Comparison of perfused volume segmentation between cone-beam CT and 99mTc-MAA SPECT/CT for treatment dosimetry before selective internal radiation therapy using 90Y-glass microspheres.

PURPOSE: To compare the reliability and accuracy of the pre-treatment dosimetry predictions using cone-beam computed tomography (CBCT) versus 99mTc-labeled macroaggregated albumin (MAA) SPECT/CT for perfused volume segmentation in patients with hepatocellular carcinoma treated by selective internal radiation therapy (SIRT) using 90Y-glass microspheres. MATERIALS AND METHODS: Fifteen patients (8 men, 7 women) with a mean age of 68.3±10.5 (SD) years (range: 47-82 years) who underwent a total of 17 SIRT procedures using 90Y-glass microspheres for unresectable hepatocellular carcinoma were retrospectively included. Pre-treatment dosimetry data were calculated from 99mTc-MAA SPECT/CT using either CBCT or 99mTc-MAA SPECT/CT to segment the perfused volumes. Post-treatment dosimetry data were calculated using 90Y imaging (SPECT/CT or PET/CT). The whole liver, non-tumoral liver, and tumor volumes were segmented on CT or MRI data. The mean absorbed doses of the tumor (DT), non-tumoral liver, perfused liver (DPL) and perfused non-tumoral liver were calculated. Intra- and interobserver reliabilities were investigated by calculating Lin's concordant correlation coefficients (ρc values). The differences (biases) between pre- and post-treatment dosimetry data were assessed using the modified Bland-Altman method (for non-normally distributed variables), and systematic bias was evaluated using Passing-Bablok regression. RESULTS: The intra- and interobserver reliabilities were good-to-excellent (ρc: 0.80-0.99) for all measures using both methods. Compared with 90Y imaging, the median differences were 5.8Gy (IQR: -12.7; 16.1) and 5.6Gy (IQR: -13.6; 10.2) for DPL-CBCT and DPL-99mTc-MAA SPECT/CT, respectively. The median differences were 1.6Gy (IQR: -29; 7.53) and 9.8Gy (IQR: -28.4; 19.9) for DT-CBCT and DT-99mTc-MAA SPECT/CT respectively. Passing-Bablok regression analysis showed that both CBCT and 99mTc-MAA SPECT/CT had proportional biases and thus tendencies to overestimate DT and DPL at higher post-treatment doses. CONCLUSION: CBCT may be a reliable segmentation method, but it does not significantly increase the accuracy of dose prediction compared with that of 99mTc-MAA SPECT/CT. At higher doses both methods tend to overestimate the doses to tumors and perfused livers.

Self-crosslinked fibrous collagen/chitosan blends: Processing, properties evaluation and monitoring of degradation by bi-fluorescence imaging.

Porous collagen/chitosan scaffolds with different Collagen:Chitosan (Coll:Ch) ratios were prepared by freeze-drying followed by self-crosslinking via dehydrothermal treatment (DHT) and characterized as biomaterials for tissue engineering. Cy7 and Cy5.5 fluorochromes were covalently grafted to collagen and chitosan, respectively. Thus, it was possible, using optical fluorescence imaging of the two fluorochromes, to simultaneously track their in vivo biodegradation, in a blend scaffold form. The fluorescence signal evolution, due to the bioresorption, corroborated with histological analysis. In vitro cytocompatibility of Coll:Ch blend scaffolds were evaluated with standardized tests. In addition, the scaffolds showed a highly interconnected porous structure. Extent of crosslinking was analyzed by convergent analysis using thermogravimetry, Fourier Transform Infrared Spectroscopy and PBS uptake. The variations observed with these techniques indicate strong interactions between collagen and chitosan (covalent and hydrogen bonds) promoted by the DHT. The mechanical properties were characterized to elucidate the impact of the different processing steps in the sample preparation (DHT, neutralization and sterilization by ß-irradiation) and showed a robust processing scheme with low impact of Coll:Ch composition ratio.

Chitosan-based hydrogels for developing a small-diameter vascular graft: in vitro and in vivo evaluation.

AIMS: Vascular grafts made of synthetic polymers perform poorly in small-diameter applications (cardiac and peripheral bypass). Chitosan is a biocompatible natural polymer that can provide a novel biological scaffold for tissue engineering development. The goal of this study was to demonstrate the biocompatibility of a novel chitosan preparation in vitro and in vivo, and to assess its potential as a scaffold for vascular applications. METHODS AND RESULTS: A series of experiments of increasing complexity, ranging from in vitro biocompatibility and hemocompatibility tests to in vivo studies in small and large animals (rats and sheep), was performed to provide a comprehensive analysis of chitosan hydrogels' biological properties. In vitro studies established that: (i) chitosan supported human endothelial progenitor cells adhesion, proliferation and resistance to physiological shear stress; (ii) chitosan did not activate platelets, the complement system, or the intrinsic coagulation pathway. In vivo results showed: (iii) no resorption of chitosan and no chronic inflammation at 60 days in a rat heterotopic implantation model (magnetic resonance imaging and histology); (iv) no flow obstruction (Doppler ultrasound) and no thrombus formation (histology and scanning electron microscopy) at 2 h after a carotid arteriotomy repair with chitosan patches in sheep. Finally, two chitosan tubes were implanted as carotid interposition grafts for 3 days in sheep showing that chitosan was strong enough to be sutured, to withstand arterial pressure, and no flow obstruction was observed through this short period. CONCLUSION: Chitosan-based hydrogels displayed promising in vitro biocompatibility and hemocompatibility properties as well as in vivo short-term performance.

A useful and easy to develop combined stress test for myocardial perfusion imaging: Regadenoson and isometric exercise, preliminary results.

BACKGROUND: Regadenoson, a selective A2a receptor agonist, is a vasodilator increasingly used in myocardial perfusion imaging. Adjunction of isometric exercise is a simple method that could improve side effect profile while providing better image quality. METHODS: Patients undergoing SPECT MPI were prospectively enrolled in handgrip-Regadenoson (HG-Reg test, N = 20) and Regadenoson (Reg) stress test (N = 40). Investigator blinded to stress test analyzed clinical data and images. RESULTS: Heart rate (HR) increase was statistically higher in the HG-Reg group (27 vs 22 bpm, P = .019). Decrease in SBP was less frequent in the HG-Reg group than in the Reg group (55% vs 85.5%, P = .005), there were less drops >10 mmHg (45% vs 77.7%, P = .012). During stress testing, fewer subjects reported at least one side effect in the HG-Reg compared to Reg group (70% vs 92.5%, P = .021). Images were more often classified as good in the HG-Reg group (75% vs 52.5% in the Reg group, P = .25). CONCLUSIONS: Adjunction of handgrip exercise to Regadenoson administration is a well-tolerated and easy method, without loss of time. Furthermore, image quality seems to be better.

Comparison of the Antimicrobial Properties of Silver Impregnated Vascular Grafts with and without Triclosan.

OBJECTIVES: The aim was to compare the antimicrobial efficacy of the silver impregnated collagen coated polyester vascular graft (IGS) with an identical graft combining silver and triclosan (IGSy). METHODS: This was an in vitro study. A non-antimicrobial collagen polyester vascular graft served as control (IG). The IG, IGS, and IGSy grafts were contaminated separately with inoculates of each of the following micro-organisms: Staphylococcus epidermidis (SE), methicillin resistant Staphylococcus aureus (MRSA), and Escherichia coli producing extended spectrum beta-lactamase (ESBL-EC) or Candida albicans (CA). MRSA, ESBL-EC, and CA were obtained from retrieved infected grafts. The in vitro antimicrobial efficacies of the contaminated grafts were evaluated by time to kill assays over a 24 hour period in accordance with CLSI Guideline M26-A. All assays were repeated six times. Bacterial survival numbers were obtained at 1, 4, 8, and 24 hours using a standard plate count procedure. Bactericidal activity was defined as a 3 log10 reduction factor (logRF). To calculate the overall difference in the mean log10 CFU/mL within 24 hours, a one way ANOVA with a Bonferroni correction was calculated separately for each graft. RESULTS: The IG graft showed an increase in the number of viable organisms for the four strains tested. IGSy offered better antimicrobial properties than IGS for both ESBL-EC and MRSA, since only the IGSy graft achieved > 3 logRF and fulfilled the standard criteria for bactericidal activity at 24 hours with 3.78 and 4.08 logRF, respectively. For samples inoculated with SE and CA, both antimicrobial grafts achieved 24 hour bactericidal activity with > 3 logRF. However, for CA the one-way ANOVA analysis demonstrated that the IGSy graft performed differently in terms of speed of antimicrobial action, appearing more active as early as 4 hours following inoculation (p = .007). CONCLUSION: In the in vitro conditions, the Synergy vascular graft combining silver with triclosan demonstrated better short-term antimicrobial activity than the silver graft for all micro-organisms tested.

Nasal irrigation: From empiricism to evidence-based medicine. A review.

Nasal irrigation plays a non-negligible role in the treatment of numerous sinonasal pathologies and postoperative care. There is, however, a wide variety of protocols. The present review of the evidence-based literature sought objective arguments for optimization and efficacy. It emerged that large-volume low-pressure nasal douche optimizes the distribution and cleansing power of the irrigation solution in the nasal cavity. Ionic composition and pH also influence mucociliary clearance and epithelium trophicity. Seawater is less rich in sodium ions and richer in bicarbonates, potassium, calcium and magnesium than is isotonic normal saline, while alkaline pH and elevated calcium concentration optimized ciliary motility in vitro. Bicarbonates reduce secretion viscosity. Potassium and magnesium promote healing and limit local inflammation. These results show that the efficacy of nasal irrigation is multifactorial. Large-volume low-pressure nasal irrigation using undiluted seawater seems, in the present state of knowledge, to be the most effective protocol.

[Recurrent syncope in head and neck cancer: a case report]. / Tumeur ORL responsable de syncopes à répétition: cas clinique.

The repeated syncopes in case of head and neck cancer are a complication rarely described in the literature. They occur when the tumor invade the carotid sinus or the afferent fibers of the glossopharyngeal nerve. We report the case of a 62-year-old man presented episodes of syncope synchronous of a recurrent hypopharyngeal tumor scheduled for chemotherapy and gastrostomy. A computerized tomography showed a voluminous tumor expanded to the carotid and parapharyngeal spaces. After treatment by isporenaline chlorhydrate in intensive care unit, a pacemaker was implanted to prevent syncopes and allowed the beginning of the chemotherapy.

Peri-infarct ischaemia assessed by cardiovascular MRI: comparison with quantitative perfusion single photon emission CT imaging.

OBJECTIVE: To develop a new method for the cardiac MR (CMR) quantification of peri-infarct ischaemia using fused perfusion and delayed-enhanced images and to evaluate this method using quantitative single photon emission CT (SPECT) imaging as a reference. METHODS: 40 patients presenting with peri-infarct ischaemia on a routine stress (99m)Tc-SPECT imaging were recruited. Within 8 days of the SPECT study, myocardial perfusion was evaluated using stress adenosine CMR. Using fused perfusion and delayed-enhanced images, peri-infarct ischaemia was quantified as the percentage of myocardium with stress-induced perfusion defect that was adjacent to and larger than a scar. This parameter was compared with both the percent myocardium ischaemia (SD%) and the ischaemic total perfusion deficit (TPD). The diagnostic performance of CMR in detection of significant coronary artery stenosis (of ≥70%) was also determined. RESULTS: On SPECT imaging, in addition to peri-infarct ischaemia, reversible perfusion abnormalities were detected in a remote zone in seven patients. In the 33 patients presenting with only peri-infarct ischaemia, the agreement between CMR peri-infarct ischaemia and both SD% and ischaemic TPD was excellent [intraclass coefficient of correlation (ICC) = 0.969 and ICC = 0.877, respectively]. CMR-defined peri-infarct ischaemia for the detection of a significant coronary artery stenosis showed an areas under receiver-operating characteristic curve of 0.856 (95% confidence interval, 0.680-0.939). The best cut-off value was 8.1% and allowed a 72% sensitivity, 96% specificity, 60% negative predictive value and 97% positive predictive value. CONCLUSION: This proof-of-concept study shows that CMR imaging has the potential as a test for quantification of peri-infarct ischaemia. ADVANCES IN KNOWLEDGE: This study demonstrates the proof of concept of a commonly known intuitive idea, that is, evaluating the peri-infarct ischaemic burden by subtracting delayed enhancement from first-pass perfusion imaging on CMR.

Attachment of human endothelial cells to polyester vascular grafts: pre-coating with adhesive protein assemblies and resistance to short-term shear stress.

Cardiovascular prosthetic bypass grafts do not endothelialize spontaneously in humans, and so they pose a thrombotic risk. Seeding with cells improves their performance, particularly in small-caliber applications. Knitted tubular polyethylene-terephthalate (PET) vascular prostheses (6 mm) with commercial type I collagen (PET/Co) were modified in the lumen by the adsorption of laminin (LM), by coating with a fibrin network (Fb) or a combination of Fb and fibronectin (Fb/FN). Primary human saphenous vein endothelial cells were seeded (1.50 × 10(5)/cm2), cultured for 72 h and exposed to laminar shear stress 15 dyn/cm(2) for 40 and 120 min. The control static grafts were excluded from shearing. The cell adherence after 4 h on PET/Co, PET/Co +LM, PET/Co +Fb and PET/Co +Fb/FN was 22%, 30%, 19% and 27% of seeding, respectively. Compared to the static grafts, the cell density on PET/Co and PET/Co +LM dropped to 61% and 50%, respectively, after 120 min of flow. The cells on PET/Co +Fb and PET/Co +Fb/FN did not show any detachment during 2 h of shear stress. Pre-coating the clinically-used PET/Co vascular prosthesis with LM or Fb/FN adhesive protein assemblies promotes the adherence of endothelium. Cell retention under flow is improved particularly on fibrin-containing (Fb and Fb/FN) surfaces.

Cell interactions between human progenitor-derived endothelial cells and human mesenchymal stem cells in a three-dimensional macroporous polysaccharide-based scaffold promote osteogenesis.

Several studies have reported the benefits of mesenchymal stem cells (MSCs) for bone tissue engineering. However, vascularization remains one of the main obstacles that must be overcome to reconstruct large bone defects. In vitro prevascularization of the three-dimensional (3-D) constructs using co-cultures of human progenitor-derived endothelial cells (PDECs) with human bone marrow mesenchymal stem cells (HBMSCs) appeared as a potential strategy. However, the crosstalk between the two lineages has been studied in two-dimensional (2-D), but remains unknown in 3-D. The aim of this study is to investigate the cell interactions between PDECs and HBMSCs in a porous matrix composed of polysaccharides. This biodegradable scaffold promotes cell interactions by inducing multicellular aggregates composed of HBMSCs surrounded by PDECs. Cell aggregation contributes to the formation of junctional proteins composed of Connexin43 (Cx43) and VE-cadherin, and an activation of osteoblastic differentiation of HBMSCs stimulated by the presence of PDECs. Inhibition of Cx43 by mimetic peptide 43GAP27 induced a decrease in mRNA levels of Cx43 and all the bone-specific markers. Finally, subcutaneous implantations for 3 and 8 weeks in NOG mice revealed an increase in osteoid formation with the tissue-engineered constructs seeded with HBMSCs/PDECs compared with those loaded with HBMSCs alone. Taking together, these results demonstrate that this 3-D microenvironment favored cell communication, osteogenesis and bone formation.

Effects of a single 1200-mg preoperative dose of gabapentin on anxiety and memory.

BACKGROUND: Gabapentin has antihyperalgesic and potential anxiolytic effects. We therefore evaluated the effects of gabapentin premedication on anxiety, amnesia, and sedation. We tested the primary hypothesis that 1200mg of oral gabapentin 2 to 3h before surgery reduces preoperative anxiety. Our secondary hypothesis was that gabapentin administration is sedative without causing preoperative amnesia. STUDY DESIGN: Prospective, randomized and placebo-controlled study. METHODS: Surgical patients having general anaesthesia were randomly assigned to either 1200mg oral gabapentin (n=32) or an identical-looking placebo (n=32) 2 to 3h before anaesthesia. Anxiety, sedation, and amnesia were quantified before premedication, 2h thereafter, and postoperatively. Preoperative anxiety was measured using the Spielberger state trait anxiety inventory (STAI state) and the visual analogue scale anxiety (VAS). Memory was assessed with the picture recall test of Snodgrass and Vanderwart. Results were compared with t, Mann-Whitney U, or Chi(2) tests as appropriate, P<0.05 was considered statistically significant. RESULTS: STAI state, our primary outcome, decreased significantly in the gabapentin group, from 37.2 to 30.8, and remained unchanged in the placebo group, from 39.3 to 37.9 (P=0.003). The VAS score for anxiety also decreased, but not significantly, from 28.2 to 19.2 in the gabapentin group and from 28.7 to 24.7 in the placebo group (P=0.065). No difference was observed in the amnesic effect; nor did the groups differ in terms of recovery times or sedation scores. CONCLUSION: Gabapentin premedication, 1200mg, provided preoperative anxiolysis without causing sedation or impairing preoperative memory.

Whatever their differentiation status, human progenitor derived - or mature - endothelial cells induce osteoblastic differentiation of bone marrow stromal cells.

Association of the bone-forming osteoblasts (OBs) and vascular endothelial cells (ECs) into a biomaterial composite provides a live bone graft substitute that can repair the bone defect when implanted. An intimate functional relationship exists between these cell types. This communication is crucial to the coordinated cell behaviour necessary for bone development and remodelling. Previous studies have shown that direct co-culture of primary human osteoprogenitors (HOPs) with primary human umbilical vein endothelial cells (HUVECs) stimulates HOPs differentiation and induces tubular-like networks. The present work aims to test the use of human bone marrow stromal cells (HBMSCs) co-cultured with human endothelial progenitor cells in order to assess whether progenitor-derived ECs (PDECs) could support osteoblastic differentiation as mature ECs do. Indeed, data generated from the literature by different laboratories considering these co-culture systems appear difficult to compare. Monocultures of HUVECs, HOPs, HBMSCs (in a non-orientated lineage), PDECs (from cord blood) were used as controls and four combinations of co-cultures were undertaken: HBMSCs-PDECs, HBMSCs-HUVECs, HOPs-PDECs, HOPs-HUVECs with ECs (mature or progenitor) for 6 h to 7 days. At the end of the chosen co-culture time, intracellular alkaline phosphatase (ALP) activity was detected in HOPs and HBMSCs and quantified in cell extracts. Quantitative real-time polymerase chain reaction (qPCR) of ALP was performed over time and vascular endothelial growth factor (VEGF) was measured. After 21 days, calcium deposition was observed, comparing mono- and co-cultures. We confirm that ECs induce osteoblastic differentiation of mesenchymal stem cells in vitro. Moreover, HUVECs can be replaced by PDECs, the latter being of great interest in tissue engineering.

Carbon nanotubes have a deleterious effect on the nose: the first in vitro data.

BACKGROUND: The information currently available concerning carbon nanotubes toxicity is disturbing and conflicting. Moreover, little is known about their effect on the nasal cavities, which are the first target for nanoparticles. MATERIAL AND METHOD: We investigated the cytotoxicity (50 to 0.5 microg/mL) of double-walled carbon nanotube with two independent tests (MTT, Wst-1) on normal human nasal epithelial cells after 12-day exposure (control untreated nasal cells and A549). Nasal cell differentiation function, oxidative stress, the morphological features of cells in contact with DWCNTs and the localizations of the latter were also investigated. RESULTS: Exposure revealed a dose-dependent decrease in cell metabolic activity and cell growth. In nearly all conditions, normal human nasal epithelial cells were more sensitive than malignant ones. Even with both tests, the cytotoxic threshold dose could not be accurately determined because of dye adsorption by DWCNTs. Nasal cells showed stronger cytokeratin 7 and persistent UEA-I immunostaining. Cytokeratin 19 production was increased at 25 microg/mL and mucus production was stimulated from 0.5 microg/mL. A significant increase in Reactive Oxygen Species was observed from 25 microg/mL. The cell plasma membrane showed several holes and DWCNTs were present in the cytoplasm. CONCLUSION: DWCNTs seem to have a deleterious effect on nasal cells after 12-day exposure.

Polyelectrolyte multilayer film and human mesenchymal stem cells: an attractive alternative in vascular engineering applications.

Mesenchymal stem cells (MSCs) have tremendous potential as a cell source for regenerative medicine due to their capacity for differentiation into endothelial-like cells when seeded on nonmodified cover glasses. This absence of removable surface, preventing recovery of cell sheet, constitutes a critical obstacle to predict an application in tissue engineering. It remains unknown whether MSCs differentiation could be realized when the cells are cultivated on a scaffold that could be used in vascular engineering. In this study, we propose to differentiate human MSCs into endothelial-like cells on surfaces coated with polyelectrolyte multilayer film (PMF) and fibronectin (control surfaces). We quantified Platelet Endothelial Cell Adhesion Molecule (PECAM) and von Willebrand Factor (vWF) expressions (endothelial cell specific markers) and nitric oxide (NO) production, which is representative of the cell functionality. After only two weeks of differentiation, we showed, on PMF, that MSCs expressed PECAM and vWF, exhibiting a differentiation into endothelial-like cells, which functionality was explored by a significant production of nitrites. These results highlight the importance of PMF to get human MSCs differentiation and suggest that this film of nanometer thickness opens a new route for vascular bioengineering by pre-seeding hMSCs directly into a vascular graft functionalized by a removable coating.

[PET-CT in thoracic disease]. / TEP-TDM et thorax.

PET-CT imaging merges metabolic data obtained after injection of a tracer labelled with a positron emitter, with CT anatomical data. This whole-body technique provides (i) an improved spatial resolution and (ii) when the tracer is ¹8FDG, quantification of tissue glucose metabolism. In thoracic oncology, ¹8FDG PET-CT imaging allows diagnosis, staging, follow-up of treatment efficiency, and detection of recurrence. Furthermore, its potential usefulness in inflammatory and infectious diseases should be emphasized. Its main contra-indication is pregnancy, and a good knowledge of its technical procedure is mandatory. The most currently used quantification index is the standardized uptake value (SUV), whose interpretation requires caution.

Salvage treatment for venous aneurysm complicating vascular access arteriovenous fistula: use of an exoprosthesis to reinforce the vein after aneurysmorrhaphy.

OBJECTIVES: We report a new salvage technique for treating venous aneurysms (VAs) complicating vascular access arteriovenous fistula (AVF) using externally reinforced venous aneurysmorrhaphy. DESIGN: A retrospective study over a 20-month period from a single centre. PATIENTS: Patients presenting to the vascular surgery department, Bordeaux University Hospital for revision of a vascular access AVF were included. METHODS: Reinforced venous aneurysmorrhaphy consisted in removal of redundant vessel wall followed by reinforcement using an external prosthetic graft. Patency, diameter and flow were assessed by duplex ultrasound at 1, 6 and 12 months after salvage. RESULTS: Thirty-eight eligible patients were identified. Five were excluded because VA was associated with central vein stenosis; the remaining 33 underwent salvage. Indications were rapidly expanding or painful VA in seven cases; VA with frequent bleeding or damaged overlying skin in eight; VA in close relation to a stenosis in two; and VA associated with high-flow rate in 16. Cannulation was attempted after 30 days. Mean follow-up time was 12 S.D. 5 months (range: 4-22). Two repaired AVFs failed. Primary 1-year patency was 93%. No aneurysm or infection occurred. Reduction of high flow was successful in 12 of 16 patients. The remaining four required re-operation. CONCLUSIONS: Reinforced venous aneurysmorrhaphy is effective in controlling venous dilation and achieving patency. Reduction of high-flow rates was not always achieved. Further study is needed to evaluate long-term efficacy of this treatment.

Polyelectrolyte multilayer films allow seeded human progenitor-derived endothelial cells to remain functional under shear stress in vitro.

There is considerable interest in making multilayer films for various applications, among which are cell contacting biomaterials, allowing new opportunities to prepare functionalized biomaterials. In this study we have explored the capability of poly(sodium-4-styrene sulfonate)/poly(allylamine hydrochloride) polyelectrolyte multilayer films (PMFs) as functional coatings for human progenitor-derived endothelial cells (PDECs), since the latter are a potential source of endothelial-type cells to be used in bioartificial vascular substitutes. We performed investigations with PDECs derived from peripheral blood and characterized as endothelial cells. After forming a confluent monolayer on PMFs they were exposed to laminar pulsatile physiological shear stress. We investigated whether PDECs were able to withstand shear stress and to respond at the mRNA (microarray analysis) and protein levels (thrombomodulin and tissue factor functional activity), in comparison with collagen I and fibrin glue used as controls. After shear stress the PDECs remained spread on the substrates, with a resulting increase in the number of expressed genes. Considering the functional significance of our findings for the regulation of coagulation and fibrinolytic factors, mRNA tissue plasminogen activator and thrombomodulin, profibrinolytic and thrombin inhibiting respectively, were overexpressed in PDECs after 6h shear stress. von Willebrand factor showed down-regulation, while tissue factor was up-regulated. We can speculate that PMFs could favour anti-thrombogenic activity by PDECs because activated protein C generation, measuring thrombomodulin activity, was particularly high on PMFs, but unchanged after 6h shear stress. Thus, PMFs could represent suitable coatings able to provide functional surfaces for endothelialization with PDECs.

[Erythropoietin: indications and measurement]. / Erythropoïétine : Quand la prescrire ? Pourquoi et comment la doser ?

Erythropoietin (EPO) is the principal haematopoietic growth factor of the red blood cell line. Its major role is to stimulate the red blood cell production. EPO synthesis by peritubular cells in the kidney is regulated by oxygen concentration and must lead adaptation of the organism to face many different physiological situations. An imbalance can lead either to anaemia or polycythemia. Synthetic EPO, so-called recombinant, has definitively changed the treatment in the anaemia of chronic renal failure and regularly find new indications, legal (anaemia of cancer, anaemia of chronic inflammatory syndromes, myelodysplastic syndromes, neurology, cardiology...) or illegal (doping substance in sport). This article reviews the physiology, the role and the indications of EPO in clinical routine practice and define why and how EPO should be measured. We also focus on the analytical requirements for serum EPO concentration determination, especially in the differential diagnosis of polycythemias (secondary polycythemia/Polycythemia Vera).

Cell-to-cell communication between osteogenic and endothelial lineages: implications for tissue engineering.

There have been extensive research efforts to develop new strategies for bone tissue engineering. These have mainly focused on vascularization during the development and repair of bone. It has been hypothesized that pre-seeding a scaffold with endothelial cells could improve angiogenesis and bone regeneration through a complex dialogue between endothelial cells and bone-forming cells. Here, we focus on the paracrine signals secreted by both cell types and the effects they elicit. We discuss the other modes of cell-to-cell communication that could explain their cell coupling and reciprocal interactions. Endothelial cell-derived tube formation in a scaffold and the dialogue between endothelial cells and mesenchymal stem cells provide promising means of generating vascular bone tissue-engineered constructs.