Frontiers in Bioengineering and Biotechnology最新文献

Existing Mechanical Insufflation-Exsufflation (MI-E) devices often overlook the impact of cough airflow pressure on mucus clearance, particularly lacking in control over airway pressure during the expiratory phase, which can lead to airway collapse and other types of airway damage. This study optimizes the design of cough assist system and explores the effectiveness of PID and adaptive control methods in regulating airway pressure. The adaptive control method compensates for hose pressure drop by online estimation of the ventilatory hose characteristics. It achieves precise tracking of target pressure and ensures the generation of peak flow rates effective for mucus clearance, even in the absence of known patient lung physiological states and unknown hose leakage parameters. Through a series of comparative experiments, this paper confirms the significant advantages of adaptive control in reducing oscillations and overshoot, capable of more stable and precise airway pressure adjustments. This improved control strategy not only enhances clinical safety but also significantly improves therapeutic outcomes and reduces the risk of complications. The findings indicate that the revamped cough assist system, employing an adaptive control strategy, can effectively prevent airway damage during assisted coughing, offering a safer and more effective sputum clearance solution for critically ill patients with expectoration disorders.

Objective: To investigate the neuromuscular activity characteristics of Tai Chi athletes and identify optimal muscle synergy patterns.

Method: Data were collected from 12 elite Tai Chi athletes using a Vicon motion capture system, a Kistler 3D force plate, and a Noraxon surface electromyography system. Muscle synergy patterns were extracted using Non-negative Matrix Factorization.

Results: Four muscle synergy patterns were identified in each of the three phases of the leg stirrup movement, with the optimal synergy pattern for each phase determined as follows: knee lift phase: rectus femoris and vastus lateralis of the right leg; extension phase: rectus femoris, vastus lateralis, biceps femoris, and medial gastrocnemius of the right leg; recovery phase: rectus femoris, vastus lateralis, and medial gastrocnemius of the right leg. These patterns explain the muscle coordination activities for each phase.

Conclusion: This study identified the optimal muscle synergy patterns for each phase, supporting the fluidity and force generation of the leg stirrup movement. This provides Tai Chi athletes with a more efficient way to exert strength and maintain balance.

Background: The success of using bone mineral density and/or FRAX to predict femoral osteoporotic fracture risk is modest since they do not account for mechanical determinants that affect bone fracture risk. Computed Tomography (CT)-based geometric, densitometric, and finite element-derived biomarkers have been developed and used as parameters for assessing fracture risk. However, to quantify these biomarkers, segmentation of CT data is needed. Doing this manually or semi-automatically is labor-intensive, preventing the adoption of these biomarkers into clinical practice. In recent years, fully automated methods for segmenting CT data have started to emerge. Quantifying the accuracy, robustness, reproducibility, and repeatability of these segmentation tools is of major importance for research and the potential translation of CT-based biomarkers into clinical practice.

Methods: A comprehensive literature search was performed in PubMed up to the end of July 2024. Only segmentation methods that were quantitatively validated on human femurs and/or pelvises and on both clinical and non-clinical CT were included. The accuracy, robustness, reproducibility, and repeatability of these segmentation methods were investigated, reporting quantitatively the metrics used to evaluate these aspects of segmentation. The studies included were evaluated for the risk of, and sources of bias, that may affect the results reported.

Findings: A total of 54 studies fulfilled the inclusion criteria. The analysis of the included papers showed that automatic segmentation methods led to accurate results, however, there may exist a need to standardize reporting of accuracy across studies. Few works investigated robustness to allow for detailed conclusions on this aspect. Finally, it seems that the bone segmentation field has only addressed the concept of reproducibility and repeatability to a very limited extent, which entails that most of the studies are at high risk of bias.

Interpretation: Based on the studies analyzed, some recommendations for future studies are made for advancing the development of a standardized segmentation protocol. Moreover, standardized metrics are proposed to evaluate accuracy, robustness, reproducibility, and repeatability of segmentation methods, to ease comparison between different approaches.

Chronic and infected wounds, particularly those caused by bacterial infections, present significant challenges in medical treatment. This study aimed to develop a novel nanoparticle formulation to enhance wound healing by combining antimicrobial and photothermal therapy using albumin as a carrier for Tanshinone IIA and the near-infrared photothermal agent IR780. The nanoparticles were synthesized to exploit the antimicrobial effects of Tanshinone IIA and the photothermal properties of IR780 when exposed to near-infrared laser irradiation. Characterization of the nanoparticles was performed using Transmission Electron Microscopy (TEM) and spectroscopic analysis to confirm their successful synthesis. In vitro antibacterial activity was evaluated using cultures of methicillin-resistant Staphylococcus aureus (MRSA), and in vivo efficacy was tested in a mouse model of MRSA-infected wounds. Wound healing progression was assessed over 16 days, with statistical analysis performed using two-way ANOVA followed by Tukey's post-hoc test. The nanoparticles demonstrated significant photothermal properties, enhancing bacterial eradication and promoting the controlled release of Tanshinone IIA. In vitro studies showed superior antibacterial activity, especially under photothermal activation, leading to a substantial reduction in bacterial viability in MRSA cultures. In vivo, nanoparticle treatment combined with near-infrared laser irradiation significantly improved wound closure rates compared to controls and treatments without photothermal activation. By the 16th day post-treatment, significant improvements in wound healing were observed, highlighting the potential of the combined photothermal and pharmacological approach. These findings suggest that albumin-loaded nanoparticles containing Tanshinone IIA and IR780, activated by near-infrared light, could offer an effective therapeutic strategy for managing chronic and infected wounds, promoting both infection control and tissue repair.

Introduction: Mesenchymal stem cell-derived extracellular vesicles (MSC EVs) hold significant promise for regenerative medicine. Lyophilization of EVs significantly enhances their translational potential. While, lyophilized EVs have been studied from a morphological perspective, the functional stability of these EVs and their cargo following lyophilization need to be mechanistically investigated.

Methods: In this study, we investigated the functional and mechanistic bioactivity of fresh versus lyophilized MSC EVs, specifically focusing on functionally engineered osteoinductive EVs developed in our laboratory. We utilized dimethyl sulfoxide (DMSO) as a cryoprotectant and conducted pathway-specific in vitro and in vivo experiments to assess the stability and functionality of the EVs.

Results: Our findings show that using DMSO as a cryoprotectant before lyophilization preserves the functional stability of engineered MSC EVs. In vitro experiments demonstrated that the endocytosis, cargo integrity, and pathway-specific activity of lyophilized EVs were maintained when DMSO was used as the cryoprotectant. Additionally, in vivo bone regeneration studies revealed that the functionality of cryoprotected lyophilized EVs was comparable to that of freshly isolated EVs.

Discussion: These results provide a foundation for evaluating the functionality of lyophilized EVs and exploring the use of DMSO and other cryoprotectants in EV-based therapies. Understanding the functionality of lyophilized naïve and engineered EVs from a mechanistic perspective may enhance validation approaches for tissue regeneration strategies.

[This corrects the article DOI: 10.3389/fbioe.2023.1171450.].

Introduction: Murine models are used to test the effect of anti-osteoporosis treatments as they replicate some of the bone phenotypes observed in osteoporotic (OP) patients. The effect of disease and treatment is typically described as changes in bone geometry and microstructure over time. Conventional assessment of geometric changes relies on morphometric scalar parameters. However, being correlated with each other, these parameters do not describe separate fractions of variations and offer only a moderate insight into temporal changes.

Methods: The current study proposes a novel image-based framework that employs deformable image registration on in vivo longitudinal images of bones and Principal Component Analysis (PCA) for improved quantification of geometric effects of OP treatments. This PCA-based model and a novel post-processing of score changes provide orthogonal modes of shape variations temporally induced by a course of treatment (specifically in vivo mechanical loading).

Results and discussion: Errors associated with the proposed framework are rigorously quantified and it is shown that the accuracy of deformable image registration in capturing the bone shapes (∼1 voxel = 10.4 μm) is of the same order of magnitude as the relevant state-of-the-art evaluation studies. Applying the framework to longitudinal image data from the midshaft section of ovariectomized mouse tibia, two mutually orthogonal mode shapes are reliably identified to be an effect of treatment. The mode shapes captured changes of the tibia geometry due to the treatment at the anterior crest (maximum of 0.103 mm) and across the tibia midshaft section and the posterior (0.030 mm) and medial (0.024 mm) aspects. These changes agree with those reported previously but are now described in a compact fashion, as a vector field of displacements on the bone surface. The proposed framework enables a more detailed investigation of the effect of disease and treatment on bones in preclinical studies and boosts the precision of such assessments.

Purpose: To ascertain the relationship between cervical curvature, neck muscle activity and neck disability in patients with chronic nonspecific neck pain (CNNP).

Methods: Ninety participants (mean age = 27.2, female/male ratio = 7/2) with CNNP volunteered. The Neck Disability Index was used to assess neck disability. To indicate the electromyographic characteristics of the axioscapular muscles, the root mean squares and median frequencies of upper trapezius and levator scapula were used. Cervical curvature was measured with a flexible ruler.

Results: Disability of the neck was significantly correlated with curvature (r = -0.599, p < 0.001), upper trapezius root mean square (RMS) (r = 0.694, p < 0.001) and levator RMS (r = 0.429, p < 0.05). Multiple regression analysis produced a significant predictive equation that could predict disability: 33.224- 0.515 × Curvature + 0.156 × Levator RMS - 0.059 × Upper trapezius median frequency + 0.636 × upper trapezius RMS + 0.020 × levator median frequency, with R² = 0.622.

Conclusion: Cervical curvature as well as different axioscapular muscle activity were found to be related to level of disability. These findings have implications for clinical management of CNNP.

Bone defects can arise from trauma or pathological factors, resulting in compromised bone integrity and the loss or absence of bone tissue. As we are all aware, repairing bone defects is a core problem in bone tissue engineering. While minor bone defects can self-repair if the periosteum remains intact and normal osteogenesis occurs, significant defects or conditions such as congenital osteogenesis imperfecta present substantial challenges to self-healing. As research on mesenchymal stem cell (MSC) advances, new fields of application have emerged; however, their application in orthopedics remains one of the most established and clinically valuable directions. This review aims to provide a comprehensive overview of the research progress regarding MSCs in the treatment of diverse bone defects. MSCs, as multipotent stem cells, offer significant advantages due to their immunomodulatory properties and ability to undergo osteogenic differentiation. The review will encompass the characteristics of MSCs within the osteogenic microenvironment and summarize the research progress of MSCs in different types of bone defects, ranging from their fundamental characteristics and animal studies to clinical applications.