by Group E17, and Group E15 was the least affected.

CONCLUSIONS

Development of both Chiari malformation and exposed spinal cord injury are progressive during gestation. Preterm delivery in this mouse model of congenital MMC may minimize the degree of injury to the spinal cord neural tissue and the degree of Chiari malformation.

Enhanced reclosure of surgically induced spinal open neural tube defects in chick embryos by injecting human bone marrow stem cells into the amniotic cavity

OBJECTIVE

To evaluate the reclosure-promoting capacity of a neural stem cell line (F3) and a human bone marrow stem cell line (B10) injected into the amniotic cavity of spinal open neural tube defects (ONTDs) of chick embryos of Hamburger and Hamilton stage 18 or 19.

METHODS

Fifteen chick embryos that survived the procedure were obtained for each of 4 groups: untreated control, F3-, B10-, and HFF-1 (human foreskin fibroblast)-treated groups. Embryos in the control group underwent ONTD surgery but no cell injection.

RESULTS

Compared with the untreated control and HFF-1 groups, the B10 group showed enhanced reclosure at 3, 5, and 7 days after injection, whereas the F3 group did not. B10 cells were not incorporated into reclosed neural tubes but simply covered ONTDs during the process of reclosure. F3 cells did not cover ONTDs. The cell survival of F3 cells exposed to the chick amniotic fluid in vitro for 48 hours was significantly lower than that of B10 cells.

CONCLUSION

The results confirmed that B10 cells enhance reclosure of ONTDs by covering and protecting neural tissues, not by direct cell incorporation. The lack of reclosure capacity in the F3 group may be related to the poor survival of F3 cells in the amniotic fluid.

Altered expression of 14-3-3ζ protein in spinal cords of rat fetuses with spina bifida aperta

Background

A large number of studies have confirmed that excessive apoptosis is one of the reasons for deficient neuronal function in neural tube defects (NTDs). A previous study from our laboratory used 2-D gel electrophoresis to demonstrate that 14-3-3ζ expression was low in the spinal cords of rat fetuses with spina bifida aperta at embryonic day (E) 17. As a member of the 14-3-3 protein family, 14-3-3ζ plays a crucial role in the determination of cell fate and anti-apoptotic activity. However, neither the expression of 14-3-3ζ in defective spinal cords, nor the correlation between 14-3-3ζ and excessive apoptosis in NTDs has been fully confirmed.

Methodology/Principal Findings

We used immunoblotting and quantitative real-time PCR (qRT-PCR) to quantify the expression of 14-3-3ζ and double immunofluorescence to visualize 14-3-3ζ and apoptosis. We found that, compared with controls, 14-3-3ζ was down-regulated in spina bifida between E12 and E15. Excessive apoptotic cells and low expression of 14-3-3ζ were observed in the dorsal region of spinal cords with spina bifida during the same time period. To initially explore the molecular mechanisms of apoptosis in NTDs, we investigated the expression of microRNA-7 (miR-7), microRNA-375 (miR-375) and microRNA-451 (miR-451), which are known to down-regulate 14-3-3ζ in several different cell types. We also investigated the expression of p53, a molecule that is downstream of 14-3-3ζ and can be down-regulated by it. We discovered that, in contrast to the reduction of 14-3-3ζ expression, the expression of miR-451, miR-375 and p53 increased in spina bifida rat fetuses.

Conclusions/Significance

These data suggest that the reduced expression of 14-3-3ζ plays a role in the excessive apoptosis that occurs in spina bifida and may be partly regulated by the over-expression of miR-451 and miR-375, and the consequent up-regulation of p53 might further promote apoptosis in spina bifida.

In spina bifida aperta, muscle ultrasound can quantify the "second hit of damage"

PURPOSE

In spina bifida aperta (SBA), the "second-hit hypothesis" addresses consequences by delayed neurological damage superimposed upon the congenital myelomeningocele (MMC). This secondary damage is postulated to underlie the disappearance of leg movements shortly after birth. Innovative fetal surgery might prevent this, but results are methodologically hard to prove in small and heterogeneous treatment groups. We reasoned that delayed postnatal alterations in muscle ultrasound density (MUD = muscle echogenicity) could quantitatively reflect consequences by "the second hit" of damage. In the present study, we investigated whether delayed postnatal leg-MUD alterations are associated with postnatal muscle function loss.

METHODS

We cross-sectionally assessed leg-MUD in 16 postnatally operated SBA children (MMC-L5; at 0, 6, and 12 months; in n = 11/16; 11/16, and 15/16 children, respectively) and compared outcomes with 13 healthy control children. Additionally, we assessed SBA MUD caudal and cranial to the MMC and calculated MMC-L5 impact by: dMUD((MMC-L5)) = [MUD(calf muscle/S1-2)] - [MUD(quadriceps muscle/L2-4)] and associated outcomes with leg muscle function caudal to the MMC.

RESULTS

At 0 month, clinically discernible dMUD was more often increased in SBA than in control newborns (p < .05), but a relationship between absolute quantitative differences and leg muscle dysfunction was still lacking. At 6-12 months, additionally increased dMUD outcomes coincided with SBA leg muscle dysfunction (p < .05).

CONCLUSIONS

In post-neonatal SBA, secondarily increased dMUD (i.e., MMC impact) coincides with leg muscle dysfunction. This may implicate that muscle ultrasound could provide a quantitative tool to assess the neuromuscular impact by the second hit of damage.

Meconium staining of the brainstem with open myelomeningocele

Meconium staining of open myelomeningoceles has been reported to occur both prenatally and postnatally, but meconium staining of the brainstem has not been previously documented. The authors present a case of meconium staining of the brainstem in an infant with a meconium-stained myelomeningocele, Chiari malformation Type II, and hydrocephalus and discuss possible implications for prenatal and perinatal care.

Comparative proteomics of spinal cords of rat fetuses with spina bifida aperta

Neural tube defects (NTDs) are complex congenital anomalies of the central nervous system, with a prevalence of 5 per 10,000 worldwide. However, current therapeutics for NTDs are unsatisfactory. The neurological complications remain the main problem for therapy. Neurological dysfunction could result from the primary defect or injuries to the uncovered neural tissue in the uterus. However, the pathological changes in the uncovered neural tissue have not been described. Here, we present our comparative proteomics study of the spinal cord from rat fetuses with all-trans retinoic-acid-induced spina bifida aperta. Proteins from spinal cords were subjected to 2-D gel electrophoresis, then protein identification by mass spectrometry. We identified 13 proteins with differential expression between normal spinal cords and those with spina bifida aperta. These identified proteins were reported to be involved in signal transduction, cell adhesion and migration, protein folding and apoptosis. We confirmed 4 identified proteins by immunoblot analysis and assessed their mRNA levels by quantitative real-time PCR. This is the first comparative proteomics of spinal cords from rat fetuses with spina bifida aperta. We demonstrate protein alterations that reflect the pathological situation of the uncovered neural tissue, which may help improve the treatment of NTDs.

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.

Myeloschisis repair in a premature neonate with a birth weight of 599 g

This report describes the case of a neonate with myeloschisis weighing 599 g that underwent an operation for spinal cord reconstruction resulting in substantial neuronal functional recovery. At 28 weeks of gestation, oligohydramnios was detected and the female fetus was diagnosed with intrauterine growth retardation. At birth by emergency caesarean section, she showed lumbosacral myeloschisis and complete paralysis of the lower extremities. Surgical repair and spinal cord reconstruction was performed 2 days after birth by closing the neural placode. Total blood loss was only 2 ml. Within 3 months of the operation, lower extremity neurologic function gradually improved down to the level of the knee joint. To our knowledge, this case is the lowest recorded body weight for a neonate with myeloschisis repair at birth, and this further suggests the possibility of improvement of lower extremity neurologic function after birth and surgical reconstruction.

Congenital myelomeningocele - do we have to change our management?

BACKGROUND

Eagerly awaiting the results of the Management of Myelomeningocele Study (MOMS) and with an increasing interest in setting up intrauterine myelomeningocele repair (IUMR), the optimal management of patients suffering from congenital myelomeningocele (MMC) has become a matter of debate again. We performed a cross-sectional study at our referral-center for MMC to determine the outcome for our expectantly managed patients.

MATERIALS AND METHODS

A computed chart review at our institution revealed 70 patients suffering from MMC. Forty-three patients were eligible for the study and analyzed further. A retrospective analysis was performed only in patients that underwent MMC repair within the first two days of life and were seen at our outpatient clinic between 2008 and 2009 for a regular multidisciplinary follow-up. Data were collected on: gestational age (GA) and weight at birth, age at shunt placement and shunt status after the first year of life, radiological evidence for Arnold-Chiari malformation (ACM) and tethered cord (TC), need for surgery for TC, bladder function, lower leg function and educational level. Data were compared to published results for IUMR and to studies of historical controls.

RESULTS

Patients were born with MMC between 1979 and 2009 and are now 13.3 ± 8.9 (mean ± SD) years of age. At birth, mean GA was 37.8 ± 2.3 weeks and mean weight was 2921.3 ± 760.3 g, both significantly higher than in IUMR patients. Shunt placement in our cohort was required in 69.8% at a mean age of 16.0 ± 10.7 days, which was less frequent than for historical controls. Amongst our cohort, radiological observations showed 57.1% had ACM II and 41.9% had TC. Only two of our patients underwent a surgical correction for TC. Clean intermittent catheterization was performed in 69.7% of our patients, 56.4% were (assisted) walkers and 64.1% attended regular classes, both comparable to historical controls.

CONCLUSIONS

With a close and interdisciplinary management by pediatric surgeons, neurologists and urologists, the long-term outcome of patients suffering from MMC can currently be considered satisfactory. With respect to the known drawbacks of fetal interventions for mother and child, especially preterm delivery, the results of the MOMS trial should be awaited with caution before proceeding with a complex intervention like IUMR.

Expression of neuronal antigens and related ventral and dorsal proteins in the normal spinal cord and a surgically induced open neural tube defect of the spine in chick embryos: an immunohistochemical study

OBJECTIVE

The aims of this study were to elucidate the processes of neuronal differentiation and ventrodorsal patterning in the spinal cord of the chick embryo from embryonic day (E) 3 to E17 and to study the effect of a prenatal spinal open neural tube defect (ONTD) on these processes.

METHOD

Expression patterns of neuronal antigens (neuronal nuclear antigen, neurofilament-associated protein (NAP), and synaptophysin) and related ventral markers [sonic hedgehog, paired box gene (PAX)6, and islet-1], and dorsal markers (bone morphogenetic protein, Notch homolog 1, and PAX7) were investigated in the normal spinal cord and in a surgically induced spinal ONTD in chick embryos. Four normal and ONTD chick embryos were used for each antigen group.

RESULT & CONCLUSION

There were no differences in the expression of neuronal and ventrodorsal markers between the control and ONTD groups. NAP and synaptophysin were useful for identifying dorsal structures in the distorted anatomy of the ONTD chicks.

Effects of birth advancement in Chiari malformation in a surgical myelomeningocele model in rabbits

BACKGROUND/PURPOSE

In myelomeningocele (MMC), Chiari II malformation progresses during gestation because of the continuous loss of cerebrospinal fluid at the site of the defect. Our purpose was to assess the impact of birth advancement (BA) and prenatal corticosteroid treatment (PCT) on Chiari malformation in a surgical MMC model in rabbits.

METHODS

A surgical MMC-like defect was created in 75 fetal rabbits. Animals were distributed into 4 groups depending on the treatment received: not treated and those undergoing BA + PCT, BA, or PCT. The degree of Chiari malformation in newborn rabbits was defined as the percentage of downward protrusion of the hindbrain between the end of the occipital bone and the beginning of the first vertebral arch.

RESULTS

The degree of hindbrain herniation was 80% (8.15) in the not treated group, 36.8% (10.57) in BA + PCT, 41.8% (8.27) in BA, and 44.4% (8.32) in PCT. The BA + PCT, BA, and PCT groups showed less severe hindbrain herniation than not treated animals (mean decrease, 39.86%; SD, 10.57; P = .000). There were no significant differences between the BA + PCT, BA, and PCT groups (P = .311).

CONCLUSIONS

Birth advancement and prenatal administration of corticosteroids decrease the severity of the hindbrain herniation component of Chiari II malformation in surgical MMC in fetal rabbits.

In utero meconium passage in fetuses and newborns with myelomeningocele

OBJECT

The authors retrospectively investigated whether midgestational fetal myelomeningocele (fMMC) repair alters intrauterine meconium exposure.

METHODS

Prior to the National Institutes of Health Management of Myelomeningocele Study, 54 fetuses underwent fMMC repair at the authors' institution. Forty-six fMMC sacs were available for pathological examination and 53 MMC sacs from postnatally repaired MMCs (pMMCs) were available for comparison. The presence and distribution of meconium were blindly evaluated using a grading system defined as follows: absent (no meconium present), mild (<10 meconium-positive histiocytes [MPHs]/hpf), moderate (10-25 MPHs/hpf), and severe (>25 MPHs/hpf). Hall's bile stain was used to confirm meconium and Prussian blue and Fontana Masson stains to exclude hemosiderin and melanin, respectively.

RESULTS

Compared to pMMCs (79%), meconium histiocytosis was less prevalent in fMMC sacs (57%; p=0.017). Meconium staining was completely absent in 43% of the fMMC sacs. Mild meconium histiocytosis was found in 35% fMMC and 61% pMMC sacs (p=0.035). There was no statistical difference between groups with moderate and severe meconium histiocytosis.

CONCLUSIONS

Meconium passage in MMCs can occur early in fetal life. Fetal MMC repair may reduce the duration of meconium exposure, thereby potentially limiting the toxic injury to the vulnerable neural elements.

Prenatal diagnosis, fetal surgery, recurrence risk and differential diagnosis of neural tube defects

Prenatal screening with alpha-fetoprotein (AFP) and ultrasonography have allowed the prenatal diagnosis of neural tube defects (NTDs) in current obstetric care, and open spina bifida has been considered a potential candidate for in utero treatment in modern pediatric surgery. This article provides an overview of maternal serum AFP screening, amniotic fluid AFP assays, amniotic fluid acetylcholinesterase immunoassays and level II ultrasound for NTDs, prenatal repair of fetal myelomeningocele, recurrence risk of NTDs, and differential diagnosis of NTDs on prenatal ultrasound.

Vascular and apoptotic changes in the placode of myelomeningocele mice during the final stages of in utero development

OBJECT

Myelomeningocele (MMC) is a primary neurulation defect that is associated with devastating neurological disabilities in affected newborns. To better characterize the in utero neurodegenerative process of MMC, the authors investigated the changes in vascular organization, apoptosis, and the presence of inflammatory cells during gestation by using a mutant mouse model of MMC.

METHODS

The curly tail/loop tail (ct/lp) mutant mouse model of MMC was chosen to obtain fetuses at different stages of gestation. Mouse fetuses harboring MMC were harvested by caesarean section at embryonic Days 14.5, 16.5, and 18.5 (complete mouse gestation at 19 days, 6 mice/group); littermate fetuses with the same gestational age but without an MMC were used as controls. Samples of the MMC placode or normal spinal cord were stained for immunocytochemical labeling with caveolin antibody (endothelium marker) and activated caspase-3 antibody (apoptosis marker). Samples were morphometrically analyzed with a computer-assisted image analyzer.

RESULTS

The MMC mice presented with an increase in vascular density from embryonic Days 16.5-18.5 and an enhanced number of apoptotic cells at embryonic Day 18.5, compared with controls. There were scarce signals of an inflammatory reaction in the MMC placode, as a few infiltrating neutrophils were seen only at embryonic Day 18.5.

CONCLUSIONS

Fetal placodes in MMC mice showed evidence of increased vascular density since embryonic Day 16.5 and increased apoptosis at embryonic Day 18.5. These new data support the view that in utero changes of the MMC placode, occurring during the last stages of gestation, contribute to the neuropathological manifestations in full-term newborns with MMC.

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.

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.

Scanning electron microscopy of fetal murine myelomeningocele reveals growth and development of the spinal cord in early gestation and neural tissue destruction around birth

BACKGROUND

Previous studies demonstrated that the spinal cord within a fetal myelomeningocele (MMC) lesion suffers progressive destruction during gestation. This study aims at elucidating this pathophysiologic feature on a cellular and ultrastructural level in a model of genetically determined MMC.

METHODS

Curly tail/loop tail mouse fetuses at various gestational stages and neonates were analyzed electron-microscopically to document time-point and nature of neural tissue development and pathologic alterations within the MMC.

RESULTS

At embryonic day (E) 8.5 and E9.5, round cells displaying multiple microvilli covered the entire region of interest, and some specimens showed initial stages of neurulation. At E10.5, neurulation was terminated in normal animals, whereas the neural placode remained unfolded in MMC fetuses and became distinguishable from adjacent epidermal layers. At E15.5, an apparently normal differentiation was found. Until this time-point, there was no tissue damage or inflammation. Thereafter, increasingly severe tissue alterations were identified with ongoing gestation leading to almost complete loss of neural tissue at birth.

CONCLUSION

We show here in fetal mice with MMC that, apart from absent neurulation, growth and development of the otherwise perfectly intact exposed spinal cord appear normal in early gestation, whereas later, the unprotected neural tissue is progressively destroyed.

Fetal surgery for neural tube defects

Open spina bifida remains a major source of disability despite an overall decrease in incidence. It is frequently diagnosed prenatally and can thus - potentially - be treated by fetal surgery. Animal studies and preliminary human studies strongly suggest that at least a portion of the neurological abnormalities seen in these patients are secondary, and occur in mid-gestation. It is estimated that approximately 400 fetal operations have now been performed for myelomeningocele world wide. Despite this large experience, the technique remains of unproven benefit. Preliminary results suggest that fetal surgery results in reversal of hindbrain herniation (the Chiari II malformation), a decrease in shunt-dependent hydrocephalus, and possibly improvement in leg function, but these findings might be explained by selection bias and changing management indications. A randomized prospective trial (the MOMS trial) is currently being conducted by three centers in the United States, and is estimated to be completed in 2009.

In utero topographic analysis of astrocytes and neuronal cells in the spinal cord of mutant mice with myelomeningocele

OBJECT

Myelomeningocele (MMC) is the most severe form of spina bifida causing severe neurological deficits. Injury to the placode has been attributed to in utero aggression. In this study, glial and neuronal cell changes in both number and topography in mice with MMC were investigated during gestation.

METHODS

The curly tail/loop-tail mice model of MMC was used, and fetuses were harvested using caesarean surgery at Days 14.5, 16.5, and 18.5 (full gestation at 19 days). Immunohistochemical analyses of the MMC placodes and the normal spinal cords from the control group were performed using anti-glial fibrillary acidic protein (astrocytes) and mouse anti-neuronal nuclear (neurons) antibodies. Light microscopy was used along with computer-assisted morphometric evaluation. Progressive increases in astrocytes in the spinal cord of all mouse fetuses were found between Days 14.5 and 18.5 of gestation. This increase was significantly higher in the placodes of mice with MMC than in those of normal mice, particularly in the posterior region. Neuronal labeling at Day 14.5 of gestation was similar between mice with MMC and control mice. At Day 16.5 of gestation there was a deterioration of neural tissue in MMC fetuses, mainly in the posterior region, progressing until the end of gestation with a marked loss of neurons in the entire MMC placode.

CONCLUSIONS

This study delineated the quantitative changes in astrocytes and neurons associated with MMC development during the late stages of gestation. The detailed topographic analysis of the MMC defines the timing of the intrauterine insult and how the placode lesions progress. This study supports the current concept of placode protection through in utero surgery for fetuses with MMC.

Fetal spina bifida in a mouse model: loss of neural function in utero

OBJECT

The devastating neurological deficit associated with myelomeningocele has previously been assumed to be a direct and inevitable consequence of the primary malformation-failure of neural tube closure. An alternative view is that secondary damage to the pathologically exposed spinal cord tissue in utero is responsible for the neurological deficiency. If the latter mechanism were shown to be correct, it would provide an objective rationale for the performance of in utero surgery for myelomeningocele, because coverage of the exposed spinal cord could be expected to alleviate or perhaps prevent neurodegeneration. To examine this question, the authors studied the development of neuronal connections and neurological function of mice during fetal and neonatal stages in a genetic model of exposed lumbosacral spina bifida.

METHODS

The persistently exposed spinal cord of mouse fetuses carrying both curly tail and loop-tail mutations exhibited essentially normal anatomical and functional hallmarks of development during early gestation (embryonic Days 13.5-16.5), including sensory and motor projections to and from the cord. A significant proportion of fetuses with spina bifida at early gestation exhibited sensorimotor function identical to that seen in age-matched healthy controls. However, at later gestational stages, increasing neurodegeneration within the spina bifida lesion was detected, which was paralleled by a progressive loss of neurological function.

CONCLUSIONS

These findings provide support for the hypothesis that neurological deficit in human myelomeningocele arises following secondary neural tissue destruction and loss of function during pregnancy.

The effect of prenatal treatment with steroids and preterm delivery in a model of myelomeningocele on the rabbit foetus

Damage of neural elements (spinal cord and encephalus) in myelomeningocele (MMC) seems to be progressive during gestation because of amniotic fluid chemical contact and continuous leakage of CSF. We studied the effect of preterm delivery and steroid treatment in a model of MMC in the rabbit foetus. Twelve New Zealand White rabbits underwent laparotomy and hysterotomy at 23 days of gestation. Fifty-nine out of 107 foetuses underwent lumbar laminectomy (three to four levels). Dura was opened to expose the neural elements to the amniotic fluid. Six rabbits underwent caesarean section on gestational day 31 for fetal harvest; three of them had no treatment (group T) and three received corticosteroid treatment (group TC). The other six rabbits underwent caesarean section on gestational day 29 for fetal harvest (preterm delivery); three of them had no treatment (group P) and three received corticosteroid treatment (group PC). Alive newborns were clinically, neurophysiologically and histologically analysed. None of mothers died during the procedure. After birth, animals in group preterm showed statistically significant less deformity than animals in group at term. Lower kyphosis was observed in group PC (preterm and steroids). Pain related and spontaneous mobility of lower extremities was higher in groups treated with corticosteroids (TC and PC). Only newborns at term (T and TC groups) showed response to evoked potentials (CMEPs). The response was earlier and higher in group treated with steroids (TC). Histologically, we observed progressive lesion of the spinal cord. Groups treated with steroids (TC and PC) show less inflammatory response. Arnold-Chiari malformation was present in all groups. Animals in group preterm with steroids show statistically significant less herniation than those group at term. Preterm delivery and prenatal steroid therapy seem to be an effective treatment to get less neural injury (spinal cord and encephalus) in myelomeningocele foetuses.

Assessment of neurosurgical outcome in children prenatally diagnosed with myelomeningocele and development of a protocol for fetal surgery to prevent hydrocephalus

INTRODUCTION

Prenatal diagnosis of myelomeningocele (MMC) has permitted a better planning for optimum management of the disease. More recently, it has allowed for a possible intrauterine repair of the spinal defect.

OBJECTIVE

To describe neurosurgical outcome in children with myelomeningocele and follow-up at a referral center in Fetal Medicine. Patients were characterized for the development of a protocol suitable for fetal surgery, and fetuses who were possible candidates for intrauterine surgery were identified.

MATERIALS AND METHODS

A retrospective descriptive analysis was performed of 98 cases of fetal myelomeningocele, seen at CAISM-UNICAMP, from January 1994 to December 2002, identifying cases with a possible indication for fetal surgery.

RESULTS

Mean gestational age at diagnosis was 29 weeks (17-39); level of lesion was above the sacral region in 92.84%; association with hydrocephalus occurred in 78.57%. During clinical course, 82.5% of patients had neurogenic bladder and 60% had neural and mental deficits. Potential intrauterine repair rate was 11.57%, using criteria from the protocol developed in our service.

CONCLUSION

Myelomeningocele is associated with severe and frequent sequelae. In virtually 12% of our cases, fetal surgery could have been offered as a therapeutic option.

Reclosure of surgically induced spinal open neural tube defects by the intraamniotic injection of human embryonic stem cells in chick embryos 24 hours after lesion induction

OBJECT

The authors previously reported that human embryonic stem cells (hESCs) injected into the amniotic cavity of chick embryos immediately after neural tube incision in a surgically induced spinal open neural tube defect (ONTD) model promote the reclosure capacity of neural tubes. To simulate more closely the clinical situation of human ONTDs, in which a substantial time period elapses before the prenatal diagnosis of spinal ONTDs, the authors investigated whether this reclosure capacity remains enhanced by the intraamniotic injection of hESCs at 24 hours after ONTD induction.

METHODS

One hundred twenty-two chick embryos with ONTDs were randomly assigned to two groups: the control group (59 embryos) and the hESC-injection group (hESC group, 63 embryos). After the neural tubes of both groups had been opened, the hESC group underwent direct intraamniotic injection with hESCs marked with an enhanced green fluorescent protein at 24 hours after ONTD induction. The lengths of the remnant ONTDs were measured and the presence of hESCs was determined at 4, 6, and 8 days after ONTD induction. No difference in survival rates was observed between the two groups. The mean length of the ONTDs, adjusted for body length at the time of death and initial lesion length, was significantly shorter in the hESC group than in the control group (p < 0.001). No hESCs were found within reclosed neural tubes; rather, they covered the defect area during the reclosure process.

CONCLUSIONS

The authors demonstrate that hESCs injected into the amniotic cavity at 24 hours after ONTD induction enhance reclosure ability in chick embryos.

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.

Arnold-Chiari in a fetal rat model of dysraphism

Dysraphism is a defect in neural tube development, leading to dysplastic growth of the spinal cord and meninges. Myelomeningocele (MM) is just one of its forms. Hydrocephalus is among the most important alterations in MM and occurs as a consequence of Arnold-Chiari malformation (AC). Experimental models have been developed in sheep, rabbits and rats to study MM physiopathology, allowing a more detailed evaluation of clinical parameters involved in this anomaly.

OBJECTIVE

Using the experimental model of dysraphism in fetal rats, the aim of this study was to evaluate the relevance of AC malformations, clinical parameters and grade of histological lesions.

MATERIALS AND METHODS

Three groups with 16 fetuses in each were compared, MM, Control and Sham, after intrauterine surgical creation of MM on day 18.5 of gestation (term = 22 days). AC was evaluated by photographic comparison of sagittal cuts of fetal heads. Clinical and histological evaluations were also made.

RESULTS

88% of AC (14/16) in MM fetuses were obtained, besides 100% of clinical alterations. Necrosis and erosion of the spinal cord exposed to amniotic fluid were verified in histology.

CONCLUSION

The presence of AC in the dysraphism rat model was high. These results allowed the use of this model to study alterations and intrauterine evolution of MM in a fashion similar to those observed in humans.

Fetal anal incontinence evaluated by amniotic fluid digestive enzyme assay in myelomeningocele spina bifida

The goals of this study were to determine whether anal sphincter dysfunction in spina bifida develops during fetal life or after birth and whether it reflects the severity of spina bifida and therefore can be used as a criterion to select the cases that could benefit from in uterosurgery. Total protein and digestive enzyme activities [gamma-glutamyl transpeptidase (GGTP), aminopeptidase M (AMP), and alkaline phosphatase isoenzymes including the intestinal form (iALP)] were assayed retrospectively in amniotic fluid from 80 myelomeningocele spina bifida cases without unrelated associated malformation (gestational age 14-33 wk). A normal enzyme activity profile was observed in 46 of the 80 cases. Two abnormal profiles were observed: 1) bilious vomiting, characterized by abnormally high GGTP and AMP activities but normal iALP, and 2) digestive enzyme leakage, characterized by abnormally high activities of GGTP, AMP, and iALP, typical of anal incontinence. No relation was observed between these enzyme activity profiles and the different secondary signs of spina bifida or the level of the damage. In conclusion, anal sphincter dysfunction in spina bifida revealed by amniotic fluid digestive enzyme activities occurred before 24 wk in fetal life in 28.7% of cases. This criterion may be indicative of the severity of spina bifida and therefore perhaps could be used to select cases that are suited to in utero surgery. It could also be used to establish the potential benefit of this surgery in fecal incontinence.

Spina bifida

Spina bifida results from failure of fusion of the caudal neural tube, and is one of the most common malformations of human structure. The causes of this disorder are heterogeneous and include chromosome abnormalities, single gene disorders, and teratogenic exposures. However, the cause is not known in most cases. Up to 70% of spina bifida cases can be prevented by maternal, periconceptional folic acid supplementation. The mechanism underlying this protective effect is unknown, but it is likely to include genes that regulate folate transport and metabolism. Individuals with spina bifida need both surgical and medical management. Although surgical closure of the malformation is generally done in the neonatal period, a randomised clinical trial to assess in utero closure of spina bifida has been initiated in the USA. Medical management is a lifelong necessity for individuals with spina bifida, and should be provided by a multidisciplinary team.

Evolução de 58 fetos com meningomielocele e o potencial de reparo intra-útero

INTRODUÇÃO: O diagnóstico pré natal da meningomielocele (MM) permite melhor planejamento de sua abordagem e, mais recentemente , um possível reparo intra-útero. OBJETIVO: Descrição da evolução perinatal de fetos com MM, acompanhados em um centro de referência em Medicina Fetal, identificando os possíveis fetos candidatos à cirurgia intra-uterina. MÉTODO: Análise retrospectiva descritiva de 58 casos de MM fetal, atendidos no CAISM-UNICAMP, de janeiro de 1997 a dezembro de 2001, identificando-se os casos cuja indicação de cirurgia fetal seria possível. RESULTADOS: Média da idade gestacional ao diagnóstico de 29 semanas (17-39); nível da lesão acima da região sacral em 85%; associação com hidrocefalia em 86%; taxa de complicações cirúrgicas de 39%. Na evolução, 98% apresentaram bexiga neurogênica e 60% deficiência neuro-mental. O potencial reparo intra-útero foi de 42%. CONCLUSÃO: MM está associada a graves e frequentes sequelas. Quase um terço dos nossos casos poderiam ter tido a cirurgia fetal como opção terapêutica.

Foetal surgery for spina bifida

In utero repair of open spina bifida or myelomeningocele (MMC) is now performed in selected patients and presents an additional alternative to obstetricians and neonatologists counselling expectant mothers carrying a foetus with MMC. Early foetal intervention may improve neurologic outcomes and reduce the hindbrain herniation associated with the Arnold-Chiari II malformation in open spina bifida. These changes may improve long-term neurologic function and limit requirements for shunt placements and other surgical interventions. Further research is needed to better understand the pathophysiology of MMC, the ideal timing and technique of repair, and the long-term impact of in utero intervention. A prospective, randomized clinical trial is planned comparing prenatal MMC repair with postnatal repair.

Prenatal intervention for urinary obstruction and myelomeningocele

Widespread use of ultrasonography has resulted in an increase in the recognition of fetal hydronephrosis. The enthusiasm that accompanied early interventions has been tempered by the experience and results obtained over the past 2 decades. The goal has remained the same: to identify patients with serious prenatal obstruction and to identify those which may benefit from intervention. Myelomeningocele remains a devastating congenital anomaly. Fetal and experimental studies suggested that patients with myelomeningocele could benefit from prenatal intervention. Advances in technology and perinatal management have made intervention for more complex malformations such as myelomeningocele possible. This article will review current knowledge and will detail rational management for the management of prenatal hydronephrosis. The current state of antenatal myelomeningocele repair and the urologic implications will be described as well.

Evaluation of femur length during the second and third trimesters in fetuses with myelomeningocele

OBJECTIVES

To determine if the femur length of fetuses with myelomeningocele is shorter in the second and third trimesters compared with that of normal fetuses.

METHODS

We retrospectively collected measurements of femur length, head circumference, biparietal diameter and abdominal circumference from detailed obstetric ultrasound studies performed during the second and third trimesters in 31 fetuses with myelomeningocele and 43 fetuses with no detectable anomaly. The gestational age predicted by each parameter (based on Hadlock's tables) was compared with the true gestational age (based on last menstrual period), using the ANCOVA test to determine if there was a statistically significant difference between the two groups of fetuses.

RESULTS

There was no significant difference in femur length (P = 0.60) or in abdominal circumference (P = 0.85) between fetuses with myelomeningocele and normal fetuses. Fetuses with myelomeningocele did have a significantly lower biparietal diameter and head circumference (P < or = 0.001).

CONCLUSIONS

Myelomeningocele is not associated with reduced femur length in the second and third trimesters, suggesting that the known postnatal lower extremity foreshortening in patients with myelomeningocele develops late in gestation or after birth.

Intrauterine myelomeningocele repair

Preliminary studies have suggested that IUMR reduces the incidence of shunt-dependent hydrocephalus and the severity of the Chiari malformation. An RCT is in progress to confirm these results. Future efforts will revolve around refinement of the procedure with the goal of reducing risk. Robot-assisted surgery holds the promise of achieving this goal. If it is successful. IUMR might well become the standard therapy for myelomeningocele, resulting in a significant reduction in the devastating morbidity associated with this disease.

Chronology of neurological manifestations of prenatally diagnosed open neural tube defects

OBJECTIVE

To evaluate the incidence and chronology of sonographic markers of neurological compromise in prenatally diagnosed neural tube defects.

METHODS

We reviewed our ultrasound database from 1988 to 1999 to identify all cases of prenatally diagnosed neural tube defects. All patients received an initial detailed targeted ultrasound evaluation with subsequent evaluations every 4-6 weeks. Cases involving multiple congenital anomalies, aneuploidy, or inadequate follow-up were excluded. Specific ultrasound markers assessed included the presence of ventriculomegaly (> 10 mm) and clubfoot.

RESULTS

Forty-seven cases of neural tube defects were identified over the study interval. After exclusions, 42 cases were available for evaluation. The overall incidence of ventriculomegaly and clubfoot in the study cohort was 86% and 38%, respectively. In the 33 patients with initial ultrasound examination performed at < 24 weeks' gestation, 76% (25/33) had evidence of ventriculomegaly and 30% (10/33) and clubfoot. Only 9% (1/11) of the patients managed expectantly developed evidence of ventriculomegaly and 3/11 (27%) developed clubfoot from the time of the initial ultrasound examination to delivery.

CONCLUSIONS

Ultrasound markers of neurological compromise are early and frequent findings associated with fetal neural tube defects. Development of ventriculomegaly is an uncommon occurrence later in gestation, while the risk for developing clubfoot appears to increase as gestation progresses.