Effects of Bmi1 on proliferation of cranial suture mesenchymal cells in mice / 中华整形外科杂志

Objective@#To explore the effects of Bmi1 on proliferation of mouse cranial suture mesenchymal cells.@*Methods@#Primary posterior frontal and sagittal suture derived cells were isolated from the 2-5 d old C57BL/6 suckling mice (n=6) of the same brood and cultured. Flow cytometry and multilineage differentiation assay were performed to identify the mesenchymal stem cells (MSCs) characteristics of the 2 kinds of cranial suture-derived cells. The mRNA expression of stem cell related genes, Bmi1, Twist1, Gli1 and Axin2 were detected by real-time quantitative polymerase chain reaction (RT-PCR). Then, the proliferation and downstream protein expression were analyzed after down-regulation of Bmi1 in the sagittal suture derived MSCs by transfecting Bmi1 siRNA. The t test was used to compare the mean between two groups. Statistical significance was set at P<0.05.@*Results@#The mouse cranial suture derived cells were successfully cultured in vitro. These cells expressed typical MSCs markers, CD44, CD90, CD73, except for CD34. These cells had osteogenic, adipogenic and chondrogenic differentiation potency. RT-PCR results showed that the mRNA expressions of Bmi1 (0.006 30±0.000 58 vs 0.002 60±0.000 34, t=5.430, P=0.005 6), Twist1(0.000 31±0.000 04 vs 0.000 15±0.000 02, t=3.343, P=0.028 8), Axin2(0.000 33±0.000 03 vs 0.000 17±0.000 05, t=3.067, P=0.037 4) and Gli1 (0.001 10±0.000 13 vs 0.000 60±0.000 33, t=3.956, P=0.016 7) were significantly decreased in the posterior frontal suture MSCs compared with those in sagittal suture derived cells. Among them, Bmi1 has the largest decline. After down-regulation of Bmi1 in sagittal suture MSCs, the protein expression level of Ink4a was significantly up-regulated compared with the control group, and the cell proliferation ability was significantly decreased.@*Conclusions@#Inhibition of Bmi1 expression can up-regulate the expression of Ink4a protein and decrease the proliferation ability of suture MSCs, which may lead to craniosynostosis.

Visibility of Sutures of the Orbit and Periorbital Region Using Multidetector Computed Tomography

OBJECTIVE: Knowledge of cranial suture morphology is crucial in emergency medicine, forensic medicine, and maxillofacial reconstructive surgery. This study assessed the visibility of sutures of the orbit and periorbital region on multidetector computed tomography. MATERIALS AND METHODS: Multidetector computed tomography scans of 200 patients (127 males, 73 females; mean age 51.3 years; range, 6-92 years) were evaluated retrospectively. The slice thicknesses varied from 0.5 to 1 mm, and the tube current from 25 to 370 mAs, depending on the CT indication. The visibility of sutures was estimated according to a 4-point scale from "not visible" to "well visible". The chi-squared test was used to test the association of the visibility of sutures with the slice thickness, tube current, and age of patients. Statistical significance was assumed at p < 0.05. RESULTS: Overall, best visibility was found for the sutura frontozygomatica (98%), sutura frontonasalis (88.5%), and sutura sphenozygomatica (71.5%), followed by the sutura zygomaticomaxillaris (65.8%), sutura temporozygomatica (41.8%), sutura frontomaxillaris (44.5%), and sutura sphenofrontalis (31%). Poor visibility was found for the sutura frontolacrimalis (16.8%) and sutura frontoethmoidalis (1.3%). The sutura ethmoidomaxillaris, sutura lacrimomaxillaris, and sutura ethmoidolacrimalis were not visible. CONCLUSION: Although the sutures of the superior, lateral, and inferior orbit are well visible, those of the medial orbit are poorly visible on CT scans.

Quantitative Analysis of Developmental Process of Cranial Suture in Korean Infants

OBJECTIVE: The purpose of this study was to elucidate the anatomical development of physiologic suture closure processes in infants using three dimensional reconstructed computed tomography (CT). METHODS: A consecutive series of 243 infants under 12 months of age who underwent three dimensional CT were included in this study. Four major cranial sutures (sagittal, coronal, lambdoidal and metopic suture) were classified into four suture closure grades (grade 0=no closure along the whole length, grade 1=partial or intermittent closure, grade 2=complete closure with visible suture line, grade 3=complete fusion (ossification) without visible suture line), and measured for its closure degree (suture closure rates; defined as percentage of the length of closed suture line divided by the total length of suture line). RESULTS: Suture closure grade under 12 months of age comprised of grade 0 (n=195, 80.2%), grade 1 (n=24, 9.9%) and grade 2 (n=24, 9.9%) in sagittal sutures, whereas in metopic sutures they were grade 0 (n=61, 25.1%), grade 1 (n=167, 68.7%), grade 2 (n=6, 24%) and grade 3 (n=9, 3.7%). Mean suture closure rates under 12 months of age was 58.8% in metopic sutures, followed by coronal (right : 43.8%, left : 41.1%), lambdoidal (right : 27.2%, left : 25.6%) and sagittal sutures (15.6%), respectively. CONCLUSION: These quantitative descriptions of cranial suture closure may help understand the process involved in the cranial development of Korean infants.

Rat cranial sutures in vitro: a new experimental model for studying the osteogenic effect to tensile force / 中华医学美学美容杂志

Objective To develop an in vitro model for cranial suture of neonatal SD rat. Methods The parietal hones with the sagittal suture were removed from SD rats (19-days old) for organ culture. In the experimental group, tensile force 3.92×10~(-3) N (0.4 g) was applied by helical springs, whereas no tension (0 N) was set in control group. These explants were observed under inverted microscope. At the end of the incubation period for 24 hours, general conditions were observed under inverted microscope and histological conditions were observed after hematoxylin and eosin stain. Results Under inverted micro-scope, sutures had no obvious changes in control group, whereas sutures were enlarged gradually in the experimental group. With histological observation, sutures developed normally in control group, but in experimental group, osteohlasts and capillary vessels proliferated actively in the suture. Conclusions In vitro model of cranial suture can be cultured and grown successively.

Expression of homeobox gene MSX-2 during cranial suture fusion of SD rats / 上海第二医科大学学报

Objective To investigate the expression of homeobox gene MSX-2 during cranial suture fusion of SD rats and discuss its significance. Methods SD rats aged 1, 2, 5, 8, 12, 15, 18, 22, 30 and 45 days were selected, and immunohistochemistry and Real-time PCR were employed to localize and quantify the expression of MSX-2 in different regions of cranial sutures. Results MSX-2 expressed in calvarial suture tissues including the extreme ends of the osteogenic fronts and the underlying dura mater. The expression of MSX-2 was low in posterior frontal suture (PF) and sagittal suture (SAG) from postnatal day 1 to day 8 before the initiation of suture fusion, while it was higher in PF than in SAG from postnatal day 12 to day 22 after the initiation of PF suture fusion. The expression of MSX-2 significantly declined in PF and was moderately higher than that in SAG from postnatal day 30 to day 45 after the initiation of suture fusion. Conclusion There is different expression of MSX-2 in PF and SAG during different suture fusion periods, which suggests the expression of MSX-2 may participate in the regulation of cranial bone development and the fusion of cranial sutures.

The pathogenesis of craniosynostosis in the fetus

Craniosynostosis occurs in approximately 1:2000 live births. It may affect the coronal, sagittal, metopic and lambdoid sutures in isolation or in combination. Although non-syndromic synostoses are more common, over 150 genetic syndromes have been identified. Recent advances in genetic mapping have linked chromosomal mutations with craniosynostotic syndromes. Despite the identification of these genetic mutations, the fundamental biomolecular mechanisms mediating cranial suture biology remain unknown. Today, many laboratories are investigating murine cranial suture biology as a model for human cranial suture development and fusion. Normal murine cranial suture biology is very complex, but evidence suggests that the dura mater provides the biomolecular blueprints (e.g. the soluble growth factors), which guide the fate of the pleuripotent osteogenic fronts. While our knowledge of these dura-derived signals has increased dramatically in the last decade, we have barely begun to understand the fundamental mechanisms that mediate cranial suture fusion or patency. Interestingly, recent advances in both premature human and programmed murine suture fusion have revealed unexpected results, and have generated more questions than answers.

In vitro Fusion of the Posterior Frontal Calvarial Suture in the Mouse

The mechanism underlying cranial suture fusion remains yet unknown. An in vitro tissue culture model of cranial sutures permits exclusion of biomechanical factors that may affect the fusion and patency of cranial sutures. The posterior frontal cranial sutures were placed in a tissue culture model. The experimental groups consisted of control group, and two groups cultured in TGF-beta enriched medium with and without the underlying dura mater. Results showed in vitro fusion of the explanted cranial sutures in vitro 39 days postnatal. Cranial suture fusion was accelerated in the TGF- beta < treated group with intact dura mater(postnatal 32days). Cranial suture fusion in the TGF- beta treated dura denuded group occurred, though in a delayed manner compared to the dura intact group.

The changes of cranial suture induced by the distraction forces in growing goats / 实用口腔医学杂志

Objective:To observe the response and changes of cranial suture to the distraction forces in growing goats.Methods:A custom-made distractor was used for expanding coronal suture of 11 growing goats at the rate of 0.4 mm/day for 8 days.The animals were killed 0,2 and 4 weeks respectively after completion of suture distraction application. X-ray examination was taken and the distracted suture samples were harvested and processed for scanning electron microscopic observation and immunohistochemistry examination of BMP and TGF-? expression. The coronal sutures taken from other undistracted animals were used as the controls. Results:The coronal sutures were separated successfully in distracted goats. 0 and 2 weeks after application of suture distraction, the collagen fiber bundles were strengthened and aligned in the direction of the distraction. Strong expression of BMP and TGF-? were detected in the fibroblast-like cells and the active osteoblasts. 4 weeks after suture distraction, signs of intramembranous ossification were found in the edge areas of the distracted suture, and the positive staining of BMP and TGF-? was still noted in the osteoblasts around the newly formed bone trabeculae. Conclusion:BMP and TGF-? may play important roles in the process of bone formation and remodeling during suture distraction osteogenesis.