BackgroundBioprosthetic aortic valves (BPAV) have been increasingly used for surgical aortic valve replacement (SAVR), but long-term complications associated with structural valve deterioration remain a concern. The structural behaviour of the valve and its surrounding haemodynamics play a key role in the long-term outcome of SAVR, and these can be quantitively analysed by means of fluid-structure interaction (FSI) simulation. The aim of this study was to develop a fully coupled FSI model for patient-specific analysis of BPAV haemodynamics.MethodsUsing the Edwards Magna Ease valve as an example, the workflow included reconstruction of the aortic root from CT images and the creation of valve geometric model based on available measurements made on the device. Two-way fully coupled FSI simulations were performed under patient-specific flow conditions derived from 4D flow magnetic resonance imaging (MRI), the latter also provided data for model validation.ResultsThe simulation results were in good agreement with haemodynamic features extracted from 4D flow MRI and relevant data in the literature. Furthermore, the FSI model provided additional information that cannot be measured in vivo, including wall shear stress and its derivatives on the valve leaflets and in the aortic root.ConclusionThe FSI workflow presented in this study offers a promising tool for patient-specific assessment of aortic valve haemodynamics, and the results may help elucidate the role of haemodynamics in structural valve deterioration.

Carbon dots (CDs) are a class of nanobiomaterials with significant potential in bone regeneration. Their excellent biocompatibility, tunable fluorescence, high stability, low toxicity, and abundant functional groups make CDs promising candidates for efficient drug delivery and bone tissue regeneration. CDs contribute to targeted drug release, enhance osteogenic differentiation, and interact with cellular components to facilitate bone formation. Recent research highlights the roles of CDs in scaffold-based approaches, offering controlled drug delivery and real-time bioimaging capabilities. This review provides a comprehensive overview of CDs in bone regeneration, with a focus on their synthesis, functionalization, and biomedical applications. It begins by exploring CD synthesis methods, physicochemical properties, and mechanisms of action. Next, it discusses CD-based drug delivery systems and their applications in bone regeneration. Finally, the review highlights the challenges and future perspectives in optimizing CDs for enhanced therapeutic outcomes.

BackgroundHyperlipidemia is known to impair endothelial function. We have recently shown that hyperlipidemia also blunts native post-ischemic capillary enlargement that is important for efficient skeletal muscle recovery from ischemia as it supports the recovery of arterial driving pressure and through intussusception increases capillary density. The correction of capillary reactivity under hyperlipidemia could, therefore, improve post-ischemic skeletal muscle recovery. This study tested the ability of adenoviral (Ad) vascular endothelial growth factor (VEGF) gene therapy to rescue capillary enlargement and improve post-ischemic muscle repair in hyperlipidemic mice.MethodsAdVEGF or AdLacZ-control vector were delivered into the calf muscles of aged, hyperlipidemic LDLR−/−ApoB100/100 mice (n = 58) after induction of acute ischemia. The effects of AdVEGF on capillary phenotype, tissue edema, restoration of blood flow parameters, microvascular hemoglobin oxygenation and tissue damage/regeneration were evaluated using immunohistological analyses, magnetic resonance imaging, contrast-enhanced ultrasound imaging, photoacoustic imaging and histological analyses, respectively, up to 29 days after induced ischemia and gene transfer.ResultsIt was found that AdVEGF gene therapy was able to promote capillary enlargement (P < 0.05) that led to recovery of arterial driving pressure in ischemic LDLR−/−ApoB100/100 muscles. However, capillary enlargement induced by AdVEGF in the hyperlipidemic mice was delayed, had a long-lasting effect (P < 0.05) and did not promote intussusception. Instead, side-effects of VEGF-induced capillary enlargement, i.e., tissue edema (P < 0.01) and subsequently delayed blood flow recovery (P < 0.05), aggravated ischemic tissue damage (P < 0.01).ConclusionHyperlipidemia or old age did not seem to impair AdVEGF-induced capillary enlargement. However, regarding the side-effects of capillary enlargement, therapies trying to promote post-ischemic skeletal muscle recovery through angiogenesis should consider not only capillary size or density but also timing and dynamics of the capillary changes.

Indocyanine green (ICG) is a small molecule approved by the U.S. Food and Drug Administration (FDA) for liver function imaging and angiography. ICG can be used not only for near-infrared imaging but also for photodynamic and photothermal therapy. However, the hydrophilicity of ICG leads to a relatively short blood circulation time, and it is easily cleared by organs such as the liver. Moreover, it lacks the targeting ability to the diseased sites. By using the natural porous metal-organic frameworks (MOFs) as the carrier, high-efficiency loading of ICG molecule can be achieved, which has significantly broadened its biomedical applications. This review comprehensively summarizes the research work in recent years regarding the utilization of MOF as a carrier to load ICG in the bioapplication such as malignant cancer inhibition, antibacterial treatment, and the treatment of Alzheimer’s disease. It focuses on summarizing the design concepts of different types of MOF carriers for loading ICG molecules. Meanwhile, it emphasizes the enhanced therapeutic effects achieved when multiple treatment modalities realized through post-modification are combined with ICG-mediated phototherapy. It is expected that through the summary of this review, the biomedical applications of ICG in the field of disease treatment can be further promoted.

IntroductionThe conventional (CDL) and sumo (SDL) deadlifts are two fundamental techniques used in competitive lifting and as effective exercises for strengthening the knee and hip muscles. This study aims to investigate their biomechanical differences through a comprehensive analysis of joint kinematics, joint kinetics, and muscle activation.Materials and MethodsThirty experienced male lifters performed both CDL and SDL at 85% of their one repetition maximum (1-RM). Lower limb joint range of motion (ROM), internal joint moments, and muscle activation of key lower limb and spinal muscles were recorded and analyzed. Paired t-tests and Statistical parametric mapping (SPM) were used to compare parameters between lifting techniques (p < 0.025).ResultsSDL showed greater ROM in the frontal and transverse planes, particularly at the hip and knee, whereas CDL involved greater hip flexion and ankle dorsiflexion. CDL generated higher hip extension moments, while SDL produced greater frontal and transverse plane joint moments at the hip and knee. Additionally, SDL induced a greater ankle inversion moment. In the transverse plane, ankle moments were higher in CDL during phase 1 and became greater in SDL in phase 2. Regarding EMG peak values, the biceps femoris exhibited greater activation in CDL across both phases. The tibialis anterior and the erector spinae thoracis demonstrated greater activation in CDL during phase 1 and phase 2, respectively. Conversely, the vastus lateralis exhibited higher peak activation in SDL, but only during phase 1.ConclusionCDL is more effective for targeting posterior chain, particularly the hip extensors, while SDL emphasizes anterior chain involvement and induces greater mediolateral stabilization demands. SDL may be particularly beneficial for knee reinforcement and increases frontal plane demands, supporting its relevance in rehabilitation contexts that require enhanced mediolateral stability. These findings highlight the importance of selecting the appropriate deadlift technique according to specific training or rehabilitation objectives.

ObjectiveTo investigate and compare the effects of mental fatigue (MF) on biomechanical characteristics associated with non-contact anterior cruciate ligament injury (NC-ACLI) in male college students during stop-jump (SJ) and single-leg landing (SL), and whether it increases NC-ACLI risk.MethodsMF was induced by a 45-min Stroop task and measured using the visual analogue scale for MF (VAS-MF), while motion capture, force platforms, and surface electromyography (SEMG) evaluated biomechanical variables before and after MF induction in thirty-six subjects. Kinematic, kinetic, and SEMG data were analyzed using two-factor repeated measures ANOVA and rank-based nonparametric ANOVA.ResultsFollowing MF induction, VAS-MF scores increased significantly. The ANOVA showed that in both maneuvers, peak vertical ground reaction force increased, while ankle dorsiflexion angle and knee flexion moment decreased. In SJ, knee flexion and internal rotation angles and internal rotation moment decreased, whereas knee abduction moment increased; these parameters did not change significantly in SL. The median frequency of biceps femoris SEMG decreased in SL but remained unchanged in SJ. No significant differences were found in hip flexion angle, knee adduction angle, or SEMG measures of rectus femoris, tibialis anterior, gastrocnemius lateral head, or biceps femoris root mean square.ConclusionMF partly influences NC-ACLI biomechanics and increases risk in both maneuvers—more pronounced in SJ than in SL—potentially due to MF’s impact on central nervous system function, cognition, and attention. MF should be considered in NC-ACLI prevention strategies.

IntroductionIn cases of hip joint damage, such as osteoarthritis (OA), rheumatoid arthritis (RA), avascular necrosis, or hip fractures, total hip arthroplasty (THA) is a critical surgical intervention. For individuals whose hip abnormalities stem from congenital issues, injuries, or previous operations, this procedure can encounter considerable obstacles, including complex bone defects, soft tissue deficiencies, and an increased risk of infections, which may result in poor alignment, joint instability, and higher need for revisions. This study explored the application of personalized, three-dimensional (3D)-printed porous tantalum buttresses designed specifically for acetabular reconstruction. Renowned for its compatibility with human biology, tantalum facilitates superior integration with natural bone.MethodsThe development process started with the generation of meticulous computer-aided design (CAD) models, derived from preoperative imaging techniques such as computed tomography (CT) scans and (magnetic resonance imaging) MRIs, which allowed for the creation of components precisely matching each patient’s unique anatomical structure. The 3D-printed porous tantalum buttresses were made by cutting-edge additive manufacturing methods. The porosity of the tantalum structure promoted the growth of new bone tissue into the implant, improving its stability and durability. During surgeries, the buttress was positioned to reconstruct the acetabulum, laying a solid foundation for the artificial hip joint.ResultsThe results of our study showed that all surgeries were successfully completed with no significant vascular or nerve damage. Postoperative evaluations showed that the buttress had excellent biomechanical function and firm fixation, with a large amount of bone ingrowth, improving the fitness and performance of the implant while reducing the possibility of subsequent problems such as loosening or dislocation.DiscussionThis innovative technique has great potential in clinical practice for better outcomes and quality of life for patients with complex hip deformities.

PurposeThis study aimed to evaluate the effect of the degree of facet joint resection under the combined action of large-channel endoscopy and visualized trephines on lumbar biomechanics.MethodsThe original CT data of a healthy male volunteer were selected. An L3-5 lumbar spine model, M0, was established via the three-dimensional finite element method. Different degrees of resection of the superior articular process of L4 were simulated via a visualized trephine during the operation, and six models were established (M1: tip resection; M2: resection of the ventral 1/3; M3: resection of the ventral 1/2; M4: resection of the ventral 2/3; M5: resection of the ventral 3/4; and M6: complete resection). Loads were applied to the model to simulate six motions of flexion, extension, left/right lateral bending, and left/right rotation. The stress distributions of the vertebral body, intervertebral disc and articular cartilage of the L3-4 segment and adjacent segments were observed.ResultsCompared with M0, L4 vertebral stress was elevated in the M1 model, L4 vertebral stress was reduced in the M2 and M3 models, and L4 vertebral stress was significantly elevated in the M4, M5, and M6 models (P < 0.05). Compared with M0, the differences in the L3 vertebral body, L5 vertebral body, L3-4 disc, and L4-5disc stresses were not statistically significant (P > 0.05) in the M1, M2, and M3 models, whereas the stresses were significantly higher (P < 0.05) in the M4, M5, and M6 models. Compared with M0, the difference in L3-4 facet joints stress between the M1, M2 and M3 models was not statistically significant (P > 0.05), whereas the L3-4 facet joints stress between the M4, M5 and M6 models were significantly higher (P < 0.05), with a greater increase on the left facet joint.ConclusionWhen more than half of the superior articular process of L4 is resected under large-channel endoscopy, the stress on the vertebral body, intervertebral disc and articular cartilage of the L3-4 segment increases, which may cause iatrogenic instability but has no significant effect on the stress on the vertebral body or intervertebral disc of adjacent segments.

Bioprinting incorporates printable biomaterials into 3D printing to create intricate tissues that maintain a defined 3D structure while supporting the survival and function of relevant cell types. A major challenge in 3D bioprinting is tuning material properties to ensure compatibility with different types of cells, while accurately mimicking the physiological microenvironment. Developing novel bioinks tailored to specific applications can help address this challenge by combining various materials and additives to tune the bioink formulation. Microspheres - small spherical particles - can incorporate drugs or growth factors to enable their controlled release, encapsulate cells to provide protection during printing, and provide structural reinforcement to tune mechanical properties and enable complex architectures. The particles range in size from 1 to 1000 μm and can be tuned to meet desired functions by optimizing their mode of production and the materials used for fabrication. This review presents an overview of microsphere production methods and considerations for optimizing the production process. It then summarizes how microspheres have been used to date in bioprinting applications. Finally, the existing challenges associated with the creation and use of microspheres are discussed along with avenues for future research.

IntroductionCardiac fibroblasts deposit and turnover the extracellular matrix in the heart, as well as secrete soluble factors that play critical roles in development, homeostasis, and disease. Coculture of CFs and human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) enhances CM mechanical output, yet the mechanism remains unclear.MethodsHere, we use an in vitro engineered platform to compare the effects on CM mechanical function of direct CM-CF Coculture and soluble signaling alone through CF Conditioned Medium to a CM Only monoculture. Mechanical analysis is performed using digital image correlation and custom software to quantify the coordination and organization of CM contractile behavior.ResultsCM-CF Coculture induces larger CM contractile strains, and an increased rate of spontaneous contraction compared to CM Only. Additionally, CM-CF Cocultures have increased contractile anisotropy and myofibril alignment and faster kinetics. The paracrine effects of fibroblast conditioned medium (FCM) are sufficient to induce larger contractile strains and faster contraction kinetics with these effects remaining after the removal of FCM. However, FCM does not influence CM spontaneous rate, contractile alignment, anisotropy, or relaxation kinetics compared to CM Only control.DiscussionThese data suggest that hiPSC-CFs exert dynamic and multifactorial effects on the mechanical function of hiPSC-CMs and highlight the importance of CFs in both the native heart and in vitro cardiac models. Further, this work demonstrates the applicability of the coculture–conditioned medium–monoculture paradigm to decouple the effects of paracrine factor and cell-cell signaling on hiPSC-CM mechanical function and maturation.