Alterations in vascular pattern of the developing palate in normal and spontaneous cleft palate mouse embryos

Cleft lip and palate cause large variations in size and location of the posterior superior alveolar canal

OBJECTIVE

The aim of this study was to evaluate the posterior superior alveolar canal (PSAC) in patients with cleft lip and palate (CLP) as compared to patients with no cleft lip and palate (NC) using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This was a retrospective multicenter study based on two steps: (1) evaluating intra- and inter-calibration and (2) detecting the presence or absence of PSAC and its location, diameter, and anastomosis with anterior superior alveolar canal.

RESULTS

A total of 300 patients were selected for the study, out of which 150 were categorized as CLP (75 men, 75 women; mean age: 29.8 years) and 150 were categorized as NC (75 men, 75 women; mean age: 40.3 years). PSAC in patients with CLP and NC was visible in 100% of the cases, in men and women, bilaterally. PSAC location in CLP was middle and upper third of the maxillary sinus as compared to NC (lower third) (chi-squared < 0.001). PSAC mean diameter in CLP was 1.12 mm. It was larger compared to 0.6 mm in NC (t-test < 0.0001).

CONCLUSION

PSAC location in patients with CLP was predominantly in the middle and upper third of the maxillary sinus, compared with NC. PSAC mean diameter in CLP was 1.12 mm. It was larger compared to that of 0.6 mm in NC.

CLINICAL RELEVANCE

These anatomical variations in CLP are important and should be acknowledged by surgeons for the following reasons: (1) to perform pre-surgical planning, (2) to avoid bleeding, and (3) to avoid neurosensory alterations.

Evaluation of canalis sinuosus in individuals with cleft lip and palate: a cross-sectional study using cone beam computed tomography

OBJECTIVE

To evaluate the canalis sinuosus (CS) in individuals with cleft lip and palate (CLP) and compare the findings with individual's NON-CLP using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

The sample consisted of 100 CBCT exams of NON-CLP individuals (G1 group) and 200 of CLP individuals (G2 group). Recorded parameters included presence of CS, accessory canal to the CS, diameter greater than 1 mm, gender, age, localization in relation to teeth, and adjacent structures. Statistical tests were used to compare the findings between groups. A p value of < 0.05 was considered as significant.

RESULTS

A higher prevalence of accessory canal was found in the G2 (p < 0.001). The anteroposterior diameter of the right side CS in G2 was higher than G1 (p < 0.05), with average of 1.4 mm ± 0.4 mm. The accessory canal had a larger diameter in G2 than G1 (p < 0.05) with average of 1.3 mm ± 0.3 mm. Between UCLP, the CS presented the largest diameter for the side NON-CLP (p < 0.001). The accessory canal was more distant from the cortical buccal in G2 (P < 0.05). The dental region incidence of the accessory canal was molars and premolars for G2 and canines and incisors in G1.

CONCLUSION

Individuals with CLP show higher prevalence of accessory canal to the CS with larger diameters than NON-CLP. It is necessary that the professional make adequate planning prior to surgeries, using the CBCT, in order to avoid neurovascular lesions, since these individuals undergo several surgeries in the CS region.

Endothelial neuropilin disruption in mice causes DiGeorge syndrome-like malformations via mechanisms distinct to those caused by loss of Tbx1

The spectrum of human congenital malformations known as DiGeorge syndrome (DGS) is replicated in mice by mutation of Tbx1. Vegfa has been proposed as a modifier of DGS, based in part on the occurrence of comparable phenotypes in Tbx1 and Vegfa mutant mice. Many additional genes have been shown to cause DGS-like phenotypes in mice when mutated; these generally intersect in some manner with Tbx1, and therefore impact the same developmental processes in which Tbx1 itself is involved. In this study, using Tie2Cre, we show that endothelial-specific mutation of the gene encoding the VEGFA coreceptor neuropilin-1 (Nrp1) also replicates the most prominent terminal phenotypes that typify DGS. However, the developmental etiologies of these defects are fundamentally different from those caused by absence of TBX1. In Tie2Cre/Nrp1 mutants, initial pharyngeal organization is normal but subsequent pharyngeal organ growth is impaired, second heart field differentiation is normal but cardiac outflow tract cushion organization is distorted, neural crest cell migration is normal, and palatal mesenchyme proliferation is impaired with no change in apoptosis. Our results demonstrate that impairment of VEGF-dependent endothelial pathways leads to a spectrum of DiGeorge syndrome-type malformations, through processes that are distinguishable from those controlled by Tbx1.

Transforming growth factor-beta3 promotes mesenchymal cell proliferation and angiogenesis mediated by the enhancement of cyclin D1, Flk-1, and CD31 gene expression during CL/Fr mouse lip fusion

BACKGROUND

Cleft lip with or without cleft palate is the most common congenital anomaly in the craniofacial region. Knowledge of the molecular mechanisms behind normal lip fusion can contribute to better intervention and improved functional clinical outcome. Transforming growth factor-beta3 (TGF-beta3) has been implicated in lip morphogenesis. Therefore, we hypothesized that TGF-beta3 functions during lip fusion through regulation of angiogenesis and mesenchymal cell cycle progression during early developmental stages.

METHODS

To test this hypothesis we used the CL/Fraser mouse model, which has a high incidence of cleft lip. Lips isolated from embryonic day (ED) 11.5 mouse embryos were allowed to develop in serum-free organ cultures in the presence or absence of TGF-beta3. The lips that developed in these cultures fused in 2 days.

RESULTS

During normal development, we detected positive immunoreactions for TGF-beta3 at the site of fusion. We also detected mesenchymal cells that were immunopositive for Flk-1 and CD31, which are markers for endothelial cell precursors. Exogenous TGF-beta3 accelerated lip fusion in culture. This enhancement was associated with an increase in the number of capillary blood vessels in the lips cultured in the presence of TGF-beta3, in comparison with controls. In tandem, TGF-beta3 increased the level of expression of both Flk-1 and CD31. Our data suggest that an elevated level of TGF-beta3 may promote angiogenesis in developing lips that is mediated by increased Flk-1 and CD31 expression. We also detected increased cyclin D1 expression (a marker for cell proliferation) in the presence of TGF-beta3, which suggests that TGF-beta3 promoted cell proliferation.

CONCLUSIONS

TGF-beta3 promoted cell proliferation and angiogenesis in lip mesenchymal tissues. These events led to enhanced lip fusion in the presence of TGF-beta3.

Microarray analysis of murine palatogenesis: temporal expression of genes during normal palate development

The mammalian face is assembled in utero in a series of complex and interdependent molecular, cell and tissue processes. The orofacial complex appears to be exquisitely sensitive to genetic and environmental influence and this explains why clefts of the lip and palate are the most common congenital anomaly in humans (one in 700 live births). In this study, microarray technology was used to identify genes that may play pivotal roles in normal murine palatogenesis. mRNA was isolated from murine embryonic palatal shelves oriented vertically (before elevation), horizontally (following elevation, before contact), and following fusion. Changes in gene expression between the three different stages were analyzed with GeneChip microarrays. A number of genes were upregulated or downregulated, and large changes were seen in the expression of loricrin, glutamate decarboxylase, gamma-amino butyric acid type A receptor beta3 subunit, frizzled, Wnt-5a, metallothionein, annexin VIII, LIM proteins, Sox1, plakophilin1, cathepsin K and creatine kinase. In this paper, the changes in genetic profile of the developing murine palate are presented, and the possible role individual genes/proteins may play during normal palate development are discussed. Candidate genes with a putative role in cleft palate are also highlighted.

Isolated maxillary bending in CL/FR strain mice: observation of craniofacial deformity and inheritance pattern

OBJECTIVE

The CL/Fr mouse, known as a strain with spontaneous cleft lip and/or palate (CL/P), has been used as an animal model to investigate etiology in CL/P.

METHOD

We examined a facial asymmetry mutant discovered in a CL/Fr mouse colony that was not associated with CL/P and was shown to be inheritable in subsequent generations. Facial asymmetry became apparent with postnatal growth, whereas it was not detectable at birth, and was termed "maxillary bending" (MB) based on the characteristic bending of the maxilla.

RESULTS

As a result of selective breeding, an 'MB line', In which MB was observed in 21.68% (67/309) in addition to CL/P in 17.80% (55/309) of the offspring, was developed in the CL/Fr colony. In mating experiments between the MB line and C57BL/6J, all F1 progeny showed the normal phenotype. MB was observed in 0.72% (1/139) of the F2 generation, and the backcross generation showed segregation of MB in 6.25% (22/352) and CL/P in 1.42% (5/352). These instances suggested the occurrence of an additional mutation in the CL/Fr mouse genome controlled by an autosomal recessive gene with low penetrance. However, since the CL/Fr mouse primarily has a developmental deficiency in the maxilla, the possibility that CL/P and MB share common etiologic factors cannot be completely ruled out.

CONCLUSION

The maxillary bending retains significance, as this mutant can serve as an animal model of abnormal facial growth. Elucidation of the etiologic relationship between MB and CL/P may provide clues to clarifying the deficiency in first branchial arch in the mouse.