Toward an understanding of nonsyndromic craniosynostosis: altered patterns of TGF-beta receptor and FGF receptor expression induced by intrauterine head constraint

Retroperitoneal liposarcoma and craniosynostosis: possible genomic relationship, case report, and literature review

Based on a case report, this review explores the genomic landscape for patients with liposarcomas and possible relationships with gene mutations related to craniosynostosis. We describe the case of a 40-year-old man, known for a surgical correction of craniosynostosis before the age of 1 year, who underwent a radical resection of a voluminous retroperitoneal liposarcoma; histopathological analysis revealed a low-grade well-differentiated, mostly sclerosing, liposarcoma. A genetic analysis searching for mutations in blood DNA was performed and did not detect any specific mutation. A literature review was also conducted. Several tumors related to syndromic and non-syndromic craniosynostosis are mentioned in the literature; no specific link with retroperitoneal liposarcoma is established but the FGFR3 mutation is detected in dedifferentiated liposarcomas. To date, no case has been reported in the literature demonstrating a genetic relationship between craniosynostosis and low-grade differentiated retroperitoneal liposarcoma. We conclude that further studies for gene complex mutations should be conducted to show a possible genetic relationship between retroperitoneal liposarcoma and craniosynostosis.

Coronal and lambdoid suture evolution following total vault remodeling for scaphocephaly

OBJECTIVE

Different types of surgical procedures are utilized to treat craniosynostosis. In most procedures, the fused suture is removed. There are only a few reports on the evolution of sutures after surgical correction of craniosynostosis. To date, no published study describes neosuture formation after total cranial vault remodeling. The objective of this study was to understand the evolution of the cranial bones in the area of coronal and lambdoid sutures that were removed for complete vault remodeling in patients with sagittal craniosynostosis. In particular, the investigation aimed to confirm the possibility of neosuture formation.

METHODS

CT images of the skulls of children who underwent operations for scaphocephaly at the Hôpital Femme Mère Enfant, Lyon University Hospital, Lyon, France, from 2004 to 2014 were retrospectively reviewed. Inclusion criteria were diagnosis of isolated sagittal synostosis, age between 4 and 18 months at surgery, and availability of reliable postoperative CT images obtained at a minimum of 1 year after surgical correction. Twenty-six boys and 11 girls were included, with a mean age at surgery of 231.6 days (range 126-449 days). The mean interval between total vault reconstruction and CT scanning was 5.3 years (range 1.1-12.2 years).

RESULTS

Despite the removal of both the coronal and lambdoid sutures, neosutures were detected on the 3D reconstructions. All combinations of neosuture formation were seen: visible lambdoid and coronal neosutures (n = 20); visible lambdoid neosutures with frontoparietal bony fusion (n = 12); frontoparietal and parietooccipital bony fusion (n = 3); and visible coronal neosutures with parietooccipital bony fusion (n = 2).

CONCLUSIONS

This is the first study to report the postoperative skull response after the removal of normal patent sutures following total vault remodeling in patients with isolated sagittal synostosis. The reappearance of a neosuture is rather common, but its incidence depends on the type of suture. The outcome of the suture differs with the incidence of neosuture formation between these transverse sutures. This might imply genetic and functional differences among cranial sutures, which still have to be elucidated.

Increased Incidence of Ophthalmologic Findings in Children With Concurrent Isolated Nonsyndromic Metopic Suture Abnormalities and Deformational Cranial Vault Asymmetry

OBJECTIVE

The purpose of this project was to study the incidence of ophthalmologic findings which are known to be risk factors for amblyopia in children who have coexisting metopic suture abnormalities and deformational plagiocephaly (DP) and brachycephaly (DB).

DESIGN

Institutional Review Board-approved retrospective study reviewing records of a consecutive cohort of children under 2 years of age with metopic suture abnormalities and cranial vault asymmetries seen in both the plastic surgery and ophthalmology clinics from 2007 to 2017.

SETTING

Institutional tertiary care center with all care in plastic surgery under the senior author and the standard of care accepted in pediatric ophthalmology under one of two ophthalmologists.

PATIENTS

After application of exclusion criteria, 76 children diagnosed with metopic suture abnormalities and DP/DB were included in the study. Patients with severe trigonocephaly, other suture involvement, syndromic diagnoses, and primary ocular disorders were excluded.

MAIN OUTCOME MEASURES

Describe the incidences of refractive errors (astigmatism, hyperopia, and myopia), anisometropia, strabismus, and amblyopia within the study population.

RESULTS

In our patient population, the rates of amblyopia (17.1%) and strabismus (15.8%) are higher than the general pediatric population rates of 1.5% to 1.8% and 2.4% to 3.6%, respectively. Overall, 47.4% had significant refractive error: 28.9% with astigmatism, 15.8% with hyperopia, 5.3% with myopia, and 10.5% with anisometropia.

CONCLUSIONS

In our patient population, children with coexisting metopic suture abnormalities and DP or DB had significant risk for amblyopia, strabismus, and refractive errors.

Assessment of the Outcome of Calvarial Vault Remodeling and Spring-Mediated Cranioplasty in the Correction of Isolated Sagittal Suture Synostosis

BACKGROUND

Sagittal synostosis is the commonest form of nonsyndromic isolated craniosynostosis. Calvarial vault remodeling (CVR) and spring-mediated cranioplasty (SMC) are the commonly used correction techniques.

AIM OF THE WORK

To study and compare clinical and radiographic outcomes of CVR and SMC in the correction of isolated sagittal suture synostosis.

METHODS

A prospective cohort with the patients were divided into group; I (SMC) and II (CVR), each 15 patients. They were observed to evaluate the outcome and detect complications.

RESULTS

Mean operative time was 59.2 minutes in SMC and 184 minutes in CVR. Mean intraoperative blood loss was 26 mL in SMC and 64.7 mL in CVR. Intraoperative complications in SMC were dural tear in 1 patient and superior sagittal sinus injury in another patient, while in CVR 2 patients with dural tears and a 3rd with superior sagittal sinus injury. Postoperative complications in SMC were exposed spring, gaped wound, and parietal eminence elevation, while in CVR 2 patients needed blood transfusion. The mean hospital stays was 1.4 days in SMC and 4.1 days in CVR. In SMC, the relative increase in cephalic index varied between 5.5% and 8.2%, while for CVR, it varied between 5.1% and 7.9%.

CONCLUSION

The SMC and CVR are safe procedures, with good long-term results and significant objective changes toward normalization of the skull morphology in isolated sagittal craniosynostosis. The SMC is less invasive and associated with reduced hospital stays, decreased blood loss, and can be performed at a younger age than CVR with a lower morbidity.

GLI1 and AXIN2 Are Distinctive Markers of Human Calvarial Mesenchymal Stromal Cells in Nonsyndromic Craniosynostosis

All skeletal bones house osteogenic stem cell niches, in which mesenchymal stromal cells (MSC) provide progenitors for tissue growth and regeneration. They have been widely studied in long bones formed through endochondral ossification. Limited information is available on the composition of the osteogenic niche in flat bones (i.e., skull vault bones) that develop through direct membranous ossification. Craniosynostosis (CS) is a congenital craniofacial defect due to the excessive and premature ossification of skull vault sutures. This study aimed at analysing the expression of GLI1, AXIN2 and THY1 in the context of the human skull vault, using nonsyndromic forms of CS (NCS) as a model to test their functional implication in the aberrant osteogenic process. The expression of selected markers was studied in NCS patients' calvarial bone specimens, to assess the in vivo location of cells, and in MSC isolated thereof. The marker expression profile was analysed during in vitro osteogenic differentiation to validate the functional implication. Our results show that GLI1 and AXIN2 are expressed in periosteal and endosteal locations within the osteogenic niche of human calvarial bones. Their expression is higher in MSC isolated from calvarial bones than in those isolated from long bones and tends to decrease upon osteogenic commitment and differentiation. In particular, AXIN2 expression was lower in cells isolated from prematurely fused sutures than in those derived from patent sutures of NCS patients. This suggests that AXIN2 could reasonably represent a marker for the stem cell population that undergoes depletion during the premature ossification process occurring in CS.

Recent Advances in Craniosynostosis

Craniosynostosis is a pathologic craniofacial disorder and is defined as the premature fusion of one or more cranial (calvarial) sutures. Cranial sutures are fibrous joints consisting of nonossified mesenchymal cells that play an important role in the development of healthy craniofacial skeletons. Early fusion of these sutures results in incomplete brain development that may lead to complications of several severe medical conditions including seizures, brain damage, mental delay, complex deformities, strabismus, and visual and breathing problems. As a congenital disease, craniosynostosis has a heterogeneous origin that can be affected by genetic and epigenetic alterations, teratogens, and environmental factors and make the syndrome highly complex. To date, approximately 200 syndromes have been linked to craniosynostosis. In addition to being part of a syndrome, craniosynostosis can be nonsyndromic, formed without any additional anomalies. More than 50 nuclear genes that relate to craniosynostosis have been identified. Besides genetic factors, epigenetic factors like microRNAs and mechanical forces also play important roles in suture fusion. As craniosynostosis is a multifactorial disorder, evaluating the craniosynostosis syndrome requires and depends on all the information obtained from clinical findings, genetic analysis, epigenetic or environmental factors, or gene modulators. In this review, we will focus on embryologic and genetic studies, as well as epigenetic and environmental studies. We will discuss published studies and correlate the findings with unknown aspects of craniofacial disorders.

Signaling Mechanisms Underlying Genetic Pathophysiology of Craniosynostosis

Craniosynostosis, is the premature fusion of one or more cranial sutures which is the second most common cranial facial anomalies. The premature cranial sutures leads to deformity of skull shape and restricts the growth of brain, which might elicit severe neurologic damage. Craniosynostosis exhibit close correlations with a varieties of syndromes. During the past two decades, as the appliance of high throughput DNA sequencing techniques, steady progresses has been made in identifying gene mutations in both syndromic and nonsyndromic cases, which allow researchers to better understanding the genetic roles in the development of cranial vault. As the enrichment of known mutations involved in the pathogenic of premature sutures fusion, multiple signaling pathways have been investigated to dissect the underlying mechanisms beneath the disease. In addition to genetic etiology, environment factors, especially mechanics, have also been proposed to have vital roles during the pathophysiological of craniosynostosis. However, the influence of mechanics factors in the cranial development remains largely unknown. In this review, we present a brief overview of the updated genetic mutations and environmental factors identified in both syndromic and nonsyndromic craniosynostosis. Furthermore, potential molecular signaling pathways and its relations have been described.

Whole-Proteome Analysis of Human Craniosynostotic Tissue Suggests a Link between Inflammatory Signaling and Osteoclast Activation in Human Cranial Suture Patency

BACKGROUND

The pathophysiology of nonsyndromic craniosynostosis remains poorly understood. The authors seek to understand the cause of this condition with a specific focus on how osteoclasts may contribute to craniosynostosis. Here, the authors characterize proteins differentially expressed in patent and fused cranial sutures by comparing their respective proteomes.

METHODS

Fused and patent suture samples were obtained from craniosynostotic patients undergoing surgery at a single academic medical center. Extracted protein from samples was interrogated using mass spectrometry. Differential protein expression was determined using maximum likelihood-based G-test with a q-value cutoffs of 0.5 after correction for multiple hypothesis testing. Immunolocalization of lead protein candidates was performed to validate proteomic findings. In addition, quantitative polymerase chain reaction analysis of corresponding gene expression of proteins of interest was performed.

RESULTS

Proteins differentially expressed in patent versus fused sutures included collagen 6A1 (Col6A1), fibromodulin, periostin, aggrecan, adipocyte enhancer-binding protein 1, and osteomodulin (OMD). Maximum likelihood-based G-test suggested that Col6A1, fibromodulin, and adipocyte enhancer-binding protein 1 are highly expressed in patent sutures compared with fused sutures, whereas OMD is up-regulated in fused sutures compared with patent sutures. These results were corroborated by immunohistochemistry. Quantitative polymerase chain reaction data point to an inverse relationship in proteins of interest to RNA transcript levels, in prematurely fused and patent sutures that potentially describes a feedback loop mechanism.

CONCLUSIONS

Proteome analysis validated by immunohistochemistry may provide insight into the mechanism of cranial suture patency and disease from an osteoclast perspective. The authors results suggest a role of inflammatory mediators in nonsyndromic craniosynostosis. Col6A1 may aid in the regulation of suture patency, and OMD may be involved in premature fusion. Additional validation studies are required.

Cell Mechanics of Craniosynostosis

Craniosynostosis is the premature fusion of the calvarial sutures that is associated with a number of physical and intellectual disabilities spanning from pediatric to adult years. Over the past two decades, techniques in molecular genetics and more recently, advances in high-throughput DNA sequencing have been used to examine the underlying pathogenesis of this disease. To date, mutations in 57 genes have been identified as causing craniosynostosis and the number of newly discovered genes is growing rapidly as a result of the advances in genomic technologies. While contributions from both genetic and environmental factors in this disease are increasingly apparent, there remains a gap in knowledge that bridges the clinical characteristics and genetic markers of craniosynostosis with their signaling pathways and mechanotransduction processes. By linking genotype to phenotype, outlining the role of cell mechanics may further uncover the specific mechanotransduction pathways underlying craniosynostosis. Here, we present a brief overview of the recent findings in craniofacial genetics and cell mechanics, discussing how this information together with animal models is advancing our understanding of craniofacial development.

Syndromic Craniosynostosis Can Define New Candidate Genes for Suture Development or Result from the Non-specifc Effects of Pleiotropic Genes: Rasopathies and Chromatinopathies as Examples

Craniosynostosis is a heterogeneous condition caused by the premature fusion of cranial sutures, occurring mostly as an isolated anomaly. Pathogenesis of non-syndromic forms of craniosynostosis is largely unknown. In about 15–30% of cases craniosynostosis occurs in association with other physical anomalies and it is referred to as syndromic craniosynostosis. Syndromic forms of craniosynostosis arise from mutations in genes belonging to the Fibroblast Growth Factor Receptor (FGFR) family and the interconnected molecular pathways in most cases. However it can occur in association with other gene variants and with a variety of chromosome abnormalities as well, usually in association with intellectual disability (ID) and additional physical anomalies. Evaluating the molecular properties of the genes undergoing intragenic mutations or copy number variations (CNVs) along with prevalence of craniosynostosis in different conditions and animal models if available, we made an attempt to define two distinct groups of unusual syndromic craniosynostosis, which can reflect direct effects of emerging new candidate genes with roles in suture homeostasis or a non-specific phenotypic manifestation of pleiotropic genes, respectively. RASopathies and 9p23p22.3 deletions are reviewed as examples of conditions in the first group. In particular, we found that craniosynostosis is a relatively common component manifestation of cardio-facio-cutaneous (CFC) syndrome. Chromatinopathies and neurocristopathies are presented as examples of conditions in the second group. We observed that craniosynostosis is uncommon on average in these conditions. It was randomly associated with Kabuki, Koolen-de Vries/KANSL1 haploinsufficiency and Mowat–Wilson syndromes and in KAT6B-related disorders. As an exception, trigonocephaly in Bohring-Opitz syndrome reflects specific molecular properties of the chromatin modifier ASXL1 gene. Surveillance for craniosynostosis in syndromic forms of intellectual disability, as well as ascertainment of genomic CNVs by array-CGH in apparently non-syndromic craniosynostosis is recommended, to allow for improvement of both the clinical outcome of patients and the accurate individual diagnosis.

Application of Laser Capture Microdissection to Craniofacial Biology: Characterization of Anatomically Relevant Gene Expression in Normal and Craniosynostotic Rabbit Sutures

OBJECTIVE

Fusion of the cranial sutures is thought to depend on signaling among perisutural tissues. Mapping regional variations in gene expression would improve current models of craniosynostosis. Laser capture microdissection (LCM) isolates discrete cell populations for gene expression analysis. LCM has rarely been used in the study of mineralized tissue. This study sought to evaluate the potential use of LCM for mapping of regional gene expression within the cranial suture.

DESIGN

Coronal sutures were isolated from 10-day-old wild-type and craniosynostotic (CS) New Zealand White rabbits, and LCM was used to isolate RNA from the sutural ligament (SL), osteogenic fronts (OF), dura mater, and periosteum. Relative expression levels for Fibroblast Growth Factor 2 (FGF2), Fibroblast Growth Factor Receptor 2 (FGFR2), Transforming Growth Factor Beta 2 (TGFβ-2), Transforming Growth Factor Beta 3 (TGFβ-3), Bone Morphogenetic Protein 2 (BMP-2), Bone Morphogenetic Protein 4 (BMP-4), and Noggin were determined using quantitative real-time PCR.

RESULTS

A fivefold increase in TGFβ2 expression was detected in the CS SL relative to wild type, whereas 152-fold less TGFβ-3 was detected within the OF of CS animals. Noggin expression was increased by 10-fold within the CS SL, but reduced by 13-fold within the CS dura. Reduced expression of FGF2 was observed within the CS SL and dura, whereas increased expression of FGFR2 was observed within the CS SL. Reduced expression of BMP-2 was observed in the CS periosteum, and elevated expression of BMP-4 was observed in the CS SL and dura.

CONCLUSIONS

LCM provides an effective tool for measuring regional variations in cranial suture gene expression. More precise measurements of regional gene expression with LCM may facilitate efforts to correlate gene expression with suture morphogenesis and pathophysiology.

Does an elevated bony ridge along the course of the metopic suture equal metopic synostosis? Implications for management

Metopic synostosis represents an increasingly prevalent form of nonsyndromic craniosynostosis. Premature fusion of the metopic suture classically results in trigonocephaly, hypotelorism, temporal narrowing, and a pronounced midline forehead ridge. However, as varying degrees of skull deformity exist, there is confusion regarding the appropriate management for an infant with a metopic ridge. We report on a 2-month-old infant with clinical manifestations of metopic synostosis but with a patent metopic suture documented on computed tomography scan. We examine the implications for management related to fusion of the suture, age of the patient, and severity of the head deformity.

Fibroblast growth factor (FGF) signaling in development and skeletal diseases

Fibroblast growth factors (FGF) and their receptors serve many functions in both the developing and adult organism. Humans contain 18 FGF ligands and four FGF receptors (FGFR). FGF ligands are polypeptide growth factors that regulate several developmental processes including cellular proliferation, differentiation, and migration, morphogenesis, and patterning. FGF-FGFR signaling is also critical to the developing axial and craniofacial skeleton. In particular, the signaling cascade has been implicated in intramembranous ossification of cranial bones as well as cranial suture homeostasis. In the adult, FGFs and FGFRs are crucial for tissue repair. FGF signaling generally follows one of three transduction pathways: RAS/MAP kinase, PI3/AKT, or PLCγ. Each pathway likely regulates specific cellular behaviors. Inappropriate expression of FGF and improper activation of FGFRs are associated with various pathologic conditions, unregulated cell growth, and tumorigenesis. Additionally, aberrant signaling has been implicated in many skeletal abnormalities including achondroplasia and craniosynostosis. The biology and mechanisms of the FGF family have been the subject of significant research over the past 30 years. Recently, work has focused on the therapeutic targeting and potential of FGF ligands and their associated receptors. The majority of FGF-related therapy is aimed at age-related disorders. Increased understanding of FGF signaling and biology may reveal additional therapeutic roles, both in utero and postnatally. This review discusses the role of FGF signaling in general physiologic and pathologic embryogenesis and further explores it within the context of skeletal development.

Gene expression profiling in human craniosynostoses: a tool to investigate the molecular basis of suture ossification

INTRODUCTION

Non-syndromic craniosynostoses (NSC) occur as isolated skull malformations due to the premature ossification of one (single-suture forms) or more (complex forms) calvarial sutures and represent the most frequent form of craniosynostosis worldwide. The etiology of NSC is still largely unknown as a genetic basis can be rarely demonstrated especially in single-suture forms. In these cases, during the prenatal/perinatal development of affected patients, only one suture undergoes a premature direct ossification within an otherwise physiologically grown skull. This could suggest that definite somatic alterations, possibly due to unclear environmental agents, occur locally at the site of premature suture fusion during skull development. A promising tool to investigate the molecular mechanisms that may orchestrate this event is the comparative analysis of suture- and synostosis-derived tissues and cells.

PURPOSE

This review focuses on the different studies that attempted to clarify this issue using genome-wide microarray-based technologies for the comparative analysis of gene expression profiles. All relevant results have been comprehensively reviewed, possibly compared, and critically discussed.

CONCLUSION

Due to the heterogeneity of the dataset available in the literature, a univocal CRS-associated molecular profile could not be deciphered. Most differentially expressed genes are found in different studies to be involved in extracellular matrix remodeling.

Nonsyndromic craniosynostosis

Nonsyndromic craniosynostosis is more commonly encountered than syndromic cases in pediatric craniofacial surgery. Affected children display characteristic phenotypes according to the suture or sutures involved. Restricted normal growth of the skull can lead to increased intracranial pressure and changes in brain morphology, which in turn may contribute to neurocognitive deficiency. Management has primarily focused on surgical correction of fused sutures prior to 12 months of age to optimize correction of the deformity and to ameliorate the effects of increased intracranial pressure. However, emphasis has recently shifted to better understanding the pathogenesis of neurocognitive impairment observed in these children, along with genetic mutations that contribute to premature suture fusion. Such understanding will provide opportunities for earlier and more specific neurocognitive interventions and for the development of targeted genetic therapy to prevent pathologic suture fusion. The authors review the common types of nonsyndromic craniosynostosis and the epidemiological, genetic, and neurodevelopmental details that are currently known from the literature. In addition, they present the rationale for surgical correction, offer suggestions for timing of intervention, and present some nuances of techniques that they find important in producing consistent results.

Role of RANK-RANKL-OPG axis in cranial suture homeostasis

Craniosynostosis is a significant disorder affecting 1 in 2500 live births worldwide. Although a large body of work has focused on dural regulation and the contributions of molecular mediators such as fibroblast growth factor, bone morphogenetic protein, and transforming growth factor β, minimal attention has been directed toward osteoclast function in cranial suture biology. Receptor activator of nuclear factor κB (RANK) is an essential mediator of osteoclastogenesis and osteoclast activation. In this study, physiologic fusion of posterior frontal sutures in murine development correlated with decreasing protein expression of RANK in comparison to age-matched coronal and sagittal sutures via immunohistochemical survey. However, RANK mRNA did not exhibit a similar pattern suggesting that RANK is regulated at the protein level. Fused cranial sutures in nonsyndromic craniosynostotic children also showed decreased levels of RANK staining in immunohistochemistry in comparison to patent sutures from the same patients. Immunohistochemistry with a RANK ligand antibody did not show differences in fused or patent sutures. Moreover, RANK knockdown in calvarial strip suture cultures displayed increased bone density specifically in the suture line after infection with small interfering RANK viruses. Cranial suture biology, similar to bone biology in general, likely depends on a complex interplay between osteoblasts and osteoclasts. We now report a temporospatial correlation between RANK expression and suture morphology that suggests that osteoclast activity is important in maintenance of cranial suture patency in normal physiology and disease. Furthermore, RANK downregulation promoted suture fusion establishing a causal relationship between the presence of RANK and patency.

A girl with metopic synostosis and trisomy 13 mosaicism: case report and review of the literature

Trisomy 13, or Patau syndrome is a rare chromosomal disorder characterized by a triad of cleft lip and palate, postaxial polydactyly and microcephaly. Complete, partial, or mosaic forms of the disorder can occur. Mosaic trisomy 13 is very rare, it occurs in only 5% of all patients with trisomy 13 phenotype. Metopic synostosis (MS) is premature fusion of the metopic suture, which is part of the frontal suture. It results in a V-shaped abnormality at the front of the skull. MS may occur in a syndromic or nonsyndromic form. We report on a 24-day-old girl with hypotonia, MS, trigonocephaly, capillary hemangioma, hypotelorism, upward slanting palpebral fissures, epicanthal folds, small nose with anteverted nares, high palate, ankyloglossia, long philtrum, low-set ears, short neck, postaxial polydactyly of both hands and feet and congenital heart defect. Cytogenetic analysis demonstrated trisomy 13 mosaicism; 46,XX[58]/47,XX,+13[42]. Although MS has been previously reported in complete and partial forms of trisomy 13, it has not been reported in mosaic form of trisomy 13. Our report supports the evidence that trisomy 13 causes MS. It also emphasizes the need for cytogenetic investigations in patients presenting with MS and multiple congenital anomalies for providing accurate diagnosis, genetic counseling, and prenatal diagnosis.

Effects of uterine cervix constriction on Wistar rats

PURPOSE

To verify if uterine cerclage can induce craniosynostosis or any cranial deformity in new born Wistar rats.

METHODS

One pregnant female Wistar rat underwent laparotomy on day 18 of gestation and the uterus cervix was closed with a 3-0 nylon suture to avoid delivery, that occurs normally on the 21 day. The suture was released after 48 hours beyond the normal gestation period. The female rat delivered 11 pups. Six surviving rats from the delivery (group A - constrained group). Two rats were born from another mother and in the same age were used as control group (group B - 2 nonconstrained controls) were allowed to grow. They were sacrificed 1.2 years after their birth all the eight animals. Linear measurement, routine histology and computed tomography of the skull were performed at the time of their death to evaluate the cranial asymmetries by measurements of the anatomical landmarks of the craniofacial skeleton of the rats on the two groups and compared then.

RESULTS

We did not observe statistically significant differences in any of the compared measurements (p>0.05) obtained through the morphologic and radiologic methods. Histologic examinations did not reveal any sign of premature fusion or suture imbrications. Critical decrease in longitudinal body size was noticed as the limbs too in all the animals of group A.

CONCLUSION

Constriction of uterine cervix leads to fetus suffering, even death for a few animals, associated to small body size, but not to craniosynostosis.

Etiological heterogeneity and clinical characteristics of metopic synostosis: Evidence from a tertiary craniofacial unit

Metopic synostosis (MS) accounts for approximately 10-15% of all craniosynostosis and is etiologically heterogeneous. This study aimed to examine the causes of MS, as observed in a tertiary craniofacial unit. We reviewed the case notes of 110 children with a diagnosis of MS, attending the craniofacial unit in Oxford between 1991 and 2008. Our results showed 38 children (38/110 or 34.6%) who had at least one additional structural abnormality or had a known syndromic diagnosis were classed as having syndromic MS. Chromosomal abnormalities were noted in 8/38 (21.4%) children: mosaic marker chromosome 2, 9p deletion (2/8), 11q deletion, 12pter deletion and duplication of 15q25 with other additional chromosomal abnormalities (3/8). Other syndromic diagnoses included Silver-Russell syndrome and Greig cephalopolysyndactyly. Prenatal exposure to sodium valproate (VPA) was noted in 8/110 children (7.8%), with the dose of the VPA being >or=1,000 mg/day in all cases. Other prenatal exposures reported in this study were: maternal diabetes (6/110), enoxaparin for hypercoagulable state (1/110), and thyroxine (1/110). The majority of patients (72/110 or 65.4%) had nonsyndromic MS. Speech delay was present in 11 children with nonsyndromic MS (11/72 or 15.3%) and 10 children with syndromic MS (10/38 or 26.3%). We conclude that approximately two-thirds of all MS is nonsyndromic. Prenatal exposure to VPA is a common cause of MS. Maternal diabetes, not previously linked to MS, was noted in 5.5% of cases. Chromosomal abnormalities account for about 6% of MS. An increased risk of speech delay is seen with both the syndromic and nonsyndromic forms.

Force-induced craniosynostosis in the murine sagittal suture

BACKGROUND

The cause of nonsyndromic craniosynostosis remains elusive. Although compressive forces have been implicated in premature suture fusion, conclusive evidence of force-induced craniosynostosis is lacking. The purpose of this study was to determine whether cyclical loading of the murine calvaria could induce suture fusion.

METHODS

Calvarial coupons from postnatal day-21, B6CBA, wild-type mice (n = 18) were harvested and cultured. A custom appliance capable of delivering controlled, cyclical, compressive loads was applied perpendicular to the sagittal suture within the coupon in vitro. Nine coupons were subjected to 0.3 g of force for 30 minutes each day for a total of 14 days. A control group of nine coupons was clamped in the appliance without loading. Analysis of suture phenotype was performed using alkaline phosphatase and hematoxylin and eosin staining techniques and in situ hybridization analysis using bone sialoprotein.

RESULTS

Control group sagittal sutures-which normally remain patent in mice-showed their customary histologic appearance. In contradistinction, sagittal sutures subjected to cyclic loading showed histologic evidence of premature fusion (craniosynostosis). In addition, alkaline phosphatase activity and bone sialoprotein expression were observed to be increased in the experimental group when compared with matched controls.

CONCLUSIONS

An in vitro model of force-induced craniosynostosis has been devised. Premature fusion of the murine sagittal suture was induced with the application of controlled, cyclical, compressive loads. These results implicate abnormal forces in the development of nonsyndromic craniosynostosis, which supports our global hypothesis that epigenetic phenomena play a crucial role in the pathogenesis of craniosynostosis.

Differential effects of TGF-beta isoforms on murine fetal dural cells and calvarial osteoblasts

BACKGROUND

Proteins within the transforming growth factor (TGF)-beta family play a central role in both normal and pathologic calvarial morphogenesis. Previous work has suggested differential functions of the TGF-beta isoforms in these processes. Little is known, however, about effects of TGF-betas on the underlying dura. Furthermore, studies on the effects of TGF-beta isoforms on osteoblasts have been conflicting. The purpose of this study was to determine the effect of TGF-beta isoforms, specifically TGF-beta1 and TGF-beta3, on fetal calvarial osteoblast and dural cell differentiation, proliferation, and apoptosis.

METHODS

Primary cultures of fetal calvarial osteoblasts and dural cells were established from embryonic day-18 CD-1 mice. Cells were treated for 48 hours with TGF-beta1 or TGF-beta3. Northern blot analysis, cell counts, and apoptosis assays were performed.

RESULTS

In dural cells, TGF-beta1 stimulated the expression of early osteodifferentiation genes and resulted in a slight decrease in cell number and no effect on apoptosis. Similar results were observed in osteoblasts. TGF-beta3 had little or no effect on the genes studied in both cell types but resulted in increased apoptosis and concomitant decreases in cell number in both cell types.

CONCLUSIONS

This study demonstrates that dural cells respond to TGF-beta and that this response is isoform-specific. TGF-beta1 stimulates osteodifferentiation of previously uncommitted cells in the dura. It also stimulates early events in bone matrix deposition and has little effect on late markers of bone differentiation in osteoblasts and dural cells. Both isoforms result in decreases in cell number. TGF-beta3 results in greater decreases in cell number and isoform-specific stimulation of apoptosis in both dural cells and calvarial osteoblasts.

Postoperative Anti-Tgf-β2 Antibody Therapy Improves Intracranial Volume and Craniofacial Growth in Craniosynostotic Rabbits

Postoperative resynostosis and secondary craniofacial growth abnormalities are common sequelae after craniofacial surgery. It has been suggested that an overexpression of transforming growth factor-beta2 (Tgf-beta2) may be related to craniosynostosis and contribute to postoperative resynostosis. Interference with Tgf-beta2 function using neutralizing antibodies may inhibit resynostosis and improve postoperative craniofacial growth; the present study was designed to test this hypothesis. Twenty-nine New Zealand white rabbits with bilateral coronal suture synostosis were used: 1) suturectomy controls (n=9); 2) suturectomy with nonspecific, control IgG antibody (n=9); and 3) suturectomy with anti-Tgf-beta2 antibody (n=11). At 10 days of age, a 3 mm x 15-mm coronal suturectomy was performed. The sites in groups 2 and 3 were immediately filled with 0.1 cc of a slow resorbing collagen gel mixed with either IgG (100 microg/suture) or anti-Tgf-beta2 (100 microg/suture). Three-dimensional computed tomography scan reconstructions of the skulls and cephalographs were obtained at 10, 25, 42, and 84 days of age. Computed tomography scan data revealed patent suturectomy sites and significantly (P<0.05) greater intracranial volumes by 84 days of age in rabbits treated with anti-Tgf-beta2 compared with controls. Cephalometric analysis revealed significant (P<0.05) differences in craniofacial, cranial vault, and cranial base growth by 84 days of age in rabbits treated with anti-Tgf-beta2 compared with controls. These data support the initial hypothesis that interference with Tgf-beta2 function inhibited postoperative resynostosis and improved cranial vault growth in this rabbit model. Thus, this biologically based therapy may be a potential surgical adjunct in the treatment of infants with craniosynostosis.

Pitfalls for the pediatrician: positional molding or craniosynostosis?

Abnormal head morphology is common among infants and often leads parents to ask their pediatricians for guidance. While the vast majority of such children development and prevent adverse neurobehavioral sequelae secondary to increased intracranial pressure or impaired cerebral growth. The coordination of a multidisciplinary team in the setting of a center experienced in the management of craniosynostosis will assure the best possible results for each patient.

Brain morphology in nonsyndromic unicoronal craniosynostosis

Studies of isolated craniosynostosis have shown biomechanical and biochemical influences on the craniofacial phenotype, resulting from both genetic and epigenetic factors. Much less attention has been directed toward the morphology of the brain, despite the interactive nature of the developing skull and developing brain. The aim of this study is to define the morphology of the brain in nonsyndromic unilateral coronal synostosis (UCS) in order to form more complete hypotheses about the cause of craniosynostosis. Landmark coordinate data were collected from 3D magnetic resonance image reconstructions of the brain in a sample of UCS patients and an age-matched morphologically normal cohort. These data were analyzed using Euclidean distance matrix analysis. The results of our study demonstrate that despite the basic similarity of overall shape of the brain and skull in UCS, the effects of craniosynostosis on the brain are not localized to structures immediately adjacent to the fused suture or to the endocranial surface of the skull. Rather, alterations are observed throughout the volume of the brain, with subcortical structures altered in conjunction with cortical changes. These results indicate that the morphological correlates are different for brain and skull and suggest that there is a large degree of independence in the developmental trajectories of the brain and skull.

Intermittent Hydrostatic Compression Promotes Nitric Oxide Production and Osteodifferentiation of Fetal Dural Cells

PURPOSE

The aim of these studies was to evaluate the biologic response of fetal dural cell cultures to compressive mechanical force.

METHODS

Primary cell cultures from the dura mater of E18 CD-1 mice were subjected to 2 PSI of intermittent hydrostatic compression (IHC) at a frequency of 0.5 Hz. Quantitative measures of the expression of Osterix (Osx), osteopontin (OP), endothelial nitric oxide synthase (eNOS) and Noggin were performed by RT-PCR following 3, 6, and 12 hours of exposure to IHC. Nitric oxide production was quantified through the measurement of NO metabolites following 6 hours of exposure to IHC.

RESULTS

IHC resulted in an increase in Osx, OP, and eNOS expression compared with controls at all time points. The expression of Noggin decreased at all time points. Exposure to IHC resulted in a significant increase in the production of NO metabolites at 6 hours when compared with controls.

CONCLUSIONS

These experiments indicate that dural cell biology is significantly altered following exposure to IHC. Specifically, IHC promotes production of NO and osteodifferentiation in fetal dural cell cultures, with increases in the expression of osteoinductive genes and decreases in inhibitors of osteogenesis.

Gene Expression Profiling in the Rat Cranial Suture

Although many theories have attempted to explain the etiopathogenesis of premature cranial suture fusion, which results in craniosynostosis, recent studies have focused on the role of growth factors and receptors. Using a well-established model of cranial suture biology, the authors developed a novel approach to quantitatively analyze the gene expression profiles of candidate cranial suture growth factors and their receptors. We collected suture mesenchyme and adjacent osteogenic fronts from Sprague-Dawley rats at postnatal days 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 35. RNA was extracted from posterior frontal (PF) and sagittal (SAG) sutures, and reverse transcription-polymerase chain reaction (RT-PCR) was performed for cranial suture candidate cytokines BMP2, BMP3, BMP4, FGF-2, FGFR1, FGFR2, FGFR4, TGF-betaRI, TGF-betaRII, and TGF-betaRIII. The authors confirmed quantitative RT-PCR results with Southern and dot blot analyses. Suture growth factor and receptor expression levels changed significantly with time. Expression levels decreased toward baseline in the SAG suture by day 35. There was a marked difference in FGFR1, FGF-2, TGF-betaRI, and TGF-betaRII expression levels when comparing the fusing PF and nonfusing SAG sutures. Although FGF-2 ligand expression was low, FGF receptor 1 (FGFR1) levels were markedly elevated with a bimodal expression pattern in both PF and SAG similar to that of BMP2, BMP3, and BMP4. Although there were statistically significant differences in TGF-betaRI and TGF-betaRII expression in the PF and SAG sutures, TGF-betaRIII levels were unchanged. The authors report a novel approach to cranial suture growth factor/receptor profiling and confirm their results with standard analytic tools. The data confirm, quantify, and extend the results of previously published studies. By quantifying the gene expression profiles of normal cranial suture biology, we may begin to understand the aberrant growth factor cascades of craniosynostosis and devise targeted therapeutic interventions that can alter the course of this malady.

Molecular screening for microdeletions at 9p22-p24 and 11q23-q24 in a large cohort of patients with trigonocephaly

Trigonocephaly is a rare form of craniosynostosis characterized by the premature closure of the metopic suture. To contribute to a better understanding of the genetic basis of metopic synostosis and in an attempt to restrict the candidate regions related to metopic suture fusion, we studied 76 unrelated patients with syndromic and non-syndromic trigonocephaly. We found a larger proportion of syndromic cases in our population and the ratio of affected male to female was 1.8 : 1 and 5 : 1 in the non-syndromic and syndromic groups, respectively. A microdeletion screening at 9p22-p24 and 11q23-q24 was carried out for all patients and deletions in seven of them were detected, corresponding to 19.4% of all syndromic cases. Deletions were not found in non-syndromic patients. We suggest that a molecular screening for microdeletions at 9p22-p24 and 11q23-q24 should be offered to all syndromic cases with an apparently normal karyotype because it can potentially elucidate the cause of trigonocephaly in this subset of patients. We also suggest that genes on the X-chromosome play a major role in syndromic trigonocephaly.

Transforming growth factor-beta isoform expression in the perisutural tissues of craniosynostotic rabbits

OBJECTIVE

To describe the expression patterns of the various transforming growth factor-beta (Tgf-beta) isoforms, known to be involved in suture development, in the perisutural tissues of rabbits with naturally occurring craniosynostosis and relate such differential expression to the pathogenesis of premature suture fusion.

METHOD

Twenty-one coronal sutures were harvested from six wild-type control New Zealand White rabbits and five rabbits with familial coronal suture synostosis at 25 days of age for histomorphometric and immunohistochemical analyses. Tgf-beta isoform immunoreactivity was assessed using indirect immunoperoxidase procedures with specific antibodies.

RESULTS

Synostosed sutures had significantly (p <.01) greater bone area and relatively more osteoblasts and osteocytes in the osteogenic fronts, compared with wild-type sutures. Tgf-beta isoform immunoreactivity showed differential staining patterns between wild-type and synostosed perisutural tissues. In wild-type sutures, Tgf-beta1 and Tgf-beta3 immunoreactivity was significantly (p <.001) greater than Tgf-beta2 staining in all perisutural tissues. In synostosed sutures, the opposite pattern was observed, with Tgf-beta2 immunoreactivity significantly (p <.001) greater than Tgf-beta1 and Tgf-beta3 in the osteogenic fronts, dura mater, and periosteum.

CONCLUSIONS

Findings from this study suggest that an overexpression of Tgf-beta2, either in isolation or in association with an underexpression of Tgf-beta1 and Tgf-beta3, may be related to premature suture fusion (craniosynostosis) in this pathological rabbit model. These abnormal expression patterns may be involved in premature suture fusion either through increased cell proliferation, decreased apoptosis of the osteoblasts or both at the osteogenic fronts.

TGF-beta1, FGF-2, and receptor mRNA expression in suture mesenchyme and dura versus underlying brain in fusing and nonfusing mouse cranial sutures

Recent studies have supported a functional role for the transforming growth factor beta-1 (TGF-beta1) and fibro-blast growth factor 2 (FGF-2) signaling cascades in the process of mouse cranial suture fusion. TGF-beta1 and FGF-2 protein expression have been shown to be elevated in the fusing posterior frontal suture versus the nonfusing sagittal suture. The authors evaluated simultaneous mRNA expression of TGF-beta1 and its R1 receptor and FGF-2 and its R2 receptor during mouse cranial suture fusion. They evaluated the suture mesenchyme-dura complex separately from the underlying brain to determine whether there is tissue-specific biologic activity (i.e., brain versus suture mesenchyme-dura) for each cytokine and receptor. Data were collected from 150 male CD-1 mice studied over five time periods from postnatal days 22 to 45. They utilized reverse-transcriptase polymerase chain reaction as a means to detect TGF-beta1, TGF-beta receptor 1 (TGF-betaR1), FGF-2, and FGF receptor 2 (FGFR2) mRNA expression in mouse cranial tissues, beginning with the period of initiation of posterior frontal cranial suture fusion (postnatal day 22) and extending through completion of posterior frontal suture fusion (postnatal day 45). Expression of FGF-2 was significantly greater in posterior frontal suture mesenchyme and dura compared with sagittal suture mesenchyme and dura during the period of initiation of posterior frontal suture fusion, localizing this cytokine's expression to posterior frontal suture mesenchyme and dura during the process of cranial suture fusion. TGF-beta1 and FGFR2 mRNA expression was found to be up-regulated in posterior frontal suture mesenchyme and dura relative to the underlying brain tissue throughout the study period, whereas TGF-betaR1 and FGF-2 mRNA expression was significantly elevated relative to the underlying brain only at time points corresponding to the initiation of posterior frontal suture fusion (between postnatal days 22 and 31). These results indicate that there is tissue-specific mRNA expression of TGF-beta1, FGF-2, and their receptors between suture mesenchyme and dura and the underlying brain, which correlates with the period of posterior frontal suture fusion in the mouse model. Differences in gene expression between suture mesenchyme and dura relative to the underlying brain may be an important regulator of cranial suture biology. Understanding these differences may eventually help to identify possible targets and time windows by which to most effectively modulate cranial suture fusion.

Craniosynostosis and altered patterns of fetal TGF-beta expression induced by intrauterine constraint

Recent work has demonstrated that fusion of the calvarial sutures is mediated by locally elaborated soluble growth factors, including the transforming growth factor-betas (TGF-betas), leading some to speculate that external biomechanical forces play little role in suture development. Clinical evidence has long suggested, however, that fetal head constraint may play a critical role in the pathogenesis of many cases of nonsyndromic craniosynostosis. The purpose of these experiments was to test the hypothesis that intrauterine constraint leads to an alteration in normal patterns of TGF-beta expression and that these alterations are associated with craniosynostosis. Fetal constraint was induced by allowing C57Bl/6 murine fetuses to grow for 2.5 days beyond the normal 20-day gestation by performing uterine cerclage on the eighteenth day. Cranial suture morphology was examined in hematoxylin and eosin-stained sections and in cleared whole-mount specimens, double stained with alizarin red S and Alcian blue. Expression patterns of TGF-beta1 and TGF-beta3 were examined by immunohistochemical techniques. Gross and microscopic examination of the cranial sutures of 17 constrained fetuses revealed changes that ranged from narrowing to complete osseous obliteration of the coronal and squamosal sutures. All sutures of 14 nonconstrained control pups remained patent. Fetal head constraint was associated with increased TGF-beta1 immunoreactivity within the new bone and the underlying dura when compared with nonconstrained age-matched controls. TGF-beta3 immunoreactivity was associated with the dura underlying patent, nonconstrained sutures, whereas constraint-induced synostosis was characterized by down-regulation of dural TGF-beta3 expression. These experiments confirm the ability of intrauterine constraint to induce premature fusion of the cranial sutures and provide evidence that intrauterine head constraint induces the expression of osteogenic growth factors in fetal calvarial bone and the underlying dura.