Micro-CT Observation Research Articles

Characterization of a spontaneous osteopetrosis model using RANKL-dysfunctional mice

Tumor necrosis factor superfamily member 11 (TNFSF11), or receptor activator of nuclear factor-κB ligand (RANKL), is a crucial osteoclast-stimulating factor binding to RANK on osteoclast membranes. Mouse models are powerful tools for understanding the genetic mechanisms of related diseases. Here, we examined the utility of Tnfsf11 mutation in mice for understanding the mechanisms of bone remodeling and dysmorphology. The Tnfsf11gum mouse, discovered in 2011 at Jackson Laboratory, was used to study the genetic landscape associated with TNFSF11 inactivation in bone marrow tissues. Tnfsf11gum/+ and Tnfsf11+/+ mice were subjected to Micro-CT observation, ELISA analysis, histological evaluation, and massively-parallel mRNA sequencing (RNA-Seq) analysis. Tnfsf11gum/+ mice exhibited severe osteopetrotic changes in the bone marrow cavity, along with significantly lower serum RANKL levels and a reduced number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in the bone marrow compared to those in Tnfsf11+/+ mice. However, tooth eruption between Tnfsf11gum/+ and Tnfsf11+/+ mice did not differ. Furthermore, genes involved in osteoblast proliferation and differentiation, including Gli1, Slc35b2, Lrrc17, and Junb were differentially expressed. Heterozygous mutation of TNFSF11 was also associated with a slightly increased expression of genes involved in osteoclast proliferation and differentiation, including Tcirg1, Junb, Anxa2, and Atp6ap1. Overall, we demonstrate that single gene mutations in Tnfsf11 cause bone resorption instability without significantly altering the genes related to osteoblast and osteoclast activity in the bone marrow cavity, thus establishing an optimal resource as an experimental animal model for bone resorption in bone biology research.

Irradiation multi-scale damage and interface effects of 3D braided carbon fiber/epoxy composites subjected to high dose γ-rays

The serious damage caused to 3D braided carbon fiber (CF)/epoxy (EP) composites in high-energy irradiation environments is a pressing research topic that has not yet been reported. This study analyzed the γ-irradiation multi-scale damage of the matrix, interfaces, and near-interface regions in 3D braided CF/EP composites with three different braiding angles (18°, 28°, 38°) at atomic, microscopic, and macroscopic scales. The molecular structure and atomic charge information alterations of epoxy matrix were characterized using soft X-ray absorption spectroscopy (sXAS). When the irradiation dose reached 1000 KGy, the compressive strength of composites decreased by 20.88 %, 18.07 %, and 16.60 %, respectively, with an increase in the braiding angle. Micro-CT observation, along with statistical computing, confirmed that irradiation causes interface damage and increases the defect volume of 3D braided composites. Nanoindentation was used to compare the modulus of carbon fiber, interface, near-interface regions and matrix in irradiated composites and the function of CF/resin interface as an irradiation defect capture site in the irradiation resistance of resin-matrix composites has been newly established. In addition, the mechanism behind the effect of braiding angle on macroscopic properties was also analyzed.

Enhanced bone regeneration by osteoinductive and angiogenic zein/whitlockite composite scaffolds loaded with levofloxacin.

Promoting angiogenesis following biomaterial implantation is essential to bone tissue regeneration. Herein, the composite scaffolds composed of zein, whitlockite (WH), and levofloxacin (LEVO) were fabricated to augment bone repair by facilitating osteogenesis and angiogenesis. First, three-dimensional composite scaffolds containing zein and WH were prepared using the salt-leaching method. Then, as a model antibiotic drug, the LEVO was loaded into zein/WH scaffolds. Moreover, the addition of WH enhanced the adhesion, differentiation, and mineralization of osteoblasts. The zein/WH/LEVO composite scaffolds not only had significant osteoinductivity but also showed excellent antibacterial properties. The prepared composite scaffolds were then implanted into a calvarial defect model to evaluate their osteogenic induction effects in vivo. Micro-CT observation and histological analysis indicate that the scaffolds can accelerate bone regeneration with the contribution of endogenous cytokines. Based on amounts of data in vitro and in vivo, the scaffolds present profound effects on improving bone regeneration, especially for the favorable osteogenic, intensive angiogenic, and alleviated inflammation abilities. The results showed that the synthesized scaffolds could be a potential material for bone tissue engineering.

Detecting and Quantifying Xylem Embolism by Synchrotron-Based X-Ray Micro-CT.

The vulnerability to xylem embolism is a key trait underlying species-specific drought tolerance of plants, and hence is critical for screening climate-resilient crops and understanding vegetation responses to drought and heat waves. Yet, accurate determination of embolism in plant's xylem is challenging, because most traditional hydraulic techniques are destructive and prone to artefacts. Hence, direct and in vivo synchrotron-based X-ray micro-CT observation of xylem conduits has emerged as a key reference technique for accurate quantification of vulnerability to xylem embolism. Micro-CT is nowadays a fundamental tool for studies of plant hydraulic architecture, and this chapter describes the fundamentals of acquisition and processing of micro-CT images of plant xylem.

Identification of biological components for sialolith formation organized in circular multi-layers

According to the previous studies of sialolithiasis reported so far, this study is aimed to identify the biological components of sialolith, which show different ultrastructures and chemical compositions from other stones, cholelith and urolith. Twenty-two specimens obtained from 20 patients were examined histologically, and analyzed with micro-CT, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). All sialoliths (n = 22) observed in this study showed a central nidus, which was filled with organoid matrix admixed with exosome vesicles, loose calcium apatite crystals, and many bacteria. The micro-CT and SEM observation clearly defined a single or multiple central nidus(es) encircled by highly calcified compact zone. The circular compact zone showed a band-like calcification, about 1–3 mm in thickness, and usually located between the central nidus and the peripheral multilayer zone. But some sialoliths (n = 5) showed severe erosion of compact zone by expanding multilayered zone depending on the level of calcification and inflammation in sialolith. By observing TEM images, many exosome vesicles and degraded cytoplasmic organelles were found in the central nidus, and some epithelial cells were also found in the calcified matrix of peripheral multilayer zone. Particularly, EDS analysis indicated the highest Ca/P ratio in the intermediate compact zone (1.77), and followed by the central nidus area (1.39) and the peripheral multilayer zone (0.87). Taken together, these data suggest that the central nidus containing many inflammatory exosomes and degraded cytoplasmic organelles has a potential to induce a band-like calcification of compact zone, and followed by the additional multilayer deposition of exfoliated salivary epithelial cells as well as salivary materials. Thereby, the calcium apatite-based sialolith is gradually growing in its volume size, and eventually obstructs the salivary flow and provides a site for the bacterial infection.

Effect of Synchronized Laser Shock Peening on Decreasing Defects and Improving Microstructures of Ti-6Al-4V Laser Joint.

Repairing processing is a significant method for damaged high-cost Ti-6Al-4V components to decrease economic loss, which usually utilizes a welding technique. For a large-size structural component, welding processing is commonly completed in air conditioning, which makes it difficult to avoid welding defects. To this end, an appropriate matching technique is important for improving welding performance. In the present research, asynchronized laser shock peening (ALSP) and synchronized laser shock peening (SLSP) techniques were utilized to decrease the influence of macro welding defects on laser-welded Ti-6Al-4V joints. The results show that SLSP has a greater effect on inducing surface plastic deformation on Ti-6Al-4V joints with a pitting depth of more than 25 microns while ALSP can lead to a pitting depth of about 15 microns. Through micro-CT observation a long hot crack exists in the central area of as-welded joints with a length of about 2.24 mm, accompanied by lots of pores in different sizes on double sides. After ALSP processing, some pores are eliminated while others are enlarged, and one-side crack tips present closure morphology. However, some microcracks exist on the side-wall of hot cracks. With the influence of SLSP, significant shrinkage of pores can be observed and both sides of crack tips tend to be closed, which presents a better effect than ALSP processing. Moreover, greater effects of grain refinement and thermal stress release could be achieved by SLSP processing than ALSP, which can be ascribed to dynamic recrystallization. For the as-welded joint, the ultimate tensile strength (UTS) and elongation (EL) values are 418 MPa and 0.73%, respectively. The values of UTS and EL in the ALSP processed joint are increased to 437 MPa and 1.07%, which are 4.55% and 46.48% higher than the as-welded joint, respectively. Such values after SLSP processing are 498 MPa and 1.23%, which are 19.14% and 68.49% higher than the as-welded joint, respectively.

Application of Nano-Calcium Phosphate Coated Porous Tantalum Scaffold in Repair of Rabbit Cartilage Defect

Calcium coated scaffolds and their role in repair of bone defects have been widely studied in the last decades. This study aimed to evaluate the effect of bone morphogenetic protein-7 (BMP-7) loaded nano-calcium phosphate (CaP) coated porous tantalum scaffolds (PTS) on regenerative and reparative potency of cartilage defects in rabbits. We used New Zealand white rabbit cartilage defect models. The subjects were randomly grouped into 4: (1) a control group (no treatment), (2) a PTS group, (3) a CaP/PTS group, and (4) a CaP/PTS/BMP-7 groups. The characterization and in vitro biocompatibility of each scaffold were evaluated. Following scaffold implantation, we evaluated the gross observation score, Micro-CT observation parameters, and the mRNA of target genes. No visible difference was detected in water contact angle (WCA) and cell proliferation activity after co-culture among the PTS, CaP/PTS, and CaP/PTS/BMP-7 scaffold groups (P >0.05). Gross observation scores, trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular mineral density (TMD), bone volume fraction (BV/TV), COL2A1, SOX-9, Aggrecan, and RUNX-2 showed an obvious increase among the PTS, CaP/PTS, and CaP/PTS/BMP-7 groups to those with no treatment (P <0.05). Also, the PPARγ showed an obvious decline (P <0.05). Gross observation scores, Tb.Th, Tb.N, TMD, BV/TV, COL2A1, SOX-9, Aggrecan, and RUNX-2 increased and PPARγ decreased in CaP/PTS/BMP-7 group to PTS and CaP/PTS groups (P <0.05). Our findings indicate that PT scaffolds enhance the reparative potency of cartilage defects in New Zealand rabbits promoted the repair of cartilage defects in rabbits. This effect is boosted among those treated with the BMP-7 loaded nano-CaP coated PTS, and this group showed improved regenerative and reparative potency.

Preparation and bone repair capability of a new plastic bone filler material

To prepare a new plastic bone filler material with adhesive carrier and matrix particles derived from human bone, and evaluate its safety and osteoinductive ability through animal tests. The human long bones donated voluntarily were prepared into decalcified bone matrix (DBM) by crushing, cleaning, and demineralization, and then the DBM was prepared into bone matrix gelatin (BMG) by warm bath method, and the BMG and DBM were mixed to prepare the experimental group's plastic bone filler material; DBM was used as control group. Fifteen healthy male thymus-free nude mice aged 6-9 weeks were used to prepare intermuscular space between gluteus medius and gluteus maximus muscles, and all of them were implanted with experimental group materials. The animals were sacrificed at 1, 4, and 6 weeks after operation, and the ectopic osteogenic effect was evaluated by HE staining. Eight 9-month-old Japanese large-ear rabbits were selected to prepare 6-mm-diameter defects at the condyles of both hind legs, and the left and right sides were filled with the materials of the experimental group and the control group respectively. The animals were sacrificed at 12 and 26 weeks after operation, and the effect of bone defect repair were evaluated by Micro-CT and HE staining. In ectopic osteogenesis experiment, HE staining showed that a large number of chondrocytes could be observed at 1 week after operation, and obvious newly formed cartilage tissue could be observed at 4 and 6 weeks after operation. For the rabbit condyle bone filling experiment, HE staining showed that at 12 weeks after operation, part of the materials were absorbed, and new cartilage could be observed in both experimental and control groups; at 26 weeks after operation, the most of the materials were absorbed, and large amount of new bone could be observed in the 2 groups, while new bone unit structure could be observed in the experimental group. Micro-CT observation showed that the bone formation rate and area of the experimental group were better than those of the control group. The measurement of bone morphometric parameters showed that the parameters at 26 weeks after operation in both groups were significantly higher than those at 12 weeks after operation ( P<0.05). At 12 weeks after operation, the bone mineral density and bone volume fraction in the experimental group were significantly higher than those in the control group ( P<0.05), and there was no significant difference between the two groups in trabecular thickness ( P>0.05). At 26 weeks after operation, the bone mineral density of the experimental group was significantly higher than that of the control group ( P<0.05). There was no significant difference in bone volume fraction and trabecular thickness between the two groups ( P>0.05). The new plastic bone filler material is an excellent bone filler material with good biosafety and osteoinductive activity.

Effect and mechanism of ultraviolet-cross-linkable chitosan-carbon dots-morin hydrogel treating for rat cartilage injury

To construct a ultraviolet-cross-linkable chitosan-carbon dots-morin (NMCM) hydrogel, observe whether it can repair cartilage injury by in vivo and in vitro experiments, and explore the related mechanism. The chitosan was taken to prepare the ultraviolet (UV)-cross-linkable chitosan by combining methacrylic anhydride, and the carbon dots by combining acrylamide. The two solutions were mixed and added morin solution. After UV irradiation, the NMCM hydrogel was obtained, and its sustained release performance was tested. Chondrocytes were separated from normal and knee osteoarticular (KOA) cartilage tissue donated by patients with joint replacement and identified by toluidine blue staining. The 3rd generation KOA chondrocytes were co-cultured with the morin solutions with concentrations of 12.5, 25.0, 50.0 µmol/L and NMCM hydrogel loaded with morin of the same concentrations, respectively. The effects of morin and NMCM hydrogel on the proliferation of chondrocytes were detected by cell counting kit 8 (CCK-8). After co-cultured with NMCM hydrogel loaded with 50 µmol/L morin, the level of collagen type Ⅱ (COL-Ⅱ) of KOA chondrocytes was detected by immunofluorescence staining, and the level of reactive oxygen species (ROS) was detected by 2, 7-dichlorodihydrofluorescein diacetate (DCFH-DA) probe. Twenty 4-week old Sprague Dawley rats were selected to construct a articular cartilage injury of right hind limb model, and were randomly divided into two groups ( n=10). The cartilage injury of the experimental group was repaired with NMCM hydrogel loaded with 25 µmol/L morin, and the control group was not treated. At 4 weeks after operation, the repair of cartilage injury was observed by micro-CT and gross observation and scored by the International Cartilage Repair Association (ICRS) general scoring. The cartilage tissue and subchondral bone tissue were observed by Safranine-O-fast green staining and COL-Ⅱ immunohistochemistry staining and scored by ICRS histological scoring. The expressions of tumor necrosis factor α (TNF-α), nuclear factor κB (NK-κB), matrix metalloproteinase 13 (MMP-13), and COL-Ⅱ were detected by Western blot and real-time fluorescence quantitative PCR. NMCM hydrogels loaded with different concentrations of morin were successfully constructed. The drug release rate was fast in a short period of time, gradually slowed down after 24 hours, and the amount of drug release was close to 0 at 96 hours. At this time, the cumulative drug release rate reached 88%. Morin with a concentration ≤50 µmol/L had no toxic effect on chondrocytes, and the proliferation of chondrocytes improved under the intervention of NMCM hydrogel ( P<0.05). NMCM hydrogel loaded with morin could increase the level of COL-Ⅱ in KOA chondrocytes ( P<0.05) and reduce the level of ROS ( P<0.05), but it did not reach the normal level ( P<0.05). Animal experiments showed that in the experimental group, the articular surface was rough and the defects were visible at 4 weeks after operation, but the surrounding tissues were repaired and the joint space remained normal; in the control group, the articular surface was rougher, and no repair tissue was found for cartilage defects. Compared with the control group, the experimental group had more chondrocytes, increased COL-Ⅱ expression, and higher ICRS gross and histological scores ( P<0.05); the relative expressions of MMP-13, NF-κB, and TNF-α protein and mRNA significantly decreased ( P<0.05), and the relative expressions of COL-Ⅱ protein/COL-2a1 mRNA significantly increased ( P<0.05). NMCM hydrogel can promote chondrocytes proliferation, down regulate chondrocyte catabolism, resist oxidative stress, protect chondrocytes from cartilage injury, and promote cartilage repair.

Delivery of bone morphogenetic protein-2 by crosslinking heparin to nile tilapia skin collagen for promotion of rat calvaria bone defect repair.

Collagen has been widely used as a biomaterial for tissue regeneration. At the present, aqua-collagen derived from fish is poorly explored for biomedical material applications due to its insufficient thermal stability. To improve the bone repair ability and thermal stability of fish collagen, the tilapia skin collagen was crosslinked by EDC/NHS with heparin to bind specifically to BMP-2. The thermal stability of tilapia skin collagen crosslinked with heparin (HC-COL) was detected by differential scanning calorimetry (DSC). Cytotoxicity of HC-COL was assessed by detecting MC3T3-E1 cell proliferation using CCK-8 assay. The specific binding of BMP-2 to HC-COL was tested and the bioactivity of BMP-2-loaded HC-COL (HC-COL-BMP-2) was evaluated in vitro by inducing MC3T3-E1 cell differentiation. In vivo, the bone repair ability of HC-COL-2 was evaluated using micro-CT and histological observation. After crosslinking by EDC/NHS, the heparin-linked and the thermostability of the collagen of Nile Tilapia were improved simultaneously. HC-COL has no cytotoxicity. In addition, the binding of BMP-2 to HC-COL was significantly increased. Furthermore, the in vitro study revealed the effective bioactivity of BMP-2 binding on HC-COL by inducing MC3T3-E1 cells with higher ALP activity and the formation of mineralized nodules. In vivo studies showed that more mineralized and mature bone formation was achieved in HC-COL-BMP-2 group. The prepared HC-COL was an effective BMP-2 binding carrier with enough thermal stability and could be a useful biomaterial for bone repair.

Bird impact response and damage mechanism of 3D orthogonal woven composite aeroengine blades

Various gelatin simulated bird projectiles were used to impact two key positions of three-dimensional (3D) orthogonal woven composite stator blades used in aeroengines: the center and leading edge at the blade back. The effects of impact velocity, projectile weight, and impact position on the macro damage mode were determined. Numerical simulations were conducted using the constitutive model developed in our previous work (Liu et al. 2023). The numerical simulation results were in good agreement with the experimental results. Combined test results, micro-CT and SEM observation and the numerical simulation results, the internal damage mechanism of the blade was explored. Four types of damage modes were seen under bird strike: edge damage on the narrow blade root, cracks on both sides of the narrow blade root, damage in the impact area, and complete fracture. Furthermore, the impact energy thresholds for visible damage and fracture were obtained for different bird weights and impact locations, which is of great significance to the anti-bird-strike design of composite blades.

The effect of fiber preform configuration on in-plane compressive behavior of high porosity needled carbon/carbon composites in elevated temperature environment

The in-plane compressive behavior of the high porosity needled carbon/carbon (C/C) composites can be used to examine the interlaminar state and the material integrity. The room and elevated temperature in-plane compressive experiments of the high porosity needled C/C composites were conducted to study the effect of local fiber configuration state on the failure modes and damage mechanisms combining with the scanning electron microscope (SEM) and micro-computed tomography (Micro-CT) observation. The porosity was also determined by processing Micro-CT images, which was used to calculate the mechanical properties of constituents. The refined finite element (FE) model considering explicitly the distribution of needling punched regions of the real compressive specimen was established to reproduce the damage and failure process component materials in the high porosity needled C/C composites during the experiment at elevated temperature. The effect of needling parameters, such as the needling depth and the thickness ratio between fiber net layer and non-woven cloth layer, on the compressive mechanical properties of the high porosity needled C/C composites was studied using the parametric FE model. The variation curves of the compressive strength with these needling parameters were obtained, which could guide to choose the proper high porosity needled C/C composites for manufacturing the lightweight thermal protection tile after introducing the oxidation resistant ceramic matrix.

The potential role of herbal extract Wedelolactone for treating particle-induced osteolysis: an in vivo study

BackgroundOsteolysis is one of the most prevalent clinical complications affecting people who undergo total joint replacement (TJR). Wedelolactone (WDL) is a coumestan compound derived from the Wedelia chinensis plant and has been demonstrated to exhibit anti-inflammatory properties. This study aimed to investigate the oral administration of WDL as a potential treatment for particle-induced osteolysis using a well-established mice calvarial disease model.MethodsThirty-two C57BL/6 J mice were randomized into four groups: Sham, vehicle, osteolysis group with oral WDL treatment for 4 weeks (WDL 4w), and osteolysis group treated for 8 weeks (WDL 8w). Micro-CT was used to quantitatively analyze the bone mineral density (BMD), bone volume/tissue volume (BV/TV) and trabecular bone thickness (Tb.Th). Osteoclast numbers were also measured from histological slides by two investigators who were blind to the treatment used.ResultsThe results from micro-CT observation showed that BMD in the WDL 8w group improved significantly over the vehicle group (p < 0.05), but there was no significant difference between WDL 4w and 8w for BV/TV and Tb.Th. Osteoclast numbers in the WDL 4w group were also lower than the vehicle group (p < 0.05), but the difference between WDL 8w and 4w groups was not significant.ConclusionsParticle-induced osteolysis is an inevitable long-term complication after TJR. The results of this animal study indicate that an oral administration of WDL can help reduce the severity of osteolysis without adverse effects.

Insights into the enhanced effect of Low-Intensity Ultrasound on anammox granular sludge by relieving the embolism

Like the lethal cardiovascular embolism in humans, the serious blockage of the mass transfer channel can inactivate anammox granular sludge (AnGS). Also like the therapeutic thrombolysis in humans, the remediatory dredging of the mass transfer channel can sustain the function of AnGS. In this study, the ultrasound was thus explored to remediate the embolism of AnGS. It turned out that Low-Intensity Ultrasound (LIU) with an energy density of 5.6 kJ/(g-VSS·cm2) was optimal to achieve an obvious increase in specific anammox activity of AnGS by 34.8% to 420.3 mg-N/(g-VSS·d). The improved mass transfer of AnGS and cell membrane permeability of anammox bacteria (AnAOB) was revealed to mainly contribute to the enhanced activity. After treatment with LIU under optimal conditions, the mass transfer efficiency of AnGS was improved by 26.9% with enhanced permeability, and the proportions of pores larger than 50 μm in the surface layer of AnGS increased by 13.7% evidenced by the micro-CT observation. Correspondingly, the permeability of AnAOB was increased by inducing instantaneous pores on the cell membrane, thus stimulating the metabolism by 6.9%. Further analysis demonstrated that LIU was capable of breaking the hydrogen bonds of protein in the EPS and loosening its spatial structure, which would benefit the partially exfoliation and dissolution of EPS and resulted in enlarging and dredging pores, thus relieving the embolism of AnGS. Consequently, the results of this study could deepen the understanding of granules treated by ultrasound and also provide a promising technique for raising the ceiling of nitrogen removal performance by AnGS.

Combined Application of Er:YAG and Nd:YAG Lasers Enhances Osseointegration at Dental Bone-Implant Interface

The combination of a bone and an implant surface is a dynamic biological process. By improving the osseointegration efficiency of the bone tissue around the implant surface, the implant can obtain long-term stability. In this study, we have investigated the potential applications of dual-wavelength lasers (Er:YAG laser and Nd:YAG laser) in implantations and observed their possible efficacy in promoting tissue repair around the implant. The animal experimental model of a rabbit femoral defect implant was used to simulate the process of tissue reconstruction around the implant in humans. The results indicated that by micro-CT observation, it was obvious that the bone mineral density (BMD) values of the dual-wavelength laser group were significantly higher than those of other groups. Furthermore, VG staining clearly showed that there was no obvious physiological gap detected between the implant and the surrounding bone tissues in the dual-wavelength laser group. HE staining further revealed that no significant influx of inflammatory cells was observed around the implants. Immunohistochemical staining of OCN and VEGF showed that the positive area percentages of the dual-wavelength laser group were significantly higher than other groups at the same time point. Therefore, the application of a dual-wavelength laser in implantations can exhibit a positive effect on promoting the reconstruction of bone tissues.

Quantification and visualization of metastatic lung tumors in mice.

Histopathological examination is important for the diagnosis of various diseases. Conventional histopathology provides a two-dimensional view of the tissues, and requires the tissue to be extracted, fixed, and processed using histotechnology techniques. However, there is an increasing need for three-dimensional (3D) images of structures in biomedical research. The objective of this study was to develop reliable, objective tools for visualizing and quantifying metastatic tumors in mouse lung using micro-computed tomography (micro-CT), optical coherence tomography (OCT), and field emission-scanning electron microscopy (FE-SEM). Melanoma cells were intravenously injected into the tail vein of 8-week-old C57BL/6 mice. The mice were euthanized at 2 or 4weeks after injection. Lungs were fixed and examined by micro-CT, OCT, FE-SEM, and histopathological observation. Micro-CT clearly distinguished between tumor and normal cells in surface and deep lesions, thereby allowing 3D quantification of the tumor volume. OCT showed a clear difference between the tumor and surrounding normal tissues. FE-SEM clearly showed round tumor cells, mainly located in the alveolar wall and growing inside the alveoli. Therefore, whole-tumor 3D imaging successfully visualized the metastatic tumor and quantified its volume. This promising approach will allow for fast and label-free 3D phenotyping of diverse tissue structures.

Experimental Study on the Bone Morphogenetic Protein 1-Modified Bone Marrow Mesenchymal Stem Cell Sheets to Promote Mandibular Distraction Osteogenesis.

ObjectiveThe present study aims to increase the concentration of genetically modified bone marrow mesenchymal stem cells (BMSCs) in the distraction osteogenesis (DO) interstitial space and induce the conversion of BMSCs to osteoblasts to improve the osteogenic efficiency in DO and shorten the treatment period.MethodsBone morphogenetic protein 1 (BMP-1) and green fluorescent protein (GFP) gene-modified cell sheets of BMSCs were constructed by tissue engineering. Thirty-six New Zealand white rabbits were randomly divided into three groups: group A (the blank control group), group B (the GFP group) with the injection of GFP gene-modified BMSC sheets into the DO gap, and group C (the BMP-1 group) with the injection of BMP-1 gene-modified BMSC sheets into the DO gap. Rabbits in all three groups were distracted for 5 days at a distraction rate of 2.0 mm/d, once/day. After distraction, the above-mentioned cell sheet suspension was injected into the distraction gap to observe osteogenesis, which was observed by gross specimen observation, micro-computed tomography (Micro-CT) scanning, and histomorphology.ResultsThe gross specimen observation showed that all animals had smooth and continuous bone cortex in the distraction region with relatively high hardness. The osteogenesis quality or hardness was ranked from the highest to the lowest, as Group C > Group B > Group A. Micro-CT and histomorphological observation revealed that group C had better maturation and bone volume of the new bone in the DO region at weeks 3 and 6 than groups B and A.ConclusionBMP-1 gene-modified BMSC sheets could effectively promote the formation of new bone during rapid DO in the mandible, compensating for the poor osteogenesis caused by rapid distraction and providing a new approach to shorten the DO treatment period in clinical practice.

Fabricated CAD/CAM Post-Core Using Glass Fiber-Reinforced Resin Shows Innovative Potential in Restoring Pulpless Teeth.

The prevention of root fractures of pulpless teeth is an important clinical issue to maintain healthy teeth through lifetime. The aim of this study was to examine a clinically effective treatment method for strengthening vulnerable pulpless teeth using CAD/CAM (computer-aided design/computer-aided manufacturing) fiber-reinforced post-core by conducting a fracture resistance test. A post-core made with a fiber-reinforced resin disk TRINIA (TR, SHOFU, Kyoto, Japan) was fabricated using a CAD/CAM system. The fiber-layer orientation of the CAD/CAM post-core was parallel to the axis of the restored tooth. A post-core using a conventional composite and a fiber post (CF) was also prepared. A fracture resistance test of teeth restored with the post-cores and zirconia crowns was conducted using a universal testing machine, and fracture patterns were identified by micro-CT observation. The fracture load of the roots restored with TR was 1555.9 ± 231.8 N, whereas that of CF was 1082.1 ± 226.7 N. The fracture load of TR was 43.8% that was significantly higher than that of CF (Student’s t-test, p < 0.05). The restored teeth with CAD/CAM resin post-core were found to be repairable even after fracture. These results suggest that the CAD/CAM indirect fiber post-core has the potential to strengthen the vulnerable pulpless teeth.

Effect of concentrated growth factor combined with mineralized collagen material on the adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells and the osteogenic effect in vivo

To explore the effects of concentrated growth factor (CGF) combined with mineralized collagen (MC) materials on the adhesion, proliferation, and differentiation of bone marrow mesenchymal stem cells (BMSCs) and their osteogenic effects in vivo, and to provide a theoretical basis for the combined application of CGF and MC materials in bone defect regeneration and repair. CGF was prepared from venous blood of healthy volunteers, and then CGF extracts (CGFe) were prepared. In vitro experiment: human BMSCs (hBMSCs) were divided into 4 groups. Groups A, B, and C were cultured with α-MEM medium [containing 10% fetal bovine serum (FBS) and 1% double antibody] containing 2%, 5%, and 10%CGFe, respectively; group D was cultured with α-MEM medium (containing 10%FBS and 1% double antibody) without CGFe. Scanning electron microscopy was used to observe the effect of CGFe on cell adhesion. Cell counting kit 8 (CCK-8) was used to detect the effect of CGFe on cell proliferation. After osteogenic induction, alkaline phosphatase (ALP) activity was detected and Western blot was performed to detect osteopontin (OPN) expression. In vivo experiment: Eighteen New Zealand big-eared rabbits were used to prepare circular bone defect models on the left and right mandibles, and implant CGF gel (prepared from autologous venous blood)+MC material (volume ratio 1∶1, experimental group) and simple MC material (control group), respectively. At 4, 8, and 12 weeks after operation, 6 rabbits were sacrificed respectively to obtain materials, and Micro-CT scanning was performed to observe the formation of new bone and material degradation in vivo. In vitro experiments: Scanning electron microscopy showed that the cells of groups A, B, and C spread better on MC materials than group D, with more pseudopodia. CCK-8 method showed that different concentrations of CGFe could promote cell proliferation, and the absorbance ( A) value of cells cultured for 2, 3, 5, and 7 days was in the order of group C>group B>group A>group D, the differences were significant ( P<0.05). ALP activity test showed that its activity was proportional to the osteogenic induction time and CGFe concentration ( P<0.05). Western blot analysis of osteogenic induction culture for 14 days showed that the relative expression of OPN protein in groups A, B, and C was significantly higher than that in group D, and the higher the CGFe concentration, the higher the relative expression of OPN protein ( P<0.05). In vivo experiment: Micro-CT observation showed that the new bone formation and material degradation of the experimental group were better than those of the control group at 4, 8, and 12 weeks after operation. Quantitative detection showed that the volume of new bone volume, new bone volume fraction, trabeculae number, and trabecular thickness of the experimental group were significantly higher than those of the control group at each time point, the residual material volume, residual material volume fraction, and trabecular separation were significantly lower than those of the control group, all showing significant differences ( P<0.05). CGF can effectively promote the adhesion, proliferation, and osteogenic differentiation of BMSCs on MC materials, and 10%CGFe has the most significant effect. The combined application of CGF and MC material can significantly promote bone formation in vivo.

Lab-based in-situ micro-CT observation of gaps in prepreg laminates during consolidation and cure

An experimental technique was developed to obtain 3D microstructural information on two typical lay-up features that often appear in automated fibre placement (AFP) or automated tape laying (ATL). Parallel-ply gaps between adjacent courses and ply-drop gaps needed to change the thickness of composite laminates were studied. Using a lab-based CT scanner, the different squeezing and bleeding mechanisms were obser ved while the manufacturing process was occurring. The initially large gaps were closed by fibre and/or resin flow, with the parallel-ply gap consolidating faster and reaching a lower porosity level than the ply-drop gap. However, after reaching a minimum porosity, previously consolidated voids reappeared and remained locked into the final microstructure. The in-situ CT data was helpful to identify opportunities for future process model developments. Overall, lab-based in-situ micro-CT was proven to be an effective and accessible technique to study how composite features evolve through the manufacturing process.