Formation Of New Bone Research Articles

An in vitro and in vivo study of biodegradable Zn–Cu–Li alloy with high strength and ductility fabricated by hot extrusion combined with room-temperature ECAP

Deformation processing is a commonly used strategy to improve the microstructure and hence mechanical properties of biodegradable Zn alloys. However, a single conventional processing method is usually limited in achieving this goal. In this work, hot extrusion combined with room-temperature equal channel angular pressing (ECAP) was used to fabricate biodegradable Zn–Cu–Li alloy. Compared to the hot-extruded alloy, the further ECAPed alloys have significantly finer Zn grains and precipitate more submicron- and nano-sized ε-CuZn4 particles. Moreover, the 4-pass as-ECAPed alloy exhibits the best comprehensive mechanical properties with yield strength of 315 ± 3 MPa, ultimate tensile strength of 444 ± 13 MPa and elongation of 81 ± 5%, which are 13.3%, 38.8% and 72.3% higher than those of the hot-extruded alloy, respectively. In addition, in vitro and in vivo tests were performed on the 4-pass as-ECAPed alloy to evaluate its corrosion behavior, antibacterial property, cytotoxicity and biocompatibility. In vitro results showed that the 4-pass as-ECAPed alloy exhibits better corrosion resistance than the 8-pass alloy. Also, it shows good antibacterial property, hemocompatibility and cytocompatibility. In vivo results demonstrated that the 4-pass as-ECAPed alloy exhibits faster and more uniform degradation than the pure Zn (as a control group). Both the pure Zn and 4-pass as-ECAPed alloy promote formation of new bone, the mass of which increases over time. The 4-pass as-ECAPed alloy shows slightly weaker osteogenic capacity but better overall osteointegration than the pure Zn. Furthermore, both the pure Zn and 4-pass as-ECAPed alloy exhibit good in vivo biosafety.

Extracellular vesicles derived from Msh homeobox 1 (Msx1)-overexpressing mesenchymal stem cells improve digit tip regeneration in an amputee mice model

In adult mammals, limb regeneration is limited by the absence of blastemal cells (BCs) and the lack of the regenerative signaling cascade. The utilization of transgenic cells circumvents the limitations associated with the absence of BCs. In a previous investigation, we successfully regenerated mouse phalanx amputations using blastema-like cells (BlCs) generated from bone marrow-derived mesenchymal stem cells (mBMSCs) overexpressing Msx1 and Msx2 genes. Recently, extracellular vesicles (EVs) have emerged as potent biological tools, offering a promising alternative to manipulated cells for clinical applications. This research focuses on utilizing BlCs-derived extracellular vesicles (BlCs-EVs) for regenerating mouse digit tips. The BlCs were cultured and expanded, and then EVs were isolated via ultracentrifugation. The size, morphology, and CD81 marker expression of the EVs were confirmed through Dynamic Light Scattering (DLS), Scanning Electron Microscope (SEM), and Western Blot (WB) analyses. Additionally, WB analysis demonstrated the presence of MSX1, MSX2, FGF8, and BMP4 proteins. The uptake of EVs by mBMSCs was shown through immunostaining. Effects on cell proliferation, migration, and osteogenic activity post-treatment with BlCs-EVs were assessed through MTT assay, scratch assay, and Real-time PCR. The regenerative potential of BlCs-EVs was evaluated in a mouse digit tip amputation model using histological assessments. Results indicated that BlCs-EVs enhanced several abilities of mBMSCs, such as migration, proliferation, and osteogenesis in vitro. Notably, BlCs-EVs significantly improved digit tip regeneration in mice, promoting the formation of new bone and nails, which was absent in control groups. In summary, BlCs-EVs are promising tools for digit tip regeneration, avoiding the ethical concerns associated with using genetically modified cells.

Functional and structural construction of photothermal-responsive PEEK composite implants to promote bone regeneration and bone-implant integration

Although poly (ether-ether-ketone) (PEEK) has been widely used in orthopedic surgeries, its clinical efficacy is challenged by ineffective bone regeneration and insufficient osteointegration. Herein, inspired by the Mortise-and-tenon joint in traditional Chinese architectural art, a novel strategy has been developed to construct photothermal-responsive PEEK composite implants, with tapered lock-groove edges as proof of concept, by incorporating graphene oxide (GO) loaded with polydopamine-coated nano-zirconia (PDA@ZrO2) into PEEK (namely PGPZ composite). The PGPZ composite exhibits improved mechanical properties, good cytocompatibility and blood compatibility, excellent antibacterial ability and osteogenic activity remotely controlled by near-infrared irradiation (NIR). The cranial defects experiment on rabbits reveals that repeated NIR treatment on PGPZ composite implant significantly accelerates endogenous bone regeneration. More importantly, abundant newly-formed bone has materialized in the lock grooves, forming interlocked Mortise-and-tenon joints with the implant. This study not only pave the way for further clinical applications of the PEEK composite implants with improved bioactivities to promote bone regeneration and osteointegration, but also providing a novel strategy for structural and functional design of various tissue engineering implants.

Mesenchymal stem cell-derived protein extract induces periodontal regeneration: MSC-protein induces periodontal regeneration

BackgroundPeriodontal disease is characterized by chronic inflammation and destruction of supporting periodontal tissues, ultimately leading to tooth loss. In recent years, “cell-free treatment” without stem cell transplantation has attracted considerable attention for tissue regeneration. This study investigated the effects of extracts of mesenchymal stem cells (MSC-extract) and their protein components (MSC-protein) on the proliferation and migration of periodontal ligament (PDL) cells and whether MSC-protein can induce periodontal regeneration. MethodsMSC-extract and MSC-protein were obtained by subjecting mesenchymal stem cells (MSCs) to freeze–thaw cycles and acetone precipitation. Cell proliferation was examined using a WST-8 assay and Ki67 immunostaining, and cell migration was examined using Boyden chambers. The MSC-protein content was analyzed using liquid chromatography-mass spectrometry, protein arrays, and enzyme-linked immunosorbent assays (ELISAs). Gene expression in MSC-protein-treated PDL cells was examined using RNA-sequencing and Gene Ontology analyses. The regenerative potential of MSC-protein was examined using micro-computer tomography (CT) and histological analyses after transplantation into a rat periodontal defect model. ResultsMSC-extract and MSC-protein promoted the proliferation and migration of PDL cells. Protein array and ELISA revealed that MSC-protein contained high concentrations of basic fibroblast growth factor (bFGF) and hepatocyte growth factor (HGF). Exogenous bFGF promoted the proliferation and migration of PDL cells. Furthermore, the transplantation of MSC-protein enhanced periodontal tissue regeneration with the formation of new alveolar bone and PDLs. ConclusionsThese results indicate that the MSC-protein promotes the proliferation and migration of PDL cells and induces significant periodontal tissue regeneration, suggesting that the MSC-protein could be used as a new cell-free treatment for periodontal disease.

Evaluation of the Regenerative Capacity of Demineralized Bone Matrix vs Fat Graft in Alveolar Cleft Model in Albino Rats.

This study was performed to evaluate the regenerative capacity of demineralized bone matrix vs fat graft, both guided by pericardium membrane in alveolar cleft model in albino rats. A total of 72 rats were required in this study. A surgical bone defect with a 7 mm length × 4 mm width × 3 mm depth was created as a model of an alveolar cleft, then the rats were divided randomly into four equal groups each group contained 18 rats: control group (defect only), the membrane group (the defect was covered by the pericardium membrane), the demineralized bone matrix (DBM) group (the defect was filled with DBM guided by pericardium membrane) and fat group (the defect was filled with a fat graft guided by the pericardium membrane). Around 6 rats from each group were euthanized after 2, 4, and 8 weeks. Skulls were scanned with cone beam computed tomography (CBCT) and harvested for histological evaluation with routine H&E immunohistochemical stains (Anti-osteocalcin and Anti-Wnt5a). The data was recorded and statistically analyzed by a two-way ANOVA. The study showed a notable formation of new bone, and expression of OCN and Wnt5a were notably increased by time in the fat group. However, the density of bone grafts and OCN and Wnt5a expression decreased with time in the DBM group. Control and membrane groups showed negative OCN and Wnt5a immune-reactivity in the cleft site. Fat graft results were superior to DBM results with regard to mucosal closure and accelerated bone regeneration, and may represent an effective treatment for alveolar cleft reconstruction. Finding an inexpensive, accessible, biocompatible and easily manipulated treatment for craniofacial reconstruction and fat graft fulfilled the desired aims. Further investigations with prolonged evaluation periods are needed. How to cite this article: Abdel Raouf E, Elsherbini AM, Abdel Salam Yousef Y, et al. Evaluation of the Regenerative Capacity of Demineralized Bone Matrix vs Fat Graft in Alveolar Cleft Model in Albino Rats. J Contemp Dent Pract 2024;25(6):554-562.

Identifying a suitable material model to simulate the mechanical load transfer into the humeral bone in stemless shoulder endoprostheses

AbstractModern shoulder arthroplasties with stemless implants help to preserve the original bone substance of the proximal humerus and to reduce potential risks of conventional implants. Their shape allows newly formed bone to grow directly through the implant. However, it is not fully explained how an optimal fixation of the implant by formation of new bone can be achieved or stimulated. In this context, we develop a method to simulate the mechanical loading of the proximal humerus during the surgery using the finite element method to investigate whether one or more mechanical stress variables can be correlated with measurement data of cell activity in the bone, which is available in the form of SPECT/CT data. This contribution presents measurements with explanted humeral heads from patients undergoing planned total shoulder arthroplasties in order to parameterize a material model for trabecular bone to be used in the finite element simulation. The raw data of these measurements were published and can be accessed for further investigations.

Photobiomodulation Modulates Proliferation and Gene Expression Related to Calcium Signaling in Human Osteoblast Cells.

Introduction: Photobiomodulation with low-level laser treatment can enhance bone formation by stimulating the cell division of osteoblasts and increasing the amount of protein deposition, thus encouraging the formation of new bone. The aim of this study was to evaluate the effects of photobiomodulation with a low-level laser on proliferation and gene expression related to calcium signaling in human osteoblasts. Methods: Osteoblastic cell lines of the hFOB1.19 lineage, human osteoblasts, were grown and assigned into two groups, control (C; n=78 cultured wells) and photobiomodulation (L; n=78 cultured wells) with n=6 per day of the experimental period. Cells were cultured (immature at 34 ºC), and after maturation at 37 ºC, group L cells were exposed to laser irradiation with a low-level laser device (gallium and aluminum arsenide), at a wavelength of 808 nm, a power output of 200 mW, and a power density of 200 mW/cm2. The energy delivered to the cells was 37 J/cm2, with a beam area of 0.02 mm2 and an exposure time of 5 seconds. This treatment was applied daily for a period of 13 days. Following this, the number of cells was counted, and RNA was isolated, measured, and then converted into cDNA for further quantification using a comparative Ct method with real-time polymerase chain reaction. The results were then subjected to statistical analysis through a Mann-Whitney test, with a significance level of P<0.05. Results: The cell count in the L group (37.25x10±4±22.02) was statistically higher compared to the control group (22.75x10±4±7.660) with a P value of 0.0259. The values of 2-ΔΔCt for S100A6, plasma membrane calcium ATPase (PMCA), and calmodulin genes indicated hyper-expression on the thirteenth day, while the osteocalcin gene showed hypo-expression. Conclusion: The study suggests that the photobiomodulation mechanism with a low-level laser may regulate gene expression in human osteoblasts in a dose-dependent and cumulative manner.

Electrospun PVP Fibers as Carriers of Ca2+ Ions to Improve the Osteoinductivity of Titanium-Based Dental Implants.

Although titanium and its alloys are widely used as dental implants, they cannot induce the formation of new bone around the implant, which is a basis for the functional integrity and long-term stability of implants. This study focused on the functionalization of the titanium/titanium oxide surface as the gold standard for dental implants, with electrospun composite fibers consisting of polyvinylpyrrolidone and Ca2+ ions. Polymer fibers as carriers of Ca2+ ions should gradually dissolve, releasing Ca2+ ions into the environment of the implant when it is immersed in a model electrolyte of artificial saliva. Scanning electron microscopy, energy dispersive X-ray spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy confirmed the successful formation of a porous network of composite fibers on the titanium/titanium oxide surface. The mechanism of the formation of the composite fibers was investigated in detail by quantum chemical calculations at the density functional theory level based on the simulation of possible molecular interactions between Ca2+ ions, polymer fibers and titanium substrate. During the 7-day immersion of the functionalized titanium in artificial saliva, the processes on the titanium/titanium oxide/composite fibers/artificial saliva interface were monitored by electrochemical impedance spectroscopy. It can be concluded from all the results that the composite fibers formed on titanium have application potential for the development of osteoinductive and thus more biocompatible dental implants.

Critical-sized marginal defects around implants in the rabbit mandible.

The mandible of the rabbit is considered a reliable model to be used to study bone regeneration in defects. The aim of the present study was to evaluate the formation of new bone around implants installed in defects of either 5 or 10mm in the mandible of rabbits. In 12 rabbits, 3mm deep circumferential defect, either 5 or 10mm in diameter, were prepared bilaterally and an implant was placed in the center. A collagen membrane was placed to close the entrance. After 10 weeks, biopsies were taken, histological slides were prepared, and different regions of the defects were analyzed. Similar amounts of new bone were found in both defects. However, most of the 5mm defects were filled with new bone. New bone was observed closing the entrance of the defect and laid onto the implant surface. Only in a few cases the healing was incomplete. Despite a similar percentage of new bone found within the 10mm defects, the healing was incomplete in most of the cases, presenting a low rate of bone formation onto the implant surface within the defect. Only one case presented the closure of the entrance. The dimensions of the defect strongly influenced the healing so that a circumferential marginal defect of 10mm around an implant in the mandible body should be considered a critical-sized defect. The presence of the implant and of residues of teeth might have strongly influenced the healing.

In vivo analysis of hybrid hydrogels containing dual growth factor combinations, and skeletal stem cells under mechanical stimulation for bone repair

Bone tissue engineering requires a combination of materials, cells, growth factors and mechanical cues to recapitulate bone formation. In this study we evaluated hybrid hydrogels for minimally invasive bone formation by combining biomaterials with skeletal stem cells and staged release of growth factors together with mechanotransduction. Hybrid hydrogels consisting of alginate and decellularized, demineralised bone extracellular matrix (ALG/ECM) were seeded with Stro-1+ human bone marrow stromal cells (HBMSCs). Dual combinations of growth factors within staged-release polylactic-co-glycolic acid (PLGA) microparticles were added to hydrogels to mimic, in part, the signalling events in bone regeneration: VEGF, TGF-β3, PTHrP (fast release), or BMP-2, vitamin D3 (slow release). Mechanotransduction was initiated using magnetic fields to remotely actuate superparamagnetic nanoparticles (MNP) targeted to TREK1 ion channels. Hybrid hydrogels were implanted subcutaneously within mice for 28 days, and evaluated for bone formation using micro-CT and histology. Control hydrogels lacking HBMSCs, growth factors, or MNP became mineralised, and neither growth factors, HBMSCs, nor mechanotransduction increased bone formation. However, structural differences in the newly-formed bone were influenced by growth factors. Slow release of BMP-2 induced thick bone trabeculae and PTHrP or VitD3 increased bone formation. However, fast-release of TGF-β3 and VEGF resulted in thin trabeculae. Mechanotransduction reversed the trabecular thinning and increased collagen deposition with PTHrP and VitD3. Our findings demonstrate the potential of hybrid ALG/ECM hydrogel–cell–growth factor constructs to repair bone in combination with mechanotransduction for fine-tuning bone structure. This approach may form a minimally invasive reparative strategy for bone tissue engineering applications.

Construction of a Titanium-Magnesium Composite Internal Fixation System for Repairing Bone Defects.

The repair and regeneration of maxillofacial bone defects are major clinical challenges. Titanium (Ti)-magnesium (Mg) composites are a new generation of revolutionary internal fixation materials encompassing the mechanical strength and bioactive advantages of Ti and Mg alloys, respectively. This study was aimed to construct a Ti-Mg composite internal plate/screw fixation system to fix and repair bone defects. Further, the effects of different internal fixation systems on bone repair were analyzed through radiological and histological analyses. Notably, Ti6Al4V with rolled Mg foil was used as the experimental group, and a bone defect model of transverse complete amputation of the ulna in rabbits similar to the clinical condition was established. The internal fixation system with the highest osteogenic efficiency was selected based on in vivo results, and the direct and indirect bone repair abilities of the selected materials were evaluated in vitro. Notably, the thin Mg foil-Ti6Al4V internal fixation system exhibited the best fixation effect in the bone defect model and promoted the formation of new bone and early healing of bone defect areas. In vitro, the thin Mg foil-Ti6Al4V composite enhanced the activity of MC3T3-E1 cells; promoted the proliferation, adhesion, extension, and osteogenic differentiation of MC3T3-E1 cells; and regulated new bone formation. Further, it also promoted the polarization of RAW264.7 cells to M2 macrophages, induced the osteogenic immune microenvironment, and indirectly regulated the bone repair process. Therefore, a internal fixation system holds a promising potential for the internal fixation of maxillofacial bone defects. Our findings provide a theoretical and scientific basis for the design and clinical application of Ti-Mg internal fixation systems.

Effect of Swimming Training on Bone Tissue in Humans

Introduction and purpose: The skeletal system performs many important functions in the human body. It primarily bears the heavy loads associated with movement, protects internal organs, and participates in the regulation of mineral homeostasis. Through continuous processes of bone remodeling and modeling, optimal levels of calcium and phosphorus in the serum are achieved. The balanced removal of old bone tissue by osteoclasts and the formation of new bone by osteoblasts maintain the mechanical properties necessary for the proper functioning of the musculoskeletal system. Bone modeling has been shown to be activated in response to mechanical loading from physical activity. Conversely, the absence of significant loading (as in space travel, i.e., microgravity conditions) leads to increased bone resorption. Osteocytes, as the most numerous group of cells in the skeletal system, are mechanosensitive and are thought to respond to stimuli such as fluid flow, mechanical deformations, and hydrostatic pressure. In response, they regulate the work of osteoclasts and osteoblasts, translating into the regulation of processes occurring in the bone matrix.[1] It is suspected that the type, intensity, and nature of physical exercises can significantly influence these processes. The aim of this work is to gather information on the impact of swimming training (an example of physical exercise in conditions of partial gravity reduction) on the human skeletal system.

Quality assessment of regenerated bone in intraosseous and intramuscular scaffolds by spectroscopy and nanoindentation

The efficiency of synthetic bone grafts can be evaluated either in osseous sites, to analyze osteoconduction or ectopically, in intramuscular or subcutaneous sites, to assess osteoinduction. Bone regeneration is usually evaluated in terms of the presence and quantity of newly formed bone, but little information is normally provided on the quality of this bone. Here, we propose a novel approach to evaluate bone quality by the combined use of spectroscopy techniques and nanoindentation. Calcium phosphate scaffolds with different architectures, either foamed or 3D-printed, that were implanted in osseous or intramuscular defects in Beagle dogs for 6 or 12 weeks were analyzed. ATR-FTIR and Raman spectroscopy were performed, and mineral-to-matrix ratio, crystallinity, and mineral and collagen maturity were calculated and mapped for the newly regenerated bone and the mature cortical bone from the same specimen. For all the parameters studied, the newly-formed bone showed lower values than the mature host bone. Hardness and elastic modulus were determined by nanoindentation and, in line with what was observed by spectroscopy, lower values were observed in the regenerated bone than in the cortical bone. While, as expected, all techniques pointed to an increase in the maturity of the newly-formed bone between 6 and 12 weeks, the bone found in the intramuscular samples after 12 weeks presented lower mineralization than the intraosseous counterparts. Moreover, scaffold architecture also played a role in bone maturity, with the foamed scaffolds showing higher mineralization and crystallinity than the 3D-printed scaffolds after 12 weeks.

Self-setting calcium phosphate cement scaffolds with pre-forming and in-situ forming interconnected macropores: Comparative study in vitro and in vivo

Creating interconnected macropores in calcium phosphate cement (CPC) is an effective strategy to promote its degradation and osteogenesis. However, little attention has been given to the osteogenic effect of the CPC scaffolds with pre-forming and in-situ forming interconnected macropores. Herein, two types of CPC scaffolds were prepared by infiltrating CPC pastes into 3D-printed polycaprolactone (PCL) and poly(lactic-co-glycolic acid) (PLGA) networks. Meanwhile, the sacrificial PCL network within CPC was dissolved to obtain the CPC scaffold with approximately 300 μm macropores, whereas the PLGA network was retained within the CPC to obtain the PLGA/CPC scaffold. The results indicated that the PLGA/CPC scaffold showed higher degradation rate and compressive strength compared to the CPC scaffold with pre-forming interconnected macropores. However, the proliferation rate and alkaline phosphatase activity of mouse bone mesenchymal stem cells cultured with the CPC scaffold were superior to those cultured with the PLGA/CPC scaffold. In addition, greater formation of new bone and material degradation in the CPC scaffold compared to the PLGA/CPC scaffold after implanted in the rabbit femoral defects.

The Impact of Orthodontic Extrusion on Keratinized Gingiva.

Background and Objectives: The key factor that enables osteoblastic activity and the formation of new bone, as well as gingiva, during orthodontic tooth extrusion (OE) is the periodontal ligament. The reaction of periodontal tissues associated with changes in the gingiva is a part of orthodontic tooth displacement. The aim of this study was to examine the effect of OE on the width of the zone of the keratinized and attached gingiva, the position of the mucogingival junction, and the height of the interdental papillae in the region where the OE was performed as well as in the adjacent region. Materials and Methods: This research included 28 adult patients (both orthodontically treated and untreated). The treated group included 15 patients, in whom orthodontic extrusion of the upper or lower frontal teeth was indicated and performed. The untreated group included 13 patients, with no previous or undergoing orthodontic treatment. Patients with periodontal disease and periodontal pockets in the frontal region and patients allergic to iodine were excluded from the study. Gingivomorphometric measurements were performed on two occasions in three groups of teeth (24 extruded and 30 agonist teeth in the treated patients; 66 teeth in the untreated patients). Statistical analysis of the obtained data was performed using the software package SPSS version 26.0. Results: Orthodontic extrusion induced changes in the position of the mucogingival line and an increase in the width of the keratinized gingiva. There were no statistically significant effects on the depth of the gingival sulcus, the attached gingiva width, or the height of the interdental papillae. Conclusions: Orthodontic tooth extrusion has an effect on the periodontium in the observed region. Vertical orthodontic force, directed towards the coronal plane, affects the surrounding soft oral tissues.

RhoA/ROCK-TAZ Axis regulates bone formation within calvarial trans-sutural distraction osteogenesis

BackgroundCraniofacial skeletal deformities can be addressed by applying tensile force to sutures to prompt sutural bone formation. The intricate process of mechanical modulation in craniofacial sutures involves complex biomechanical signal transduction. The small GTPase Ras homolog gene family member A (RhoA) functions as a key mechanotransduction protein, orchestrating the dynamic assembly of the cytoskeleton by activating the Rho-associated coiled-coil containing protein kinase (ROCK). Transcriptional coactivator with PDZ-binding motif (TAZ) serves as a crucial mediator in the regulation of genes and the orchestration of biological functions within the mechanotransduction signaling pathway. However, the role of RhoA/ROCK-TAZ in trans-sutural distraction osteogenesis has not been reported. MethodsWe utilized pre-osteoblast-specific RhoA deletion mice to establish an in vivo calvarial trans-sutural distraction model and an in vitro mechanical stretch model for pre-osteoblasts isolated from neonatal mice. Micro-CT and histological staining were utilized to detect the formation of new bone in the sagittal suture of the skull as well as the activation of RhoA, Osterix and TAZ. The activation of ROCK-limk-cofilin and the nuclear translocation of TAZ in pre-osteoblasts under mechanical tension were detected through Western blot, qRT-PCR, and immunofluorescence. ResultsThe osteogenic differentiation of pre-osteoblasts was facilitated by mechanical tension through the activation of RhoA and Rho-associated kinase (ROCK), while ablation of RhoA impaired osteogenesis by inhibiting pre-osteoblast differentiation after suture expansion. Furthermore, inhibiting RhoA expression could block tensile-stimulated nuclear translocation of TAZ by preventing F-actin assembly through ROCK-LIM-domain kinase (LIMK)-cofilin pathway. In addition, the TAZ agonist TM-25659 could attenuate impaired osteogenesis caused by ablation of RhoA in pre-osteoblasts by increasing TAZ nuclear accumulation. ConclusionsThis study demonstrates that mechanical stretching promotes the osteogenic differentiation of pre-osteoblasts in trans-sutural distraction osteogenesis, and this process is mediated by the RhoA/ROCK-TAZ signaling axis. Overall, our results may provide an insight for potential treatment strategies for craniosynostosis patients through trans-sutural distraction osteogenesis.

Clinical evaluation of new bone formation during limb lengthening in children using ultrasound combined with superb microvascular imaging

AimsGiven the possible radiation damage and inaccuracy of radiological investigations, particularly in children, ultrasound and superb microvascular imaging (SMI) may offer alternative methods of evaluating new bone formation when limb lengthening is undertaken in paediatric patients. The aim of this study was to assess the use of ultrasound combined with SMI in monitoring new bone formation during limb lengthening in children.MethodsIn this retrospective cohort study, ultrasound and radiograph examinations were performed every two weeks in 30 paediatric patients undergoing limb lengthening. Ultrasound was used to monitor new bone formation. The number of vertical vessels and the blood flow resistance index were compared with those from plain radiographs.ResultsWe categorized the new bone formation into three stages: stage I (early lengthening), in which there was no obvious callus formation on radiographs and ultrasound; stage II (lengthening), in which radiographs showed low-density callus formation with uneven distribution and three sub-stages could be identified on ultrasound: in Ia punctate callus was visible; in IIb there was linear callus formation which was not yet connected and in IIc there was continuous linear callus. In stage III (healing), the bone ends had united, the periosteum was intact, and the callus had disappeared, as confirmed on radiographs, indicating healed bone. A progressive increase in the number of vertical vessels was noted in the early stages, peaking during stages IIb and IIc, followed by a gradual decline (p &lt; 0.001). Delayed healing involved patients with a prolonged stage IIa or those who regressed to stage IIa from stages IIb or IIc during lengthening.ConclusionWe found that the formation of new bone in paediatric patients undergoing limb lengthening could be reliably evaluated using ultrasound when combined with the radiological findings. This combination enabled an improved assessment of the prognosis, and adjustments to the lengthening protocol. While SMI offered additional insights into angiogenesis within the new bone, its role primarily contributed to the understanding of the microvascular environment rather than directly informing adjustments of treatment.Cite this article: Bone Joint J 2024;106-B(7):751–758.

Enhancement of Local Osseointegration and Implant Stability of Titanium Implant in Osteoporotic Rats by Biomimetic Multilayered Structures Containing Catalpol.

This study examined the surface modification of titanium (Ti) implants to enhance early-stage osseointegration, which reduced the failure rate of internal fixation in osteoporotic fractures that inherently decrease in bone mass and strength. We employed a layer-by-layer electroassembly technique to deposit catalpol-containing hyaluronic acid/chitosan multilayers onto the surface of Ti implants. To evaluate the in vitro osteoinductive effects of catalpol-coated Ti implants, the robust osteoblast differentiation capacity of the murine preosteoblast cell line, MC3T3-E1, was employed. Furthermore, the performance of these implants was evaluated in vivo through femoral intramedullary implantation in Sprague-Dawley rats. The engineered implant effectively regulated catalpol release, promoting increased bone formation during the initial stages of implantation. The in vitro findings demonstrated that catalpol-coated Ti surfaces boosted ALP activity, cell proliferation as measured by CCK-8, and osteogenic protein expression via WB analysis, surpassing the uncoated Ti group (P < 0.05). In vivo micro-computed tomography (CT) and histological analyses revealed that catalpol-coated Ti significantly facilitated the formation and remodeling of new bone in osteoporotic rats at 14 days post-implantation. This study outlines a comprehensive and straightforward methodology for the fabrication of biofunctional Ti implants to address osteoporosis.

HIF-1α and MIF enhance neutrophil-driven type 3 immunity and chondrogenesis in a murine spondyloarthritis model.

The hallmarks of spondyloarthritis (SpA) are type 3 immunity-driven inflammation and new bone formation (NBF). Macrophage migration inhibitory factor (MIF) was found to be a key driver of the pathogenesis of SpA by amplifying type 3 immunity, yet MIF-interacting molecules and networks remain elusive. Herein, we identified hypoxia-inducible factor-1 alpha (HIF1A) as an interacting partner molecule of MIF that drives SpA pathologies, including inflammation and NBF. HIF1A expression was increased in the joint tissues and synovial fluid of SpA patients and curdlan-injected SKG (curdlan-SKG) mice compared to the respective controls. Under hypoxic conditions in which HIF1A was stabilized, human and mouse neutrophils exhibited substantially increased expression of MIF and IL-23, an upstream type 3 immunity-related cytokine. Similar to MIF, systemic overexpression of IL-23 induced SpA pathology in SKG mice, while the injection of a HIF1A-selectiveinhibitor (PX-478) into curdlan-SKG mice prevented or attenuated SpA pathology, as indicated by a marked reduction in the expression of MIF and IL-23. Furthermore, genetic deletion of MIF or HIF1A inhibition with PX-478 in IL-23-overexpressing SKG mice did not induce evident arthritis or NBF, despite the presence of psoriasis-like dermatitis and blepharitis. We also found that MIF- and IL-23-expressing neutrophils infiltrated areas of the NBF in curdlan-SKG mice. These neutrophils potentially increased chondrogenesis and cell proliferation via the upregulation of STAT3 in periosteal cells and ligamental cells during endochondral ossification. Together, these results provide supporting evidence for an MIF/HIF1A regulatory network, and inhibition of HIF1A may be a novel therapeutic approach for SpA by suppressing type 3 immunity-mediated inflammation and NBF.

Comparative Evaluation of the Differentiation and Proliferation Potential of Dental Pulp Stem Cells on Hydroxyapatite/Beta-Tricalcium Bone Graft and Bovine Bone Graft: An In Vitro Study.

Stem cells of mesenchymal origin have good proliferative capacity when compared to other stem cell types. Dental pulp stem cells (DPSCs) are a variety of mesenchymal cells obtained from the pulpal tissue of teeth and are abundantly available and easy to obtain. DPSCs facilitate and improve the formation of new bone using different bone graft scaffolds. This present study aims to evaluate and compare the osteogenic potential of DPSCs on alloplastic and xenogeneic bone grafts. Hydroxyapatite and beta-tricalcium bone graft and bovine bone graft were used in a triplicate manner in the laboratory. DPSCs were obtained from the pulpal tissue of extracted third molars in the laboratory. The cytotoxicity, osteogenic potential, and difference in the rate of proliferation of mesenchymal cells on the biomaterials were assessed. Darker purple staining was seen in the case of hydroxyapatite/beta-tricalcium bone graft on MTT colorimetric assay stating that there was an increase in cell viability in hydroxyapatite/beta-tricalcium bone graft as compared to the bovine bone graft. Hydroxyapatite/beta-tricalcium bone graft showed more osteogenic potential as compared to the bovine bone graft as a higher degree of red staining was seen in Alizarin staining. Higher cell viability and higher osteogenic proliferation and differentiation were seen on the hydroxyapatite/beta-tricalcium bone graft compared to the bovine bone scaffold.