Biomedical subjects

Pierre Hardouin

Publications and source records attributed to Pierre Hardouin.

5 recordsLinked to original sources

PubMed2002

The influence of culture conditions on extracellular matrix proteins synthesized by osteoblasts derived from rabbit bone marrow.

The influence of culture conditions on the extracellular matrix (ECM) protein expressions of rabbit bone marrow stromal cells has been studied. The focus was on the effects of two kinds of sera, fetal calf serum (FCS) and Ultroser, on cells treated with dexamethasone. The induction of osteoblastic differentiation by dexamethasone addition is confirmed, particularly when cells are cultured in FCS. Bone marrow stromal cells produce alkaline phosphatase positive CFU-F and produce ECM with some mineralized nodules. Analysis by means of two-dimensional gel electrophoresis showed important changes in the composition of ECM proteins after dexamethasone treatment. Overexpression, underexpression, and new synthesized proteins were observed. The most significant modification was linked to the synthesis of four new proteins visible in the acidic area with a low molecular weight of around 17 kDa. These proteins did not correspond to those ECM proteins known to be induced by dexamethasone. Moreover, the effect of dexamethasone on osteoblastic differentiation induction appears very limited when cells are cultured in Ultroser compared to FCS. The protein pattern with Ultroser is different to that obtained with FCS. Cells cultured in Ultroser synthesized no new protein. The different behavior of cells according to the type of medium used is discussed in terms of the osteogenic factors present in the two different sera.

Animals↗

PubMed2002

The biodegradation mechanism of calcium phosphate biomaterials in bone.

This study was undertaken to understand the biodegradation mechanisms of calcium phosphate (Ca-P) biomaterials with different crystallization. Two types of sintered Ca-P porous ceramic (HA and beta-TCP) and a Ca-P bone cement (CPC) were implanted into cavities drilled in rabbit femoral and tibiae condyles. The results have shown that a material biodegradation was rapid in the beta-TCP and the CPC, but very weak in the HA. This biodegradation presented a decrease of material volume from the periphery to the center as well as a particle formation causing phagocytosis by numerous macrophages and multinucleated giant cells in the CPC. In the beta-TCP, there was a peripheral and central decrease of material volume as well as an absence of particle formation or visible phagocytosis. The process of biodegradation is considered to be directly influenced by the type of material crystallization. The sintered bioceramics processed at a high temperature exhibit good crystallization and are primarily degraded by a process dependent on interstitial liquids. However, the bone cement is formed by physicochemical crystallization and is degraded through a dissolution process associated with a cellular process.

Animals↗

PubMed2002

Kyphoplasty.

A variant of vertebroplasty known as "kyphoplasty" has been suggested for correcting vertebral compression fractures. A balloon placed inside the vertebral body is inflated to create a cavity, thereby restoring vertebral body height and allowing low-pressure cement injection. This procedure is gaining popularity in the United States. Over 1000 patients had been treated by the end of 2000. However, kyphoplasty is costly (chiefly because the balloon is disposable) and has not been evaluated in carefully designed studies. Although retrospective findings have been reported as highly promising, they are not sufficient to validate this procedure. The principle is innovative and the procedure deserves further investigation as a potentially effective means of correcting loss of vertebral height. Furthermore, use of a bone substitute instead of cement deserves investigation.

Humans↗

PubMed2002

In vitro control of human bone marrow stromal cells for bone tissue engineering.

For the clinical application of cultured human mesenchymal stem cells (MSCs), cells must have minimal contact with fetal calf serum (FCS) because it might be a potential vector for contamination by adventitious agents. The use of human plasma and serum for clinical applications also continues to give rise to considerable concerns with respect to the transmission of known and unknown human infectious agents. With the objective of clinical applications of cultured human MSCs, we tested the ability of autologous plasma, AB human serum, FCS, and artificial serum substitutes containing animal-derived proteins (Ultroser G) or vegetable-derived proteins (Prolifix S6) to permit their growth and differentiation in vitro. To conserve as much autologous plasma as possible, we attempted to mix it at decreasing concentrations with the serum substitute containing vegetable-derived mitogenic factors. Under control conditions, by day 10 all the fibroblast colony-forming units (CFU-Fs) were alkaline phosphatase (ALP) positive. However, their number and size were highly variable among donors. Better CFU-F formation was obtained with Ultroser G, and with human AB serum and autologous plasma mixed at, respectively, 5 and 1% with Prolifix S6. The effects of these mixtures on CFU-F formation demonstrate synergy, with the human serum or plasma supplying the factors that favor differentiation of MSCs while Prolifix S6 supplies the mitogenic factors. Finally, we demonstrated the possibility of controlling human MSC growth and differentiation in vitro. Notably, by means of a minimal quantity of human serum or human plasma mixed with a new serum substitute containing vegetable-derived proteins, we displayed growth and differentiation of human MSCs comparable to that obtained with FCS or serum substitutes containing animal-derived proteins. These results will have crucial significance for future applications of cultured human MSCs in bone tissue engineering.

Alkaline Phosphatase↗

PubMed1997

New Injectable Composites for Bone Replacementd.

A new class of biomaterials is emerging: injectable composites for bone replacement. They include injectable ceramics and injectable calcium phosphate hydraulic cements, such as calcium deficient hydroxyapatite cements, dahllite cements, or brushite cements. Their main advantages are their biocompatibility, resorbability, osteoconductivity, and injectability, which allows a delivery with a syringe and a needle through a percutaneous approach. Furthermore, they can be used for the controlled delivery of antibiotics or bone morphogenetic proteins. Their mechanical properties remain nonsatisfactory as compared to orthopedic cement [polymethylmetacrylate (PMMA)], but these materials still have a great potential for improvement. There is a large field of potential clinical applications for these composites, especially in implantology, bone surgery, traumatology, interventional radiology, and rheumatology. However, the biological properties of a limited number of these compounds have been studied so far and further biological evaluations, as well as rigorous clinical studies, remain to be made.

Journal Article↗