Biomedical subjects

X Frank Walboomers

Publications and source records attributed to X Frank Walboomers.

8 recordsLinked to original sources

PubMed2006

The performance of human dental pulp stem cells on different three-dimensional scaffold materials.

The aim of this study was to investigate the in vitro and in vivo behavior of human dental pulp stem cells (DPSCs) isolated from impacted third molars, when seeded onto different 3-dimensional (3-D) scaffold materials: i.e. a spongeous collagen, a porous ceramic, and a fibrous titanium mesh. Scaffolds were loaded with DPSC, and subsequently divided into two groups. The first group was cultured in osteogenic differentiation medium in vitro for 4 weeks. The second group of samples was implanted subcutaneously in nude mice for 6 or 12 weeks. Samples cultured in vitro were analyzed by scanning electron microscopy and RT-PCR for dentin sialophosphoprotein (DSPP) expression. In vivo samples were evaluated by histology, RT-PCR and immunohistochemistry. The results indicated that in vitro, cells developed abundant deposition of mineralized extracellular matrix (ECM) with expression of DSPP in all 3-D materials. The simultaneous implantation experiment showed formation of tissue that was DSPP positive in all three scaffolds materials. However, the aspect of the formed tissues in all scaffolds resembled more connective tissue than a dentin-like tissue. Limited calcification of the ECM was only seen in the ceramic scaffold. In both experiments, no other differences could be attributed to the different materials used. In conclusion, the in vivo behavior of DPSC and their relations with 3-D scaffold materials should be further studied before clinical use can be considered.

Animals↗

PubMed2006

Collagen type V enhances matrix contraction by human periodontal ligament fibroblasts seeded in three-dimensional collagen gels.

Extracellular matrix components play an important role in modulating cellular activity. To study such capacities of the matrix, fibroblasts are frequently cultured in a three-dimensional gel and contraction is assessed as a measure of cellular activity. Since a connective tissue contains several types of collagen, we investigated the effect of gels composed of collagen I alone or in combination with 10% collagen III and/or 5% collagen V on contraction by human periodontal ligament fibroblasts. Gels containing collagen V contracted much faster than those without this type of collagen. Blocking of the integrin beta1-subunit with an activity-blocking antibody delayed (gels with collagen V) or almost completely blocked (gels without collagen V) contraction. Use of an antibody directed against integrin alpha2beta1 resulted in delay of gel contraction for gels both with and without collagen V. Anti-integrin alpha v beta3 or RGD peptides partially blocked contraction of gels containing collagen V, but had no effect on gels consisting of collagen I alone. The beta1-containing integrins are involved in the basal contraction by fibroblasts that bind to collagens I and III. The enhanced contraction, stimulated by collagen V, appears to be mediated by integrin alpha v beta3. We conclude that collagen V may play an important modulating role in connective tissue contraction. Such a modulation may occur during the initial stages of wound healing and/or tissue regeneration.

Adult↗

PubMed2006

Bone-like tissue formation using an equine COLLOSS E-filled titanium scaffolding material.

COLLOSS, a bovine extracellular matrix product containing native BMPs has already shown osteoinductive properties. To overcome problems with risk of transmissable spongiform encephalopathy (TSE) infection, an equine derived version was investigated in this study, named COLLOSS E. Disc- and tube-shaped implants were made from titanium fibre mesh. The central space of tubes was filled and the discs were impregnated with the COLLOSS E material to assess osteo-induction. These implants and non-loaded controls were implanted subcutaneously into the back of Wistar rats. After implantation periods of 2, 8, and 12 weeks, the implants were retrieved and sections were made. Histology showed a thin fibrous capsule surrounding the titanium mesh and a very mild tissue reaction. The disc implants, loaded or non-loaded, showed no bone formation at all. After 2 weeks of implantation 3 out of 5 of the loaded tubes showed bone formation with a mean of 0.3 mm2 areas of new formed bone, after 8 weeks 3 out of 6 and 0.7 mm2, and after 12 weeks this increased to 6 out of 6 and 1.0 mm2. In the non-loaded tubes only connective tissue in growth was seen. In conclusion, it was demonstrated that COLLOSS E material, loaded in a titanium fibre mesh tube shows osteoinductive properties. The effect of COLLOSS E has to be investigated further in orthotopic sites, which resemble more the final clinical application for bone reconstruction.

Animals↗

PubMed2006

Transforming growth factor-beta1 release from a porous electrostatic spray deposition-derived calcium phosphate coating.

This study evaluated the utilization of a porous coating, derived with electrostatic spray deposition (ESD), as a carrier material for transforming growth factor-beta1 (TGF-beta1). A porous beta-tricalcium phosphate coating was deposited with ESD, and 10 ng of (125) I-labeled TGF-beta1 was loaded on the substrates. A burst release during the first hour of incubation of >90% was observed, in either culture medium or phosphate-buffered saline (PBS). Ninety-nine percent of the growth factor was released after 10 days of incubation. All samples were able to inhibit epithelial cell growth, indicating that the growth factor had remained bioactive after release. Thereafter, osteoblast-like cells were seeded upon substrates with or without 10 ng of TGF-beta1. While proliferation of osteoblast-like cells was increased on TGF-beta1-loaded substrates, differentiation was inhibited or delayed. In conclusion, a porous ESD-derived calcium phosphate coating can be used as a carrier material for TGF-beta1, when a burst release is desired.

Animals↗

PubMed2005

Fabrication, characterization, and biological assessment of multilayered DNA-coatings for biomaterial purposes.

This study describes the fabrication of two types of multilayered coatings onto titanium by electrostatic self-assembly (ESA), using deoxyribosenucleic acid (DNA) as the anionic polyelectrolyte and poly-d-lysine (PDL) or poly(allylamine hydrochloride) (PAH) as the cationic polyelectrolyte. Both coatings were characterized using UV-vis spectrophotometry, atomic force microscopy (AFM), X-ray photospectroscopy (XPS), contact angle measurements, Fourier transform infrared spectroscopy (FTIR), and for the amount of DNA immobilized. The mutagenicity of the constituents of the coatings was assessed. Titanium substrates with or without multilayered DNA-coatings were used in cell culture experiments to study cell proliferation, viability, and morphology. Results of UV-vis spectrophotometry, AFM, and contact angle measurements clearly indicated the progressive build-up of the multilayered coatings. Furthermore, AFM and XPS data showed a more uniform build-up and morphology of [PDL/DNA]-coatings compared to [PAH/DNA]-coatings. DNA-immobilization into both coatings was linear, and approximated 3microg/cm(2) into each double-layer. The surface morphology of both types of multilayered DNA-coatings showed elevations in the nanoscale range. No mutagenic effects of DNA, PDL, or PAH were detected, and cell viability and morphology were not affected by the presence of either type of multilayered DNA-coating. Still, the results of the proliferation assay revealed an increased proliferation of primary rat dermal fibroblasts on both types of multilayered DNA-coatings compared to non-coated controls. The biocompatibility and functionalization of the coatings produced here, will be assessed in subsequent cell culture and animal-implantation studies.

Animals↗

PubMed2005

Periodontal ligament and gingival fibroblast adhesion to dentin-like textured surfaces.

It is known that the (micro-) structure of a substrate surface is of major influence on the growth behaviour of adherent cells. In the current study, we aimed to produce a surface that exactly mimics the structure of natural dentin, and to describe the effect of this surface on the growth behaviour of primary periodontal ligament fibroblasts (PDLF) or gingival fibroblasts (GF). First, we used scanning electron microscopy (SEM) and morphometric techniques to analyse the porous dentin structure. Then, using a template made by photolithographic techniques, cell culture dishes with similar surface structure were made. On these dishes, and on smooth controls, primary PDLF and GF were seeded and assayed up to 14 days for proliferation, alkaline phosphatase (ALP) activity, and collagen content. Also, cell morphology was observed with SEM and transmission electron microscopy (TEM). Results showed that GF showed significantly less ALP activity than PDLF. Abundant collagen fibres were only formed by GF grown on the textured surfaces. SEM assessment showed equal spreading of both cell types on smooth and textured surfaces. TEM showed a preferential deposition of ECM material in the texture porosity. From our study we can conclude that dentin-like surfaces have no negative effect on either cell type, and could be used to enhance extracellular matrix deposition in GF formation. However, considerable differences were observed between primary cells from different animals. Therefore, final efficacy of the surfaces remains to be proven in implantation experiments.

Animals↗

PubMed2004

Bone tissue induction, using a COLLOSS-filled titanium fibre mesh-scaffolding material.

Scaffold materials for bone tissue engineering often are supplemented with bone morphogenetic proteins (BMPs). In the current study we aimed to investigate COLLOSS, a bovine extracellular matrix product containing native BMPs. Hollow cylindrical implants were made, with a length of 10 mm, a 3 mm inner diameter, and a 5 mm outer diameter, from titanium fibre mesh. The central space of the tube was filled with 20 mg COLLOSS. Subsequently, these implants, as well as non-loaded controls, were implanted subcutaneously into the back of Wistar rats, with n=6 for all study groups. After implantation periods of 2, 8, and 12 weeks, tissue-covered implants were retrieved, and sections were made, perpendicular to the long axis of the tube. Histology showed, that all implants were surrounded by a thin fibrous tissue capsule. After 2 weeks of implantation, the COLLOSS material was reduced in size inside the loaded implants, but no bone-like tissue formation was evident. After 8 weeks, in two out of six loaded specimens, new-formed bone- and bone marrow-like tissues could be observed. After 12 weeks, this had increased to five out of six COLLOSS-loaded samples. The amount of bone-like tissue did not differ between 8 and 12 weeks, and on average occupied 15% of the central space of the tube. In the non-loaded control samples, only connective tissue ingrowth was observed. In conclusion, we can say that COLLOSS material loaded in a titanium fibre mesh tube, showed bone-inducing properties. The final efficacy of these osteo-inductive properties has to be confirmed in future large animal studies.

Animals↗

PubMed2003

The attachment and growth behavior of osteoblast-like cells on microtextured surfaces.

In previous studies, we showed that the application of microgrooves on a surface can direct cellular morphology and the deposition of mineralized matrix of osteoblast-like cells (Biomaterials 20 (1999) 1293; Clin. Oral Impl Res. 11 (2000) 325). In this study, we evaluated the attachment and growth behavior of these cells, using scanning- and transmission electron microscopy (SEM/TEM). Smooth and microgrooved polystyrene substrates were made (groove depth 0.5-1.5 microm, groove- and ridge width 1-10 microm). On these substrates, osteoblast-like cells were cultured for periods up to 16 days. SEM showed that the cells, and their extensions, closely followed the surface on smooth and wider grooved (>5 microm) substrates. In contrast, narrow grooves (<2 microm) were bridged. After 16 days of incubation, the matrix showed extensive deposition of collagen fibrils, and the formation of calcified nodules. With TEM it was shown that on the smooth and wider grooved substrates, focal adhesions were spread throughout the surface. However, on narrow grooves focal adhesions were always positioned on the edges of surface ridges only. Apparently, most extracellular matrix (ECM) was produced by the cells that directly adhered to the substrate. Deposition of ECM was seen in the surface grooves, as well as in between the cell layers. On basis of the current study and previous experiments, we conclude that microgrooves are able to influence bone cell behavior by (1) determining the alignment of cells and cellular extensions, (2) altering the formation and placement of cell focal adhesions, and (3) altering ECM production. Therefore, microgrooved surfaces seem interesting to be applied on bone-anchored implants.

Animals↗