Frontiers in Bioengineering and Biotechnology最新文献

Sit-to-stand (STS) assistance should not only reduce effort but also preserve or shape neuromuscular activity patterns. We propose a data-driven control strategy for an assistive chair with two degrees of freedom (vertical and horizontal seat motion) to infer desired multi-muscle activation during STS. The chair is parameterized by four binary variables (fast/slow vertical and horizontal velocities, and early/late onset timing for each axis), yielding 16 control combinations. Surface EMG from eight lower-limb muscles was collected from six healthy adult males across all control combinations (10 trials per condition). We extracted hundred-dimensional EMG features by segmenting STS into four phases and computing summary statistics per muscle and phase. Four $L_1$ -regularized logistic regression classifiers were trained to infer each control variable from EMG features, enabling a classifier-based statistical mapping from target EMG features to chair control parameters. The classifiers achieved F-scores of 0.96 and 0.99 for forward and upward speed, and 0.89 and 0.82 for forward and upward timing, respectively. In an offline evaluation, the estimated control parameters inferred EMG feature patterns significantly closer to the target than non-target parameter combinations. These results suggest that low-DoF seat motion can be used to modulate higher-dimensional muscle activation patterns during STS, providing a basis for future real-time and individualized assistive control.

Introduction: Breast cancer remains one of the most prevalent and life-threatening conditions among women worldwide, making early detection and accurate diagnosis essential. In this study, we present a two-stage computer-aided diagnosis framework designed for the automated analysis of breast ultrasound images.

Methods: The proposed system first employs a U-Net-based semantic segmentation model to detect and localize potential tumor regions. The model is trained and evaluated on a comprehensive dataset comprising normal, benign, and malignant cases. For each input image, the U-Net predicts a binary tumor mask; images with no detected tumor regions are classified as normal and excluded from further analysis. In the second stage, images identified as tumor-bearing undergo feature extraction to characterize the shape and morphology of the segmented tumor. Specifically, four handcrafted features-circularity, solidity, eccentricity, and extent-are computed from the predicted masks. These features are then used to train a support vector machine (SVM) classifier that distinguishes between benign and malignant tumors.

Results: The segmentation model achieved an average Mask Intersection over Union% (Mask IoU) score of 91%, while the classification model reached an accuracy of 98.23% on the training set and 97.42% on the test set.

Discussion: Unlike end-to-end deep learning approaches that often function as black boxes with limited clinical interpretability, our two-stage framework combines accurate deep learning-based segmentation with lightweight, handcrafted morphological feature classification using support vector machine. This design achieves high performance while preserving explainability through clinically meaningful shape descriptors, making it particularly suitable for real-world clinical deployment.

Introduction: State-of-the-art finite element human body models (FE HBMs) with active muscle controllers can predict occupant kinematics during braking and steering, which are typical pre-crash interventions aiming at avoiding crashes. Information about the pre-crash occupant kinematics can be used in the design of systems that influence the occupant position in the pre-crash phase and the interaction between the occupant and the restraints in both the pre- and in-crash phases. For driver HBMs, active shoulder muscles are required to reproduce the load between the steering wheel and the torso. The shoulder is the most freely moving joint in the body, and the stability of the shoulder complex depends on muscle activity. Thus, intermuscular load sharing cannot be determined solely from the geometrical location of the muscle because other muscles co-contract to maintain stability during the movement. The aims of this study were to implement a new controller, which introduces load sharing based on physical tests with volunteers, into the shoulder of an FE-HBM and to compare its performance with that of volunteers subjected to dynamic elbow loading.

Methods: A new shoulder muscle controller for use in FE-HBMs was developed, including directionally dependent intermuscular load sharing based on recorded muscle activity from volunteers. The controller performance was evaluated by simulating a volunteer experiment, exposing the subjects to dynamic loading of their elbow in eight directions.

Results: Elbow kinematics were compared between the model and volunteers. A sensitivity study was also performed to evaluate the controller gains. The model successfully predicted peak elbow displacements for all loading directions.

Discussion: One limitation in the current study was the use of a submodel and a simplified experimental setup. In a braking or steering maneuver, head and torso inertia would introduce forces to the shoulder, instead of forces introduced in the elbow as in this study. Because these two scenarios are mechanically similar, a simplified approach was used instead, as this allowed for an experiment where the force magnitude and direction could be easily controlled. Hence, the developed shoulder muscle controller is ready to be implemented and evaluated in a full-body active FE-HBM exposed to driver maneuvers.

This review summarizes the critical role of the Notch signaling pathway in cardiac development, congenital heart disease, and myocardial regeneration. The Notch signaling pathway exerts a profound impact on cardiac health and disease progression by finely regulating the fate determination of cardiac progenitor cells, cardiac morphogenesis, and the proliferation and apoptosis of cardiomyocytes. The article also explores the research progress of the Notch signaling pathway as a potential therapeutic target and looks forward to future research directions.

Bone defects caused by trauma, malignant tumors, and other diseases are common symptoms in orthopedic surgery, and when they exceed the critical size of autologous repair, bone transplantation is required. Artificial bone scaffolds are an effective way to repair large bone defects. An ideal artificial bone scaffold should not only have appropriate mechanical properties and biocompatibility, but also have good osteoinductive properties. This paper proposed a bionic porous structure design method based on Voronoi diagram. In the design process, controlling pore morphology and pore size by adjusting irregularity and porosity. In addition, the designed scaffolds were fabricated through laser powder bed fusion (L-PBF) with Ti-6Al-4V powders. The mechanical characteristics were evaluated by static mechanical simulation with ABAQUS and fatigue tests, and the permeability characteristics were analyzed by fluid simulation with COMSOL and in vitro test. The research results showed that fatigue meet the natural bone implant criteria by controlling the porosity and irregularity. And the mathematical relationship between fatigue characteristics and porosity and irregularity parameters was fitted. It can effectively predict the fatigue characteristics of the scaffold and improve its application in natural bone. At the same time, the designed structure has closer permeability to the natural bone, and was conducive to cell proliferation. Therefore, the porous structure based on Voronoi diagram may have good application potential in the bionic design of bone implants.

Introduction: Nanozymes have emerged as promising substitutes for natural enzymes in chemiluminescent immunoassays, offering distinct catalytic advantages and superior stability. Despite their potential, many conventional nanozymes are constrained by a strong dependence on pH, which limits their effectiveness in certain assay environments. This highlights the need for nanozymes that maintain robust catalytic activity under alkaline conditions and are compatible with luminol-based detection systems.

Methods: In this study, we synthesized platinum nanoparticle-modified Prussian blue cubes (PB@Pt) and evaluated their enzyme-mimicking activity. The catalytic performance of PB@Pt was assessed under both weakly acidic and alkaline conditions. Its ability to enhance the luminol-H₂O₂ chemiluminescence (CL) system was investigated, and the CL signals were compared to those generated by natural horseradish peroxidase (HRP). Based on these properties, a novel CL immunoassay utilizing PB@Pt was developed for the sensitive detection of vascular endothelial growth factor (VEGF).

Results and discussion: The synthesized PB@Pt exhibited high catalase (CAT)-like activity across a broad pH range, including alkaline media. Remarkably, in alkaline conditions, PB@Pt catalyzed the luminol-H₂O₂ reaction, producing CL signals significantly stronger than those achieved with natural HRP. Leveraging this enhanced performance, the established PB@Pt-based CL immunoassay enabled a wide linear detection range, ultra-low detection limits, high specificity, and excellent stability for VEGF quantification. This work introduces a novel strategy for designing CAT-mimicking nanozyme probes, thereby broadening their utility in CL immunoassays and advancing the clinical translation of nanozyme-based diagnostics for applications such as biomarker screening and point-of-care testing (POCT).

Autologous tissue-engineered epithelial sheets (TEESs) are generally transported by dedicated couriers. The cost of this technology can be reduced by using cold-chain courier services, in which the TEESs are subjected to X-rays during security checks. We exposed TEESs to a widely used X-ray luggage-control system to the maximum dose limited by regional regulations. DNA fragmentation, unique variants by exome sequencing, and proliferative capabilities were not altered after X-ray exposure. Thus, repeated exposure to X-ray radiation of luggage-control systems did not induce changes in TEESs genetically or biologically, which should simplify the transport of grafts.

[This corrects the article DOI: 10.3389/fbioe.2023.1156951.].

The meniscus is a fibrocartilaginous tissue essential for load distribution, shock absorption, and knee joint stability, yet its intrinsic healing potential is limited, particularly in the avascular inner zone. Conventional treatments such as partial meniscectomy, repair, or transplantation often fail to restore long-term biomechanical and biological function, underscoring the need for regenerative strategies. Meniscus tissue engineering (TE) has emerged as a promising approach that combines biomaterial scaffolds with stem cells to recreate the structural and functional complexity of the native tissue. This narrative review summarizes recent advances in scaffold design and cell-based therapies for meniscus repair. Natural materials such as collagen, alginate, and silk fibroin provide biocompatibility and bioactivity but lack sufficient mechanical strength, whereas synthetic polymers including PGA, PLA, PLGA, and polyurethane offer tunable degradation and structural reinforcement but are biologically inert. Composite scaffolds that integrate these material classes-through multiphase, gradient, or layered designs-represent a promising strategy to replicate zonal heterogeneity and anisotropic mechanics. On the cellular side, bone marrow-, adipose-, and synovium-derived mesenchymal stem cells have demonstrated potential for zone-specific regeneration, while induced pluripotent stem cells present opportunities for patient-specific therapies but remain limited by safety concerns. Advances in cell seeding strategies, including dynamic perfusion and 3D bioprinting, have further improved scaffold-cell integration. Finally, emerging technologies such as 3D/4D printing, smart responsive biomaterials, controlled drug delivery, dynamic bioreactors, and AI-assisted scaffold design provide new opportunities to overcome persistent challenges of vascularization, mechanical anisotropy, and clinical translation. While significant obstacles remain, the convergence of materials science, stem cell biology, advanced fabrication, and computational modeling offers a promising roadmap toward clinically viable meniscus regeneration.

Background: Magnesium degradation-induced variable fixation plates (MVFPs) offer different fixation modes during fracture healing, but their biomechanical reliability is not well established.

Materials and methods: CT images of femurs from volunteers were used to build a model, and Abaqus software simulated deformation, stress, and relative displacement under various stress conditions. Mechanical tests including vertical loading, four-point bending, torsion, and fatigue were conducted using femur simulation models and suitable magnesium shims were screened.

Results: Finite element analysis showed that under 700N vertical loading, MVFP exhibited 83%-116% of the total deformation, 88%-120% of the maximum stress, and 86%-121% of the average relative displacement compared to locking plate (LP). Under 250N four-point bending, these were 76%-186%, 73%-183%, and 61%-170%, respectively. Under 10Nm torsional moment, they were 102%-109%, 114%-118% (for implants), and 110%-113%, respectively. In vitro biomechanical tests showed that MVFP had greater total and relative displacements but lower axial, four-point bending, and torsional stiffness (81.5%, 68.5%, and 63.9% of LP, respectively). Fatigue testing indicated both LP and MVFP samples endured 100,000 cycles of 700N vertical load without failure. The MVFP with a 0.5 mm shim exhibited superior stiffness and offered greater space for elastic deformation compared to the 1 mm shim.

Conclusion: Although MVFP's stiffness slightly decreases compared to LP after shim degradation, it improves interfragmentary micromotion and reduces stress shielding while maintaining good fatigue resistance. MVFP with 0.5 mm axial micromotion shows promise for further development and clinical application.