3D vasculature segmentation using localized hybrid level-set method

Background: Intensity inhomogeneity occurs in many medical images, especially in vessel images. Overcoming the difficulty due to image inhomogeneity is crucial for the segmentation of vessel image. Methods: This paper proposes a localized hybrid level-set method for the segmentation of 3D vessel image. The proposed method integrates both local region information and boundary information for vessel segmentation, which is essential for the accurate extraction of tiny vessel structures. The local intensity information is firstly embedded into a region-based contour model, and then incorporated into the level-set formulation of the geodesic active contour model. Compared with the preset global threshold based method, the use of automatically calculated local thresholds enables the extraction of the local image information, which is essential for the segmentation of vessel images. Results: Experiments carried out on the segmentation of 3D vessel images demonstrate the strengths of using locally specified dynamic thresholds in our level-set method. Furthermore, both qualitative comparison and quantitative validations have been performed to evaluate the effectiveness of our proposed model. Conclusions: Experimental results and validations demonstrate that our proposed model can achieve more promising segmentation results than the original hybrid method does

A Distance Transformation Deep Forest Framework With Hybrid-Feature Fusion for CXR Image Classification

Detecting pneumonia, especially coronavirus disease 2019 (COVID-19), from chest X-ray (CXR) images is one of the most effective ways for disease diagnosis and patient triage. The application of deep neural networks (DNNs) for CXR image classification is limited due to the small sample size of the well-curated data. To tackle this problem, this article proposes a distance transformation-based deep forest framework with hybrid-feature fusion (DTDF-HFF) for accurate CXR image classification. In our proposed method, hybrid features of CXR images are extracted in two ways: hand-crafted feature extraction and multigrained scanning. Different types of features are fed into different classifiers in the same layer of the deep forest (DF), and the prediction vector obtained at each layer is transformed to form distance vector based on a self-adaptive scheme. The distance vectors obtained by different classifiers are fused and concatenated with the original features, then input into the corresponding classifier at the next layer. The cascade grows until DTDF-HFF can no longer gain benefits from the new layer. We compare the proposed method with other methods on the public CXR datasets, and the experimental results show that the proposed method can achieve state-of-the art (SOTA) performance. The code will be made publicly available at https://github.com/hongqq/DTDF-HFF

Chondrogenic Regeneration Using Bone Marrow Clots and a Porous Polycaprolactone-Hydroxyapatite Scaffold by Three-Dimensional Printing

Scaffolds play an important role in directing three-dimensional (3D) cartilage regeneration. Our recent study reported the potential advantages of bone marrow clots (MC) in promoting extracellular matrix (ECM) scaffold chondrogenic regeneration. The aim of this study is to build a new scaffold for MC, with improved characteristics in mechanics, shaping, and biodegradability, compared to our previous study. To address this issue, this study prepared a 3D porous polycaprolactone (PCL)-hydroxyapatite (HA) scaffold combined with MC (Group A), while the control group (Group B) utilized a bone marrow stem cell seeded PCL-HA scaffold. The results of in vitro cultures and in vivo implantation demonstrated that although an initial obstruction of nutrient exchange caused by large amounts of fibrin and erythrocytes led to a decrease in the ratio of live cells in Group A, these scaffolds also showed significant improvements in cell adhesion, proliferation, and chondrogenic differentiation with porous recanalization in the later culture, compared to Group B. After 4 weeks of in vivo implantation, Group A scaffolds have a superior performance in DNA content, Sox9 and RunX2 expression, cartilage lacuna-like cell and ECM accumulation, when compared to Group B. Furthermore, Group A scaffold size and mechanics were stable during in vitro and in vivo experiments, unlike the scaffolds in our previous study. Our results suggest that the combination with MC proved to be a highly efficient, reliable, and simple new method that improves the biological performance of 3D PCL-HA scaffold. The MC-PCL-HA scaffold is a candidate for future cartilage regeneration studies.Cell & Tissue EngineeringBiotechnology & Applied MicrobiologyCell BiologySCI(E)[email protected]; [email protected]; [email protected]

Copper-based biomaterials for bone and cartilage tissue engineering

Backgroud: Tissue engineering using cells, scaffolds, and bioactive molecules can promote the repair and regeneration of injured tissues. Copper is an essential element for the human body that is involved in many physiological activities and in recent years, copper has been used increasingly in tissue engineering. Methods: The current advances of copper-based biomaterial for bone and cartilage tissue engineering were searched on PubMed and Web of Science. Results: Various forms of copper-based biomaterials, including pure copper, copper ions, copper nanoparticles, copper oxides, and copper alloy are introduced. The incorporation of copper into base materials provides unique properties, resulting in tuneable porosity, mechanical strength, degradation, and crosslinking of scaffolds. Copper also shows promising biological performance in cell migration, cell adhesion, osteogenesis, chondrogenesis, angiogenesis, and antibacterial activities. In vivo applications of copper for bone and cartilage tissue engineering are discussed. Conclusion: This review focuses on copper’s physiochemical and biological effects, and its applications in bone and cartilage tissue engineering. The potential limitations and future perspectives are also discussed. Translational potential of this article: This review introduces the recent advances in copper-based biomaterial for bone and cartilage tissue engineering. This revie could guide researchers to apply copper in biomaterials, improving the generation of bone and cartilages, decrease the possibility of infection and shorten the recovery time so as to decrease medical costs

Fractal dimension: A complementary diagnostic indicator of osteoporosis to bone mineral density

Morbidity of osteoporosis is increasing as the world population grows and ages, but bone mineral density (BMD) as a common-used diagnostic indicator is not omnipotent in predicting the bone fragility. According to the definition of osteoporosis by World Health Organization (WHO), the present hypothesis proposes an additional fractal-dimension indicator less than 3 to measure the structural change of bones, and further to diagnose osteoporotic patients with complications, to which BMD is insensitive. Literature reports support that the fractal dimension is more sensitive than BMD in specific cases. The hypothesis shows a promise not only in improving the accuracy of screening osteoporotic patients as a complementary indicator to BMD, but also in evaluating mechanical properties of osteoporotic bone and bone-repair effect of bone tissue engineering

Application of Electrospun Nanofiber Membrane in the Treatment of Diabetic Wounds

Diabetic wounds are complications of diabetes which are caused by skin dystrophy because of local ischemia and hypoxia. Diabetes causes wounds in a pathological state of inflammation, resulting in delayed wound healing. The structure of electrospun nanofibers is similar to that of the extracellular matrix (ECM), which is conducive to the attachment, growth, and migration of fibroblasts, thus favoring the formation of new skin tissue at the wound. The composition and size of electrospun nanofiber membranes can be easily adjusted, and the controlled release of loaded drugs can be realized by regulating the fiber structure. The porous structure of the fiber membrane is beneficial to gas exchange and exudate absorption at the wound, and the fiber surface can be easily modified to give it function. Electrospun fibers can be used as wound dressing and have great application potential in the treatment of diabetic wounds. In this study, the applications of polymer electrospun fibers, nanoparticle-loaded electrospun fibers, drug-loaded electrospun fibers, and cell-loaded electrospun fibers, in the treatment of diabetic wounds were reviewed, and provide new ideas for the effective treatment of diabetic wounds

A novel nitroreductase-enhanced MRI contrast agent and its potential application in bacterial imaging

Nitroreductases (NTRs) are known to be able to metabolize nitro-substituted compounds in the presence of reduced nicotinamide adenine dinucleotide (NADH) as an electron donor. NTRs are present in a wide range of bacterial genera and, to a lesser extent, in eukaryotes hypoxic tumour cells and tumorous tissues, which makes it an appropriate biomarker for an imaging target to detect the hypoxic status of cancer cells and potential bacterial infections. To evaluate the specific activation level of NTR, great efforts have been devoted to the development of fluorescent probes to detect NTR activities using fluorogenic methods to probe its behaviour in a cellular context; however, NTR-responsive MRI contrast agents are still by far underexplored. In this study, para-nitrobenzyl substituted T1-weighted magnetic resonance imaging (MRI) contrast agent Gd-DOTA-PNB (probe 1) has been designed and explored for the possible detection of NTR. Our experimental results show that probe 1 could serve as an MRI-enhanced contrast agent for monitoring NTR activity. The in vitro response and mechanism of the NTR catalysed reduction of probe 1 have been investigated through LC–MS and MRI. Para-nitrobenzyl substituted probe 1 was catalytically reduced by NTR to the intermediate para-aminobenzyl substituted probe which then underwent a rearrangement elimination reaction to Gd-DOTA, generating the enhanced T1-weighted MR imaging. Further, LC–MS and MRI studies of living Escherichia coli have confirmed the NTR activity detection ability of probe 1 at a cellular level. This method may potentially be used for the diagnosis of bacterial infections

Fabrication and Properties of the Multifunctional Rapid Wound Healing <i>Panax notoginseng</i>@Ag Electrospun Fiber Membrane

The Panax notoginseng@Ag core/shell electrospun fiber membrane was prepared by coaxial electrospinning combined with the UV reduction method (254 nm). The prepared Panax notoginseng@Ag core/shell nanofiber membrane has a three-dimensional structure, and its swelling ratio could reach as high as 199.87%. Traditional Chinese medicine Panax notoginseng can reduce inflammation, and the silver nanoparticles have antibacterial effects, which synergistically promote rapid wound healing. The developed Panax notoginseng@Ag core/shell nanofiber membrane can effectively inhibit the growth of the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus. The wound healing experiments in Sprague Dawley mice showed that the wound residual area rate of the Panax notoginseng@Ag core/shell electrospun nanofiber membrane group was only 1.52% on day 9, and the wound of this group basically healed on day 12, while the wound residual area rate of the gauze treatment group (control group) was 16.3% and 10.80% on day 9 and day 12, respectively. The wound of the Panax notoginseng@Ag core/shell electrospun nanofiber membrane group healed faster, which contributed to the application of the nanofiber as Chinese medicine rapid wound healing dressings

Mechanical effect on the evolution of bone formation during bone ingrowth into a 3D-printed Ti-alloy scaffold

Bone ingrowth into scaffold under mechanical stimulus is a fundamental issue in bone repair. To evaluate the mechanical effect on the bone repair process, we here studied the evolution of in-scaffold bone formation through characterizing the varying bone volume percentage by animal experiment and mathematical modeling. First, 10 Ti-alloy scaffolds were implanted into the left posterior limbs of 10 rabbits. The 10 rabbits were divided into two groups: five rabbits were in the low-stress-stimulus group with casted plasters, and the rest five in high-stress-stimulus group without plasters. Then, the bone volume percentages at five time points were collected by micro-CT examination. Correspondingly, the dynamic bone ingrowth process was also numerically simulated. The result showed that the bone volume percentages of the two groups in the experiment and simulation were comparable, and the great mechanical stimulus improved the bone formation. This work provides experimental and numerical methods to study the mechanical-regulated bone ingrowth in bone tissue engineering, and can be used to engineer bone substitute for the clinical rehabilitation.</p