China experts' consensus on preventive and interceptive orthodontic treatments of malocclusions of children / 华西口腔医学杂志

Malocclusion is one of the three most common oral diseases reported by World Health Organization(WHO). In China, its incidence rate is rising. Malocclusion seriously affects the dental and maxillofacial function, facial appearance and growth development of nearly 260 million children in China, and what is more, it affects their physical and mental health development. Malocclusion occurrence is related to genetic and environmental factors. Early treatment of malocclusion can create a good dental and maxillofacial development environment, correct abnormal growth and control the adverse effects of abnormal genetic factors. It can effectively reduce the prevalence of children's malocclusion and enhance their physical and mental health. This is an urgent need from the economic perspective of our society, so it has great practical and social significance. Experts from the project group "standard diagnose and treatment protocols for early orthodontic intervention of malocclusions of children" which initiated by China National Health Institute of Hospital Administration wrote the "China Experts' Consensus on Preventive and Interceptive Orthodontic Treatments of Malocclusions of Children", which aims to guide and popularize the clinical practice, improve the clinical theory and practice level, and accelerate the disciplinary development of early treatment of children's malocclusion in China. The consensus elaborates the harmfulness of malocclusion and the necessity of early treatment, and brings up the principles and fundamental contents. Based on the law of dental and maxillofacial development, this paper puts forward the guiding suggestions of preventive and interceptive treatments in different stages of dental development ranging from fetus to early permanent dentition. It is a systematic project to promote and standardize the early treatment of malocclusion. Through scientific and comprehensive stratified clinical practice and professional training, the clinical system of early treatment of malocclusion in China will eventually be perfected, so as to comprehensively care for children's dental and maxillofacial health, and improve their oral and physical health in China.

Oral treatment for obstructive sleep apnea syndrome / 华西口腔医学杂志

Obstructive sleep apnea syndrome (OSAS) is a common clinical disease with high incidence and low treating proportion, difficult evaluation, and complicated nosogenesis. OSAS can cause systematic impairments. Various treatment methods were applied in clinical setting with the tendency of cross-disciplinary promotion. Oral treatment plays an exceedingly important role in OSAS research and therapy. This study reports the oral treatment involving OSAS therapy.

Response of bone marrow mesenchymal stem cells to mechanical stretch and gene expression of transforming growth factor-beta and insulin-like growth factor-II under mechanical strain / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the response of rat bone marrow mesenchymal stem cells (MSCs) to a single period of mechanical strain and expression patterns of transforming growth factor-beta (TGF-beta) and insulin-like growth factor-II (IGF-II) after mechanical stretch.</p><p><b>METHODS</b>Bone marrow MSCs were isolated from SD rats and cultured in vitro. A four-point bending apparatus were used to perform a single period of mechanical strain (2000 microepsilon, 40 min) on MSCs. Cellular proliferation and alkaline phosphatase (ALP) activity of MSCs were examined and gene expression patterns of TGF-beta and IGF-II were detected by SYBR green quantitative real-time RT-PCR.</p><p><b>RESULTS</b>Cell proliferation, ALP activity and expression of TGF-beta and IGF-II were all significantly up-regulated in stretched MSCs when compared with their controls. The mRNA levels of TGF-beta and IGF-II got top increase immediately after mechanical loading and increased about 51.44 and 8.92 folds, respectively, when compared with control cells. Expression of TGF-beta and IGF-II decreased with time and returned to control level at 12 h after mechanical stimulus, despite of a small increase at 6 h.</p><p><b>CONCLUSION</b>The mechanical stretch can promote MSCs proliferation, up-regulate its ALP activity and induce a time-dependent expression increase of TGF-beta and IGF-II which in turn result in osteogenic differentiation of MSCs. Mechanical stimulus is a key stimulator for osteogenic differentiation of MSCs and vital for bone formation in distraction osteogenesis.</p>

Expression of bone-related genes in bone marrow MSCs after cyclic mechanical strain: implications for distraction osteogenesis / 国际口腔科学杂志·英文版

<p><b>AIM</b>Understanding the response of mesenchymal stem cells (MSCs) to mechanical strain and their consequent gene expression patterns will broaden our knowledge of the mechanobiology of distraction osteogenesis.</p><p><b>METHODOLOGY</b>In this study, a single period of cyclic mechanical stretch (0.5 Hz, 2,000 microepsilon) was performed on rat bone marrow MSCs. Cellular proliferation and alkaline phosphatase (ALP) activity was examined. The mRNA expression of six bone-related genes (Ets-1, bFGF, IGF-II, TGF-beta, Cbfa1 and ALP) was detected using real-time quantitative RT-PCR.</p><p><b>RESULTS</b>The results showed that mechanical strain can promote MSCs proliferation, increase ALP activity, and up-regulate the expression of these genes. A significant increase in Ets-1 expression was detected immediately after mechanical stimulation, but Cbfa1 expression became elevated later. The temporal expression pattern of ALP coincided perfectly with Cbfa1.</p><p><b>CONCLUSION</b>The results of this study suggest that mechanical strain may act as a stimulator to induce differentiation of MSCs into osteoblasts, and that these bone-related genes may play different roles in the response of MSCs to mechanical stimulation.</p>

Osteogenic differentiation of rat bone marrow mesenchymal stem cell after transfection with recombinant pAd-bone morphogenetic protein-7 / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To study the effect of recombinant pAd-BMP-7 on osteogenic differentiation of rat bone marrow mesenchymal stem cells (MSC).</p><p><b>METHODS</b>Recombinant pAd-bone morphogenetic protein (BMP) 7 was constructed and the titer of recombinant adenovirus was determined. pAd-BMP-7 and pAdTrack-CMV were used to transfect rat MSC. Transfection efficiency was measured by fluorescent microscope and BMP-7 expression was detected by RT-PCR and immunocytochemical analysis. The MSC were then randomly divided into 3 groups: group A received pAd-BMP-7 transfection, group B was transfected with pAdTrack-CMV, and group C received pAdTrack-CMV transfection plus bone supplements. Osteogenic differentiation of MSC was evaluated by examination of mineralization nodes formation.</p><p><b>RESULTS</b>The titer of pAd-BMP-7 reached about 2.0 x 10(15) pfu/L and transfection efficiency of exogenous gene was nearly 99% at day 2. The expression of exogenous gene sustained about 5 to 7 weeks, with a higher level during first 3 weeks. After transfection, transcription of BMP-7 and expression of BMP-7 protein were also verified in MSC. Compared with the negative results in group B, mineralization nodes were formed in both group A and group C. However, group A showed better formation of mineralization nodes than group C (P < 0.01).</p><p><b>CONCLUSIONS</b>The results of this study indicated that recombinant pAd-BMP-7 can successfully transfect rat MSC and accelerate their osteogenic differentiation. The technique explored in this study provides a unique and valuable gene engineering approach for reconstruction of craniofacial bone defects.</p>

Effects of mesenchymal stem cells transplantation on cranial suture distraction osteogenesis in growing goats / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To observe the effects of mesenchymal stem cells (MSCs)on cranial suture under mechanical strain in growing goats.</p><p><b>METHODS</b>10 growing goats were used in this study. A customized distractor was used for distraction of the coronal suture at a rate of 0.4 mm/day for 8 days. The experimental group(5 goats) was injected with autologous MSCs into the distracted region, whereas the control group (5 goats) with injection of physiological saline. All animals were killed at 4 weeks after the end of distraction. Scanning electron microscopy and histological analysis were taken to observe the samples.</p><p><b>RESULTS</b>4 weeks after the end of distraction, the cranial sutures in all animals were separated successfully. The new bone formation at the edge of suture in the experimental group was superior to that in the control group.</p><p><b>CONCLUSION</b>Autologous MSCs transplantation may promote the cranial suture distraction osteogenesis in the growing goats.</p>

The changes of cytoskeleton F-actin in rat bone marrow mesenchymal stem cells and calvarial osteoblasts under mechanical strain / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To explore the response of rat bone marrow mesenchymal stem cells (MSCs and calvarial osteoblasts to mechanical strain and the consequent changes of cytoskeleton F-actin.</p><p><b>METHODS</b>Bone marrow MSCs and calvarial osteoblasts were isolated from SD rats and cultured in vitro. Mechanical stretch was performed on passage 3 cells at 2 000 microepsilon for 0, 2, 6 and 12 hours using four-point bending system. The response of cells and the distribution of F-actin were observed using fluorescent staining under laser scanning confocal microscope and the morphological parameters were quantified using image analysis software Laserpix.</p><p><b>RESULTS</b>Under mechanical stretch, the fluorescent staining decreased obviously at both MSCs and osteoblasts, and F-actin filaments were rearranged and became tenuous, thinner, and abnormally distributed. The outline of nucleus became unclear and apoptotic changes were observed at some of both cells. Cellular size decreased more significantly in MSCs than in osteoblasts. Quantity analysis showed that total area of cells, total fluorescent density and green fluorescent density (F-actin) were all significantly decreased in MSCs (P < 0.05 or P < 0.01), and total fluorescent density, green fluorescent density and red fluorescent density (nuclei) did also in osteoblasts (P < 0.05 or P < 0.01).</p><p><b>CONCLUSION</b>Mechanical stretch caused extensive response on both MSCs and osteoblasts which led to the rearrangement of F-actin filament and apoptosis in some of these cells. MSCs were more sensitive to mechanical strain than osteoblasts.</p>

Construction of recombinant plasmid pEGFP-BMP7 and its expression in rat bone marrow mesenchymal stem cells in vitro / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To construct recombinant plasmid pEGFP-BMP7 and determine its expression in rat bone marrow mesenchymal stem cells (MSCs) in vitro.</p><p><b>METHODS</b>cDNA of target gene was obtained from neonatal rat kidney by RT-PCR. After sequencing the target gene, the cDNA was subcloned into a eukaryote plasmid pEGFP-N1 by directed cloning and then digested with two restrictive endonucleases to verify the correctiveness of the recombinant plasmid pEGFP-BMP7. Rat bone marrow MSCs were transiently transfected with the pEGFP-BMP7 and transfection efficiency of the Green Fluorescent Protein (GFP) was determined. RT-PCR and immunocytochemical analysis were also performed to detect the expression of BMP7 in rat MSCs.</p><p><b>RESULTS</b>1 311 bp cDNA fragment was obtained by RT-PCR and sequence analysis showed it matched perfectly with that of rat BMP7 gene except a single nucleotide change at 756 bp from T to A. Digestion of the recombinant plasmid showed two 1.3 kb and 4.7 kb fragments and their size were same as those of BMP7 and pEGFP. This indicated that BMP7 cDNA was successfully subcloned into pEGFP. Transient transfection showed an efficiency of 33% at day 2 in rat MSCs. After transfection, transcription of BMP7 was detected in MSCs and expression of BMP7 protein was also verified.</p><p><b>CONCLUSION</b>Recombinant eukaryote plasmid pEGFP-BMP7 was successfully constructed and expressed in rat bone marrow MSCs. This procedure may provide a unique method for stimulation of callus formation in distraction osteogenesis and reconstruction of craniofacial bone defects.</p>

Effect of nerve growth factor and Schwann cells on axon regeneration of distracted inferior alveolar nerve following mandibular lengthening / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To study the effect of nerve growth factor (NGF) and Schwann cells on axon regeneration of the inferior alveolar nerve following mandibular lengthening with distraction osteogenesis.</p><p><b>METHODS</b>Unilateral mandibular osteodistraction was performed in 9 healthy adult male goats with a distraction rate of 1 mm/d. Every 3 goats were killed on days 7, 14 and 28 after mandibular lengthening, respectively. The inferior alveolar nerves in the distraction callus were harvested and processed for ultrastructural and NGF immunohistochemical study. The inferior alveolar nerves from the contralateral side were used as controls.</p><p><b>RESULTS</b>On day 7 after distraction, axon degeneration and Schwann cell proliferation were observed, and very strong staining of NGF in the distracted nerve was detected. On day 14 after distraction, axon regeneration and remyelination were easily observed, and NGF expression started to decline. On day 28 after distraction, the gray scale of NGF immunoreactivity recovered to the normal value and the Schwann cells almost recovered to their normal state.</p><p><b>CONCLUSIONS</b>Gradual mandibular osteodistraction can result in mild or moderate axon degeneration of the inferior alveolar nerve. Nerve trauma may stimulate the proliferation of Schwann cells and promote the synthesis and secretion of NGF in the Schwann cells. Schwann cells and NGF might play important roles in axon regeneration of the injured inferior alveolar nerve following mandibular lengthening.</p>