Engineered implant surfaces: modification of cell and tissue response by microgrooves

Contains fulltext : 146812.pdf (Publisher’s version ) (Open Access)165 p

The formation of tertiary dentin after pulp capping with a calcium phosphate cement, loaded with PLGA microparticles containing TGF-beta1.

Contains fulltext : 70770.pdf (publisher's version ) (Open Access)The aim of the current study was to evaluate the effect of a calcium phosphate material equipped with poly (lactic-co-glycolic acid) microspheres for pulp capping, and to measure the dentin bridge formation, when using various concentrations of transforming growth factor (TGF) beta1. Preset samples were made (2 mm diameter; 2 mm height), containing 0 (controls), 20, or 400 ng TGF-beta1. These were placed in goat incisors. Incisors capped with glass-ionomer cement only were used as negative controls. Twelve weeks after pulp capping, the incisors were retrieved, processed for histology, and graded on basis of tertiary dentin formation. The results showed that new dentin formation was seen in all samples, except the negative controls. The histological grading indicated significant differences between the samples loaded with high amount of TGF-beta1 versus the three other groups (p < 0.05). In conclusion, our study demonstrated that the composite with 400 ng TGF-beta1 was able to trigger resident stem cells in the pulp to differentiate into odontoblast-like cells and to induce the formation of tertiary dentin. The material might be a good candidate for vital pulp therapy. Production and manipulation methods could be improved for follow-up studies

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

Contains fulltext : 47324.pdf (publisher's version ) (Closed access)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

Effect of microtextured surfaces on the performance of percutaneous devices.

Contains fulltext : 48564.pdf (publisher's version ) (Closed access)Along the percutaneous part of implantable devices, like (semi-)permanent catheters, epithelial downgrowth can occur. This process can eventually lead to implant loss. Various treatments for the catheter surface have been proposed, to improve their performance. The purpose of the current study was to investigate the effect of a microgroove pattern on the tube surface, on epithelial downgrowth. Catheterlike implants were made of silicone tubes, with anchoring cuffs made of titanium-fiber mesh. A thin sheet of silicone with microgrooves was applied on the tubes. Two types of texturing were used, a square groove of 10 microm wide and 1 microm deep; or a V-shaped groove of 40 microm wide. The grooves were directed either along the long axis of the catheter tube (grooves perpendicular to the skin surface) or circling around the catheter (grooves directed parallel to the skin surface). As controls, catheters with a smooth outer surface were used. Implants were placed in 30 rats, with a follow-up period of 9 weeks. During this time, animals were inspected biweekly, and catheter exit sites were evaluated using a scoring system. At the end of the 9-week period the implants and surrounding tissues were processed for histological evaluation. For the clinical evaluation of the exit sites, no statistical differences were found between the study groups. Histologically, epithelial downgrowth was observed for all samples. The histomorphometrical measurements showed that there were no differences in downgrowth between the smooth and parallel-grooved catheters. However, there was increased epithelial downgrowth along the catheters with grooves perpendicular to the skin. In conclusion, a grooved microtexture can direct epithelial tissue ingrowth, but this study found no beneficial effects of the guidance phenomenon

Multilineage Differentiation Potential of Stem Cells Derived from Human Dental Pulp after Cryopreservation.

Contains fulltext : 49996.pdf (publisher's version ) (Open Access

[Bone substitutes, growth factors and distraction osteogenesis]

Contains fulltext : 69329.pdf (publisher's version ) (Open Access)Up to the present time, bone transplants are commonly used to reconstruct bone defects. Recently, several bone substitutes have been suggested to overcome the disadvantages of the procedure of bone harvesting. However, research reveals that an autogenous bone graft is still the gold standard. To replicate the structure and function of natural bone, growth factors or even living, bone-forming cells can be added to enhance the formation of new bone. In that case, one speaks of cell-based tissue-substition. As an alternative distraction osteogenesis, a mechanical-based way of tissue engineering is suggested. In this procedure, tissue-generation takes place without the addition of external material. A combination of both tissue-substitution techniques, consisting of the addition of bone-replacement materials or growth factors during distraction osteogenesis, has also been evaluated in research on animals, although not with unequivocal results

The effect of electrospun fibre alignment on the behaviour of rat periodontal ligament cells.

Contains fulltext : 88942.pdf (publisher's version ) (Open Access)It is envisioned that for the regeneration of highly organized structures, like tendon and ligaments, only aligned fibrous scaffolds can provide adequate topographic guidance to cells. In this study, a novel method to electrospin an aligned scaffold is presented. Electrospun fibres were deposited into a water bath and then the fibres were drawn to a rotating mandrel in a controlled manner. In this way, parallel and cross-aligned fibrous poly (lactide-co-glycolide) (PLGA) scaffolds were fabricated, which were subsequently used to study their effect on the growth behaviour of rat periodontal ligament (PDL) cells. First, the scaffolds were characterized regarding mechanical properties, scaffold stability and degradation in vitro. Then, rat PDL cells were seeded and cultured on these scaffolds for up to 7 days. Randomly oriented PLGA and solvent cast plain PLGA films served as controls. Results showed that the alignment of fibres resulted in a higher tensile stress and Young's modulus. Aligned scaffolds maintained their structural stability better compared to the controls after incubation in phosphate-buffered saline for 6 weeks. Further, cells were observed to elongate along the fibre after 3 days of culture. Proliferation and migration of PDL cells was significantly more prevalent on the aligned fibres compared to the controls. It was concluded that aligned scaffolds seem to be able to promote the organized regeneration of periodontal tissue

The influence of bone formation on anchoring percutaneous devices with titanium fibre mesh flanges.

Item does not contain fulltextFor man-made percutaneous devices (PD), it is known that anchoring will improve the clinical success. Previously, our Department has designed PDs that use a sheet of titanium (Ti) fibre mesh for anchoring. In nature, a very successful natural PD occurs, namely the tooth. Teeth are anchored in the alveolar bone. In the current study, we evaluated whether a sheet of (ectopic) bone can be made, and be used to anchor a skin-penetrating device. Using available tissue engineering techniques, sheets of Ti fibre mesh were loaded with osteoblast-like cells. These sheets, and non-loaded controls, were placed subcutaneously in 20 syngeneic rats. After four weeks 10 rats were sacrificed, and tissues were prepared for histology. On the other 10 rats, a percutaneous Ti bar was screwed. These rats were evaluated clinically up to eight weeks. Finally, also their tissues were prepared for histology. The results showed, that bone formation was only established in one cell-loaded implant, of the four-week group. Clinical evaluation, and the histomorphometrical data, showed no differences between cell-loaded and unloaded samples. We concluded that the combination of Ti mesh with rat bone marrow cells was not able to generate bone formation after subcutaneous implantation predictably. Thus, our original aim could not be met. On the other hand, our results did confirm the biocompatible behaviour of a PD equipped with a Ti fibre mesh anchoring flange