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

Histological evaluation of acute covering of an experimental neural tube defect with biomatrices in fetal sheep.

Contains fulltext : 49874.pdf (publisher's version ) (Closed access)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

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

Item does not contain fulltextBACKGROUND/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

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

<p>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.</p><p>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)) = [MUDcalf muscle/S1-2] -aEuro parts per thousand[MUDquadriceps muscle/L2-4] and associated outcomes with leg muscle function caudal to the MMC.</p><p>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).</p><p>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.</p>