Biomedical subjects

K Anselme

Publications and source records attributed to K Anselme.

30 records · Page 2Linked to original sources

PubMed1999

Histological aspects in bone regeneration of an association with porous hydroxyapatite and bone marrow cells.

The osteogenic potential of an association of two kinds of hydroxyapatite (HA) porous ceramics with autologous bone marrow cells cultured with or without dexamethasone (10(-8)M) addition in the culture medium and non-cultured rabbit marrow stromal stem cells (MSCs) was tested after 4 weeks of implantation in the dorsal muscles of spine in rabbit. A significantly higher number of rabbits with implants containing bone tissue inside pores were obtained with 10(7) cells ml(-1) cultured treated with Dex. In the HA porous ceramic using naphtalen as porogen agent, the bone recolonization remains only at the periphery of implants and in the second row of pores, while in the HA porous ceramic using polymethacrylate (PMMA) microbeads as porogen agent, the bone recolonization is observed in the depth of implants. In the PMMA HA group, the Krüskal-Wallis variance analysis between the rabbits is significantly different with the percentage of number of occupied pores and occupied pores with bone tissue is different (p<0.05).

Journal Article↗

PubMed1999

Role of interconnections in porous bioceramics on bone recolonization in vitro and in vivo.

The interconnections in a porous biomaterial are the pathways between the pores. They conduct cells and vessels between pores. Thus they favour bone ingrowth inside ceramics. The aim of our study was to determine the effect on bone ingrowth of interconnections in two ceramics: hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) with the same porosity of about 50% and a mean pores size of 100-300 microm and a mean interconnection size of 30-100 microm. In vitro, four discs for osteoblast culture were studied after 14 and 28 days of incubation. The results show that human osteoblasts can penetrate interconnections over 20 microm in size, and colonize and proliferate inside macropores, but the most favourable size is over 40 microm. In vivo, eight cylinders were implanted in the middle shaft of both rabbit femurs for 12 or 24 weeks. The histomorphometric results show that interconnections in porous ceramics favour bone ingrowth inside the macropores. In the HA group the rate of calcification and bone ingrowth do not differ, and chondroid tissue is observed inside pores. But in beta-TCP, the calcification rate and the bone ingrowth increased significantly. At week 12 significant correlation between new bone ingrowth and the size of the interconnections is observed between new bone ingrowth and the density of pores. In conclusion we notice that in vivo a 20 microm interconnection size only allows cell penetration and chondroid tissue formation; however the size of the interconnections must be over 50 microm to favour new bone ingrowth inside the pores. We propose the concept of "interconnection density" which expresses the quantity of links between pores of porous materials. It assures cell proliferation and differentiation with blood circulation and extracellular liquid exchange. In resorbable materials, pore density and interconnection density are more important than their size, contrary to unresorbable materials in which the sizes and the densities are equally important.

Journal Article↗

PubMed1999

Human osteoblast adhesion on titanium alloy, stainless steel, glass and plastic substrates with same surface topography.

Osteoblast adhesion on materials will depend on the surface aspects of materials which may be described according to their surface chemistry, surface topography or surface energy. To separate the effects of roughness and composition of materials on osteoblast response, we chose to compare substrates with various surface composition but with the same smooth surface. Ti6Al4V alloy, stainless steel, glass and standard tissue culture polystyrene were tested. Adhesion was evaluated using specific antibodies against adhesion proteins and by a quantitative cell detachment assay. After 1, 7 and 14 days, cells expressed extracellularly fibronectin fibers, and intracellularly type I collagen and osteopontin. Vinculin-labeled focal contacts were visible on all materials but were more frequent on glass and stainless steel surfaces. beta_1-integrin subunit-labeled patches were visible on all surfaces at each delay. The quantitative cell detachment assay showed few differences between materials. Adhesion was higher on metallic substrates although cell proliferation was higher on glass and stainless steel compared to tissue culture polystyrene and Ti6Al4V alloy. Substrates with various surface composition but with the same surface topography did not induce significant differences of adhesion although cell proliferation was variable.

Journal Article↗

PubMed1998

Comparative study of tissue reactions to calcium phosphate ceramics among cancellous, cortical, and medullar bone sites in rabbits.

In order to understand the influence of the implantation site on bone biomaterial evaluation, we implanted cylinders of HA and beta-TCP ceramics in the femoral diaphysis and condyle of rabbits. After 3, 8, 12, and 24 weeks of implantation, histological investigation and histomorphometry were performed on undecalcified samples. Our results show that spontaneous bone healing in the empty cavities is significantly different (p < 0.05) between cortical (SBH > 80%) and cancellous bone sites (SBH < 31%) and that no new bone is formed in marrow tissue. For both porous ceramics, the highest osteogenesis was obtained in the cortical site. Osteogenesis was intermediate in the cancellous site and weak in the medullar site. The material biodegradation was the strongest in the medullar site and higher in the cancellous site than in the cortical site. Both activities were better in the beta-TCP than in the HA (p > 0.05). The marrow tissue presents a foreign-body reaction more reliable, sensitive, and durable than other bone tissues. Therefore, the cancellous bone site is a good site for evaluation of the biofunctionality of biomaterials because of the equilibrium of the osteogenesis and the biodegradation activities, but marrow tissue seems to be better for testing material biocompatibility in vivo.

Animals↗

PubMed1997

In vitro growth of human adult bone-derived cells on hydroxyapatite plasma-sprayed coatings.

The growth of adult human bone-derived cells on hydroxyapatite (HA) plasma-sprayed coatings was investigated. Such cells were difficult to grow on original plasma-sprayed coatings, even following rinsing and rubbing down. We obtained cell growth only on samples previously immersed 15 or 22 days in complete culture medium. We describe a dissolution/precipitation phenomenon on the HA coating surface assessed by modifications of Ca and P concentrations in the culture medium, by the transformation of the HA coating into carbonated HA (X-ray diffraction and infrared spectrometry and by the presence demonstrated by scanning electron microscopy of spherocrystallites on the HA after 15 days of immersion. Our results show that adult human bone-derived cells are apparently particularly sensitive to the changes in the coating surface induced by liquid immersion. We raise the question of the limits of in vitro investigations on bioactive ceramics such as HA plasma-sprayed coatings susceptible to modification by simple immersion in aqueous solutions such as cell culture medium or physiologic saline.

Adult↗

PubMed1996

[Perirenal necrotic and cystic pseudotumors in children. Report of two cases].

This work describes two cases of necrotic, encysted pseudotumors of unknown origin, in children; the lesions located on the anterior side of the kidney, near its inferior pole were remarkable for their size and their numerous adhesions to adjacent structures. The hypothesis of an initial infectious or tumoral mechanism are discussed, particularly the similarities supported by both lesions with the regressive patterns of some neuroblastomas.

Child↗

PubMed1996

[Cell culture and orthopedic surgery. 1. Principles, methods, fundamental applications].

Many reasons, in 1996, may incite orthopaedic surgeons to take an interest in cell culture. Firstly, cell culture bring informations on bone cell physiology, and the physiological properties of the skeletal cells are involved in the success of the orthopaedic surgeon's act. Secondly, in orthopaedics field's literature, more and more articles using cell culture techniques are published and surgeons need some basic knowledges to understand these results. Then, in the first part of this work, we detail the essential rudiments; vocabulary, cell culture methods, and cell physiology notions. In the second part of this work, we resume the progress realized these last years with cells cultured from the skeleton. Using these informations, surgeons will be able to appreciate the potential uses of cell cultures for diagnosis, biomaterial evaluation and for the development of new therapies.

Bone Neoplasms↗

PubMed1996

[Cell culture and orthopedic surgery. II. Medical applications. Diagnosis, biomaterials evaluation, therapy].

Currently, cell cultures are used for 3 kinds of applications in orthopaedics: diagnosis: they can help to diagnose hereditary diseases like Marfan syndrome, osteogenesis imperfecta, or some osteochondrodysplasia. biomaterial evaluation: cell cultures bring information to ensure safety and efficacy of medical devices following the European Community's directive concerning medical devices. Results of in vitro biomaterial evaluation must be related to cell types (osteoblasts or fibroblasts), cell species (human or rat) and methods used (primary cell line or immortalised cell line). therapy: first clinical applications of cell cultures have been published recently. They concern cultured autologous chondrocytes reimplantation. Bone cells cultured on biomaterials have been tested in animal reimplantation experiments. Animal cells mediated gene therapy experiments are now developed on muscle cells. Cell cultures allow also to determine the best therapeutic way to cure bone tumors. For the moment, these applications are still limited but in the next years, they could develop considerably. Therefore, orthopaedic surgeons must keep interest in this new field.

Animals↗

PubMed1993

Fate of bioresorbable poly(lactic acid) microbeads implanted in artificial bone defects for cortical bone augmentation in dog mandible.

The fate was examined of poly(lactic acid) microbeads implanted in large artificial defects created in cortical bone of dog mandibles. Two poly(lactic acid) polymers--poly(L-lactic acid) (PLA 100) and poly(DL-lactic acid) (PLA 50)--were used to make microbeads by solvent evaporation with poly(vinyl alcohol) as surfactant. Histological observation of non-decalcified mandibular bone showed that no real bone regeneration existed in the experimental bone defects 18 months after PLA 100 microbeads implantation. The same observation was made 6 months after implantation of PLA 50 microbeads. PLA 100 and PLA 50 microbeads appeared unable to induce regeneration of cortical bone defects of dog mandible, in contrast to previous observations in man for PLA 50 large implants. The failure is tentatively assigned to the presence of poly(vinyl alcohol) at the surface of microbeads.

Animals↗

PubMed1992

Inhibition of calcification in vivo by acyl azide cross-linking of a collagen-glycosaminoglycan sponge.

A collagen-glycosaminoglycan sponge composed of collagen (80%), chondroitin-4-sulfate (13.3%) and heparan sulfate (6.6%) was cross-linked using the acyl azide method or glutaraldehyde (0.0075%). Under optimal conditions, the denaturation temperature (Td) was raised to 69 degrees C (+23 degrees C) for the sponge treated by the acyl azide method and to 68 degrees C (+22 degrees C) for that treated with glutaraldehyde. The biocompatibility of the treated and control sponges was studied up to 3 months after subcutaneous implantation in rats by analysing cellular responses and calcification by histological and ultrastructural methods. A control collagen-glycosaminoglycan sponge was rapidly invaded by mononuclear cells (8 days), with the formation of granulation tissue. Calcification was observed at the periphery of the implant after 8 days, and the implant was entirely calcified after 15 days; it was degraded progressively after 30 days. Acyl azide treatment increased the persistence of the sponge in vivo up to 90 days and inhibited its calcification. A glutaraldehyde-treated sponge was completely calcified after 15 days, and calcified nodules persisted after 90 days. Thus, acyl azide method efficiently cross-linked a collagen-glycosaminoglycan sponge and inhibited calcification after subcutaneous implantation in rats (at least up to 90 days after implantation).

Animals↗

PubMed1990

Tissue reaction to subcutaneous implantation of a collagen sponge. A histological, ultrastructural, and immunological study.

The biocompatibility of a subcutaneously implanted bovine collagen sponge (Haemostagen) was studied in rats by analyzing tissue reactions up to 3 months by histological and ultrastructural methods; in addition, the level of serum antibodies to bovine type I collagen (the major implant collagen) was measured by solid-phase radioimmunoassay. By 8 h after implantation, the implant was completely filled with polymorphonuclear cells (PMNs). After 8 days, fibroblasts had developed a granulation tissue within the sponge and the PMNs had almost disappeared. The small residue that remained after 1 month consisted of some densely packed collagen fibrils containing giant cells, which had disappeared by 3 months. No antibodies to bovine type I collagen were found in the sera of implanted rats.

Animals↗

PubMed1990

Degradation of metal-labeled collagen implants: ultrastructural and X-ray microanalysis.

Three different metal salts, silver nitrate, uranyl acetate and lead citrate, are mixed with a collagen gel to produce 3 metal/collagen sponges. These sponges were implanted subcutaneously in the rat and samples harvested after 5 days of implantation. TEM observation shows that sponges are degraded and digested by macrophages, polymorphonuclear cells (PMN) and fibroblasts. We have observed that the location of the precipitates differs according to the metal added to the collagen. Lead precipitates stay longer on the collagen mesh while silver precipitates, after 5 days, are soon digested and are found in phagosomes of macrophages. Uranium precipitates are digested with the collagen and uranium/collagen associated pictures are seen in phagolysosomes. Metal precipitates accumulated in phagolysosomes of macrophagic cells are recognized by X-ray microanalysis. The degradation process of implanted collagen is discussed.

Animals↗