References of "Van Oosterwyck, Hans"
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See detailBringing regenerating tissues to life: the importance of angiogenesis in tissue engineering
Carlier, Aurélie ULg; Van Gastel, Nick; Geris, Liesbet ULg et al

Poster (2014, March 11)

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See detailIn silico biology of bone regeneration inside calcium phosphate scaffolds
Carlier, Aurélie ULg; Van Oosterwyck, Hans; Geris, Liesbet ULg

in Tissue Engineering: Computer Modeling, Biofabrication and Cell Behavior (2014)

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See detailOxygen: a critical component of critically sized defects
Carlier, Aurélie ULg; Van Gastel, Nick; Geris, Liesbet ULg et al

Poster (2013, December 19)

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See detailA mathematical model of the role of oxygen during normal and delayed fracture repair
Carlier, Aurélie ULg; Van Gastel, Nick; Carmeliet, Geert et al

Conference (2013, October 24)

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See detailA gene regulatory network model evaluating the impact of individual factors in the hypertrophic switch
Kerkhofs, Johan ULg; Van Oosterwyck, Hans; Geris, Liesbet ULg

Conference (2013, September 11)

Chondrocytes undergoing hypertrophy show a major switch in phenotype underlied by a change in expression from the chondrocyte master gene, Sox9, to the osteoblastic one, Runx2. Strategies to stimulate or ... [more ▼]

Chondrocytes undergoing hypertrophy show a major switch in phenotype underlied by a change in expression from the chondrocyte master gene, Sox9, to the osteoblastic one, Runx2. Strategies to stimulate or inhibit this switch are of use in bone and cartilage tissue engineering respectively, as well as in the prevention of ectopic hypertrophy in osteoarthritis. We have constructed a literature based network comprised of 46 nodes and 161 interactions shown to play a part in chondrocyte hypertrophy. Network dynamics are simulated in discrete time through random updating by the use of additive functions to determine each node’s value. Furthermore, each species is represented by a fast variable (activity level, as determined by post translation modifications) which is assumed to be in equilibrium with a slow variable (mRNA) at all times. Through a Monte Carlo approach the importance of each node in the stability of chondrocytic phenotypes (proliferating, hypertrophic) is assessed in random initial conditions. A perturbation analysis of the stable states is used to determine the transition likelihood between states and the influence of individual nodes in this transition as a second measure of stability. Our results show that the hypertrophic state, marked by Runx2 expression, has a larger attractor basin and is more stable to perturbation than the proliferative state characterized by Sox9. The added time resolution seems to favour the Runx2 phenotype. The results for single nodes in overexpression or knockout simulations show a certain asymmetry, indicating that factors that are necessary for maintaining a certain phenotype are not necessarily useful in inducing it. [less ▲]

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See detailTo heal or not to heal: modeling the influence of oxygen during fracture healing.
Carlier, Aurélie ULg; Geris, Liesbet ULg; Van Oosterwyck, Hans

Conference (2013, September 11)

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See detailModeling the influence of oxygen in delayed bone fracture healing.
Carlier, Aurélie ULg; Geris, Liesbet ULg; Van Oosterwyck, Hans

Conference (2013, August 25)

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See detailA computational Model to Assess the Contribution of Growth Factors to Phenotype Stability in Chondrocytes
Kerkhofs, Johan ULg; Van Oosterwyck, Hans

Conference (2013, June 17)

Cell-based tissue engineering constructs are an interesting expansion of the surgeon’s toolkit in treating long bone defects. However, the outcome of interventions with these constructs suffers from high ... [more ▼]

Cell-based tissue engineering constructs are an interesting expansion of the surgeon’s toolkit in treating long bone defects. However, the outcome of interventions with these constructs suffers from high variability barring their regular appearance in the clinic, in no small part due to the inter-patient variability in cell behaviour. In the paradigm of ‘developmental engineering’ a solution to this problem is envisioned by mimicking robust developmental processes in combination with a rigorous analysis thereof through the construction of computational models. From our knowledge of developmental biology we can form a computational model to facilitate understanding of how growth factors and transcription factors influence cell fate decisions in the growth plate and consequently answer the question whether – and how – they can boost bone healing. The model presented in this study includes 46 factors and 146 interactions between them. The dynamics of the system were simulated in a simplified manner that differentiates between slow and fast interactions. Through a Monte Carlo approach the importance of each factor in the stability of chondrocytic phenotypes (proliferating, hypertrophic) is assessed. The hypertrophic state was found to be more stable than that of the proliferating chondrocyte. This higher stability in random initial conditions seems to be conferred by faster reactions that favor the hypertrophic phenotype. Overall, the model allows the importance of several important factors in the fate decision of chondrocytes to be quantitatively assessed and can make suggestions as to how an in vitro bone forming process could be steered. [less ▲]

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See detailA multiscale model of the influence of oxygen during bone fracture healing.
Carlier, Aurélie ULg; Geris, Liesbet ULg; Van Oosterwyck, Hans

Poster (2013, April 03)

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See detailValidation of a finite element model of a unilateral external fixator in a rabbit tibia defect model.
Karunratanakul, Kavin; Kerckhofs, Greet ULg; Lammens, Johan et al

in Medical engineering & physics (2013), 35(7), 1037-43

In case of large segmental defects in load-bearing bones, an external fixator is used to provide mechanical stability to the defect site. The overall stiffness of the bone-fixator system is determined not ... [more ▼]

In case of large segmental defects in load-bearing bones, an external fixator is used to provide mechanical stability to the defect site. The overall stiffness of the bone-fixator system is determined not only by the fixator design but also by the way the fixator is mounted to the bone. This stiffness is an important factor as it will influence the biomechanical environment to which tissue engineering scaffolds and regenerating tissues are exposed. A finite element (FE) model can be used to predict the system stiffness. The goal of this study is to develop and validate a 3D anatomical FE model of a bone-fixator system which includes a previously developed unilateral external fixator for a large segmental defect model in the rabbit tibia. It was hypothesized that the contact interfaces between bone and fixator screws play a major role for the prediction of the stiffness. In vitro mechanical testing was performed in order to measure the axial stiffness of cortical bone from mid-shaft rabbit tibiae and of the tibia-fixator system, as well as the bending stiffness of individual fixator screws, inserted in bone. muCT-based case-specific FE models of cortical bone and SCREW-BONE specimens were created to simulate the corresponding mechanical test set-ups. The Young's modulus of rabbit cortical bone as well as appropriate screw-bone contact settings were derived from those FE models. We then used the derived settings in an FE model of the tibia-fixator system. The difference between the FE predicted and measured axial stiffness of the tibia-fixator system was reduced from 117.93% to 7.85% by applying appropriate screw-bone contact settings. In conclusion, this study shows the importance of screw-bone contact settings for an accurate fixator stiffness prediction. The validated FE model can further be used as a tool for virtual mechanical testing in the design phase of new tissue engineering scaffolds and/or novel patient-specific external fixation devices. [less ▲]

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See detailFluorescent oxygen sensitive microbead incorporation for measuring oxygen tension in cell aggregates.
Lambrechts, Dennis; Roeffaers, Maarten; Kerckhofs, Greet ULg et al

in Biomaterials (2013), 34(4), 922-9

Molecular oxygen is a main regulator of various cell functions. Imaging methods designed as screening tools for fast, in situ, 3D and non-interfering measurement of oxygen tension in the cellular ... [more ▼]

Molecular oxygen is a main regulator of various cell functions. Imaging methods designed as screening tools for fast, in situ, 3D and non-interfering measurement of oxygen tension in the cellular microenvironment would serve great purpose in identifying and monitoring this vital and pivotal signalling molecule. We describe the use of dual luminophore oxygen sensitive microbeads to measure absolute oxygen concentrations in cellular aggregates. Stable microbead integration, a prerequisite for their practical application, was ensured by a site-specific delivery method that is based on the interactions between streptavidin and biotin. The spatial stability introduced by this method allowed for long term measurements of oxygen tension without interfering with the cell aggregation process. By making multiple calibration experiments we further demonstrated the potential of these sensors to measure local oxygen tension in optically dense cellular environments. [less ▲]

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See detailTo heal or not to heal: a multiscale model of the influence of oxygen during bone fracture healing.
Carlier, Aurélie ULg; Geris, Liesbet ULg; Van Oosterwyck, Hans

Poster (2012, October 24)

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See detailA multiscale model of sprouting angiogenesis during fracture healing.
Carlier, Aurélie ULg; Geris, Liesbet ULg; Van Oosterwyck, Hans

Conference (2012, September 18)

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See detailA Dynamic Graph Model of Endochondral Ossification can assess the Importance of Biological Actors in Differentiation
Kerkhofs, Johan ULg; Van Oosterwyck, Hans; Geris, Liesbet ULg

Conference (2012, September 18)

Cell-based tissue engineering constructs are a promising avenue for the treatment of long bone defects since they provide the primordial ingredients for bone regeneration. The construct provides the ... [more ▼]

Cell-based tissue engineering constructs are a promising avenue for the treatment of long bone defects since they provide the primordial ingredients for bone regeneration. The construct provides the appropriate micro-environment through the carrier, cells to form tissue and chemical cues to kick start the natural bone forming process. Clearly this approach will benefit from a more comprehensive appreciation of how cell populations and the microenvironment provided by the carrier can impact on bone formation in all its complexities. A cornucopia of studies of developmental biology have revealed many biological actors that together form a central network that orchestrates cell behaviour during this process and assures its robustness. This knowledge can be brought to bear specifically in the form of a mathematical model of endochondral ossification, the dominant type of ossification. This model can facilitate the understanding of how growth factors and transcription factors influence cell fate decisions and consequently answer the question whether they can boost bone healing. The model formalism accommodates the qualitative information that is typically available in developmental studies. The network comprises 46 nodes and 161 interactions, shown to be important in endochondral ossification. To simulate network dynamics in discrete time the normalized value of each gene is determined by additive functions where all interactions are assumed to be equally powerful. Furthermore, each species is represented by a fast variable (activity level, as determined by post translation modifications) which is assumed to be in equilibrium with a slow variable (mRNA) at all times. Through a Monte Carlo approach the importance of each node in the stability of chondrocytic phenotypes (proliferating, hypertrophic) is assessed. The hypertrophic state, driven by Runx2, is more stable than the proliferating chondrocyte. This higher stability seems to be conferred by faster reactions that favor the hypertrophic phenotype. In addition, the results point out that some transcription factors are necessary for the induction of a certain phenotype, whereas other transcription factors are required to maintain the phenotype, but are not necessary capable of inducing it. Overall, the model allows the importance of several important factors in the fate decision of mesenchymal cells to be quantitatively assessed based mainly on topological information. [less ▲]

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See detailMultiscale modeling of in the influence of oxygen during bone fracture healing.
Carlier, Aurélie ULg; Van Gastel, Nick; Carmeliet, Geert et al

Poster (2012, September 17)

Detailed reference viewed: 14 (1 ULg)
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See detailMultiscale modeling of sprouting angiogenesis: tip cells are selected for the top.
Carlier, Aurélie ULg; Geris, Liesbet ULg; Van Oosterwyck, Hans

Poster (2012, September 05)

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See detailMultiscale modelling of the influence of VEGF on sprouting angiogenesis.
Carlier, Aurélie ULg; Geris, Liesbet ULg; Van Oosterwyck, Hans

Poster (2012, July 06)

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See detailBridging the Gap: A Theoretical Model of Mechanotransduction Through ERK Signalling
Kerkhofs, Johan ULg; Geris, Liesbet ULg; Bosmans, Bart et al

Conference (2012, July 02)

Detailed reference viewed: 5 (0 ULg)
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See detailTip cells at the top: a multiscale model of sprouting angiogenesis.
Carlier, Aurélie ULg; Geris, Liesbet ULg; Van Oosterwyck, Hans

Conference (2012, July 01)

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See detailRelating the Chondrocyte Gene Network to Growth Plate Morphology: From Genes to Phenotype
Kerkhofs, Johan ULg; Roberts, Scott J; Luyten, Frank P et al

in PLoS ONE (2012)

During endochondral ossification, chondrocyte growth and differentiation is controlled by many local signalling pathways. Due to crosstalks and feedback mechanisms, these interwoven pathways display a ... [more ▼]

During endochondral ossification, chondrocyte growth and differentiation is controlled by many local signalling pathways. Due to crosstalks and feedback mechanisms, these interwoven pathways display a network like structure. In this study, a large-scale literature based logical model of the growth plate network was developed. The network is able to capture the different states (resting, proliferating and hypertrophic) that chondrocytes go through as they progress within the growth plate. In a first corroboration step, the effect of mutations in various signalling pathways of the growth plate network was investigated. [less ▲]

Detailed reference viewed: 26 (9 ULg)