References of "Geris, Liesbet"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailComputational modelling of biomaterial surface interactions with blood platelets and osteoblastic cells for the prediction of contact osteogenesis.
Amor, N.; Geris, Liesbet ULg; Vander Sloten, J. et al

in Acta Biomaterialia (2011), 7(2), 779-90

Surface microroughness can induce contact osteogenesis (bone formation initiated at the implant surface) around oral implants, which may result from different mechanisms, such as blood platelet ... [more ▼]

Surface microroughness can induce contact osteogenesis (bone formation initiated at the implant surface) around oral implants, which may result from different mechanisms, such as blood platelet-biomaterial interactions and/or interaction with (pre-)osteoblast cells. We have developed a computational model of implant endosseous healing that takes into account these interactions. We hypothesized that the initial attachment and growth factor release from activated platelets is crucial in achieving contact osteogenesis. In order to investigate this, a computational model was applied to an animal experiment [7] that looked at the effect of surface microroughness on endosseous healing. Surface-specific model parameters were implemented based on in vitro data (Lincks et al. Biomaterials 1998;19:2219-32). The predicted spatio-temporal patterns of bone formation correlated with the histological data. It was found that contact osteogenesis could not be predicted if only the osteogenic response of cells was up-regulated by surface microroughness. This could only be achieved if platelet-biomaterial interactions were sufficiently up-regulated as well. These results confirmed our hypothesis and demonstrate the added value of the computational model to study the importance of surface-mediated events for peri-implant endosseous healing. [less ▲]

Detailed reference viewed: 18 (4 ULg)
Full Text
See detailMathematical modeling of cell-cell and cell-matrix adhesion in tissue engineering using continuum models
Geris, Liesbet ULg; Gerisch, A.

in Geffen, A. (Ed.) Cellular and Biomolecular Mechanics and Mechanobiology (2011)

Key factors in the formation of cell aggregates in tissue engineering and other fields are the cell-cell and cell-matrix interactions. Other important factors are culture conditions such as nutrient and ... [more ▼]

Key factors in the formation of cell aggregates in tissue engineering and other fields are the cell-cell and cell-matrix interactions. Other important factors are culture conditions such as nutrient and oxygen supply and the characteristics of the environment (medium versus hydrogel). As mathematical models are increasingly used to investigate biological phenomena, it is important that processes such as cell adhesion are adequately described in the models. Recently a technique was developed to incorporate cell-cell and cell-matrix adhesion in continuum models through the use of non-local terms. In this study we apply this technique to model adhesion in a cell-in-gel culture set-up often found in tissue engineering applications. We briefly describe the biological issues underlying this study and the various modeling techniques used to capture adhesive behaviour. We furthermore elaborate on the numerical techniques that were developed in the course of this study. Finally, we consider a tissue engineering model that describes the spatiotemporal evolution of the concentration of cells, matrix, hydrogel, matrix degrading enzymes and oxygen/nutrients in a cell-in-gel culture system. Sensitivity analyses indicate a clear influence of the different adhesive processes on the final cell and collagen density and distribution, demonstrating the significance of cell adhesion in tissue engineering and the potential of the proposed mathematical technique. [less ▲]

Detailed reference viewed: 59 (17 ULg)
Full Text
Peer Reviewed
See detailA hybrid bioregulatory model of angiogenesis during bone fracture healing
Peiffer, Veronique; Gerisch, Alf; Vandepitte, Dirk et al

in Biomechanics & Modeling in Mechanobiology (2011), 10(3), 383-395

Bone fracture healing is a complex process in which angiogenesis or the development of a blood vessel net work plays a crucial role. In this paper, a mathematicalmodel is presented that simulates the ... [more ▼]

Bone fracture healing is a complex process in which angiogenesis or the development of a blood vessel net work plays a crucial role. In this paper, a mathematicalmodel is presented that simulates the biological aspects of fracture healing including the formation of individual blood vessels. The model consists of partial differential equations, several of which describe the evolution in density of the most important cell types, growth factors, tissues and nutrients. The other equations determine the growth of blood vessels as a result of themovement of leading endothelial (tip) cells. Branching and anastomoses are accounted for in the model. The model is applied to a normal fracture healing case and subjected to a sensitivity analysis. The spatiotemporal evolution of soft tissues and bone, as well as the development of a blood vessel network are corroborated by comparison with experimental data. Moreover, this study shows that the proposed mathematical framework can be a useful tool in the research of impaired healing and the design of treatment strategies. [less ▲]

Detailed reference viewed: 41 (14 ULg)
Peer Reviewed
See detailA Boolean network model of the growth plate
Kerkhofs, Johan ULg; Roberts, Scott J; Luyten, Frank P et al

Poster (2010, November 26)

Detailed reference viewed: 8 (0 ULg)
Peer Reviewed
See detailComputational modelling of calcium mediated bone regeneration
Carlier, Aurélie ULg; Chai, Yoke Chin; Theys, Tina et al

Poster (2010, November 26)

Detailed reference viewed: 11 (2 ULg)
Peer Reviewed
See detailA mathematical model of calcium ion influence on the activity of osteogenic cells
Carlier, Aurélie ULg; Chai, Yoke Chin; Theys, Tina et al

Poster (2010, November 19)

Detailed reference viewed: 18 (3 ULg)
Peer Reviewed
See detailA Boolean network model of the growth plate
Kerkhofs, Johan ULg; Roberts, Scott J; Luyten, Frank P et al

Poster (2010, October 10)

Detailed reference viewed: 7 (0 ULg)
Peer Reviewed
See detailBMP signalling in growth plate chondrocytes: a Boolean modelling approach
Kerkhofs, Johan ULg; Roberts, Scott J; Van Oosterwyck, Hans et al

Poster (2010, September 15)

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailOccurrence and Treatment of Bone Atrophic Non-Unions Investigated by an Integrative Approach
Geris, Liesbet ULg; Reed, Anita A.C.; Vander Sloten, Jos et al

in PLoS Computational Biology (2010), 6(9), 1000915

Recently developed atrophic non-union models are a good representation of the clinical situation in which many nonunions develop. Based on previous experimental studies with these atrophic non-union ... [more ▼]

Recently developed atrophic non-union models are a good representation of the clinical situation in which many nonunions develop. Based on previous experimental studies with these atrophic non-union models, it was hypothesized that in order to obtain successful fracture healing, blood vessels, growth factors, and (proliferative) precursor cells all need to be present in the callus at the same time. This study uses a combined in vivo-in silico approach to investigate these different aspects (vasculature, growth factors, cell proliferation). The mathematical model, initially developed for the study of normal fracture healing, is able to capture essential aspects of the in vivo atrophic non-union model despite a number of deviations that are mainly due to simplifications in the in silico model. The mathematical model is subsequently used to test possible treatment strategies for atrophic non-unions (i.e. cell transplant at post-osteotomy, week 3). Preliminary in vivo experiments corroborate the numerical predictions. Finally, the mathematical model is applied to explain experimental observations and identify potentially crucial steps in the treatments and can thereby be used to optimize experimental and clinical studies in this area. This study demonstrates the potential of the combined in silico-in vivo approach and its clinical implications for the early treatment of patients with problematic fractures. [less ▲]

Detailed reference viewed: 75 (22 ULg)
Peer Reviewed
See detailExperimentally-informed Mathematical Modelling of Oxygen Tension, Cell Viability and Proliferation in Fibrin Hydrogels
Demol, Jan; Lambrechts, Dennis; Geris, Liesbet ULg et al

in Proceedings of the TERMIS-EU meeting (2010, June)

Detailed reference viewed: 11 (1 ULg)
Peer Reviewed
See detailCross-talk Modeling of Wnt, BMP and ERK Pathways during Osteochondrogenic Differentiation
Geris, Liesbet ULg; Vandeput, M.; Roberts, S. et al

in Proceedings of the TERMIS-EU meeting (2010, June)

Detailed reference viewed: 17 (2 ULg)
Full Text
Peer Reviewed
See detailConnecting biology and mechanics in fracture healing: an integrated mathematical modeling framework for the study of nonunions
Geris, Liesbet ULg; Vander Sloten, Jos; Van Oosterwyck, Hans

in Biomechanics & Modeling in Mechanobiology (2010), 9(6), 713-724

Both mechanical and biological factors play an important role in normal as well as impaired fracture healing. This study aims to provide a mathematical framework in which both regulatory mechanisms are ... [more ▼]

Both mechanical and biological factors play an important role in normal as well as impaired fracture healing. This study aims to provide a mathematical framework in which both regulatory mechanisms are included. Mechanics and biology are coupled by making certain parameters of a previously established bioregulatory model dependent on local mechanical stimuli. To illustrate the potential added value of such a framework, this coupled model was applied to investigate whether local mechanical stimuli influencing only the angiogenic process can explain normal healing as well as overload-induced nonunion development. Simulation results showed that mechanics acting directly on angiogenesis alone was not able to predict the formation of overload-induced onunions. However, the direct action of mechanics on both angiogenesis and osteogenesis was able to predict overload-induced nonunion formation, confirming the hypotheses of several experimental studies investigating the interconnection between angiogenesis and osteogenesis. This study shows that mathematical models can assist in testing hypothesis on the nature of the interaction between biology and mechanics. [less ▲]

Detailed reference viewed: 39 (18 ULg)
See detailThe biology of orthodontic tooth movement: a mathematical model
Van Schepdael, J.; Vander Sloten, Jos; Geris, Liesbet ULg

in Middleton, J.; Jacobs, C.; Walker, B. (Eds.) et al 9th International symposium on Computer Methods in Biomechanics and Biomedical Engineering (2010, February)

Detailed reference viewed: 36 (6 ULg)
Full Text
Peer Reviewed
See detailMechanical loading affects angiogenesis and osteogenesis in an in vivo bone chamber: a modeling study.
Geris, Liesbet ULg; Vandamme, Katleen; Naert, Ignace et al

in Tissue Engineering. Part A (2010), 16(11), 3353-3361

Despite a myriad of studies confirming the interaction between biology and mechanics, the exact nature of the main mechanical stimuli and their influence on the bone regeneration processes are still ... [more ▼]

Despite a myriad of studies confirming the interaction between biology and mechanics, the exact nature of the main mechanical stimuli and their influence on the bone regeneration processes are still unclear. The hypothesis of this study was that the outcome of peri-implant healing under different implant loading regimens can be explained by the influence of fluid flow on the combination of angiogenesis and osteogenesis through its influence on cell proliferation and differentiation. To investigate this hypothesis a mathematical model of bone regeneration was applied to simulate the peri-implant healing in an in vivo repeated sampling bone chamber for different axial micromechanical implant loading regimes. When mechanical loading was modeled to influence both osteogenic and angiogenic processes, a good agreement was observed between simulations and experiments concerning the amount of bone in the bone chamber, its radial and longitudinal distribution, and the bone-implant contact for different implant displacement magnitudes. [less ▲]

Detailed reference viewed: 12 (2 ULg)
Full Text
Peer Reviewed
See detailMathematical Modeling in Wound Healing, Bone Regeneration and Tissue Engineering
Geris, Liesbet ULg; Gerisch, Alf; Schugart, Richard C.

in Acta Biotheoretica (2010), 58(4), 355-367

The processes of wound healing and bone regeneration and problems in tissue engineering have been an active area for mathematical modeling in the last decade. Here we review a selection of recent models ... [more ▼]

The processes of wound healing and bone regeneration and problems in tissue engineering have been an active area for mathematical modeling in the last decade. Here we review a selection of recent models which aim at deriving strategies for improved healing. In wound healing, the models have particularly focused on the inflammatory response in order to improve the healing of chronic wound. For bone regeneration, the mathematical models have been applied to design optimal and new treatment strategies for normal and specific cases of impaired fracture healing. For the field of tissue engineering, we focus on mathematical models that analyze the interplay between cells and their biochemical cues within the scaffold to ensure optimal nutrient transport and maximal tissue production. Finally, we briefly comment on numerical issues arising from simulations of these mathematical models. [less ▲]

Detailed reference viewed: 41 (6 ULg)
Full Text
Peer Reviewed
See detailTowards a quantitative understanding of oxygen tension and cell density evolution in fibrin hydrogels
Demol, Jan; Lambrechts, Dennis; Geris, Liesbet ULg et al

in Biomaterials (2010), 32(1), 107-118

The in vitro culture of hydrogel-based constructs above a critical size is accompanied by problems of unequal cell distribution when diffusion is the primary mode of oxygen transfer. In this study, an ... [more ▼]

The in vitro culture of hydrogel-based constructs above a critical size is accompanied by problems of unequal cell distribution when diffusion is the primary mode of oxygen transfer. In this study, an experimentally informed mathematical model was developed to relate cell proliferation and death inside fibrin hydrogels to the local oxygen tension in a quantitative manner. The predictive capacity of the resulting model was tested by comparing its outcomes to the density, distribution and viability of human periosteum derived cells (hPDCs) that were cultured inside fibrin hydrogels in vitro. The model was able to reproduce important experimental findings, such as the formation of a multilayered cell sheet at the hydrogel periphery and the occurrence of a cell density gradient throughout the hydrogel. In addition, the model demonstrated that cell culture in fibrin hydrogels can lead to complete anoxia in the centre of the hydrogel for realistic values of oxygen diffusion and consumption. A sensitivity analysis also identified these two parameters, together with the proliferation parameters of the encapsulated cells, as the governing parameters for the occurrence of anoxia. In conclusion, this study indicates that mathematical models can help to better understand oxygen transport limitations and its influence on cell behaviour during the in vitro culture of cellseeded hydrogels. [less ▲]

Detailed reference viewed: 21 (1 ULg)
Peer Reviewed
See detailIn vivo, in vitro, in silico: computational tools for tissue engineering
Van Oosterwyck, Hans; Truscello, S.; Demol, Jan et al

in proceedings of the 2nd International Conference on Innovation for Sustainable Production i-SUP (2010)

Detailed reference viewed: 3 (0 ULg)
Peer Reviewed
See detailOptimizing The Micro-Environment In A Tissue Engineering Scaffold: A Computational Approach
Van Oosterwyck, Hans; Truscello, S.; Demol, J. et al

in proceedings of the Materialise World Conference (2010)

Detailed reference viewed: 8 (0 ULg)
Full Text
See detailMathematical modelling of cell aggregates for bone tissue engineering using continuum methods
Geris, Liesbet ULg; Clarke, T.; Ashbourn, J.

in Middleton, J.; Jacobs, C.; Walker, B. (Eds.) et al 9th International symposium on Computer Methods in Biomechanics and Biomedical Engineering (2010)

Detailed reference viewed: 10 (0 ULg)
Peer Reviewed
See detailExperimental and computational study of the correlation between oxygen tension, cell viability and proliferation in fibrin hydrogels
Demol, J.; Lambrechts, D.; Geris, Liesbet ULg et al

in Proceedings of the 17th conference of the European Society of Biomechanics (2010)

Detailed reference viewed: 18 (0 ULg)