References of "Luyten, Frank P"
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See detailMultifactorial Optimization of Contrast-Enhanced Nanofocus Computed Tomography for Quantitative Analysis of Neo-Tissue Formation in Tissue Engineering Constructs.
Sonnaert, Maarten; Kerckhofs, Greet; Papantoniou, Ioannis et al

in PloS one (2015), 10(6), 0130227

To progress the fields of tissue engineering (TE) and regenerative medicine, development of quantitative methods for non-invasive three dimensional characterization of engineered constructs (i.e. cells ... [more ▼]

To progress the fields of tissue engineering (TE) and regenerative medicine, development of quantitative methods for non-invasive three dimensional characterization of engineered constructs (i.e. cells/tissue combined with scaffolds) becomes essential. In this study, we have defined the most optimal staining conditions for contrast-enhanced nanofocus computed tomography for three dimensional visualization and quantitative analysis of in vitro engineered neo-tissue (i.e. extracellular matrix containing cells) in perfusion bioreactor-developed Ti6Al4V constructs. A fractional factorial 'design of experiments' approach was used to elucidate the influence of the staining time and concentration of two contrast agents (Hexabrix and phosphotungstic acid) and the neo-tissue volume on the image contrast and dataset quality. Additionally, the neo-tissue shrinkage that was induced by phosphotungstic acid staining was quantified to determine the operating window within which this contrast agent can be accurately applied. For Hexabrix the staining concentration was the main parameter influencing image contrast and dataset quality. Using phosphotungstic acid the staining concentration had a significant influence on the image contrast while both staining concentration and neo-tissue volume had an influence on the dataset quality. The use of high concentrations of phosphotungstic acid did however introduce significant shrinkage of the neo-tissue indicating that, despite sub-optimal image contrast, low concentrations of this staining agent should be used to enable quantitative analysis. To conclude, design of experiments allowed us to define the most optimal staining conditions for contrast-enhanced nanofocus computed tomography to be used as a routine screening tool of neo-tissue formation in Ti6Al4V constructs, transforming it into a robust three dimensional quality control methodology. [less ▲]

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See detailIn vivo ectopic bone formation by devitalized mineralized stem cell carriers produced under mineralizing culture condition.
Chai, Yoke Chin; Geris, Liesbet ULg; Bolander, Johanna et al

in BioResearch open access (2014), 3(6), 265-77

Functionalization of tissue engineering scaffolds with in vitro-generated bone-like extracellular matrix (ECM) represents an effective biomimetic approach to promote osteogenic differentiation of stem ... [more ▼]

Functionalization of tissue engineering scaffolds with in vitro-generated bone-like extracellular matrix (ECM) represents an effective biomimetic approach to promote osteogenic differentiation of stem cells in vitro. However, the bone-forming capacity of these constructs (seeded with or without cells) is so far not apparent. In this study, we aimed at developing a mineralizing culture condition to biofunctionalize three-dimensional (3D) porous scaffolds with highly mineralized ECM in order to produce devitalized, osteoinductive mineralized carriers for human periosteal-derived progenitors (hPDCs). For this, three medium formulations [i.e., growth medium only (BM1), with ascorbic acid (BM2), and with ascorbic acid and dexamethasone (BM3)] supplemented with calcium (Ca(2+)) and phosphate (PO4 (3-)) ions simultaneously as mineralizing source were investigated. The results showed that, besides the significant impacts on enhancing cell proliferation (the highest in BM3 condition), the formulated mineralizing media differentially regulated the osteochondro-related gene markers in a medium-dependent manner (e.g., significant upregulation of BMP2, bone sialoprotein, osteocalcin, and Wnt5a in BM2 condition). This has resulted in distinguished cell populations that were identifiable by specific gene signatures as demonstrated by the principle component analysis. Through devitalization, mineralized carriers with apatite crystal structures unique to each medium condition (by X-ray diffraction and SEM analysis) were obtained. Quantitatively, BM3 condition produced carriers with the highest mineral and collagen contents as well as human-specific VEGF proteins, followed by BM2 and BM1 conditions. Encouragingly, all mineralized carriers (after reseeded with hPDCs) induced bone formation after 8 weeks of subcutaneous implantation in nude mice models, with BM2-carriers inducing the highest bone volume, and the lowest in the BM3 condition (as quantitated by nano-computed tomography [nano-CT]). Histological analysis revealed different bone formation patterns, either bone ossicles containing bone marrow surrounding the scaffold struts (in BM2) or bone apposition directly on the struts' surface (in BM1 and BM3). In conclusion, we have presented experimental data on the feasibility to produce devitalized osteoinductive mineralized carriers by functionalizing 3D porous scaffolds with an in vitro cell-made mineralized matrix under the mineralizing culture conditions. [less ▲]

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See detailContrast-enhanced nanofocus computed tomography for virtual 3D histopathology and morphometric analysis of multiple skeletal tissues
Kerckhofs, Greet ULg; Papantoniou, Ioannis; Sonnaert, Maarten et al

Conference (2013)

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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 ▲]

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See detailEctopic bone formation by 3D porous calcium phosphate-Ti6Al4V hybrids produced by perfusion electrodeposition.
Chai, Yoke Chin; Kerckhofs, Greet ULg; Roberts, Scott J. et al

in Biomaterials (2012), 33(16), 4044-58

Successful clinical repair of non-healing skeletal defects requires the use of bone substitutes with robust bone inductivity and excellent biomechanical stability. Thus, three-dimensionally functionalised ... [more ▼]

Successful clinical repair of non-healing skeletal defects requires the use of bone substitutes with robust bone inductivity and excellent biomechanical stability. Thus, three-dimensionally functionalised porous calcium phosphate-Ti6Al4V (CaP-Ti) hybrids were produced by perfusion electrodeposition, and the in vitro and in vivo biological performances were evaluated using human periosteum derived cells (hPDCs). By applying various current densities at the optimised deposition conditions, CaP coatings with sub-micrometer to nano-scale porous crystalline structures and different ion dissolution kinetics were deposited on the porous Ti6Al4V scaffolds. These distinctive physicochemical properties caused a significant impact on in vitro proliferation, osteogenic differentiation, and matrix mineralisation of hPDCs. This includes a potential role of hPDCs in mediating osteoclastogenesis for the resorption of CaP coatings, as indicated by a significant down-regulation of osteoprotegerin (OPG) gene expression and by the histological observation of abundant multi-nucleated giant cells near to the coatings. By subcutaneous implantation, the produced hybrids induced ectopic bone formation, which was highly dependent on the physicochemical properties of the CaP coating (including the Ca(2+) dissolution kinetics and coating surface topography), in a cell density-dependent manner. This study provided further insight on stem cell-CaP biomaterial interactions, and the feasibility to produced bone reparative units that are predictively osteoinductive in vivo by perfusion electrodeposition technology. [less ▲]

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See detailA Boolean network approach to developmental engineering
Kerkhofs, Johan ULg; Roberst, Scott J; Luyten, Frank P et al

Conference (2011, June 13)

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See detailThe combined bone forming capacity of human periosteal derived cells and calcium phosphates.
Roberts, Scott J; Geris, Liesbet ULg; Kerckhofs, Greet ULg et al

in Biomaterials (2011), 32(19), 4393-405

Current knowledge suggests that the periosteum, a fibrous tissue which covers the surface of all bones, contains a population of progenitor cells which mediate the repair of bone defects. In an effort to ... [more ▼]

Current knowledge suggests that the periosteum, a fibrous tissue which covers the surface of all bones, contains a population of progenitor cells which mediate the repair of bone defects. In an effort to optimise the utilisation of this source of cells for bone engineering, herein we describe the rational selection of calcium phosphate (CaP) containing materials, based on biomaterial properties, and evaluation of their combined bone forming capacity. Five different commercially available orthopaedic 3D matrices composed of CaP particles in an open collagen network (NuOss, CopiOs, Bio-Oss((R)), Collagraft and Vitoss((R))) were evaluated in vitro and in vivo with human periosteal derived cells (hPDCs). It was found that the cell-material combinations behaved quite differently in vivo, despite apparent in vitro similarities in gene expression profiles. Bone formation was highest within the NuOss/hPDC implant at 13.03%, which also contained the highest incidence of bone marrow formation. The bone formed in this implant was chimeric with approximately 65% originating from implanted cells. Upon analysis of human specific gene expression, although it was found that predominantly osteogenic differentiation was observed within NuOss/hPDC implants, a lesser induction of chondrogenic genes was also observed. The formation of a cartilage intermediate was confirmed by histology. Additionally the NuOss/hPDC implant integrated into the mouse environment with apparent active scaffold resorption. This study demonstrates the importance of matching a cell support/biological matrix with a cell type and subsequently has outlined parameters which can be used for the rational selection of biomaterials for bone engineering. [less ▲]

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See detailA Boolean network model of the growth plate
Kerkhofs, Johan ULg; Roberts, Scott J; Luyten, Frank P et al

Poster (2010, November 26)

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See detailA Boolean network model of the growth plate
Kerkhofs, Johan ULg; Roberts, Scott J; Luyten, Frank P et al

Poster (2010, October 10)

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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)

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