bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D SPHEROID CULTURE OF CHONDROCYTES TO STUDY THE INTERACTION OF CELLS AT THE CHONDRO-OSSEOUS BORDER OF ENCHONDRAL OSSIFICATION
Authors: Enderami E. , Timmen M. , Stange R. 
Published: November 2024

IntroductionCartilage comprises chondrocytes and extracellular matrix. The matrix contains different collagens, proteoglycans, and growth factors produced by chondroprogenitor cells that differentiate from proliferating to hypertrophic chondrocytes. In vitro chondrocyte growth is challenging due to differences in behaviour between 2D and 3D cultures. Our aim is to establish a murine 3D spheroid culture method using chondrocytes to study the complex interaction of cells on the chondro-osseous border during enchondral ossification.MethodPrimary chondrocytes were isolated from the knee of WT new-born mice and used to form 10,000 cell number spheroids. We used the ATDC5-chondrocyte cell line as an alternative cell type. Spheroids were observed for 7, 14, and 21 days before embedding in paraffin for slicing. Alcian blue staining was performed to identify proteoglycan positive areas to prove the formation of extracellular matrix in spheroids. Collagen type 2, and Collagen type X expression were analyzed via quantitative real-time PCR and immunohistochemistry.ResultAlcian blue staining showed increasing matrix formation from day 7 to day 14 and proliferative chondrocytes at early time points. Both cell types showed increasing mRNA expression of Collagen type 2 from day 7 to day 21. Collagen type X positive staining starting from day 14 on confirmed the development of hypertrophic stage of chondrocytes. ATDC5 cells exhibited a slower progression in chondrogenic differentiation compared to primary chondrocytes.ConclusionIn chondrocyte spheroids, we observed proceeding differentiation of chondrocytes reaching hypertrophic phase. Primary chondrocytes showed faster development than ATDC5 cell line. Overall, spheroid culture of chondrocytes could be a good basis to study the interaction of different cells types of the chondro-osseous border by combination of chondrocytes with e.g., endothelial cells and osteoblasts within the spheroid. Those organoid cultures might also help to reduce animal experiments in the future, by mimicking complex regeneration procedures like bone growth or fracture healing.DFG(German Research Foundation)
BONE-TO-CARTILAGE INTERFACES: ADVANCING 3D-PRINTED NANOCOMPOSITES FROM NATURALLY DERIVED LOW-VISCOUS BIOMATERIALS
Authors: Maia J. , Bilo M. , Silva A. S. , Sobreiro-Almeida R. , Mano J. 
Published: November 2024

IntroductionInk engineering can advance 3D-printability for better therapeutics, with optimized proprieties. Herein, we describe a methodology for yielding 3D-printable nanocomposite inks (NC) using low-viscous matrices, via the interaction between the organic and inorganic phases by chemical coupling.MethodNatural photocurable matrices were synthesized: a protein – bovine serum albumin methacrylate (BSAMA), and a polysaccharide – hyaluronic acid methacrylate (HAMA). Bioglass nanoparticles (BGNP) were synthesized and functionalized via aminosilane chemistry. The functionalization of BSAMA, HAMA, and BGNP were quantified via NMR. To arise extrudable inks, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-Hydroxysuccinimide (NHS) chemistry was used to link innate carboxylic groups of BSAMA/HAMA and amine-functionalized BGNP. Different crosslinker and BGNP amounts were tested. Visible light photopolymerization is performed, using lithium phenyl-2,4,6-trimethylbenzoylphosphinate. The NC's rheological, mechanical, and biological behavior was evaluated before 3D extrusion printability.ResultAll composite formulations effectively immobilized and homogeneously dispersed the BGNP, turning low-viscous materials (< 1 Pa) into shear-thinning formulations with tunable increased elastic/viscous moduli (50-500 Pa). More pronounced increments were found with increasing EDC/NHS and BGNP concentrations. The resulting inks produce robust and stable scaffolds successfully retrieved after post-print photocrosslinking (1-5 kPa). Bioactivity in simulated body fluid and in vitro assays using adipose-derive stem cells revealed a similar calcium/phosphate ratio to that of hydroxyapatite, and increased viability and metabolic activity. BSAMA and HAMA demonstrated distinct natures not only in printability but also in overall cellular performance and mechanical properties, making these ideal for interfacial tissue engineering.ConclusionThis strategy demonstrated being effective and reproducible to advance nanocomposites for 3D printing using different types of biomaterials. Further, we envision using both inks to produce hierarchical constructs via extrusion printing, better mimicking bone-to-cartilage interfaces.AcknowledgementsFCT grants (DOI:10.54499/2022.04605.CEECIND/CP1720/CT0021), (BI/UI89/10303/2022), (PRT/BD/154735/2023); EU's Horizon 2020 research and innovation programs InterLynk (Nº953169) and SUPRALIFE (Nº101079482) projects; CICECO-Aveiro Institute of Materials projects (DOI:10.54499/UIDB/50011/2020), (DOI:10.54499/UIDP/50011/2020), and (DOI:10.54499/LA/P/0006/2020), financed by FCT/MCTES(PIDDAC).
ACCURATE PREDICTION OF PEDICLE SCREW LOOSENING USING HOMOGENIZED NON-LINEAR FINITE ELEMENT MODELS
Authors: Mischler D. , Kessler F. , Zysset P. , Varga P. 
Published: November 2024

IntroductionPedicle screw loosening in posterior instrumentation of thoracolumbar spine occurs up to 60% in osteoporotic patients. These complications may be alleviated using more flexible implant materials and novel designs that could be optimized with reliable computational modeling. This study aimed to develop and validate non-linear homogenized finite element (hFE) simulations to predict pedicle screw toggling.MethodTen cadaveric vertebral bodies (L1-L5) from two female and three male elderly donors were scanned with high-resolution peripheral quantitative computed tomography (HR-pQCT, Scanco Medical) and instrumented with pedicle screws made of carbon fiber-reinforced polyether-etherketone (CF/PEEK). Sample-specific 3D-printed guides ensured standardized instrumentation, embedding, and loading procedures. The samples were biomechanically tested to failure in a toggling setup using an electrodynamic testing machine (Acumen, MTS) applying a quasi-static cyclic testing protocol of three ramps with exponentially increasing peak (1, 2 and 4 mm) and constant valley displacements. Implant-bone kinematics were assessed with a stereographic 3D motion tracking camera system (Aramis SRX, GOM). hFE models with non-linear, homogenized bone material properties including a strain-based damage criterion were developed based on intact HR-pQCT and instrumented 3D C-arm scans. The experimental loading conditions were imposed, the maximum load per cycle was calculated and compared to the experimental results. HR-pQCT-based bone volume fraction (BV/TV) around the screws was correlated with the experimental peak forces at each displacement level.ResultThe nonlinear hFE models accurately (slope = 1.07, intercept = 0.2 N) and precisely (R2 = 0.84) predicted the experimental peak forces at each displacement level. BV/TV alone was a weak predictor (R2<0.31).ConclusionThe hFE models enable fast design iterations aiming to reduce the risk of screw loosening in low-density vertebrae. Improved flexible implant designs are expected to contribute to reduced complication rates in osteoporotic patients.
CHONDROGENESIS IN 3D-PRINTED HYDROGEL SCAFFOLDS SUPPLEMENTED WITH BIOACTIVE GLASS SPHERES
Authors: Gögele C. L. , Fleischmann N. , Müller S. , Liesenberg T. , Pizzadili G. , Wiltzsch S. , Gerdes T. , Schaefer-Eckart K. , Lenhart A. , Schulze-Tanzil G. 
Published: November 2024

IntroductionArticular cartilage has a low self-regeneration capacity. Cartilage defects have to be treated to minimize the risk of the onset of osteoarthritis. Bioactive glass (BG) is a promising source for cartilage tissue engineering. Until now, conventional BGs (like BG1393) have been used, mostly for bone regeneration, as they are able to form a hydroxyapatite layer and are therefore, less suited for cartilage reconstruction. The aim of this study is to study the effect of 3D printed hydrogel scaffolds supplemented with spheres of the BG CAR12N to improve the chondrogenesis of mesenchymal stem cells (MSCs).MethodBased on our new glass composition (CAR12N), small BG spheres (25-40 µm) were produced and mixed with hydrogel and primary human (h) MSCs. Grid printed scaffolds were cultivated up to 21 days in expansion or chondrogenic differentiation medium. Macroscopical images of the scaffolds were taken to observe surface changes. Vitality, DNA and sulfated glycosaminoglycan (GAG) content was semiquantitatively measured as well as extracellular matrix gene transcription.ResultIt was possible to print grid shaped hydrogel scaffolds with BG spheres and hMSCs. No significant changes in scaffold shape, surface or pore size were detected after 21 days in culture. The BG spheres were homogeneously distributed inside the grids. Vitality was significantly higher in grids with CAR12N spheres in comparison to those without. The DNA content remained constant over three weeks, but was higher in the sphere containing scaffolds than in those without BG spheres. GAG content in the grids increased not only with additional cultivation time but especially in grids with BG spheres in chondrogenic medium. Aggrecan and type II collagen gene expression was significantly higher grids cultured in the chondrogenic differentiation medium.ConclusionThis developed 3D model, is very interesting to study the effect of BG on hMSCs and to understand the influence of leaking ions on chondrogenesis.
BIOMECHANICAL ASSESSMENT OF A NOVEL PEDICLE SCREW SYSTEM USING FINITE ELEMENT ANALYSIS
Authors: Einafshar M. M. , Massaad E. , Kiapour A. 
Published: November 2024

IntroductionThe biomechanical behavior of lumbar spine instrumentation is critical in understanding its efficacy and durability in clinical practice. In this study, we aim to compare the biomechanics of the lumbar spine instrumented with single-level posterior rod and screw systems employing two distinct screw designs: paddle screw versus conventional screw system.MethodA fully cadaveric-validated 3D ligamentous model of the lumbopelvic spine served as the foundation for our comparative biomechanical analysis1. To simulate instrumentation, the intact spine was modified at the L4L5 level, employing either paddle screws or standard pedicle screws (SPS). The implants were composed of Ti-6AL-4V. Fixation at the S1 ensured consistency across loading scenarios. Loading conditions included a 400-N compressive load combined with a 10 N.m pure bending moment at the level of L1, replicating physiological motions of flexion-extension, lateral bending and axial rotation. We extracted data across various scenarios, focusing on the segmental range of motion at both implanted and adjacent levels.ResultIn the flexion of L4L5, the applied force ranged from -29.2 to 29.3 N in the paddle screw, while it ranged from -25 to 25 N in the PS system. Similarly, the extension of L4L5 ranged from -3.1 to 2.6 N in the paddle and ranged from -4.5 to 3.9 N in the SPS system. In terms of stress distributions on the screw, stress concentrations decreased in several cases in the paddle design compared to the SPS systems. Top of FormConclusionThe paddle screw enhanced the range of motion overall in both the upper adjacent segment (L3L4) and the lower adjacent segment (L5S1) compared to the conventional SPS system. The stability of the aimed segment was increased by 33% on average with the paddle screw compared to conventional PS. Increasing the stability of the host segment decreases the possibility of non-union and the rate of fusion failure 2.
MATRIX MAYHEM: INVESTIGATING THE EFFECTS OF PERICELLULAR PROTEOLYSIS ON BIOMECHANICAL PROPERTIES AND CALCIUM SIGNALLING IN ARTICULAR CARTILAGE
Authors: Nieuwstraten J. , Guilak F. , Danalache M. 
Published: November 2024

IntroductionWithin articular cartilage, chondrocytes reside within the pericellular matrix (PCM), collectively constituting the microanatomical entity known as a chondron. The PCM functions as a pivotal protective shield and mediator of biomechanical and biochemical cues. In the context of Osteoarthritis (OA), enzymatic degradation of the PCM is facilitated by matrix metalloproteinases (MMPs). This study delves into the functional implications of PCM structural integrity decline on the biomechanical properties of chondrons and impact on Ca2+ signaling dynamics.MethodChondrons isolated from human cartilage explants were incubated with activated MMP-2, -3, or -7. Structural degradation of the pericellular matrix (PCM) was assessed by immunolabelling (collagen type VI and perlecan, n=5). Biomechanical properties of chondrons (i.e. elastic modulus (EM)) were analyzed using atomic force microscopy (AFM). A fluorescent calcium indicator (Fluo-4-AM) was used to record and quantify the intracellular Ca2+ influx of chondrons subjected to single cell mechanical loading (500nN) with AFM (n=7).ResultEach of the three MMPs disrupted the structural integrity of the PCM, leading to attenuated fluorescence intensity for both perlecan and collagen VI. A significant decrease of EM was observed for all MMP groups (p<0.005) with the most notable decrease observed for MMP-2 and MMP-7 (p<0.001). In alignment with the AFM results, there was a significant alteration in Ca2+ influx observed for all MMP groups (p<0.05), in particular for MMP-2 and MMP-7 (p<0.001).ConclusionProteolysis of the PCM by MMP-2, -3, and -7 not only significantly alters the biomechanical properties of articular chondrons but also affects their mechanotransduction profile and response to mechanical loading, indicating a close interconnection between these processes. These findings underscore the influence of an intact pericellular matrix (PCM) in protecting cells from high stress profiles and carry implications for the transmission of mechanical signaling during OA onset and progression.
TIE2-ENHANCED NUCLEUS PULPOSUS CELL-DERIVED EXTRACELLULAR VESICLES ENHANCE DEGENERATIVE DISC CELL VIABILITY IN VITRO
Authors: Ambrosio L. , Schol J. , Fernández C. R. , Papalia R. , Vadalà G. , Denaro V. , Sakai D. 
Published: November 2024

IntroductionIntervertebral disc degeneration (IDD) is a progressive process affecting all disc tissues, namely the nucleus pulposus (NP), annulus fibrosus (AF), and cartilaginous endplates (CEPs). Several cell-based therapies have been proposed to replenish the disc cell population and promote tissue regeneration. However, cell-free therapeutics have been increasingly explored due to potentially higher advantages and cost-effectiveness compared to cell transplantation. Recently, extracellular vesicles (EVs) isolated from healthy Tie2+-NP cells (NPCs) have shown promising regenerative outcomes on degenerative NPCs (dNPCs). The aim of this study was to assess the effect of such EVs on all disc cell types, including AF cells (AFCs) and CEP cells (CEPCs), compared to EVs isolated from bone-marrow derived mesenchymal stromal cells (BM-MSCs).MethodNPCs harvested from young donors underwent an optimized culture protocol to maximize Tie2 expression (NPCsTie2+). BM-MSCs were retrieved from a commercial cell line or harvested during spine surgery procedures. EV characterization was performed via particle size analysis (qNano), expression of EV markers (Western blot), and transmission electron microscopy. dNPCs, AFCs, and CEPCs were isolated from surgical specimens of patients affected by IDD, culture-expanded, and treated with NPCsTie2+-EVs or BM-MSC-EVs ± 10 ng/mL IL-1b. EV uptake was assessed with PKH26 staining of EVs under confocal microscopy. Cell proliferation and viability were assessed with the CCK-8 assay.ResultUpon characterization, isolated EVs exhibited the typical exosomal characteristics. NPCsTie2+-EVs and BM-MSC-EVs uptake was successfully observed in all dNPCs, AFCs, and CEPCs. Both EV products significantly increased dNPC, AFC, and CEPC viability, especially in samples treated with NPCsTie2+-EVs.ConclusionNPCsTie2+-EVs demonstrated to significantly stimulate the proliferation and viability of degenerative cells isolated from all disc tissues. Rather than the sole NP, EVs isolated by committed progenitors physiologically residing within the disc may exert their regenerative effects on the whole organ, thus possibly constituting the basis for a new therapy for IDD.
THE POTENTIAL OF STRAIN SENSORS ON A POSTERIOR INSTRUMENTATION TO ASSESS HEALING OF TRANSOSSEOUS FRACTURES IN A LUMBAR VERTEBRA: A CADAVERIC STUDY
Authors: Heumann M. , Jacob A. , Gueorguiev B. , Richards G. , Benneker L. 
Published: November 2024

IntroductionTransosseous flexion-distraction injuries of the spine typically require surgical intervention by stabilizing the fractured vertebra during healing with a pedicle-screw-rod constructs. As healing is taking place the load shifts from the implant back to the spine. Monitoring the load-induced deflection of the rods over time would allow quantifiable postoperative assessment of healing progress without the need for radiation exposure or frequent hospital visits. This approach, previously demonstrated to be effective in assessing fracture healing in long bones and monitoring posterolateral spinal fusion in sheep, is now being investigated for its potential in evaluating lumbar vertebra transosseous fracture healing.MethodSix human cadaveric spines were instrumented with pedicle-screws and rods spanning L3 vertebra. The spine was loaded in Flexion-Extension (FE), Lateral-Bending (LB) and Axial-Rotation (AR) with an intact L3 vertebra (representing a healed vertebra) and after transosseous disruption, creating an AO type B1 fracture. The implant load on the rod was measured using an implantable strain sensor (Monitor) on one rod and on the contralateral rod by a strain gauge to validate the Monitor's measurements. In parallel the range of motion (ROM) was assessed.ResultThe ROM increased significantly in all directions in the fractured model (p≤0.049). The Monitor measured a significant increase in implant load in FE (p=0.002) and LB (p=0.045), however, not in AR. The strain gauge detected an increased implant load not only in FE (p=0.001) and LB (p=0.016), but also in AR (p=0.047). The highest strain signal was found during LB for both, the Monitor, and the strain gauge.ConclusionAfter a complete transosseous disruption of L3 vertebra the load on the implants was significantly higher than in the intact respectively healed state. Innovative implantable sensors could be used to monitor those changes allowing the assessment of healing progression based on quantifiable data rather than CT-imaging.
EFFECTS OF LOW DOSE BMP-2 AND IMMUNOMODULATION TARGETING IL-1ß ON FRACTURE HEALING IN A FEMUR DEFECT MODEL IN RATS
Authors: Schröder M. , Gens L. , Arens D. , Giger N. , Gehweiler D. , Nehrbass D. , Zderic I. , Zeiter S. , Stoddart M. , Wehrle E. 
Published: November 2024

IntroductionImmunomodulation represents a novel strategy to improve bone healing in combination with low doses of bone morphogenetic growth factors like BMP-2. This study aims to investigate the effect and timing of monoclonal anti-IL-1ß antibody administration with 1μg BMP-2 on bone healing over 14 weeks in a rat femur segmental defect model.Method2 mm femoral defects were created in 22-27 weeks-old female Fischer F344 rats, internally fixed with a plate (animal license: GR/19/2022) using established protocols for analgesia and anesthesia. Animals (n=4/group) received either a collagen sponge, a collagen sponge+1μg BMP-2 (InductOs, Medtronic) or a collagen sponge+1μg BMP-2 with a monoclonal anti-IL-1ß antibody (BioXCell, 10 mg/ml), administered intravenously under anesthesia every third day until day 15, from day 0 or 3. In vivo micro-CT was performed after surgery and at 2, 3, 4, 6, 8, 10 and 14-weeks post-OP. Mechanical properties of the operated femurs were assessed by 4-point bending (Instron5866) and compared to contralateral femurs (one-way ANOVA, GraphPad Prism8). Histopathological analysis was performed semi-quantitatively on Giemsa-Eosin-stained sections (Olympus BX63) using a six-grade severity grading scale.ResultOperated femurs with BMP-2 reached an average stiffness of 91±37% of contralateral femurs, femurs in IL-1ß groups 105±11% (day 0) and 111±12% (day 3). Administration of anti-IL-1ß+1μg BMP-2 led to faster cortical bridging (3/4 femurs bridged by week 4 for day 0, 4/4 for day 3) than 1μg BMP-2 alone (0/4 by week 4). Micro-CT results confirmed histopathological evaluation, as collagen sponge alone led to non-union, complete bicortical bridging was observed for 3/4 femurs in the BMP-2 group and for 4/4 femurs in the IL-1β groups after 14 weeks.ConclusionAnti-IL-1ß had a beneficial effect on late fracture healing with faster cortical bridging and new bone formation than 1μg BMP-2 alone.AcknowledgmentsAO foundation. We thank Andrea Furter, Alisa Hangartner and Thomas Krüger for technical support.
NOVEL APPLICATION OF THE OXFORD KNEE SCORE TO ASSESS KNEE PAIN, FUNCTION, AND QUALITY OF LIFE AFTER WEIGHT LOSS SURGERY
Authors: Federer S. , Dunne M. , Pring C. , Smith N. , Hudson P. 
Published: November 2024

IntroductionMany patients with obesity experience knee pain. Excess body weight is a modifiable risk factor for osteoarthritis (OA) and weight loss is encouraged in patients with OA. Bariatric surgery could improve or limit the progression of these conditions through significant weight loss. The Oxford Knee Score (OKS) is a validated tool in the assessment of knee replacement surgery for OA. We present a novel application of the OKS to assess knee pain & function after weight loss surgery. The primary aim of this study was to assess whether there was a significant difference in mean OKS before and 24 months after weight loss surgery.MethodEighteen female participants were included in this study. They underwent sleeve gastrectomy or Roux-en-Y gastric bypass. Patient demographics, body mass index (BMI) and OKS were collected pre- and 24 months post operatively.ResultThere was an increase in the mean OKS from 31.8 (SD 11.8) pre surgery to 36.6 (SD 12.3) at 24 months. This was statistically significant (95% CI 0.99-10.5, p=0.02). Mean BMI reduced from 46.6 kg/m2 (SD 5.8) to 33.0 kg/m2 (SD 3.5).ConclusionA significant improvement in mean OKS was seen after weight loss surgery. These findings demonstrate an improvement in knee pain & function with weight loss. This study contributes to a larger project evaluating the kinetic and kinematic changes to walking gait from weight loss.