Journal of biomedical materials research. Part B, Applied biomaterials最新文献

Comminuted fractures associated with tissue loss can adversely affect bone regeneration. Biomaterials enriched with mesenchymal stem cells (MSCs) employed for supporting osteosynthesis and potentiating osteoconduction are necessary to fill these bone defects. Natural compound biomaterials, similar to bone tissue, have been extensively tested in animal models for clinical use. Bone tissue engineering studies have used critical-size defects in ovine tibia monitored by imaging and histological examinations to evaluate the regenerative process. This study aimed to monitor the regenerative process in ovine tibial defects with or without chitosan, carbon nanotubes, or hydroxyapatite biomaterials, enriched or not enriched with MSCs. A 3-cm ostectomy was performed in 18 female Suffolk sheep. A 10-hole 4.5 mm narrow locking compression plate was used for osteosynthesis. The animals were randomly divided into three groups (n = 6): control (CON); defects filled with chitosan, carbon nanotubes, and hydroxyapatite biomaterial (BIO); and the same biomaterial enriched with bone marrow MSCs (BIO + CELL). The animals were evaluated monthly using radiographic examinations until 90 postoperative days, when they were euthanized. The limbs were subjected to micro-computed tomography (micro-CT), and bone specimens were subjected to histological evaluations. The radiographic examinations revealed construction stability without plate deviation, fracture, or bone lysis. Micro-CT evaluation demonstrated a difference in bone microarchitecture between the CON and biomaterial treatment groups (BIO and BIO + CELL). In the histological evaluations, the CON group did not demonstrate bone formation, and in the treatment groups (BIO and BIO + CELL), biocompatibility with sheep tissue was noted, and bone formation with trabeculae interspersed with remnants of the biomaterial was observed, with no differences between the groups. In conclusion, biomaterials present osteoconduction with beneficial characteristics for filling bone-lost fractures, and MSCs did not interfere with bone formation.

Treating severe bone deformities and abnormalities continues to be a major clinical hurdle, necessitating the adoption of suitable materials that can actively stimulate bone regeneration. Magnesium phosphate (MP) is a material that has the ability to stimulate the growth of bones. The current study involved the synthesis of mesoporous MP and lanthanum (La)-doped nanopowders using a chemical precipitation approach. The nanopowders were analyzed using several techniques, including XRD, FTIR, HR-TEM, BET, XPS, and FE-SEM. The results confirmed the nanopowders' size of less than 40 nm and the successful incorporation of La³⁺ ions into the MP structure. The bioactivity of the materials was assessed in vitro using simulated bodily fluid (SBF) at 37°C for a duration of 14 days in a shaker incubator (50 rpm). The SEM showed that a bone-like apatite layer formed quickly on the nanopowders' surface, proving that they have unique bioactive properties. The EDX spectra confirmed the presence of Ca, P, Mg, and La elements after immersion in SBF. The MP nanopowders, both with and without La doping, demonstrated the capacity to stimulate bone formation in a rat femoral bone defect model over a 28-day duration. Radiographic and histological studies showed that the La-doped MP nanopowders greatly improved bone repair and regeneration in comparison to the La-free nanopowders. Finally, the readily producible mesoporous MP nanomaterials, especially those with increased La doping (up to 7 wt%), exhibit significant potential for the restoration of large bone defects. Hence, fabricated nanopowders have immense promise for repairing bone criterion defects.

The bioactive glass–ceramic spacer (BGS)-7, a biosynthetic intervertebral fusion material introduced in 2014, has not been the subject of comparative clinical studies on anterior cervical discectomy and fusion (ACDF) surgery. This study, for the first time, aims to compare the radiological and clinical outcomes of the renewed BGS-7, released in 2019, with those of an allograft spacer. The comparison includes a finite element analysis of the biomechanical properties of each implant, adding a novel dimension to the research. We prospectively followed up on 29 patients who underwent ACDF using BGS-7 as the experimental group. To select a control group for comparison, 253 patients with level 1 ACDF with an allograft spacer between 2012 and 2022 were selected from our hospital. Using propensity score matching, 27 and 54 patients in the BGS-7 and allograft groups, respectively, were selected. The average subsidence length was 1.02 ± 1.44 mm per level in the BGS-7 group and 2.27 ± 2.25 mm per level in the allograft group. Subsidence was observed in 14 of 54 patients (25.9%) in the allograft group and one of 27 patients (3.7%) in the BGS-7 group (p = 0.016). In the allograft group, 16 of the 54 patients (29.6%) monitored for 6 months achieved satisfactory fusion outcomes with grades 4 and 5. Thirty-eight of 54 patients (70.4%) followed up for > 1 year in the allograft group achieved adequate fusion outcomes with grades 4 and 5. In the BGS-7 group, 17 of the 27 patients (63.0%) monitored for 6 months achieved satisfactory fusion results with grades 4 and 5. Twenty-three of the 27 patients (85.2%) followed up for > 1 year obtained adequate fusion outcomes with grades 4 and 5. There was a significant difference in the fusion rates between the two groups at 6 months (p = 0.008). BGS-7 is a reliable instrument for ACDF with no instances of instrumental failure. The BGS-7 group had positive clinical outcomes after surgery without any untoward events, and an early fusion rate with the creation of a bone bridge was noted during the 6-month follow-up period. Our findings not only indicate the safety of BGS-7 but also its practicality as a substitute for allografts in ACDF, instilling confidence in its application.

The emergence of degradable orthopedic implants for fracture fixation may abrogate the need for implant removal surgery and minimize pain associated with permanent implants. Magnesium (Mg) and its alloys are being explored as a biomaterial for degradable implants due to mechanical properties similar to those of bone. Previous in vitro studies have determined the degradation rate of pure Mg to be relatively fast when compared to bone regeneration. Hydroxyapatite (HA), the mineral component of bone, may serve as a surface coating on Mg-based implants to effectively slow and control the degradation rate. The objective of this work was to develop and implement a finite element (FE) model that utilizes a damage evolution law for pitting corrosion to predict the degradation of pure Mg (non-coated) and HA-coated pure Mg (coated) materials simulated in physiological conditions. Finite element analysis (FEA) was performed on a cylindrical Mg specimen (25.4 mm diameter, 8 mm height) through Abaqus/Standard software to incrementally monitor the damage value of each Mg element and subsequently delete fully-degraded elements from the simulation. A Fortran user-material (UMAT) subroutine assigned each element a pitting parameter, controlling the rate of degradation throughout the simulation and providing necessary inputs of elastic material properties and degradation model parameters for pure Mg and HA into Abaqus. The simulations allowed for the visualization of both pure Mg and HA-coated pure Mg degradation over a 120-day period, displaying expected degradation trends such as lower corrosion rates for HA-coated Mg and degradation propagating from the edges inward. Simulation results were calibrated with our prior results from a 30-day experimental degradation study via direct comparison with mass loss over time. Additionally, lower length scale, density functional theory (DFT) simulations were performed to provide physical meaning for the model pitting parameter. The FE simulation was extended to model resin-enclosed pure Mg and HA-coated pure Mg degradation, where only the top surface of the specimen was exposed to the corrosion surface, for investigating changes in Mg surface roughness (height) over time. The impacts of this work include the establishment of a computational model of pure Mg and HA-coated pure Mg degradation calibrated using in vitro degradation data to advance the use of Mg-based biomaterials, and more broadly, to predict degradation rates of next-generation orthopedic implants.

Histomorphometry is an important technique in the evaluation of non-traumatic osteonecrosis of the femoral head (ONFH). Quantification of empty lacunae and pyknotic cells on histological images is the most reliable measure of ONFH pathology, yet it is time and manpower consuming. This study focused on the application of artificial intelligence (AI) technology to tissue image evaluation. The aim of this study is to establish an automated cell counting platform using YOLOv8 as an object detection model on ONFH tissue images and to evaluate and validate its accuracy. From 30 ONFH model rabbits, 270 tissue images were prepared; based on evaluations by three researchers, ground truth labels were created to classify each cell in the image into two classes (osteocytes and empty lacunae) or three classes (osteocytes, pyknotic cells, and empty lacunae). Two and three classes were then annotated on each image. Transfer learning based on annotated data (80% for training and 20% for validation) was performed using YOLOv8n and YOLOv8x with different parameters. To evaluate the detection accuracy of the training model, the mean average precision (mAP (50)) and precision-recall curve were identified. In addition, the reliability of cell counting by YOLOv8 relative to manual cell counting was evaluated by linear regression analysis using five histological images unused in previous experiments. The mAP (50) for the detection of empty lacunae was 0.868 for the YOLOv8n and 0.883 for the YOLOv8x. The mAP (50) for the three classes was 0.735 for the YOLOv8n model and 0.750 for the YOLOv8x model. The quantification of empty lacunae by automated cell counting obtained in the learning was highly correlated with the manual counting data. The development of an AI-applied automated cell counting platform will significantly reduce the time and effort of manual cell counting in histological analysis.

This study presents a new innovative drug delivery system for ciprofloxacin, which is based on the formation of a zinc-doped carbon dots layer on the surface of a titanium alloy (TiAl4V6). In the study, the effectiveness of the synthesis method of a zinc-doped carbon dots layer was determined. The distribution of the layer of carbon dots on the surface of the titanium alloy was investigated using the FT-IR mapping technique, which confirmed the efficiency of the synthesis. The effective synthesis of carbon dots and the coordination of zinc ions on their surface opens the possibility of sorption of ciprofloxacin, which results in a high application potential of the obtained biomaterial. The introduction of zinc cations on the surface of the carbon dots layer resulted in high sorption results of the active substance (40 μg of drug per 1 cm² of implant). The release profile of ciprofloxacin from the modified surface of the titanium alloy indicates that this active substance can be released for up to 4 h. The biomaterial obtained in this work is also hydrophilic (about 40°), which was shown by the contact angle tests. This is an important feature and indicates a high application potential of the performed modification. The resulting layer has antibacterial properties. Growth inhibition for microorganisms such as Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Candida albicans ranged from 74% to 96%. The creation of such a layer on the titanium alloy may reduce the risk of infection during the implantation procedure.

A combined biomaterial and cell-based solution to heal critical size bone defects in the craniomaxillofacial area is a promising alternative therapeutic option to improve upon autografting, the current gold standard. A shape memory polymer (SMP) scaffold, composed of biodegradable poly(ε-caprolactone) and coated with bioactive polydopamine, was evaluated with mesenchymal stromal cells (MSCs) derived from adipose (ADSC), bone marrow (BMSC), or umbilical cord (UCSC) tissue in their undifferentiated state or pre-differentiated toward osteoblasts for bone healing in a rat calvarial defect model. Pre-differentiating ADSCs and UCSCs resulted in higher new bone volume fraction (15.69% ± 1.64%) compared to empty (i.e., untreated) defects and scaffold-only (i.e., unseeded) groups (4.41% ± 1.11%). Notably, only differentiated UCSCs exhibited a significant increase in new bone volume, surpassing both undifferentiated UCSCs and unseeded scaffolds. Further, differentiated ADSCs and UCSCs had significantly higher trabecular numbers than their undifferentiated counterparts, unseeded scaffolds, and untreated defects. Although the mineral density regenerated within the unseeded scaffold surpassed that achieved with cell seeding, the connectivity of this bone was diminished, as the regenerated tissue confined itself to the spherical morphology of the scaffold pores. The SMP scaffold alone, with undifferentiated BMSCs, with undifferentiated and differentiated ADSCs, and differentiated UCSCs (29.72 ± 1.49 N) demonstrated significant osseointegration compared to empty defects (14.34 ± 2.21 N) after 12 weeks of healing when assessed by mechanical push-out testing. Based on these results and tissue availability to obtain the cells, pre-differentiated ADSCs and UCSCs emerge as particularly promising candidates when paired with the SMP scaffold for repairing critical size bone defects in the craniofacial skeleton.