Structure and properties of porous films based on aliphatic copolyamide developed for cellular technologies.

The effect of concentration and viscosity of the copolyamide (copolymer of ε-caprolactam and hexamethylendiaminadipate) solutions in aqueous/alcoholic solvents on its phase state was studied. The films obtained by the coagulation method were characterized by monodisperse pore distribution with an average pore size of 1.3 µm. The films processed by electrospinning from copolyamide solutions were characterized by a bimodal distribution of macropores with one peak of pore radius at 2.0 µm and second peak of pore radius at 20 µm. The adhesion and proliferation of mesenchymal adhesion stem cells (ASCs) stem cells to copolyamide matrix were studied. With the help of scanning electron microscopy it was shown that both tapes porous films were characterized by good adhesion of mesenchymal ASCs stem cells. It was shown that the porous structure, transport and mechanical properties of these copolyamide films allow their use as two-dimensional matrices for cellular technology.

The interaction of osteoblasts with bone-implant materials: 1. The effect of physicochemical surface properties of implant materials.

This comparative study of various surface treatments of commercially available implant materials is intended as guidance for orientation among particular surface treatment methods in term of the cell reaction of normal human osteoblasts and blood coagulation. The influence of physicochemical surface parameters such as roughness, surface free energy and wettability on the response of human osteoblasts in the immediate vicinity of implants and on the blood coagulation was studied. The osteoblast proliferation was monitored and the expression of tissue mediators (TNF-alpha, IL-8, MMP-1, bone alkaline phosphatase, VCAM-1, TGF-beta) was evaluated after the cell cultivation onto a wide range of commercially available materials (titanium and Ti6Al4V alloy with various surface treatments, CrCoMo alloy, zirconium oxide ceramics, polyethylene and carbon/carbon composite). The formation of a blood clot was investigated on the samples immersed in a freshly drawn whole rabbit blood using scanning electron microscope. The surfaces with an increased osteoblast proliferation exhibited particularly higher surface roughness (here R(a) 3.5 microm) followed by a high polar part of the surface free energy whereas the effect of wettability played a minor role. The surface roughness was also the main factor regulating the blood coagulation. The blood clot formation analysis showed a rapid coagulum formation on the rough titanium-based surfaces. The titanium with an etching treatment was considered as the most suitable candidate for healing into the bone tissue due to high osteoblast proliferation, the highest production of osteogenesis markers and low production of inflammatory cytokines and due to the most intensive blood clot formation.

Osteogenic cells on bio-inspired materials for bone tissue engineering.

This article reviews the development of artificial bone substitutes from their older single-phase forms to novel multi-phase composites, mimicking the composition and architecture of natural bone tissue. The new generation of bone implants should be bioactive, i.e. they should induce the desired cellular responses, leading to integration of the material into the natural tissue and stimulating self-healing processes. Therefore, the first part of the review explains the common principles of the cell-material interaction and summarizes the strategies how to improve the biocompatibility and bioactivity of the materials by modifying the physico-chemical properties of the material surface, such as surface chemistry, wettability, electrical charge, rigidity, microroughness and especially nanoroughness. The latter has been shown to stimulate preferentially the growth of osteoblasts in comparison with other competitive cell types, such as fibroblasts, which could prevent fibrous tissue formation upon implantation. The second more specialized part of the review deals with materials suitable for bone contact and substitution, particularly novel polymer-based composites reinforced with fibres or inorganic particles and containing bioactive components, such as crystals of hydroxyapatite or other calcium phosphates, synthetic ligands for cell adhesion receptors or growth factors. Moreover, if they are degradable, they can be gradually replaced with a regenerating tissue.

Biological properties of the intervertebral cages made of titanium containing a carbon-carbon composite covered with different polymers.

Intervertebral cages are used in orthopaedics for stabilization of injured lumbar parts of vertebral columns. Our study provides preliminary results of tests of the biological properties of titanium cages with a variously modified carbon/carbon composite (C/C) core. This core was produced from a C/C composite modified by hydrogel materials based on poly(2-hydroxyethyl methacrylate) (HEMA) enriched with 1% collagen or 35% methylmethacrylate or 30% terc-butylmethacrylamide. We evaluated the adhesion of the cells to the tested material coating using an in vitro study of the metabolic activity and cytokine production of the cells (TNF-alpha, IL-8). We studied the biocompatibility of intervertebral cages coated with different copolymers under in vivo condition and in an implantation experiment in the porcine femurs. Both in vitro and in vivo results revealed favourable biotolerance of the use system. Modification of the composite HEMA with the use of collagen seems to have a more positive effect on the new bone tissue formed around the implanted devices than HEMA copolymerized with methylmethacrylate or terc-butylmethacrylamide.

Biological and biochemical properties of the carbon composite and polyethylene implant materials.

We studied the biocompatibility of the carbon composites and polyethylene materials with and without collagen or collagen and proteoglycan cover. We used the in vitro technology to study the adhesion of model cells evalution, their metabolic activity and the production of TNF-alpha as a cytokine model. Under in vivo condition, the biocompatibility of tested polymers were studied in the implantation experiment, subcutaneously in the interscapular region in the laboratory rat. We have found in the in vitro assay favorable proliferation and the smallest production of pro-inflammatory TNF-alpha cytokine in cells adherent to the hydrophobic polyethylene material coated with biological macromolecules. Using in vivo tests performed by the implantation of materials to the rat we demonstrated that the materials are not cytotoxic. The tissue capsule surrounding the implants was not significantly influenced by the type of the implant and the pre-treatment by the biological molecules. However, the foreign-body giant multinucleated cells were observed only in the vicinity of the collagen - covered hydrophobic polyethylene implant. Interestingly, while the collagen coating improved the biocompatibility of tested polymers in vitro, the inflammatory reaction against this covered materials was higher under in vivo conditions. The pre-treatment of carbon composites by both types of biological macromolecules reduced the occurrence of carbon debris in the implantation site. The tested carbon composites and polyethylene materials are not toxic. The pre-treatment of the materials by extracellular matrix components increased their biological tolerance in vitro and reduced implant wears in animal experiment, which can be important for the medical application.

[New materials suitable for implantation--preparation for implants]. / Nové materiály vhodné pro implantáty--príprava implantátu.

PURPOSE OF THE STUDY: Connective tissue components, particularly collagen and proteoglycan, stimulate cell proliferation and thus promote tissue regeneration. This fact was utilized to test some new implant materials, which were covered by these components, for the speed and quality of their encapsulation. MATERIAL: The materials tested included polyethylene (PE) with either a hydrophobic (HPHO) or a hydrophilic (HPHI) surface and the C-C composite. Before implantation in experimental animals, the materials were coated with a thin layer of collagen-proteoglycan copolymer. METHODS: Collagen was obtained from calf hide (ISC 40 fraction) and proteoglycan was isolated from calf cartilage with 2M GuHCl. The concentrations of elements in implant materials were assessed by the method of ESCA photoelectron spectroscopy (electron spectroscopy for chemical analysis) and, using a comparison of the values of electron binding energies at inner levels with the published ones, the chemical states of elements were identified. RESULTS: Carbon, oxygen and silicon were identified on the surface of the PE HPHI sample; carbon, oxygen, calcium, manganese and sulfur were found on the PE HPHO sample and nitrogen, oxygen and fluorine were present on the C-C composite. DISCUSSION: In our group of patients there was a small rate of rheumatoid arthritis, while in most literature these patients are predominant. In accordance with the outcomes of other authors, ASS is fraught with recurrence. ASS does not strike to fibrous capsule, like an open surgery synovectomy, and from these islands synovialis could regenerate. CONCLUSIONS: The presence of manganese and calcium on the surfaces of the materials investigated indicates the existence of a collagen-proteoglycan copolymer, which contains NH2 and COO groups derived from collagen and SO4 groups from proteoglycan. It is necessary to verify this theoretical assumption based on measurement data in a biological experiment.

Biomechanical and biological properties of the implant material carbon-carbon composite covered with pyrolytic carbon.

The aim of this study was to test C/C material (carbonized, graphitized or covered with pyrolytic carbon) designated for the use in orthopaedic and bone surgery. Using an in vitro assay we confirmed, that the cell proliferation was exhibited the mostly on the C/C composite coated with pyrolitic carbon and afterwards polished. The two latest of subsequent water extracts of this material had a slightly inhibiting effect on the cells metabolic activity. Biocompatibility test in vivo performed subcutaneously on rats did not show big differences between three tested implants (C/C composite, epoxy resine, titanium alloy), on the other hand the plates tested on pigs demonstrated foreign-body reaction induced by wear C/C composite material. Such debris were found both in the neighborhood of the implant as well as in the lymphatic node.

[The Influence of the Implanted Material (Glass Carbon) for the Proliferation of the Cell's.]. / Vliv implantacního materiálu (skelný uhlík) na proliferaci bunek.

The authors have examined the influence of the implanted material (glass carbon) for the proliferation of human embryonal fibroblasts. It has been found that the tested material did not inhibit the cell's proliferation and it performed a good biocompatibility. Key words: fibroblasts, implanted material, glass carbon.