scholarly journals Effects of mechanical loading on cortical defect repair using a novel mechanobiological model of bone healing

2017 ◽  
Author(s):  
Chao Liu ◽  
Robert Carrera ◽  
Vittoria Flamini ◽  
Lena Kenny ◽  
Pamela Cabahug-Zuckerman ◽  
...  
Keyword(s):  
Mechanical Loading ◽  
Cellular Proliferation ◽  
Fibrous Tissue ◽  
Peak Load ◽  
Physical Stimulation ◽  
Cartilage Formation ◽  
Matrix Deposition ◽  
Cortical Defect ◽  
Periosteal Surface ◽  
Defect Repair

AbstractMechanical loading is an important aspect of post-surgical care. The timing of load application relative to the injury event is thought to differentially regulate repair depending on the stage of healing. Here, we show using a novel mechanobiological model of cortical defect repair that daily loading (5 N peak load, 2 Hz, 60 cycles, 4 consecutive days) during hematoma consolidation and inflammation disrupts the injury site and activates cartilage formation on the periosteal surface adjacent to the defect. We also show that daily loading during the matrix deposition phase enhances both bone and cartilage formation at the defect site, while loading during the remodeling phase results in an enlarged woven bone regenerate. All loading regimens resulted in abundant cellular proliferation within the regenerate and at the periosteal surface and fibrous tissue formation directly above the defect. Stress was concentrated at the edges of the defect during exogenous loading, and finite element (FE)-modeled longitudinal strain (εzz) values along the anterior and posterior borders of the defect (~2200 με) were an order of magnitude larger than strain values on the proximal and distal borders (~50-100 με). These findings demonstrate that all phases of cortical defect healing are sensitive to physical stimulation. In addition, the proposed novel mechanobiological model offers several advantages including its technical simplicity and its well-characterized and spatially confined repair program, making effects of physical and biological interventions more easily assessed.

scholarly journals Cortical Thickness Adaptive Response to Mechanical Loading Depends on Periosteal Position and Varies Linearly With Loading Magnitude

2021 ◽  
Vol 9 ◽  
Author(s):  
Corey J. Miller ◽  
Silvia Trichilo ◽  
Edmund Pickering ◽  
Saulo Martelli ◽  
Peter Delisser ◽  
...  
Keyword(s):  
Bone Formation ◽  
Cross Section ◽  
Mechanical Loading ◽  
Cortical Thickness ◽  
Cross Sections ◽  
Peak Load ◽  
Neutral Axis ◽  
Cross Sectional ◽  
Periosteal Surface ◽  
Tensile Strains

The aim of the current study was to quantify the local effect of mechanical loading on cortical bone formation response at the periosteal surface using previously obtained μCT data from a mouse tibia mechanical loading study. A novel image analysis algorithm was developed to quantify local cortical thickness changes (ΔCt.Th) along the periosteal surface due to different peak loads (0N ≤ F ≤ 12N) applied to right-neurectomised mature female C57BL/6 mice. Furthermore, beam analysis was performed to analyse the local strain distribution including regions of tensile, compressive, and low strain magnitudes. Student’s paired t-test showed that ΔCt.Th in the proximal (25%), proximal/middle (37%), and middle (50%) cross-sections (along the z-axis of tibia) is strongly associated with the peak applied loads. These changes are significant in a majority of periosteal positions, in particular those experiencing high compressive or tensile strains. No association between F and ΔCt.Th was found in regions around the neutral axis. For the most distal cross-section (75%), the association of loading magnitude and ΔCt.Th was not as pronounced as the more proximal cross-sections. Also, bone formation responses along the periosteum did not occur in regions of highest compressive and tensile strains predicted by beam theory. This could be due to complex experimental loading conditions which were not explicitly accounted for in the mechanical analysis. Our results show that the bone formation response depends on the load magnitude and the periosteal position. Bone resorption due to the neurectomy of the loaded tibia occurs throughout the entire cross-sectional region for all investigated cortical sections 25, 37, 50, and 75%. For peak applied loads higher than 4 N, compressive and tensile regions show bone formation; however, regions around the neutral axis show constant resorption. The 50% cross-section showed the most regular ΔCt.Th response with increased loading when compared to 25 and 37% cross-sections. Relative thickness gains of approximately 70, 60, and 55% were observed for F = 12 N in the 25, 37, and 50% cross-sections. ΔCt.Th at selected points of the periosteum follow a linear response with increased peak load; no lazy zone was observed at these positions.

scholarly journals Effects of mechanical loading on cortical defect repair using a novel mechanobiological model of bone healing

Bone ◽  
2018 ◽  
Vol 108 ◽  
pp. 145-155 ◽  
Author(s):  
Chao Liu ◽  
Robert Carrera ◽  
Vittoria Flamini ◽  
Lena Kenny ◽  
Pamela Cabahug-Zuckerman ◽  
...  
Keyword(s):  
Mechanical Loading ◽  
Bone Healing ◽  
Cortical Defect ◽  
Defect Repair

Absence of bone sialoprotein (BSP) impairs cortical defect repair in mouse long bone

Bone ◽  
2009 ◽  
Vol 45 (5) ◽  
pp. 853-861 ◽  
Author(s):  
Luc Malaval ◽  
Laurent Monfoulet ◽  
Thierry Fabre ◽  
Laurent Pothuaud ◽  
Reine Bareille ◽  
...  
Keyword(s):  
Bone Sialoprotein ◽  
Long Bone ◽  
Cortical Defect ◽  
Defect Repair

scholarly journals An Injectable Fibrin Scaffold Rich in Growth Factors for Skin Repair

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhengwei Shao ◽  
Chengqi Lyu ◽  
Lin Teng ◽  
Xuetao Xie ◽  
Jiayue Sun ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Growth Factors ◽  
White Blood Cells ◽  
Cell Counting ◽  
Skin Defect ◽  
Matrix Deposition ◽  
Skin Repair ◽  
Thickness Skin ◽  
Fibrin Scaffold ◽  
Defect Repair

Platelet aggregates, such as PRP, PRF, and CGF, have been used alone or in combination with other grafting materials to enhance restoration outcomes. The process for preparing these autografting materials requires two-step centrifugation or specific centrifuges. In this study, we obtained an injectable fibrin scaffold (IFS) rich in growth factors by one-step centrifugation of whole blood from rabbits. The purpose of this study is to introduce some characteristics of IFS. This scaffold was characterized using various techniques, including Masson’s trichrome staining, scanning electron microscopy, porosity measurements, and cell counting. The sustained release of growth factors, including PDGF, VEGF, TGF-β1, IGF, FGF, and EGF, was quantified using ELISA assay. The obtained IFS was tested for its effects on cell proliferation, extracellular matrix deposition, and full-thickness skin defect repair. The prepared IFS is characterized by a loose fibrin network structure with white blood cells and platelets that slowly release growth factors and can promote the healing of skin defects via the promotion of cell proliferation, collagen deposition, and tissue revascularization. In addition, its liquid properties and porous structure are conducive to its application as a therapeutic component in tissue engineering.

244 CHONDROGENIC PELLET CULTURES FOR CARTILAGE TISSUE ENGINEERING GROW BY DEPOSITION OF MATRIX AND NOT BY CELLULAR PROLIFERATION

2016 ◽  
Vol 28 (2) ◽  
pp. 254 ◽  
Author(s):  
S. Johnson ◽  
D. Milner ◽  
H. Lopez-Lake ◽  
M. Wheeler
Keyword(s):  
Extracellular Matrix ◽  
Cell Proliferation ◽  
Chondrogenic Differentiation ◽  
Cellular Proliferation ◽  
Cartilage Matrix ◽  
T Test ◽  
Cartilage Tissue ◽  
Matrix Deposition ◽  
Student’S T ◽  
Student’S T Test

Pellet cultures are commonly used to study chondrogenic differentiation in vitro. Our laboratory has demonstrated pellets made with chondrocytes grow in size during culture and produce cartilage matrix, but pellets made with adipose-derived mesenchymal stem cells (ASC) grow only slightly, producing little cartilage matrix. The objective of this study was to determine if differences in chondrocyte and ASC pellet growth result from differences in cell proliferation or in deposition of extracellular matrix. Primary chondrocytes and ASC from adult pigs were cultured in Dulbecco’s modified Eagle’s medium (DMEM) with 10% fetal bovine serum. To determine baseline proliferation rates in monolayer culture, cells were grown on coverslips in 10 µM bromodeoxyuridine (BrdU) for 24 h and immunostained for BrdU labelling. For pellet cultures, 5 × 105 cells were placed in 15 mL-conical tubes, pelleted by centrifugation in 1.0 mL of chondrogenic base media (CBM: DMEM + 40 µg mL–1 of proline, 50 µM ascorbic acid-2-phosphate, 100 nM dexamethasone, and 1× insulin-transferrin-selenium), and cultured in CBM for 1, and 4 weeks. To detect proliferation in pellets, 1- and 2-week cultured samples were labelled with 10 µM BrdU for 24 h before harvest. Pellets were fixed with 4% paraformaldehyde, embedded, and sectioned on a Leica CM1900 cryostat (Leica Microsystems, Wetzlar, Germany). To assess chondrogenic differentiation and matrix expression, sections were stained for collagen II, keratin sulfate, and chondroitin sulfate. Images were captured and distance between adjacent nuclei in 1- and 4-week pellets were measured using Zeiss imaging software. As expected, cells on coverslips showed BrdU labelling, with higher labelling in ASC cultures indicating faster proliferation (n = 5, 77.3 ± 3.74% chondrocyte v. 92.1 ± 2.88% ASC; α = 0.05; P < 0.0001; Student’s t-test). However, BrdU labelling was not seen in sections from ASC or chondrocyte pellets (n = 5), at either 1 or 2 weeks. Absence of cellular proliferation in pellets was verified by negative staining for the mitotic marker Aurora KinaseB (AurKB). Cartilage matrix staining was strong in chondrocyte pellets at all time points and absent in ASC pellets. Cell nuclei were closely packed in both ASC and chondrocyte pellets at 1 week, but a significant increase in distance between adjacent nuclei with interspersed matrix staining was noted in chondrocyte pellets at 4 weeks (n = 4, 11.88 ± 0.67 µm at 1 week v. 26.85 ± 2.06 µm at 4 weeks; α = 0.05; P < 0.0001; Student’s t-test). As TGFβ3 has been shown to induce chondrogenesis in ASC, ASC pellets were cultured in CBM + 10 ng of TGFβ3 for 1 and 2 weeks (n = 4). The TGFβ3 treatment did not induce cell proliferation in pellets, as sections were negative for BrdU. However, expression of cartilage markers keratan sulfate and chondroitin were noted. Based on our data, neither ASC nor chondrocytes proliferate in pellet culture, and chondrocyte pellet growth is due to extracellular matrix deposition.

scholarly journals Sodium hyaluronate supplemented culture medium combined with joint-simulating mechanical loading improves chondrogenic differentiation of human mesenchymal stem cells

2021 ◽  
Vol 41 ◽  
pp. 616-632
Author(s):  
G Monaco ◽  
◽  
AJ El Haj ◽  
M Alini ◽  
MJ Stoddart
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Mechanical Loading ◽  
Chondrogenic Differentiation ◽  
Culture Medium ◽  
In Vitro Models ◽  
Matrix Deposition ◽  
Sulphated Glycosaminoglycan

In vitro models aim to recapitulate the in vivo situation. To more closely mimic the knee joint environment, current in vitro models need improvements to reflect the complexity of the native tissue. High molecular weight hyaluronan (hMwt HA) is one of the most abundant bioactive macromolecules in healthy synovial fluid, while shear and dynamic compression are two joint-relevant mechanical forces. The present study aimed at investigating the concomitant effect of joint-simulating mechanical loading (JSML) and hMwt HA-supplemented culture medium on the chondrogenic differentiation of primary human bone-marrow-derived mesenchymal stem cells (hBM-MSCs). hBM-MSC chondrogenesis was investigated over 28 d at the gene expression level and total DNA, sulphated glycosaminoglycan, TGF-β1 production and safranin O staining were evaluated. The concomitant effect of hMwt HA culture medium and JSML significantly increased cartilage-like matrix deposition and sulphated glycosaminoglycan synthesis, especially during early chondrogenesis. A stabilisation of the hBM-MSC-derived chondrocyte phenotype was observed through the reduced upregulation of the hypertrophic marker collagen X and an increase in the chondrogenic collagen type II/X ratio. A combination of JSML and hMwt HA medium better reflects the complexity of the in vivo synovial joint environment. Thus, JSML and hMwt HA medium will be two important features for joint-related culture models to more accurately predict the in vivo outcome, therefore reducing the need for animal studies. Reducing in vitro artefacts would enable a more reliable prescreening of potential cartilage repair therapies.

scholarly journals Platelet Rich Plasma (PRP) Produces an Atherofibrotic Histophenotype During Craniofacial Bone Repair Due to Changes of Immunohistochemical Expression of Erk1/2, p38α/β, Adiponectin and Elevated Presence of Cells Exhibiting B-scavenger Receptor (CD36+)

2016 ◽  
Vol 27 (3) ◽  
pp. 243-254 ◽  
Author(s):  
Caroline Cristine Schroeder ◽  
Juliana Souza Vieira, Rafaela Scariot ◽  
João Cesar Zielak, Geraldo Monteiro Ribeiro ◽  
Tatiana Miranda Deliberador ◽  
Andrea M. Marcaccini, Allan Fernando Giovanini
Keyword(s):  
Bone Repair ◽  
Cellular Proliferation ◽  
Platelet Rich Plasma ◽  
Bone Matrix ◽  
Scavenger Receptor ◽  
Foam Cell Formation ◽  
Immunohistochemical Expression ◽  
Craniofacial Bone ◽  
Matrix Deposition ◽  
Post Surgery

Abstract The platelet-extracellular matrix interaction in platelet rich plasma (PRP) through thrombospondin receptor-CD36 induces the secretion of growth factors responsible for cellular proliferation and differentiation during the repair process. Since CD36 also acts as a class B-scavenger-receptor for development of foam-like cells and mitogen-activated kinases, such as Erk1/2 and p38α/β, are important proteins activated by platelet growth factor, the aim of this study was to evaluate the immunohistochemical presence of CD36, Erk1/2, p38α/β during the bone repair treated and non-treated with PRP and to compare these results with the histomorphometry of repair. Simultaneously, the immunopresence of adiponectin was analyzed, which may contribute to osteogenesis at the same time it inhibits fibrosis and impairs adipogenesis and foam cell formation in the medullary area. An artificial bone defect measuring 5×1 mm was produced in the calvaria of 56 Wistar rats. The defects were randomly treated with autograft, autograft+PRP, PRP alone and sham. The animals were euthanized at 2 and 6 weeks post-surgery. Data were analyzed by ANOVA followed by non-parametric test Student Newman-Keuls (p<0.05) for histomorphometric and immunohistochemical interpretation. The results revealed that in specimens that received PRP the immunopositivity for Erk1/2, p38α/β and CD36 proteins increased significantly while the immunohistochemical expression of adiponectin decreased simultaneously. There was also an accentuated reduction of bone matrix deposition and increase of the medullary area represented by fibrosis and/or presence of foam-like cells, which exhibited immunophenotype CD36+adiponectin. The findings of this study suggest that PRP acted as an inhibitor of osteogenesis during the craniofacial bone repair and induced a pathological condition that mimics an atherofibrotic condition.

scholarly journals SUN-552 Follistatin-Like 3 (FSTL3), a Transforming Growth Factor β (TGFβ) Ligand Inhibitor, Regulates Placental Development in Mice

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Josef Huntington ◽  
Rachel Robertson ◽  
Gurtej K Dhoot ◽  
Imelda M McGonnell ◽  
Caroline Wheeler-Jones ◽  
...  
Keyword(s):  
Growth Factor ◽  
Cellular Proliferation ◽  
Transforming Growth Factor ◽  
Expression Patterns ◽  
Transforming Growth Factor Β ◽  
Placental Development ◽  
Matrix Deposition ◽  
Smad2 Phosphorylation ◽  
Placental Efficiency ◽  
And Function

Abstract Follistatin-like 3 (FSTL3), a glycoprotein that inhibits transforming growth factor-β (TGFβ) ligands such as activin, is expressed highly in the placenta and other vascular tissues. In addition, FSTL3 is strongly induced in pre-eclamptic placenta. To test the hypothesis that FSTL3 function is required for capillary bed structure and function we studied the placenta in FSTL3 gene deleted mice (FSTL3 KO). We have previously shown that FSTL3 deletion produces striking defects in the placenta when compared to WT. Placental size increases significantly in comparison to WT, at 16.5 and 18.5 dpc, with concurrent reduction in placental efficiency at 18.5 dpc. Histological analyses reveal structural differences in placental junctional zones in FSTL3 KO placenta compared to WT. Morphometric analyses show that the labyrinth area compared to the placenta area is significantly reduced in FSTL3 KO mice. We also found that activin-responsive FSTL3-synexpression genes are upregulated in FSTL3 KO placenta. Of these, EPHB4 protein is induced in the placenta along with its ligand EphrinB2. Here we show that FSTL3 deletion leads to endothelial cell expansion but reduction in blood vessel density along with increased extracellular matrix deposition. Further investigation of the placental phenotype revealed differential expression patterns of desmin and cytokeratin protein, reduced von Willebrand factor (VWF) and increased CD31 and VEGFR2 labelling within FSTL3 KO mice placental labyrinths. To identify mechanisms that might lead to the altered placental development in FSTL3 KO mice qPCR analyses were performed. Our results identified differences in the expression of crucial transcripts, such as Cdh5, Pgf, Fra1and Cited1, that are associated with the regulation of vascular biology. Additionally, we find increased Histone3 and SMAD2 phosphorylation in FSTL3 KO placenta indicating increased proliferation and activin signalling, respectively. These findings suggest that the balance between cellular proliferation and differentiation might be altered in the absence of FSTL3. Thus, we conclude that FSTL3 function, at least partly through the inhibition of activin action, is necessary for normal placental circulation and development.

Mechanical Loading Modulates Gene Expression in Chondrocyte-Seeded Agarose Hydrogels

2001 ◽  
Author(s):  
Sansan S. Lo ◽  
Robert L. Mauck ◽  
Sara L. Seyhan ◽  
Glyn D. Palmer ◽  
Van C. Mow ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mechanical Loading ◽  
Promoter Activity ◽  
Dynamic Compression ◽  
Cell Phenotype ◽  
Mrna Levels ◽  
Matrix Deposition ◽  
Matrix Gene ◽  
The Matrix ◽  
Matrix Accumulation

Abstract A successful tissue engineered articular cartilage construct needs to possess mechanical, biochemical, and histological features similar to that of native cartilage in order to serve its load-bearing function. Agarose is a suitable scaffold material for chondrocyte cultures (1,2), allowing long-term maintenance of cell phenotype and the elaboration of a functional cartilage-like matrix. This culture system facilitates further elucidation of the roles of matrix and cell-matrix interactions in the regulation of chondrocyte response to mechanical loads. We have previously shown (3) that mechanical loading at a physiologic frequency can increase the rate of matrix deposition, increasing mechanical properties of the tissue engineered constructs (∼21 fold increases in HA over day 0 with loading vs. ∼4 fold increases for free swelling controls). We have also shown that dynamic loading of transiently transfected chondrocytes in agarose hydrogels for 1 hour at 10% strain increased aggrecan promoter activity by ∼1.5 fold (4). In this study we sought to further characterize the short term response of chondrocytes to static load (by measuring aggrecan promoter activity) and the effects of dynamic compression on aggrecan gene expression over a longer (3 day) culture period (by monitoring mRNA levels). Monitoring matrix gene expression during early times of culture, when there is little matrix accumulation and the cells deform directly with the matrix (5), may provide insights into cellular responses to strain and allow for the optimization of cartilage bioreactor conditions.

scholarly journals Ultrasonic assessment and finite element modelling of thermo-mechanical damage in mortar

2017 ◽  
Vol 10 (4) ◽  
pp. 826-837 ◽  
Author(s):  
C. L. Nogueira
Keyword(s):  
Finite Element ◽  
Mechanical Loading ◽  
Peak Load ◽  
Mechanical Damage ◽  
Element Model ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Transverse Waves ◽  
Ultrasonic Assessment

ABSTRACT Experiments were conducted to evaluate degradation of mechanical properties in mortar specimens subjected to thermal and mechanical loading. Ultrasonic pulse velocity was used to assess changes in the microstructure of the specimens due to thermal and mechanical loads applied separately. Both longitudinal and transverse waves were used. At first the specimens were tested in the undamaged stage, and then they were also tested after their exposure to a non-uniform thermal load only, finally, mechanical loading was applied until peak load. A finite element model was used in the dynamic simulation of pulses propagation. Results showed that mortar mix with a larger proportion of coarser aggregates is more sensitive to mechanical loading after exposure to heat than mortar with lesser and smaller aggregate contents. Mortar mix design with less and finer aggregate did not show a reduction in the pulse velocity as intense as the mortar with more coarse aggregate, which indicates a less severe diffuse microcracking.

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