Early presentation of primary glioblastoma

Background

Clinical and neuroimaging findings of glioblastomas (GBM) at an early stage have rarely been described and those tumors are most probably under-diagnosed. Furthermore, their genetic alterations, to our knowledge, have never been previously reported.

Methods

We report the clinical as well as neuroimaging findings of four early cases of patients with GBM.

Results

In our series, early stage GBM occurred at a mean age of 57 years. All patients had seizures as their first symptom. In all early stages, MRI showed a hyperintense signal on T2-weighted sequences and an enhancement on GdE-T1WI sequences. A hyperintense signal on diffusion sequences with a low ADC value was also found. These early observed occurrences of GBM developed rapidly and presented the MRI characteristics of classic GBM within a few weeks. The GBM size was multiplied by 32 in one month. Immunohistochemical analysis indicated the de novo nature of these tumors, i.e. absence of mutant IDH1 R132H protein expression, which is a diagnostic marker of low-grade diffuse glioma and secondary GBM.

Conclusions

A better knowledge of early GBM presentation would allow a more suitable management of the patients and may improve their prognosis.     

Effect of GDNF-releasing biodegradable microspheres on the function and the survival of intrastriatal fetal ventral mesencephalic cell grafts.

The transplantation of fetal ventral mesencephalic (FVM) cell suspensions into the brain striatal system is an alternative approach for the treatment of Parkinson's disease (PD). However, one objection to this procedure is the relatively poor survival of implanted cells. Attempts have been made to improve the survival of grafted dopaminergic neurons using glial cell line-derived neurotrophic factor (GDNF). Nevertheless, the clinical application of GDNF is limited, due to the difficulties in administering a protein to the brain tissue and due to the ubiquity of its receptor, thus leading to neurological side effects. A strategy to deliver GDNF in the brain based on the intracerebral implantation of biodegradable poly(D,L-lactic acid-co-glycolic acid) sustained release microspheres has been developed. Such microparticles can be easily implanted by sterotaxy in precise and functional areas of the brain without causing damage to the surrounding tissue. Moreover, the release profile of the GDNF-loaded microspheres showed a sustained release over 56 days of biologically active GDNF at clinically relevant doses. The present study shows that the implantation of GDNF-loaded microspheres at a distance to the site of FVM cells in the 6-hydroxydopamine-lesioned rat model of PD improves dopaminergic graft survival and function. Furthermore, the unloaded and the GDNF-loaded microspheres, when they are mixed with FVM cells, may provide a mechanical support and a 3D environment inducing differentiation and increased function of dopaminergic neurons. Taken together, these results show that GDNF microspheres represent an efficient delivery system for cell transplantation studies.     

Lipid nanocapsules: Ready-to-use nanovectors for the aerosol delivery of paclitaxel

Aerosol drug delivery permits the development of dose-intensification strategies in severe, malignant lung diseases. The aim of the study was to demonstrate that the encapsulation of paclitaxel in lipid nanocapsules (LNCs), a novel drug nanocarrier for lipophilic components, allows one to provide pulmonary drug delivery of paclitaxel by nebulisation, thereby allowing preclinical and clinical studies. LNC dispersions are made into aerosols with commercial nebulisers. The structure, drug payload and cytotoxicity of nebulised LNCs were compared to fresh LNCs. The results demonstrated that LNC dispersions could be made into aerosols by using mesh nebulisers without altering the LNC structure. Only eFlow^® rapid-produced aerosols are compatible with human use: the mean duration to nebulise 3 ml of LNC dispersion is less than 9 min, with an aerosol mass median aerodynamic diameter equal to 2.7 ± 0.1 μm and a fine-particle fraction (between 1.0 and 5.0 μm) of 81.5 ± 3.1%. No modifications of drug payload or cytotoxicity effects of paclitaxel-loaded LNC (PTX–LNC) were observed. In order to carry out preclinical studies, a scaled-up LNC formulation protocol was used. Chemical parameters, such as acidity and osmolarity, were optimised, and a storage procedure for PTX–LNC batches was set-up. Animal studies are now needed to determine the tolerance and therapeutic potential of LNC dispersion aerosols.     

Design of targeted lipid nanocapsules by conjugation of whole antibodies and antibody Fab' fragments

Immunonanocapsules were synthesized by conjugation to lipid nanocapsules (LNC) of whole OX26 monoclonal antibodies (OX26 MAb) directed against the transferrin receptor (TfR). The TfR is overexpressed on the cerebral endothelium and mediates the transcytosis mechanism. Fab' fragments, known for their reduced interaction with the reticuloendothelial system, were also conjugated to LNC. This coupling was facilitated by the incorporation of lipid PEG(2000) functionalized with reactive-sulfhydryl maleimide groups (DSPE-PEG(2000)-maleimide) into LNC shells by a post-insertion procedure, developed initially for liposome pegylation. An interfacial model using the dynamic rising drop technique helped determine the parameters influencing the DSPE-PEG(2000)-maleimide insertion and the quality of the anchorage. Heat was essential to promote both an important and stable adsorption of DSPE-PEG(2000)-maleimide onto LNC. OX26 MAb were thiolated to react with maleimide functions whereas thiol residues on Fab' fragments were used directly. The number of ligands per nanocapsule was adjusted according to their initial quantity in the coupling reaction mixture, with densities from 16 to183 whole antibodies and between 42 and 173 Fab' fragments per LNC. The specific association of immunonanocapsules to cells overexpressing TfR was thus demonstrated, suggesting their ability to deliver drugs to the brain.     

Preserved regulation of renal perfusion pressure by small and intermediate conductance K<Subscript>Ca</Subscript> channels in hypertensive mice with or without renal failure

The purpose of this study was to assess, in the murine kidney, the mechanisms underlying the endothelium-dependent control of vascular tone and whether or not, in a severe model of hypertension and renal failure, K_Ca channels contribute to its regulation. Wild-type (BL) and double-transgenic female mice expressing human angiotensinogen and renin (AR) genes received either control or a high-salt diet associated to a nitric oxide (NO) synthase inhibitor treatment (BLSL and ARSL). Changes in renal perfusion pressure (RPP) were measured in isolated perfused kidneys. BLSL and AR were moderately hypertensive without kidney disease while ARSL developed severe hypertension and renal failure. In the four groups, methacholine induced biphasic endothelium-dependent responses, a transient decrease in RPP followed by a cyclooxygenase-dependent increase in RPP. In the presence or not of indomethacin, the vasodilatations were poorly sensitive to NO synthase inhibition. However, in the presence of cyclooxygenase and NO synthase inhibitors, apamin, and/or TRAM-34, blockers of K_Ca2.3 and K_Ca3.1, respectively, abolished the decrease in RPP in response to either methacholine or the two activators of K_Ca2.3/K_Ca3.1, NS309, and SKA-31. Thus, K_Ca2/3 channels play a major role in the regulation of murine kidney perfusion and this mechanism is maintained in hypertension, even when severe and associated with kidney damage.     

Progress in developing cationic vectors for non-viral systemic gene therapy against cancer

Initially, gene therapy was viewed as an approach for treating hereditary diseases, but its potential role in the treatment of acquired diseases such as cancer is now widely recognized. The understanding of the molecular mechanisms involved in cancer and the development of nucleic acid delivery systems are two concepts that have led to this development. Systemic gene delivery systems are needed for therapeutic application to cells inaccessible by percutaneous injection and for multi-located tumor sites, i.e. metastases. Non-viral vectors based on the use of cationic lipids or polymers appear to have promising potential, given the problems of safety encountered with viral vectors. Using these non-viral vectors, the current challenge is to obtain a similarly effective transfection to viral ones. Based on the advantages and disadvantages of existing vectors and on the hurdles encountered with these carriers, the aim of this review is to describe the "perfect vector" for systemic gene therapy against cancer.     

Interelationship between CD3 and CD28 pathways in a murine T cell thymoma

It is well known that the CD28 costimulatory signal is important to complement T cell receptor (TCR)/CD3-initiated T cell activation, but the mechanism by which these two distinct signaling pathways are integrated is not clearly understood. In our laboratory, we dispose of a murine T cell hybridoma transfected with human CD28 molecule which is able to produce IL-2 in response to stimulation, suggesting that the signal transduction machinery coupled to the CD28 molecule is capable of triggering effector functions. Nevertheless, the action of three immunosuppressive agents previously shown in our model, suggested an interaction between the CD3 and CD28 pathways. We confirmed here this hypothesis by transfecting the cDNA of the human CD28 molecule in the BW5147 thymoma which lacks CD3 surface expression. Stimulation of the human CD28 did not lead to IL-2 secretion while the restoration of the TCR/CD3 complex re-established the functionality of this costimulatory molecule. These data demonstrate that the IL-2 production induced by the CD28 activation pathway is dependent of the TCR/CD3 complex cell surface expression and suggest the formation of a functional membrane complex between the CD3 and CD28 molecules. The molecular basis of the functional dependence of CD28 signaling on the TCR/CD3 complex is presently unknown. Nonetheless, we showed that some early events induced by CD28 stimulation, such as PI3-kinase association, are independent of the TCR/CD3 complex expression.