Patrick Frayssinet

Background: Pet dogs spontaneously develop lymphoma. An anthracycline-based multidrug chemotherapy regimen represents the treatment cornerstone; however, cure is rarely achieved. We have been treating dogs with B-cell lymphoma with an autologous vaccine (APAVAC®) and CHOP-based chemotherapy since 2011. Methods: To better characterize the safety...

An autovaccine against canine DLBCL lymphomas associated to a CHOP protocol has proven to greatly improve the overall survival and the time to progression of a series of dogs against another series only treated by the CHOP protocol (1). This vaccine was obtained by purifying specific proteins and peptides from a node biopsy. In order that the vacci...

The most promising techniques for detecting minimal residual disease (MRD) in canine lymphoma are flow cytometry (FC) and polymerase chain reaction amplification of antigen receptor genes (PARR). However, the agreement between these methods has not been established. MRD was monitored by FC and PARR following treatment of dogs affected with diffuse...

Active immunotherapy is a promising antitumoral strategy; however its use in combination with chemotherapy in dogs with large B-cell lymphoma (DLBCL) remains largely untested. Heat shock proteins (HSPs) bind the small peptides they chaperone (HSPPCs), allowing for immunization of the host against a large repertoire of tumor-associated antigens. Hyd...

Sixty-three dogs with newly diagnosed lymphoma underwent complete staging and received the same chemotherapy. Diffuse large B-cell lymphoma was the leading histotype (44.4%), followed by peripheral T-cell lymphoma (20.6%). Indolent lymphomas accounted for 30.2% of cases. Most dogs with aggressive B-cell lymphoma had stage IV disease. Dogs with indo...

This experiment showed the feasibility of this protocol as an autologous vaccine for cancer in dogs in veterinary practice. We have also developed an in vitro test to assess the functionality of purified heat shock proteins. This test checks in a few minutes the vaccine’s ability to stimulate antigen-presenting cells (APCs) through toll-like recept...

Calcium phosphate coprecipitated with plasmid DNA (pDNA) has been used for more than two decades for in vitro cell transfection. We have evaluated calcium phosphate ceramic powder to transfect cells in vitro and in vivo. It appeared that the transfection yield was dependent on several factors such as the amount of powder in contact with the cells,...

The proinflammatory and catabolic cytokine IL-1β has been implicated in the pathogenesis of osteoarthritis (OA) by mediating synovial inflammation and cartilage degeneration. Although synovial macrophages are suggested to be the source of IL-1β, the mechanism remains unclear. Ectopic deposition of hydroxyapatite (HA) crystals in joints is closely a...

Calcium phosphate ceramics are bioactive, osteoconductive materials used as guides for bone regeneration. We were able to carry out a histological study of ceramics implanted in large mammals and humans. An identical sequence of events apparently occurred at the contact of the ceramics. The osteoblasts differentiated preferentially in close proximi...

Angular deformity in the growing skeleton of animals, especially in the radius and ulna, is occasionally seen in clinical practice. The mechanism of spontaneous correction of these angular deformities however remains to be elucidated. The purpose of our experiment was to explore the ability of a growth plate to correct an induced valgus deformity,...

Cancer cells synthesize abnormal proteins and peptides which are associated to heat shock proteins being overproduced by these cells due to the stress induced by the particular biology of cancer tissue. We have purified on hydroxylapatite powder heat shock proteins using the HAparticles as purification bed, vectors for the proteins and vaccination...

Magnetite nanoparticles were used for their ability to be heated when they are put in an oscillating magnetic field. When they are located inside tumors they can eradicate the tumor cells by heating. We have developed a biomaterial constituted by a mineral degradable matrix containing magnetite nanoparticles. This material can be injected into bone...

We describe an approach to produce an autologous therapeutic antitumor vaccine using hydroxyapatite (HA) for vaccinating cancer patients. The novel approach involved (1) the purification of part of the self-tumor antigens/ adjuvants using column chromatography with HA, (2) the employ of HA as a medium to attract antigen-presenting cells (APCs) to t...

Hydroxyapatite (HA) is widely used to coat metal parts in order to improve their biocompatibility. Analysis of retrieved tissues associated with failed implants, suggest that phagocytosis of HA wear debris by monocytes/macrophages might provide a potent stimulus for the release of a variety of cytokines. Phagocytosis involved a large variety of cel...

Coprecipitates of calcium phosphate and DNA have been used in vitro for several decades for cell transfection. We evaluated the efficiency of calcium phosphate ceramics associated to plasmid DNA in the transfection of bone cells in vitro when they are grown in tissue culture. Newborn rat calvariae and tibia epiphyses were grown on an agar surface f...

The objective of this research was to carry out an in vitro and in vivo study of the biological performance of PLLA/beta-TCP composite materials, to estimate the scope of their potential applications in bone surgery. Samples with increasing beta-TCP (0-60% w/w) contents were processed by injection molding. The in vitro study consisted of an evaluat...

The osseointegration of porous calcium phosphate ceramics once implanted evolves in several stages. The mechanism of integration of such material usually is evaluated by histologic analysis. The trace elements present in bone can be detected in the ceramic and help to provide a semiquantitative evaluation of osseointegration. Two different methods...

HA-coatings have been widely used in human surgery to increase the biocompatibility of metal alloys used as arthroplasty material. Their characteristics are of fundamental importance for their behaviour in the organism and in particular their degradation rate. We had the opportunity to perform histological analysis of human femurs containing well f...

Calcium phosphate bioceramics have been applied as bone substitutes for several decades. Aseptic loosening after total joint arthroplasty is a major problem in orthopaedic surgery. Hydroxyapatite particles from materials wear have been reported as the main cause of implant failure. For this reason, an investigation into possible wear particles from...

Guided tissue regeneration (GTR) using bioabsorbable barrier membranes has shown promising and somewhat predictable clinical results. However, limited information is available on the stages of histologic healing when these types of barriers are used. Therefore, the aim of this study was to compare three currently available bioabsorbable GTR barrier...

Short term cell cultures are usually grown in contact with biomaterials to assess cytocompatibility. Depending on the rate of material degradation or corrosion, the time of culture can be a key-point in the method which, if too short, may not show any effect of the released material on the cells. A long term culture was therefore carried out with L...

Bone regeneration is only possible if stem cells give rise to progenitors of osteoblasts, chondroblasts or chondroidocytes. Stem cells and osteogenic progenitors were evidenced in bone marrow while only progenitors can be found in periosteum. Bone marrow stem cells did show an amazing plasticity and some cells of the bone surrounding tissues such a...

Bone regeneration is only possible if stem cells give rise to progenitors of osteoblasts, chondroblasts or chondroidocytes. Stem cells and osteogenic progenitors were evidenced in bone marrow while only progenitors can be found in periosteum. Bone marrow stem cells did show an amazing plasticity and some cells of the bone surrounding tissues such a...

After calcium-phosphates biomaterials based implantation like hydroxyapatite (HA) coating, particles are released in the periprosthetic tissues. Wear-debris induced fibrous membranes contain macrophage subsets that can produce metalloproteinases (MMPs), which are considered to be key enzymes in extra-cellular matrix turnover. Tissue inhibitors of m...

Research in bone substitutes has shown that calcium phosphates, particularly hydroxyapatite are well adapted to use in prosthetics. Due to its characteristics that are close to those of bone, hydroxyapatite is used as a coating or bone defect filler. At long term, one of causes of prosthetic failure is bone lysis followed by aseptic loosening. Part...

Hydroxylapatite ceramics were developed for cell transfection in vitro and in vivo. They were tested at the contact of isolated bone cells and bone tissue culture. This experiment showed that calcium phosphate matrices are able to transfect isolated cells and cells in a tissue culture with a good efficiency.

The first-generation calcium phosphate ceramics have been in daily use in human surgery for more than a decade. They were first used as bone substitutes in devices for guided tissue regeneration then as thin coatings to improve metal biocompatibility. Calcium phosphate ceramics were the first materials to be synthesized almost exclusively for ortho...

Cartilage is a specialized connective tissue consisting of a particular extracellular matrix which encases the cells or chondrocytes which synthesize it. It has a remarkably low cell density and is unable to heal when subjected to a lesion.

The aim of this work was to study the potential healing of the growth plate in the case of a central desepiphysiodesis. A central defect was made in the distal femoral growth plate of thirty 3-week-old rabbits. In group A the growth plate defect was left empty as control. The defects of group B were implanted with a polymeric cylinder fixed in the...

The aim of this work was to study the potential healing of the growth plate in the case of a central desepiphysiodesis. A central defect was made in the distal femoral growth plate of thirty 3-week-old rabbits, In group A the growth plate defect was left empty as control. The defects of group B were implanted with a polymeric cylinder fixed in the...

Calcium phosphate bioceramics have been applied as bone substitutes for several decades. Aseptic loosening after total joint arthroplasty is a major problem in orthopaedic surgery. Hydroxyapatite particles from materials wear have been reported as the main cause of implant failure. For this reason, an investigation into possible wear particles from...

Osteolysis remains the most important problem in orthopaedic implant failure. Wear debris from the implant contains hydroxyapatite particles which have been shown to activate monocyte cells. Although the response of monocytes has been observed to be influenced by size and shape of the hydroxyapatite particles, little is known on the effect of surfa...

An asymmetrical load exerted on the growth plate induces a deformity (valgus or varus). The respective roles of amount of force and duration of compression in the mechanism of deformity have not been completely elucidated. Our experiments were carried out to (i) induce an experimental valgus deformity in lambs, (ii) asymmetrically delay the growth...

Hydroxyapatite used as bone replacement can lead to particle release in the implantation site. These particles interact with monocytes, which are the first immune cells to colonize the implant and an inflammatory site. Thanks to cryo-X-ray microanalysis, we can observe cells in a state close to the physiological one and we have access to diffusible...

The purpose of this study is to assess the current capabilities of a new technique of bone densitometry: digitalized osseous densimetry (DOD). All basic techniques currently used for noninvasive assessment of the skeleton are expensive and inappropriate to animals. Precision and accuracy has been used to described the performance characteristics of...

The use of biphasic calcium phosphate (BCP) in hip arthroplasty revision surgery is discussed. This synthetic bone substitute appears to be safe. Less morbidity makes it effective compared with other bone grafts.

Tissue engineering allows to produce ectopical bone after isolated stem cells were associated to a synthetic material. The ways to associate the cells to the material are various. We have developed a method in which a calcium phosphate ceramic was implanted under the periosteum at the contact of bone and left for several days during which they were...

Calcium phosphate cements are able to set in situ when injected into bone tissue. We evaluated the tissue reaction occurring when a DCPD-based calcium phosphate cement was either set within the bone or implanted when already set. The samples were implanted in rabbit condyles and examined histologically after 8 and 16 weeks. The relative bone surfac...

The association of osteogenic stem cells to a synthetic carrier makes possible the elaboration of bioartificial tissue. Numerous phosphocalcic ceramics does not trigger a foreign body reaction when implanted in bone tissue and thus, a number of materials are available osteogenic stem cell carriers to replace the bone tissue. Several methods can be...

The resistance of macroporous calcium phosphate ceramics to compressive strength generally is low and depends on, among other factors, porosity percentage and pore size. A compromise always is adopted between high porosity, required for a good integration, and mechanical strength, which increases with material density. We improved the strength of m...

In order to develop bone substitutes, the design of biomaterials like calcium phosphate ceramic loaded with bone growth factor are of great interest. However, it is necessary to control the amount of growth factor adsorbed onto ceramics and the kinetics of its release. Radiolabeling of insulin-like growth factor-I (IGF-I) with 125-iodine ([(125)I]-...

In order to develop bone substitutes, the design of biomaterials like calcium phosphate ceramic loaded with bone growth factor are of great interest. However, it is necessary to control the amount of growth factor adsorbed onto ceramics and the kinetics of its release. Radiolabeling of insulin-like growth factor-I (IGF-I) with 125-iodine ([125I]-IG...

The aim of our work was to study X-rays showing osteolysis after 5 years and more in 122 prosthesis and to try and assess such complication, often described in the United States but seldom in Europ. We are dealing here with 122 retaining posterior cruciate ligament, mostly cementless prothesis implanted between 1985 and 1992 84 chromium-cobalt pros...

HA ceramics are daily used in human surgery for bone healing partly due to their ability to integrate into bone. They are generally used under a macroporous form. The behaviour of dense HA after implantation is not so well known. We implanted within cortical sheep femurs dense pure HA-ceramics cylinders for periods from 2 weeks to 18 months. The sa...

We evaluated the precision and accuracy of in vivo measurements of spine bone mineral density (BMD) and bone mineral content (BMC) in five ewes using dual-energy X-ray absorptiometry (DXA, Lunar DPX-L). The short-term in vivo reproducibility expressed as the coefficient of variation (CV) varied from 0.9 to 1.6% for spine BMD and from 1 to 3.1% for...

Searching for an alternative to bone grafts in orthopedic and trauma surgery, two biphasic synthetic calcium phosphate ceramics BCP are made: the first, Eurocer 400, in granule form with a high interconnected porosity for void-filling, and the second, Eurocer 200, available in different shapes, with a good mechanical resistance in compression. Two...

Porous beta-tricalcium phosphate (betaTCP) has osteoconductive properties. The adsorption of human recombinant bone morphogenetic protein-2 (rhBMP-2) onto TCP could realize an osteoinductive bone substitute. We evaluated it on an animal model using dual-energy X-ray absorptiometry (DEXA) and solid-state 31P nuclear magnetic resonance (NMR) spectros...

Calcium phosphate ceramics implanted in bones are integrated following a sequence of biological events which has already been described. We had the opportunity to analyze histologically some HA-ceramic samples that had been implanted in humans for various periods of time. Eight biopsies were obtained from calcium phosphate ceramics implanted in di...

The aim of this study is to evaluate the resorption of a calcium phosphate ceramic composed of 75% hydroxyapatite and 25% β-tricalcium phosphate (HTCP) used as a biomaterial. The animal implantation has been made in the cortical femur of sheep. Delays of 2, 4, 8, 12, 16, 20, 28, 36 and 48 weeks between graft and analysis were used. The samples were...

Twenty-two fully hydroxyapatite-coated femoral implants were retrieved during autopsy. These components, provided with a bipolar femoral head, had been inserted for a displaced fracture of the femoral neck. The time of implantation varied from 5 days to 76 months. Osteointegration of the implant was evident, without any formation of fibrous tissue:...

HA-coatings have a complex structure due to modification of the crystallographic structure of the HA and the appearance of other calcium phosphate phases during spraying. These modifications are responsible for enhancing of the coating degradation rate by cells and extracellular fluids. Calcium phosphate debris of different sizes and characteristic...

Summary Bone reconstruction by allogeneic bone is often used in conjunction with the implantation of an HA-coated device in order to obtain the osteointegration of this latter. We studied the histological behavior of 9 allogeneic implantations in contact either with the HA-coating of acetabular component or around the femoral stem. Normal cancellou...

From the viewpoint of hard tissue response to implant materials, calcium phosphates are probably the most compatible materials presently known. During the last few years, much attention has been paid to hydroxyapatite and β-tricalcium phosphate as potential biomaterials for bone substitute. A good implantation of biomaterials in the skeleton is t...

A fully hydroxyapatite-coated femoral implant was retrieved during autopsy. This component, provided with a bipolar femoral head, had been inserted for a displaced fracture of the femoral neck 52 months before. Osseointegration of the implant was evident, without any formation of fibrous tissue :39.9% of the perimeter of the prosthesis at the level...

Calcium phosphate coatings on dental implants enhance integration of the material. Resorption of the ceramic coatings has raised some concern about the behavior of the bone-implant interfaces after the coating disappearance. Substitution of the OH- ions by fluoride in the hydroxylapatite (HA) lattice makes the calcium phosphate more stable. We inve...

Sections of tissue containing orthopedic materials are currently used to study the compatibility of those materials and to perform electron probe microanalysis at the material-tissue interface. Identification of the cells in contact with the material by Scanning electron microscopy (SEM) is of interest. We have developed a method for staining cells...

Unlabelled: Different chemical or physical methods of bone processing have been developed to decrease the antigenicity of allogeneic bone which may delay or prevent graft integration. We have developed a method based on delipidation and deproteination of the bone with a supercritical fluid and hydrogen peroxide. Cylinders of cancellous allogeneic...

Calcium phosphate cements can be handled in paste form and set in a wet medium after precipitation of calcium phosphate crystals in the implantation site. Depending on the products entering into the chemical reaction leading to the precipitation of calcium phosphates, different phases can be obtained with different mechanical properties, setting ti...

A new bone tissue process using supercritical carbon dioxide fluid extraction (SFE) has been evaluated for its ability to inactivate or eliminate viruses. Four viruses, human immunodeficiency virus type 1 (HIV-1), Sindbis virus, polio Sabin type I virus, and pseudorabies virus (PRV), were exposed to four different processing steps. In addition to s...

A new bone tissue process using supercritical carbon dioxide extraction was evaluated for viral inactivation and the allografts produced by this process were tested in an in vivo implantation experiment. Four viruses, human immunodeficiency virus type I (HIV-1), Sindbis virus, Polio Sabin type I virus and Pseudorabies virus (PRV) were assayed. Four...

The PIXE method is very suitable for applications in the biological field. We use it to study the kinetic resorption of bioceramics. The aim of this work is to compare the concentrations of mineral elements in bone to those in bioceramics. The samples are embedded in a polymethylmethacrylate resin and are considered as infinitely thick targets. The...

The decomposition of HA during plasma-spraying can lead to the appearance of calcium oxide (CaO) in the calcium phosphate coatings and an increase of the Ca/P ratio (> 1.67). Rehydration can cause an increase in the pH of the extracellular fluids in close vicinity to the coating and rapid degradation of its thickness. Metal cylinders coated with HA...

Growth plate lesions or resections may cause severe growth arrest because of the bony bridge between the epiphysis and metaphysis. Actual treatments for epiphysiodesis include resecting the bone bar and setting an interpositional material. Growth plate cultures may provide the appropriate cartilage necessary to restore growth potential when implant...

An original and reliable technique to culture growth plate chondrocytes was developed to obtain an abundant amount of mature and functional chondrocytes. Growth plates were provided from the epiphysis of 3-week-old rabbits. Isolation of the chondrocytes was optimized by the use of trypsin and collagenase. The culture was realized according to the f...

Unlabelled: Prostheses implanted in hard tissues cannot be processed for electron microscopic examination or microanalysis in the same way as those in other tissues. For these reasons, we have developed a method allowing light and electron microscopic studies as well as microanalysis of the interface between bone and biomaterials after the section...

Unlabelled: Different kinds of calcium phosphate biomaterials can be used as bone substitutes. Ceramics are constituted by HA or TCP grains linked by grain boundaries. Their porosity depends on the powder characteristics and the sintering temperature. It can be very low with a pore size inferior to one micron. The setting of calcium phosphate hydr...

Pseudo-synovial membranes are found at the interface between bone and aseptically lost prostheses. They are supposed to be due to the release of material debris at the interface with bone. They are mostly composed of macrophages and giant cells, and some fibrocytes in the deep layer of the membrane. The different histological structures present in...

It is very likely that the need for bone substitutes will increase in the next decade. The present substitutes are generally bioactive and osteoconductive. Glassy or ceramic materials have been used up to now to act as a guide for bone healing tissue and were shown to admit bone apposition at their surface, probably due to the epitaxial growth of c...

A 10 mm-long (Group #1) or 20 mmlong (Group #2) segmental osteoperiosteal defect was performed on the metatarsus of ten adult ewes (5+5). The goal of the study was to search for a critical size defect model leading to nonunion. The bone gap was maintained for three months with an internal fixation device involving two plates set in orthogonal plane...

The decomposition of HA during plasma-spraying can lead to the appearance of calcium oxide (CaO) in the calcium phosphate coatings and an increase of the Ca/P ratio (> 1.67). Rehydration can cause an increase in the pH of the extracellular fluids in close vicinity to the coating and rapid degradation of its thickness. Metal cylinders coated with HA...

Osseointegration of porous calcium phosphate ceramics evolves in several stages once implanted. Histologic analysis has often been used to evaluate the mechanism of integration of this material. Histologic parameters can be completed by physical analysis to obtain a semiquantitative evaluation of the osseointegration process. The histologic observa...

HA-ceramics used in human surgery as osteoconductive surfaces show a great variety of characteristics. Certain characteristics such as grain size, porosity, and surface area, are controlled by the sintering temperature of the slurry. We grew L-929 fibroblast cells on HA-ceramic disks that had been sintered at different temperatures ranging from 850...

Bone formation results from two different processes: endochondral bone formation and direct bone formation. The mineralization of the extracellular bone matrix (ECM) formed during one of these processes is monitored by the proteins contained in this matrix that initiate the calcium phosphate crystals nucleation and control their growth. Most of the...

BIOCERAMICS, VOL 10, SEDEL L., REY C., PROCEEDINGS OF THE 10TH INTERNATIONAL SYMPOSIUM ON CERAMICS IN MEDICINE, PARIS, FRANCE, OCTOBRE

Coral and hydroxyapatite may be used as substitution biomaterials for bone grafts. In this work, we extracted the implants from the femora to study the kinetics of elementary mineral transformation of the osseous substitutes. The use of physical analysis methods such as PIXE (particle-induced X-ray emission) shows that coral and hydroxyapatite, aft...

Embryo cells modify their cell membrane glycoconjugates during their differentiation. We studied the labelling of chick embryo tibia between Hamilton's stages 29 and 38 with a horseradish peroxydase labelled Ulex europaeus I lectin. Sections were observed with a light microscope. Chondrocytes, chondroblasts and hypertrophic chondrocytes were found...

Untreated xenogeneic bone is known to be rejected when implanted into human or animal bone. It contains bone marrow tissue which is highly antigenic. To be used as an alternative to auto and allografts, this antigenic material must be entirely removed. Removal of this soft tissue contained in the bone structure was performed using a delipidation pr...

A series of 15 autopsied femurs containing hydroxyapatite-coated (HA-coated) prostheses was analysed histologically. Their implantation time ranged from 5 days up to 3 years. The coating thickness of some prostheses and the percentage of the coating in contact with bone at different levels were evaluated using an image analysis device. After the ne...