Stress Relaxation Behavior of Collagen Type II- Silk Fibroin Composite Cartilage Scaffold under Different Degradation Cycles / 医用生物力学

Objective To study stress relaxation behaviors of cartilage scaffolds under different degradation cycles by using finite element analysis combined with theoretical models. Methods Based on the established degradation theoretical model, the elastic modulus of the scaffold was calculated under different degradation cycles. The finite element model of cartilage scaffolds was established and stress relaxation simulation was performed to analyze the variation of scaffold relaxation stress with time. The stress relaxation constitutive model was established to predict mechanical properties of the scaffold. Results The elastic modulus of cartilage scaffolds at 14 th, 28th, 42nd, 56th day after degradation was 32. 35, 31. 12, 29. 91, 28. 74 kPa, respectively. The upper layer for cartilage scaffolds was the largest. The overall relaxation stress of the scaffold decreased rapidly with time and then tended to be stable. At 8th week after degradation, the stress which the scaffold couldwithstand was still within the physiological load range of the cartilage. The predicted results of the stress relaxation constitutive model were in good agreement with the finite element simulation results. Conclusions The elastic modulus of the scaffold gradually decreases with the increase of degradation time. The longer the degradation period is, the less stress the scaffold can withstand. At the same degradation period, the larger the applied compressive strain, the larger the stress on the scaffold. Both the finite element simulation and stress relaxation constitutive model can effectively predict stress variations of cartilage scaffolds under degradation

The clinical effect of the long head of biceps tendon insertion reconstruction combined with pulley repair in the treatment of pulley system injuries / 中华骨科杂志

Objective:To investigate the clinical effect of long head of biceps tendon (LHBT) insertion reconstruction combined with pulley repair for pulley system injuries.Methods:A total of 46 patients (combined treatment group) with pulley system injury treated with LHBT insertion reconstruction combined with pulley repair in the Sports Medicine Department, Affiliated Xinhua Hospital of Dalian University from January to December 2020 were retrospectively analyzed, including 16 males and 30 females, aged 51.3±5.7 years (range, 45-72 years). 46 patients who underwent simple LHBT insertion reconstruction during the same period were selected as the control group (simple reconstruction group), including 14 males and 32 females, aged 50.6±6.7 years (range, 46-70 years). Visual analogue scale (VAS), Constant-Murley score, American Shoulder and Elbow Surgeon (ASES) score and long head of biceps tendon (LHB) score were compared preoperatively and at 1, 3, 6, 12 and 24 months postoperatively.Results:All patients were followed up for 26.2±1.5 months (range, 24-27 months). The VAS scores of the combined treatment group at 1, 3, and 6 months postoperatively were 3.4±1.3, 2.0±1.1, and 1.7±0.5, respectively, which were significantly lower than those of the simple reconstruction group 5.8±1.3, 3.5±1.1, and 2.6±0.5 ( P<0.05), while there was no significant difference between the two groups at 12 and 24 months postoperatively ( P>0.05). The Constant-Murley scores of the combined treatment group at 1, 3, and 6 months postoperatively were 31.3±4.7, 72.8±4.6, and 89.1±5.4, respectively, which were statistically greater than those of the simple reconstruction group (21.5±6.8, 52.8±5.2, and 80.1±6.2), and the differences were statistically significant ( P<0.05), while there was no statistically significant difference between the two groups at 12 and 24 months postoperatively ( P>0.05). The ASES scores of the combined treatment group at 1 and 3 months postoperatively were 56.2±6.9 and 82.7±8.2, which were statistically greater than those in the simple reconstruction group (40.2±5.6 and 62.9±8.0), while there was no statistically significant difference between the two groups at 6, 12, and 24 months postoperatively ( P>0.05). The LHB scores of the combined treatment group at 6 and 12 months postoperatively were 70.1±5.4 and 86.1±4.6, which were statistically greater than those of the simple reconstruction group (60.2±4.2 and 70.2±5.8), with statistically significant differences ( P<0.05), while there was no statistically significant difference between the two groups at 24 months postoperatively ( P>0.05). Conclusion:Arthroscopic LHBT insertion reconstruction combined with pulley system repair can relieve early postoperative shoulder pain and improve early function. It is an effective method for the treatment of pulley system injury.

Numerical Analysis on Degradation of Cartilage Scaffold under Perfusion Loading / 医用生物力学

Objective To study the effect of irrigation mechanical stimulation on scaffold degradation by numerical simulation, so as to predict its degradation degree. MethodsBased on perfusion experimental data, the fluid-solid coupling model was established by Comsol. The finite element model of scaffold was established by ABAQUS. Based on the models, the degradation performance of scaffold was simulated and predicted. Results The fluid-solid coupling simulation showed that the initial pressure at the speed of 15.79 mL/min was two-fold of that at 7.89 mL/min. Along the thickness of scaffold from the surface to the bottom, the pressures between the two velocities were decreased and gradually close to each other. The degradation of scaffold structure could be simulated dynamically by combining the degradation constitutive model with the finite element model. The obtained degradation data were consistent with the experimental data, and the residual molecular weight reached 0.643 on the 56th day. Compared with the experimental data, the simulation accuracy was higher than 98%. Conclusions The larger the perfusion velocity is, the greater the pressure on scaffold will be. Under the same perfusion velocity, the maximum force occurs on the surface of scaffold. The degradation pattern of scaffold can be predicted by applying the degradation constitutive model and the finite element model.

Study on transport of small molecule rhodamine B within different layers of cartilage / 生物医学工程学杂志

The small molecule nutrients and cell growth factors required for the normal metabolism of chondrocyte mainly transport into the cartilage through free diffusion. However, the specific mass transfer law in the cartilage remains to be studied. In this study, using small molecule rhodamine B as tracer, the mass transfer models of cartilage were built under different pathways including surface pathway, lateral pathway and composite pathway. Sections of cartilage at different mass transfer times were observed by using laser confocal microscopy and the transport law of small molecules within different layers of cartilage was studied. The results showed that rhodamine B diffused into the whole cartilage layer through surface pathway within 2 h. The fluorescence intensity in the whole cartilage layer increased with the increase of mass transfer time. Compared to mass transfer of 2 h, the mean fluorescence intensity in the superficial, middle, and deep layers of cartilage increased by 1.83, 1.95, and 3.64 times, respectively, after 24 h of mass transfer. Under lateral path condition, rhodamine B was transported along the cartilage width, and the molecular transport distance increased with increasing mass transfer time. It is noted that rhodamine B could be transported to 2 mm away from cartilage side after 24 h of mass transfer. The effect of mass transfer under the composite path was better than those under the surface path and the lateral path, and especially the mass transfer in the deep layer of cartilage was improved. This study may provide a reference for the treatment and repair of cartilage injury.

Clinical significance of tumor mutation burden in patients after R 0 resection of colorectal cancer and capecitabine-based adjuvant chemotherapy / 中华普通外科杂志

Objective:To investigate the clinical significance of TMB among CRC patients after R 0 resection and capecitabine-based adjuvant chemotherapy. Methods:Data of 82 CRC patients were reviewed retrospectively. Tumor tissue specimens were collected for DNA extraction . Somatic mutation detection and TMB analysis were performed using next-generation sequencing (NGS) of tumor-related genes. The univariate analysis between TMB status and prognosis was carried out by Kaplan-Meier survival analysis and adjusted by multivariate COX regression analysis subsequently.Results:In these 82 cases,with the median follow-up period was 5.5 years the median disease-free survival (DFS) was 4.5 years, and the median overall survival (OS) was 5.7 years. The most common mutated somatic genes were TP53, APC, KRAS and PIK3CA, with the mutation frequencies of 68.3%, 64.6%, 46.3% and 29.3%, respectively. Other somatic mutant genes were of a relatively low frequency (<25%). The overall somatic mutation burden was relatively low. TMB status was divided into TMB-L (≤3.6/Mb) and TMB-H (>3.6/Mb) according to the median TMB threshold. And the patients with TMB-L and TMB-H were 42 cases and 40 cases, respectively. The median OS in patients with TMB-L and TMB-H was 6.5 and 4.7 years, respectively (χ 2=6.59, P=0.010). TMB status was an independent factor for OS ( HR=0.73, P=0.021). Conclusion:TMB is a biomarker for evaluating the prognosis of CRC patients after surgical resection and receiving capecitabine-based adjuvant chemotherapy .

Research Progress on Regulation of Macrophage Polarization by Biomaterial Functionalized Surface / 医用生物力学

Prosthetic loosening and periprosthetic inflammation, as serious complications after joint replacement surgery, often require the secondary surgery for repair, which is easy to adversely affect the physical/mental health and economic status of patients.Studies have shown that the functional phenotype expressed by macrophages by different stimuli, namely macrophage polarization state, prolonged M1 polarization can lead to the continuation of long-term inflammation, while timely and effective M2 macrophage phenotype will lead to enhanced osteogenesis and tissue remodeling cytokine secretion and subsequent osseointegration, which play a crucial role in the development and outcome of prosthetic loosening and periprosthetic inflammation.The local micro-environment of extracellular matrix (ECM) is an important factor in the activation, migration, proliferation and fusion of macrophages. Researchers have deeply understood it mainly through the crosstalk between surface properties of biomaterials and macrophages. As an effector cell, macro-phages can perform complex spatiotemporal cellular functional responses by sensing the physical and chemical environment (surface topography, wettability, chemical composition, biological proteins) represented by surface properties of biomaterials.This paper summarizes the recent findings on macrophage polarization and material surface properties.

Research progress in biomechanical properties and numerical simulation of periodontal ligament during orthodontic tooth movement / 国际生物医学工程杂志

Orthodontic tooth movement is achieved by remodeling periodontal ligament, alveolar bone and other periodontal tissues in response to mechanical loading. The periodontal ligament is the fibrous connective tissue connecting cementum and alveolar bone, which plays an important role in the transmission, absorption and dispersion of supporting teeth and biting force. When orthodontic forces are applied to the teeth, load transfer occurs from the tooth through the periodontal ligament to the alveolar bone. The remodeling of periodontal ligament interacts with the alveolar bone formation and absorption alternately. As the initial factor of orthodontic tooth movement, the stress/strain of periodontal ligament is involved in the process of alveolar bone remodeling and affects the direction and speed of tooth movement. Therefore, the biomechanical properties of the periodontal ligament have received extensive attention. In this paper, the related researches on the structural changes and biomechanical characteristics of the periodontal ligament during orthodontic tooth movement were reviewed as well as the researches on the mechanical constitutive model of the periodontal ligament. The mechanical response and biomechanical mechanism of the periodontal ligament were discussed in order to provide a theoretical basis for accurate numerical simulation of orthodontic tooth movement.

Effects of icariin on adhesion and cytoskeleton of osteoblasts in response to the extreme mechanical environment of hypergravity / 中华骨科杂志

Objective:To establish a hypergravity loading model with a high-acceleration centrifugal loading device and to investigate the effects of different hypergravity loading and icariin on osteoblast adhesion and cytoskeleton.Methods:MC3T3-E1 cells were seeded in the dishes of cell culture at a density of 2×10 5/cm 2. And the experiment was divided into 6 groups: control group (without icariin and loading); simple administration group (only icariin); 10 G loading group (only loading); 10 G administration group (with icariin and loading); 40 G loading group (only loading); 40 G administration group (with icariin and loading). The experimental loading group was loaded with MC3T3-E1 cells using a high-acceleration centrifugal loader. And continuous loading for 3 d, 30 min per d. The control group and the simple administration group were exposed to normal gravity, and the remaining conditions were not different from the experimental group. Icariin was used at a concentration of 10 -7 mol/L in all administration groups, and the experiments were carried out according to the method of preventive administration. At the same time, the related molecular biological techniques such as alizarin red staining, alkaline phosphatase (ALP) activity measurement, CCK-8 cell proliferation experiment, cytoskeleton phalloidin staining, qPCR and Western Blot were used to detect the effects of icariin on osteoblasts adhesion protein integrin α5 and integrin β1 and cytoskeleton protein F-actin under hypergravity extreme mechanical environment. Results:All models were successfully prepared. The alizarin red staining: The icariin could significantly promote the formation of osteoblastic calcified nodules. And the 10 G loading could also promote the mineralization of osteoblasts and increase the number of mineralized nodules, while the mineralization and the number of mineralized nodules of osteoblasts are significantly reduced in 40 G loading. ALP activity test: The OD values of simple administration group, 10 G loading group and 40 G loading group were 0.246, 0.331 and 0.163, respectively. Compared with 0.207 in the control group, the differences were statistically significant ( P<0.05). The 10 G administration group and the 40 G administration group were 0.373 and 0.180, and the differences were statistically significant ( P<0.05). The results of CCK-8 proliferation experiments: The OD value of simple administration group were 0.650, which was statistically significant compared with 0.551 of control group ( P=0.031). The 10 G loading group and 40 G loading group were 1.193 and 0.245, and their differences with the control group were both statistically significant ( P<0.05). The OD value of 10G administration group and the 40 G administration group were 1.300 and 0.310, which were significantly different from the respective loading groups ( P<0.05). Phalloidin staining: 10 G loading significantly increased the number of cells, but the changes in cells morphology and skeleton were not obvious. 40 G loading significantly inhibited the increase of the number of cells, meanwhile, made the pseudopods of cells more shorter and even disappeared. 40 G loading made the seriously damage of the cytoskeleton and even cause the cells to death. Icariin had no effect on the cells morphology, but it did has a certain repair effect after the cells loading. The results of qPCR and Western Blot experiments all confirmed that the expressions of integrin α5, integrin β1 and F-actin were up-regulated after icariin treatment. 10 G loading could promote the expression of integrin α5, integrin β1 and F-actin, and 40 G loading significantly inhibited the expression of the mRNA and proteins. Conclusion:Both 10 G condition and icariin can promote the development, cell adhesion and the cytoskeleton's stability of osteoblasts, while 40 G has a significant inhibitory effect.

Research Advances in the Effect of Mechanical Regulation of Long-Chain Non-Coding RNAs on Osteogenic Differentiation of Mesenchymal Stem Cells / 医用生物力学

With the development of the 3rd-generation high-throughput sequencing technology and tissue engineering, recent studies show that many long-chain non-coding RNAs (LncRNAs) have played an important role in osteogenic differentiation of mesenchymal stem cells (MSCs). LncRNAs, which are involved in the regulation of mechanical regulation, further regulate bone-related cell functions and play a regulatory role at multiple levels, including transcription, post-transcriptional and epigenetic. LncRNAs may be involved in the osteogenic differentiation and bone remodeling of MSCs, the regulation of bone-related cell functions as a mechanical response molecule, as well as the pathological process of skeletal diseases.

Multidimensional Structure and Properties of Silk Fibroin/Collagen/Hydroxyapatite Bionic Bone Materials / 医用生物力学

Objective To construct a two-dimensional (2D) composite membrane and a three-dimensional (3D) biomimetic scaffold by silk fibroin (SF), type I collagen (Col-I) and hydroxyapatite (HA) blends in vitro, so as to study its physicochemical properties, as well as biocompatibility and explore the feasibility of its application in tissue engineering scaffold materials. Methods 2D composite membranes and 3D scaffolds were prepared by blending SF/Col-I/HA at the bottom of cell culture chamber and low temperature 3D printing combined with vacuum freeze drying. The biocompatibility was evaluated by mechanical property testing, scanning electron microscope and Micro-CT to examine the physicochemical properties of the material, and cell proliferation was detected to evaluate its biocompatibility. Results Stable 2D composite membrane and 3D porous structural scaffolds were obtained by blending and low temperature 3D printing. The mechanical properties were consistent. The pore size, water absorption, porosity and elastic modulus were all in accordance with the requirements of constructing tissue engineering bone. The scaffold was a grid-like white cube with good internal pore connectivity; HA was evenly distributed in the composite membrane, and the cells were attached to the composite membrane in a flat shape; the cells were distributed around pore walls of the scaffold. The shape of the shuttle was fusiform, and the growth and proliferation were good. Conclusions The composite membrane and 3D scaffold prepared by SF/Col-I/HA blending system had better pore connectivity and pore structure, which was beneficial to cell and tissue growth and nutrient transport. Its physicochemical properties and biocompatibility could meet the requirements of bone tissue engineering biomaterials.

Research of simulated microgravity regulate MC3T3-E1 cells differentiation through the nuclear factor-kappa B signaling pathway / 生物医学工程学杂志

In this study, we aim to investigat the effect of microgravity on osteoblast differentiation in osteoblast-like cells (MC3T3-E1). In addition, we explored the response mechanism of nuclear factor-kappa B (NF-κB) signaling pathway to "zero- " in MC3T3-E1 cells under the simulated microgravity conditions. MC3T3-E1 were cultured in conventional (CON) and simulated microgravity (SMG), respectively. Then, the expression of the related osteoblastic genes and the specific molecules in NF-κB signaling pathway were measured. The results showed that the mRNA and protein levels of alkaline phosphatase (ALP), osteocalcin (OCN) and type Ⅰ collagen (CoL-Ⅰ) were dramatically decreased under the simulated microgravity. Meanwhile, the NF-κB inhibitor α (IκB-α) protein level was decreased and the expressions of phosphorylation of IκB-α (p-IκB-α), p65 and phosphorylation of p65 (p-p65) were significantly up-regulated in SMG group. In addition, the IL-6 content in SMG group was increased compared to CON. These results indicated that simulated microgravity could activate the NF-κB pathway to regulate MC3T3-E1 cells differentiation.

Three-dimensional culture of chondrocytes/3D-printed composite scaffolds under compression loading / 中国组织工程研究

BACKGROUND: The silk fibroin/type II collagen composite scaffold has been prepared by low-temperature bio-3D printing technology in the previous study and the scaffold has good mechanical properties. Studies have shown that mechanical stimulation is beneficial to bone remodeling, and gradient loading strain is beneficial to the activation of osteoblasts and osteoclasts. OBJECTIVE: To co-culture silk fibroin/type II collagen composite scaffolds with chondrocytes under compression loading, to observe the proliferation of cells, and to observe the preliminary repair effect of silk fibroin/type II collagen composite scaffold on cartilage defects. METHODS: The silk fibroin/type II collagen composite scaffold was prepared by low-temperature 3D printing to detect the porosity of the scaffold. The passage 3 mouse chondrocytes ADTC-5 were inoculated on the silk fibroin/type II collagen composite scaffold and cultured under static culture and mechanical load respectively. (1) Static culture: blank scaffold was set as control, and cell proliferation was detected by MTT assay at 1, 3, 5, 7, 10, 14 days of inoculation. (2) Culture under mechanical load: blank scaffold was set as control. At 1 day after inoculation, 0％, 1％, 5％, 10％, 15％, 20％ compressive strains were applied to the cell-scaffold complex, and continued to load for 3 days. Cell proliferation was detected by MTT assay, and the distribution, adhesion and morphology of the cells on the scaffold were observed by scanning electron microscopy and hematoxylin-eosin staining. A cartilage defect of 3.5 mm in diameter was made in the bilateral knee joint of New Zealand rabbits. The silk fibroin/type II collagen composite scaffold was implanted onto the left side, and no material was implanted onto the right side. The repair site was observed at 8 weeks after surgery. RESULTS AND CONCLUSION: (1) The porosity of the scaffold was (89.3±3.26)％, which was conducive to cell attachment. (2) After 5 days of static culture, the chondrocytes proliferated well on the surface of the composite scaffold. Under 0％, 1％, 5％, 10％, 15％, 20％ compressive strains, the cell proliferation on the scaffold first increased and then decreased, wherein the cell proliferation was highest under 10％ compressive strain, and lowest under 20％ compressive strain. (4) Under the scanning electron microscopy, the chondrocytes in the 0％ load group were distributed in the surface of the scaffold with irregularities, the cell morphology was obvious, and the cell protrusions were fully extended. There were few or no chondrocytes on the contact surface of the 10％ load group, and more cells distributed on the lateral and internal surfaces of the first layer, but the cell morphology was flat with obvious protrusions. (5) Hematoxylin-eosin staining showed that the chondrocytes in the 0％ load group were concentrated on the surface of the scaffold, and there were almost no cells in the pores, while the chondrocytes in the 10％ load group were distributed in the scaffold pores. (6) There was still a circular defect model with no scaffold implantation, and no obvious repair appeared; similar hyaline cartilage appeared in the defect after scaffold implantation, but there was no adhesion to the surrounding defected cartilage, and the new hyaline cartilage was independent. Overall, the adsorption, proliferation and growth of chondrocytes on the silk fibroin-type II collagen scaffolds is better when the compressive strain is 10％, and the composite scaffold can be used as a repair material for cartilage defects.

The mechanical and biological responses of MC3T3-E1 cells under hypergravity / 医用生物力学

Objective To explore the effect of hypergravity on morphology and osteogenesis function of preosteoblast MC3T3-E1 ceils.Methods The cultured MC3T3-E1 cells under hypergravity by different loading forces were divided into five groups,including control group,5 g group,10 g group,15 g group and 20 g group.The experimental groups were loaded for 30 min each time in 3 successive days,and the control group with no g-value was synchronously exposed to the same surrounding.The morphology of cytoskeletal protein was observed by phalIoidin staining,The alkaline phosphatase (ALP) content was examined by ALP activity assay kit,the gene expression of ALP,collagen Ⅰ (Col Ⅰ),osteocalcin (OC),runt-related transcription factors (Runx2) was measured by real-time quantitative PCR,and the protein expression of Col Ⅰ and OC was tested by Western blotting.Results Under the condition of hypergravity,cell body of osteoblast became thinner,but its surface area increased significantly;with the structure of skeletal arrangement becoming loose,actin microfilament structure reduced so that the orderly arrangement of actin-like dispersion lowered.The gene expressions of related indicators of osteogenic differentiation including ALP,Col][,OC,Runx2 were significantly up-regulated,which was the same as Col Ⅰ protein and OC protein after hypergravity loading.A very minute quantity of small red-orange nodules was found in the control group,while the cells in experimental groups after hypergravity loading obviously formed various sizes of red-orange nodules.Conclusions Under hypergravity,changes in osteoblast morphology can be triggered by rearrangements of skeletal structure.Furthermore,osteoblast maturation and differentiation can be stimulated effectively by up-regulating differentiation-related gene and protein expressions.

Three-dimensional printed silk fibroin/collagen scaffold and its performance / 中国组织工程研究

BACKGROUND:Searching for a porous three-dimensional (3D) scaffold holding good porosity, mechanical property and biocompatibility has become a hot spot, in which, 3D printing technology also plays apart. OBJECTIVE:To prepare silk fibroin/col agen scaffolds using 3D printing technology and detect its performance. METHODS:Silk fibroin/col agen scaffolds were constructed using 3D printing technology, and the silk fibroin/col agen mass ratio was 4:2 (group A) and 4:4 (group B), respectively. The porosity, water absorption expansion rate, mechanical properties and pore size of the composite scaffolds were detected. The passage 3 rat bone marrow mesenchymal stem cel s were seeded onto the two scaffolds. The cel proliferation was detected using MTT assay at 13 days of culture, and the cel morphology was observed by hematoxylin-eosin staining and scanning electron microscope at 14 days of culture. RESULTS AND CONCLUSION:The porosity, pore size, and water absorption expansion rate of group A were significantly larger than those of group B (P<0.05), while the elasticity modulus showed no significant difference between groups. Bone marrow mesenchymal stem cel s on the two scaffolds increased gradual y with time, especial y in the group A (P<0.05). Abundant cel s distributed evenly in the group A, while few cel s distributed unevenly in the group B. These results suggest that the 3D printed scaffolds composed by silk fibroin/col agen mass ratio of 4:2 holds good physicochemical performance and cytocompatibility.

Expression of LXR-β in human gastric cancer tissue and the effect of GW3965 on the proliferation of gastric cancer cell line SGC-7901 / 中南大学学报(医学版)

OBJECTIVE@#To examine the expression of liver X receptor-β (LXR-β) in human gastric cancer tissue, and to explore the effect of GW3965, an agonist of LXRs, on proliferation of gastric cancer cell line SGC-7901.
@*METHODS@#The immunohistochemical assay was used to detect the expression of LXR-β, activating transcription factor 4 (ATF4) in gastric cancer tissues and the corresponding pericarcinoma tissues in 114 patients. Real-time quantitative PCR and Western blot were used to determine mRNA and protein levels of ATF4 and ATP-binding cassette 1 (ABCA1), one of the downstream target genes of LXRs, in SGC-7901 cells with or without GW3965 treatment. Cell counting kit-8 (CCK-8) assay was performed to detect cell proliferation. The expression of ATF4 was silenced by short hairpin RNA (shRNA).
@*RESULTS@#The expressions of LXR-β and ATF-4 were obviously down-regulated in the gastric cancer tissues than that in the corresponding pericarcinoma tissues (both P<0.05). Compared with the control cells, GW3965 treatment inhibited proliferation of SGC-7901 cells and up-regulated ATF4 and ABCA1 expressions (both P<0.05). Knockdown of ATF4 can reverse the antiproliferative effect of GW3965 on SGC-7901 cells.
@*CONCLUSION@#The expression of LXR-β is decreased in human gastric cancer tissues, and activation of LXRs by GW3965 could inhibit the proliferation of SGC-7901 cells via ATF4.

Collagen/silk fibroin nerve conduits used for repairing peripheral nerve defect:application and development / 中国组织工程研究

BACKGROUND:Peripheral nerve defect due to limb dysfunction has always been the difficulty faced by the medical profession. Ideal materials and processing technology for constructing a tissue engineering scaffold targeting peripheral nerve repair are stil in research stage. OBJECTIVE:To review the research progress in peripheral nerve repair using col agen/silk fibroin nerve conduits. METHODS:In this paper, the first author retrieved the PubMed and CNKI from 2003 to 2016 to search articles regarding methods of constructing artificial nerve scaffolds and selection of raw materials. Data from these articles were col ected, summarized and analyzed. RESULTS AND CONCLUSION:Forty-six articles were included for final analysis. Col agen and its degradation products trigger no inflammatory response in the host because of high biocompatibility and biodegradability. However, its use is largely limited by its rapid degradation and poor physical performance. Silk fibroin has a high flexibility and biocompatibility, and exhibits a slow degradation in vivo. As a rapid prototyping technique, three-dimensional printing can print various forms of scaffolds within a short time, characterized as high-quality pore structure and large-scale production. Given these, the col agen/silk fibroin nerve conduit prepared using the three-dimensional printing technology can maintain the biocompatibility and even improve the mechanical properties of the raw materials. Until now, more investigations on nerve repair using col agen or silk fibroin have been done, and we have never stopped improving the production process of these scaffolds. Therefore, the col agen/silk fibroin scaffold prepared using the three-dimensional printing technology is expected to become the main candidate for the repair of peripheral nerve defects.

Preparation and performance of a bionic spinal catheter / 中国组织工程研究

BACKGROUND:The traditional method of preparing tissue-engineered conduit has the defects of complex shape manufacturing and uncontrolable inner space structure, which cannot meet the requirements of some micro-catheters. OBJECTIVE:To prepare a bionic spinal catheter and analyze its performance. METHODS:The data model of the conduit was established using Solid Works software, and platform scan path was generated onthree-dimensionalprinter to produce the bionic spinal catheter with fibroin and colagen as raw materials. Then the water absorption, porosity, mechanical properties and celular compatibility of the conduits were detected. Next, the conduits were implanted into the subcutaneous tissue of rats and taken out at 1, 2, 3 and 4 weeks after surgery, respectively, to observe the degradation. RESULTS AND CONCLUSION:The porosity of the conduit was (53.6±1.0)%, the water absorption was (1347±19.4)%, and the compression modulus was (0.60±0.12) MPa. The micropores distributed uniformly with different size ranging from 10 to 240 μm. Spherical or fusiform stem cels survived in the pores and densely adhered to the conduit with pseudopodia. The degradation rate ofthe conduit was 20%, 59%, 74%and 100% at 1, 2, 3 and 4 weeks after surgery, respectively. These findings indicate that the artificial bionic spinal catheter has good biocompatibility and degradability.

Neural stem cells on a novel composite scaffold:growth and differentiation / 中国组织工程研究

BACKGROUND:Neural stem cel s with self-proliferation and differentiation potential are the ideal seed cel s for central nervous tissue engineering. Although col agen and silk fibroin as biological scaffold materials have been widely used, both of them used alone have certain shortcomings. Is it possible to combine the two materials to build a novel neural tissue-engineered scaffold? What is the effect of this novel scaffold on the growth and differentiation of neural stem cel s? OBJECTIVE:To observe the growth and differentiation of neural stem cel s seeded onto the novel composite scaffold. METHODS:The rat embryonic neural stem cells were inoculated onto new composite scaffolds, and then, their growth and differentiation were observed by light microscopy and scanning electron microscopy. Neural stem cells were cultured in conventional suspension culture as control group. Cell counting kit-8 assay was used to detect viability of neural stem cells in the two groups. Three-dimensional composite scaffolds carrying neural stem cells were slic ed into paraffin sections to observe the growth and differentiation of neural stem cells by hematoxylin-eosin staining and immunofluorescence staining. RESULTS AND CONCLUSION:Neural stem cel s cultured on the new composite scaffold grew and differentiated wel , and interconnected synapses were observed. Cel counting kit-8 assay showed that neural stem cel s on the scaffold grew wel , and the cel viability was significantly higher in the composite scaffold group than that in the control group (P<0.05). Hematoxylin-eosin staining and immunofluorescence staining of paraffin sections further provided evidence for good growth and differentiation of neural stem cel s on the scaffold. These results indicate that the novel composite scaffold with good biocompatibility benefits the growth and differentiation of neural stem cel s, promising a favorable application prospect.

Progress in impact mechanism of CKIP-1 gene on osteoporosis / 国际生物医学工程杂志

Osteoporosis (OP) is one of the bone metabolic diseases which seriously harms the health and lives of people. The main cause of OP is that the balance between bone formation and bone absorption, i.e. the balance of the bone remodeling process,is no longer exist. When the bone absorption dominates the process, it will lead to osteopenia, destruction of bone microstructure and increased rate of fracture. Previous studies have shown that casein kinase 2-interacting protein-1 (CKIP-1) plays an important role in the process of bone tissue proliferation and differentiation. It mainly interacts with Smad ubiquitination regulatory factor 1 (Smurf 1) to affect bone metabolism. This review analyzes and summarizes the impact of CKIP-1 on bone tissue osteogenic differentiation direction and its mechanism, which may provide new idea and research orientation for future clinical treatment of osteoporosis.

Review of experimental model of bone defect in situ healing under mechanical loading / 国际生物医学工程杂志

Tissue engineering composites for bone defect treatment is currently a hot spot of the research field.Mechanical loading on tissue engineering composites is important to bone formation and related research has attracted more and more attention.In the field of tissue engineering research,the establishment of a standardized animal model is the basis of experimental research for exploring the effects of different mechanical loading on in situ repair of bone defect and its action mechanism.This paper reviews the approaches used to establish experimental model of bone defect under mechanical loading such as animal selection,defect preparation,fixation and loading mode in order to provide a reference for related research.