BACKGROUND:MicroRNA has tissue and cel specificity, and high expression of endothelial cel-specific microRNA-126 (miR-126) plays an important role in angiogenesis.
OBJECTIVE:To explore the effect of miR-126 on transplanted free flap survival and histological activity as wel as its mechanism in angiogenesis.
METHODS:Transient transfection technology was used to enhance the expression of miR-126 in bone marrow mesenchymal stem cel s. Expression levels of macrophage inflammatory protein-1α, tumor necrosis factor-αand vascular cel adhesion molecule-1 mRNA were detected by real-time PCR, and expression levels of ERK1/2, AKT, pERK1/2, pAKT protein were measured by western blot assay. Forty-eight Sprague-Dawley rats were randomly divided into three groups (n=16 per group), fol owed by preparation of abdominal free flap models. Rats in the three groups were given injection of miR-126 mimics-transfected cel s, miR-126 mimics control-transfected cel s and PBS 1 cm and 3 cm distal to the free flap, respectively.
RESULTS AND CONCLUSION:Expression levels of macrophage inflammatory protein-1α, tumor necrosis factor-αand vascular cel adhesion molecule-1 mRNA in the cel s transfected with miR-126 mimics were decreased by 36, 3.5 and 14 times compared with those in the PBS group, respectively. Expressions levels of ERK1/2, AKT, pERK1/2, pAKT protein in the distal free flap increased significantly in the miR-126 mimics group than the other two groups, as did the ratios of pAKT/AKT and pERK1/2/ERK1/2. In addition, the expression levels of macrophage inflammatory protein-1α, tumor necrosis factor-αand vascular cel adhesion molecule-1 protein in the flap tissue fluid were significantly lower in the miR-126 mimics transfection group than the other two group. Al these findings suggest that miR-126 can promote free flap survival by creating favorable conditions for angiogenesis in the free flap tissue.

BACKGROUND:Hot-melt adhesive is safe and environmental friendly adhesive due to free of solvent, which is particularly suitable for medical applications. OBJECTIVE:To describe the types and characteristics of currently used hot-melt adhesives and to prospect the technical research and development of hot-melt adhesive for polyolefin tubes or catheters as wel as to point out the corresponding key points to the hot-melt adhesion. METHODS:Literature search was carried out in SCI, Elsevier, and CNKI with the key words of“hot melt adhesive, medical application”in English and Chinese, respectively, for the initial retrieval of relevant articles or patents published January 1995 to December 2015. RESULTS AND CONCLUSION:To date, the medical hot-melt adhesives reported in the literature could be grouped as amorphous polyolefin, thermoplastic elastomer, acrylic and polyurethane types. The heat resistance of the most of the hot-melt adhesives does not meet the requirement for steam sterilizing process. In the present review, a strategy is proposed to develop a novel hot-melt adhesive which is good for binding polyolefin parts and can undergo the sterilization process. Given this, it is essential to choose a kind of polypropylene random copolymer with a suitable melting point as a substrate. With the aid of an adjuvant agent, therefore, we can develop a novel hot-melt adhesive that exhibits a lower melting point than the polyolefin tube, withstands steam sterilization temperature to ensure that the tube is not deformed during melt adhesion and is not become invalid during sterilization.

BACKGROUND:Tissue engineering involves many disciplines such as biology, material science, medicine and engineering, so, the col aboration among different research departments is becoming an important factor to enhancing research outputs with the rapid development of related sciences and technologies. OBJECTIVE:To draw the visualizing map of col aboration network of animal-derived regenerative implantable medical devices based on tissue engineering technology and describe its evolving process and current situation. METHODS:2 518 Chinese literatures about the animal-derived regenerative implantable medical devices based on tissue engineering technology published before 31 December 2014 were searched in CNKI, WANFANG DATA and VIP. Subsequently, social network analysis was conducted on those literatures by utilizing UCINET software and SASI developed by Peking University. RESULTS AND CONCLUSION:The col aboration network of the animal-derived regenerative implantable medical devices has evolved from scattered to single-core dominated, and then to a core-edge one, characterized by increasing and extensive col aborations as wel as decreasing network density and centralization. The core units from 2010 to 2014 include Tsinghua University, General Hospital of Chinese PLA and Affiliated Nanfang Hospital of South Medical University. Also, plenty of edge institutes exist. In conclusion, edge institutes should expand their scope of cooperation, while core institutes should improve their cooperation sustainability. Furthermore, cooperation among enterprises, research institutes and clinical hospitals should be strengthened to promote the industrialization of tissue engineering technology.

BACKGROUND:The decel ularized porcine smal intestinal submucosa is a kind of bioactive extracel ular matrix, which is mainly composed of col agen, glycoprotein, proteoglycan and rich in col agen, glycosaminoglycan and various growth factors, and these components play an important role in promoting the differentiation and proliferation of tissue cel s. OBJECTIVE:To prepare the injectable smal intestinal submucosa and to investigate its co-culture with rat adipose-derived mesenchymal stem cel s in vitro. METHODS:The injectable smal intestinal submucosa and rat adipose-derived stem cel s were prepared. Cel counting kit-8 test for cel proliferation:Passage 3 adipose-derived stem cel s were seeded onto the injectable smal intestinal submucosa (experimental group) and cel s cultured under normal condition as control group. The cel proliferation was observed at 1, 3, 5 and 7 days of incubation. Live/dead staining test for the survival of cel s:Passage 3 adipose-derived stem cel s were respectively cultured in the injectable smal intestinal submucosa extracts (experimental group) and complete culture medium (control group). Cel survival was determined at 1, 3, 5 and 7 days of culture. RESULTS AND CONCLUSION:Scanning electron microscope oval and strip adipose-derived stem cel s adhered onto the material. The absorbance values in the experimental group were higher than those in the control group at 1 and 5 days of incubation (P<0.05). Cel survival:The number of cel s appeared to be in a rising trend with time in both two groups;after 1-day co-culture, al cel s in the two groups survived. Then dead cel s appeared in both two groups, showing no significant difference. These results show that the injectable smal intestinal submucosa exhibits a good cytocompatibility.

BACKGROUND:Cerebral aneurysm is a kind of mortal hemangioma, and its treatments such as endovascular embolization and clipping both cause high postoperative recurrence rate and mortality. So the stent implantation for cerebral aneurysm is coming into being. OBJECTTVE:To evaluate the hemodynamic parameters after stent implantation into cerebral aneurysm and to provide a novel feasible strategy for clinical treatment. METHODS:A retrospective analysis was preformed based on the CT image data of 11 patients with cerebral aneurysm from the Affiliated Hospital of Xinjiang Medical University. Firstly, the flexible and solid model of cerebral aneurysm was established by the MIMICS and reverse engineering. Secondly, the matching stent model was implanted into the cerebral aneurysm, and then the blood flow structure of cerebral aneurysm was analyzed by the fluid dynamics theory and the Fluent with the method of two-way flow solid coupling. Final y, comparative analysis of the kinetic parameters of cerebral aneurysm before and after implantation, including wal pressure, blood velocity, path line of the blood flow, wal shear stress, wal deformation was conducted, and blood flow characteristics after stent implantation were analyzed under different entrance velocity. RESULTS AND CONCLUSION:After implantation, the wal surface pressure was reduced about 61.1%;the blood flow velocity around the stent and the inside of the cerebral aneurysm was decelerated obviously;under setting 2 000 lines of blood flow, the number of path line of blood flow into the cerebral aneurysm reduced about 75.0%, the maximum wal shear stress decreased about 79.3%, and the maximum wal deformation reduced to a lower level. The entrance velocity was respectively v1=0.1 m/s, v2=0.2 m/s, v3=0.3 m/s and the wal pressure was in a gradient ascent;the wal shear stress increased with the velocity, meanwhile,τzou (left neck of aneurysm)<τzhong (aneurysm )<τyou (right neck of aneurysm). The path lines of blood flow mainly concentrated in the top of the aneurysm, and the blood velocity markedly affected the surface deformation. These results indicate that main hemodynamic parameters are obviously improved after stent implantation into cerebral aneurysm, and the blood velocity should never be neglectful in the treatment process.

BACKGROUND:Polylactic acid-glycolic acid polymer is a sustained-release material with relatively large drug loading and long-term release abilities that can degrade with cel growth in the body. However, its poor hydrophily easily leads to aseptic inflammation that is detrimental to the body’s recovery. OBJECTIVE:To study the release and distribution of anti-tuberculosis drug delivery materials local y oriented within the rabbit radius. METHODS:After modeling, 20 New Zealand white rabbits with distal radius bone defect were randomly divided into a control group and an experimental group, which were respectively given implantation of isoniazid-rifampicin polylactic acid-glycolic acid polymer/β-tricalcium phosphate material and isoniazid-rifampicin polylactic acid-glycolic acid polymer into the defect. Then, X-ray examination of the defect region was conducted at weeks 4, 8, 12 post implantation. Histological observation and detection of peripheral blood or local blood concentration were performed at week 12. RESULTS AND CONCLUSION:After implantation, Lane-Sandhu X-ray scores were significantly higher in the experimental group than the control group (P<0.05). The defect in the experimental group was healed completely with less release residual among newborn bone trabeculae and osteocytes were markedly visible on the material surface, while in the control group, new bone tissues were interconnected with the surrounding bone tissues at the defect site, and less release residual was found. Both peripheral blood and local blood concentrations in the experimental group were significantly higher than those in the control group after implantation (P<0.05). To conclude, the anti-tuberculosis drug delivery material, isoniazid-rifampicin polylactic acid-glycolic acid polymer/β-tricalcium phosphate, has ideal release effect that can stably deliver anti-tuberculosis drugs for a long term at a high bactericidal concentration.

BACKGROUND:The surgical management to reconstruct the stability in lumbosacral region is very chal enging. There are many techniques to reconstruct the stability of the lumbosacral region, but the internal fixation loosening, fracture and pseudoarthosis are not uncommon. OBJECTIVE:Finite element analysis was used to analyze the stability of two types of reconstruction procedures and the stress of the internal fixation system. METHODS:A 64-slice spiral CT scan was used in a subject from L1 to pelvis. The scan data were imported into the Mimics 15.0 software to generate a three-dimensional surface model. The three-dimensional solid model was established using in the SolidWorks software. The solid geometry model of the L3, 4 pedicle screws combined with single iliac screw fixation and L3,4 pedicle screws combined with dual iliac screws and anterior titanium mesh cage support fixation were constructed by the Solidworks software. Two kinds of reconstruction procedures were simulated. The models were given material properties and analyzed by using the ABAQUS software. RESULTS AND CONCLUSION:(1) The maximum stress was 195.3 MPa in the complete model, 189.5 MPa in single iliac screw model, and 149.2 MPa in dual iliac screw+titanium cage model when constrained the roof of double acetabulum and applied a vertical load of 1 000 N. (2) The axial compression rigidity was 551.572 N/mm in the complete model, 613.87 N/mm in the single iliac screw model and 1 683.50 N/mm in the dual iliac screw+titanium cage model. (3) The bending rigidity of the dual iliac screw+titanium cage model was bigger than other models at 6 directions when applied 7 N?m bending loads. The maximum stress of single iliac screw model was bigger than other models. (4) The results suggest that the dual iliac screw+titanium mesh cage reconstruction can effectively restore the stability of the lumbosacral area. The stress of internal fixation system is smal er and more dispersed. There is obvious stress concentration in the connecting rod and the tail of the single iliac screw. The single iliac screw internal fixation system is easy to fatigue fracture and loosening.

BACKGROUND:Due to anisotropic CT volume data, triangular meshes extracted from bone CT images often contain staircase surface, which wil affect the subsequent medical diagnosis. OBJECTIVE:To reconstruct patient-specific bone model based on digital geometry processing technique. METHODS:Firstly, registration was performed in image registration algorithm based on mutual information for bone CT slices, and then contours were extracted by image segmentation and a stack of contours were converted into point clouds. The normals of point clouds were estimated based on Gaussian weighted principal component analysis and the noise from point clouds was removed by trilateral filtering. Final y, bone triangular meshes were constructed by adaptive spherical cover. RESULTS AND CONCLUSION:In this paper, the proposed method could generate smoothing bone surface meshes, triangular mesh shape which was formed by the rules and adaptive distribution, for finite element analysis, computer aided manufacturing and three-dimensional printing to provide accurate three-dimensional models.

BACKGROUND:Pedicle screw fixation has been used in children with thoracic injury. Conventional method is screw implantation by hand. This method can meet the needs of surgery, but its accuracy was low, and incidence of complications was high. The application of digital image navigation aid module is possible. OBJECTIVE:To study accuracy and safety of digital image navigation aid module in thoracic pedicle screw placement. METHODS:Eight thoracic vertebral bodies were equal y and randomly assigned to the manual insertion group and the digital image navigation aid module group. Manual insertion group received manual screw insertion. In the digital image navigation aid module group, navigation aid module was made according to CT scan results combined with principle of reverse engineering and rapid prototyping. Pedicle screw was placed using the digital image navigation aid module. RESULTS AND CONCLUSION:(1) Success rate of once screw set was significantly higher in the digital imaging navigation aid module group than in the manual insertion group (P<0.05). (2) Twenty-eight screws were implanted in the digital image navigation aid module group and manual insertion group separately. The excellent and good rate of screw placement was 96%in the digital image navigation aid module group and 75%in the manual insertion group (P<0.05). (3) These findings suggested that digital image navigation aid module can effectively improve the success rate of pedicle screw insertion. Moreover, this method is simple, easy to operate, and can make a personalized nail placement program for each child.

BACKGROUND:In rabbit femur fracture model experiment, there are a few studies on whether quadriceps tendon wil affect the stability of the fixed device. OBJECTIVE:To analyze the effects of quadriceps tendon to the stability of external fixator in rabbit models of femur fracture. METHODS:The 48 New Zealand white rabbits were randomly divided into two groups. External fixator was used to make fracture model. In the experiment group, quadriceps tendon was cut. In the control group, quadriceps tendon was retained. 2 weeks later, X-ray examination was utilized to observe the number of failed external fixator in both groups from modeling to success. RESULTS AND CONCLUSION:(1) X-ray examination:2 weeks after model establishment, external fixation frame screw was free from femur in one rabbit of the experiment group, and seven rabbits in the control group. Of them, one screw was broken. Threaded portion retained in the femur. (2) External fixation failure rate:failed external fixator was found in one rabbit in the experiment group, resulting in a failure rate of 4%, and 12 rabbits in the control group, resulting in a failure rate of 50%(P<0.05). These findings suggested that cutting off the rabbit quadriceps tendon can effectively ensure the stability of the external fixator, and indirectly improve success rate of the experiment.