PubMed Health⌕ Search

Biomedical subjects

Philippe Menei

Publications and source records attributed to Philippe Menei.

At least 19 recordsLinked to original sources
PubMed2006

Neurotrophin-directed differentiation of human adult marrow stromal cells to dopaminergic-like neurons.

Marrow-isolated adult multilineage inducible (MIAMI) cells were differentiated in vitro to neuronal cells in a neurotrophin-dependent fashion. After induction, the cells revealed electrophysiological features similar to those observed in mature neurons. Primary early passage human MIAMI cells without any type of co-cultures with other cell types were used. The developmental program involved a multi-step process requiring the concerted action of brain-derived neurotrophic factor, nerve growth factor and depended on neurotrophin-3, after basic fibroblast growth factor withdrawal. MIAMI-derived neuron-like cells sequentially expressed the neuronal markers, developed a complex neurite outgrowth and arborization, and acquired electrophysiological characteristics similar to those observed in mature neurons. The young and old MIAMI-derived neuronal cells developed both inward and outward currents upon depolarization, similar to those observed in normal neurons. These results represent the earliest evidence that neurotrophin-3 can direct the differentiation of non-neural stem cells from human adult bone marrow stroma to neuron-like cells in vitro. Supplementing the aforementioned multi-step process with sonic hedgehog, fibroblast growth factor 8, and retinoic acid increased the expression of molecules involved in dopaminergic differentiation and of tyrosine hydroxylase, the rate limiting enzyme of dopamine synthesis. MIAMI cells from young and old individuals represent autologous human cell populations for the treatment of disorders of the skeletal and nervous systems and for applications in cell therapy and reparative medicine approaches.

Adolescent↗
PubMed2006

The brain tissue response to biodegradable poly(methylidene malonate 2.1.2)-based microspheres in the rat.

The aim of this study was to follow the in vivo biodegradation as well as to appreciate the brain tissue response to poly(methylidene malonate 2.1.2) (PMM 2.1.2)-based microspheres implanted into the rat brain. Ninety-three adult Sprague-Dawley female rats were engaged in the study in which 54 underwent stereotactic implantation of blank gamma-sterilized PMM 2.1.2-based microspheres, prepared by an emulsion-extraction method. Twelve rats were implanted with the same 5-fluorouracil (5-FU)-loaded microspheres. Seventeen controls received the suspension medium alone (carboxymethylcellulose aqueous solution). The animals were sacrificed on post-operative days 1, 2, 8 and months 1, 2, 3, 6, 9, 12, 15 and 18. The brains were dissected, frozen, cut in a freezing microtome, and the slides were processed for immunohistological evaluation and scanning electron microscopy. During the first few days, the moderate inflammatory response to blank or loaded PMM 2.1.2 microspheres was largely a consequence of the mechanical trauma that occurs during surgery. The macrophagous-microglial reaction was similar to the one typically found following any damage in the CNS. There were also no differences in GFAP reactivity between the implanted animals and the controls. Blank microspheres began to degrade between 3 and 6 months, while 5-FU microspheres degraded between 8 days and 1 month. The polymer degradation generated in both cases a pronounced inflammatory and immunological reaction, leading to an important cell loss, a cerebral atrophy and to the death of several animals. PMM 2.1.2 was thus shown to be inadequate for intracerebral drug delivery.

Absorbable Implants↗
PubMed2006

Effects of syngeneic cellular vaccinations alone or in combination with GM-CSF on the weakly immunogenic F98 glioma model.

Cancer vaccines are one approach for the treatment of brain tumors. Most experimental studies are performed on so-called "immunogenic" brain tumor models such as the rat 9L glioma which does not reflect characteristics of human glioblastoma. In the present study, we tested syngeneic cellular vaccinations alone or in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF) on the weakly immunogenic F98 glioma model. Previous studies have shown the efficacy of this treatment on the 9L glioma model. Fisher rats received an intracerebral implantation of F98 cells. Three days later, two subcutaneous vaccinations with irradiated F98 cells were realized in presence or absence of GM-CSF. This scheme of vaccination induced a systemic cellular and humoral immune response capable of in vitro cytolytic activity against F98 cells. However, no significant differences in survival times were noted between vaccinated and untreated animals. Animals vaccinated with GM-CSF or without GM-CSF had respectively a survival time of 26 +/- 2.1 and 25 +/- 4.4 days following tumor challenge versus 26.5 +/- 2.4 days for untreated rats. Fourteen days after the intracerebral tumor implantation, the tumors of vaccinated animals showed a robust infiltration by T lymphocytes, NK cells, dendritic cells, granulocytes and CD11b/c+ myeloid cells. This infiltration was nearly absent in untreated animals except for CD11b/c+ myeloid cells. This study shows that, contrary to the 9L glioma model, the F98 glioma model is resistant to syngeneic cellular vaccinations although a strong peripheral and intratumoral immune response can be induced. These results suggest that the F98 glioma is an attractive model to understand the mechanisms of glioma immunotherapy resistance.

Animals↗
PubMed2006

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.

Animals↗
PubMed2006

A new generation of anticancer, drug-loaded, colloidal vectors reverses multidrug resistance in glioma and reduces tumor progression in rats.

By focusing on rat glioma, we elucidated whether new lipid nanocapsules (LNC) were able to improve anticancer hydrophobic drug bioavailability while also overcoming multidrug resistance. Blank LNCs and LNCs loaded with the antineoplastic agent paclitaxel were formulated by an emulsion inversion phase process. Expression of efflux pumps by rat glioma cells was assessed by reverse transcription-PCR, Western blot, and immunohistochemistry, and their activity was followed using the tracer (99)Tc(m)-methoxyisobutylisonitrile. Modalities of LNC action were addressed by using confocal microscopy detection of fluorescently labeled LNCs, fluorescence-activated cell sorting, high-performance liquid chromatography measurement of paclitaxel release, and analysis of tumor cell growth. This revealed an interaction between LNCs and efflux pumps that resulted in an inhibition of multidrug resistance in glioma cells, both in culture and in cell implants in animals. LNCs were able to target the intracellular compartment of glioma cells, a mechanism that was abrogated by using intracellular cholesterol inhibitors but not by clathrin-coated pit or caveolae uptake inhibitors. This result can be correlated to the LNC inhibitory effects on efflux pump activity that is itself known to be stimulated by intracellular cholesterol. In parallel, we showed that paclitaxel-loaded LNCs were active reservoirs from which paclitaxel could be released. Finally, we established that paclitaxel-loaded LNCs were more efficient than the commercially available paclitaxel formulation (Taxol) for clinical use, thus reducing tumor expansion in vitro and in vivo. Considering the physiologically compatible nature of LNC excipients, these data may represent an important step towards the development of new clinical therapeutic strategies against cancers.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2006

Evaluation of particulate systems supporting tumor cell fractions in a preventive vaccination against intracranial rat glioma.

OBJECT: Irradiated autologous tumor cells are commonly used as a source of antigens in antiglioma vaccinations to activate the immune system. As cell number is often a limiting factor in these cells' preparation, the aim of the present study was to find a means that can lower the amount of cells required. Among strategies currently developed, adjuvant particulate systems offer a promising means to improve the antitumor immune response. In this study, the authors were interested in evaluating the role of particulate systems containing biodegradable microspheres that carry tumor cell fractions on their surfaces in the induction of a protective immunity in the 9L/Fischer 344 rat glioma model. The efficiency of these particulate systems was compared to that of irradiated 9L cells. METHODS: Particulate systems composed of poly(D,L-lactide-co-glycolide) (PLGA) microspheres that support 9L cell fractions on their surfaces (cell lysates or plasma membranes) or irradiated 9L cells alone were injected subcutaneously into the flanks of syngeneic Fischer 344 rats. Eighteen days later, the rats were intracranially injected with nonirradiated 9L cells. A study of survival in these animals and an analysis of the resulting immune response were then conducted. For the same amount of protein (50 microg) injected, irradiated 9L cells provided long-term survival in 30% of animals, whereas 9L plasma membranes adsorbed onto PLGA microspheres provided long-term survival in 10% of animals and cell lysates adsorbed onto microspheres provided long-term survival in 0%. Accordingly, particulate systems induced a lower T helper cell Type 1 (Th1) peripheral immune response than irradiated 9L cells. However, greater secretion of Th1 cytokines was observed when particulate systems were used than when cell fractions separated from microspheres were used, indicating the adjuvant property of these particulate systems. CONCLUSIONS: Particulate systems have adjuvant properties but are still less efficient than irradiated whole tumor cells for vaccinations. Encapsulation of an activating molecule in the microsphere will be the next developmental step in the search for efficient antiglioma vaccinations.

Animals↗
PubMed2005

Biopharmaceutics of intrathecal baclofen-loaded microparticles in a goat model.

The goal of this study was to develop a goat model allowing reliable pharmacokinetic (PK) studies of intrathecal baclofen (ITB) sustained release dosage forms using an implanted silicone catheter. ITB PK parameters (clearance, volume of distribution) following intrathecal bolus injection were determined for doses ranging from 100 to 560 microg and a comparison to human data was made. Baclofen-loaded microparticles were then implanted in the intrathecal space of goats and the resulting baclofen levels were determined during 28 days. Finally, PK parameters were used to predict cerebrospinal fluid (CSF) baclofen rates from in vitro release profiles of baclofen-loaded microspheres. The catheter was well tolerated and did not interfere with behavioral testings. Baclofen CSF clearance (mean = 8.59+/-2.43 ml/h) and volume of distribution (21.06+/-13.32 ml) were not significantly affected by the increase of the dose (p > 0.05). In vivo, the baclofen levels in CSF were stabilized at 200 microg/l after a period of 3 days. The predictive value of the in vitro release studies was good since the theoretical levels ranged between 128 and 257 microg/l. In conclusion, a large animal model was developed and allowed the biopharmaceutic evaluation of baclofen microparticles injected via intrathecal route.

Animals↗
PubMed2005

Baclofen-loaded microspheres in gel suspensions for intrathecal drug delivery: in vitro and in vivo evaluation.

Severe spasticity is a very disabling disorder treated by continuous baclofen intrathecal infusion which unfortunately remains an expensive and uncomfortable treatment. In order to address these issues, new sustained release formulations designed for intrathecal baclofen delivery were sought with the aim of minimising the burst effect of baclofen which can lead to toxicity. Baclofen was encapsulated in poly(lactide-co-glycolide) (PLGA) microspheres which were then dispersed in chitosan thermosensitive gels, Pluronic PF-127 gels, carboxymethylcellulose solutions or Ringer lactate solution. The release rate was assessed in vitro using continuous flow cells and in vivo after intrathecal injection in goats: baclofen was quantified in cerebrospinal fluid (CSF) and plasma, and the associated pharmacological effect was evaluated. The results showed that the burst effect was reduced by at least a factor of 2 in vitro, after microsphere dispersion in viscous media. In vivo, PF-127 gel was found to be the best vehicle to reduce the burst effect by a factor of 10 in CSF, and by a factor of 2 in plasma. The toxic effect of baclofen due to the burst effect was reduced by the dispersion in PF127 gels. Therapeutic levels of baclofen in CSF were maintained during at least 1 month.

Baclofen↗
PubMed2005

Baclofen-loaded microspheres: preparation and efficacy testing in a new rabbit model.

Intrathecal baclofen is the reference treatment for severe spasticity. This drug has to be injected chronically in the intrathecal space by implanted pumps which are very expensive, uncomfortable and sometimes lead to side effects. Previous work has been performed by our group to assess the feasibility of encapsulating baclofen into poly(lactide-co-glycolide) (PLGA) microspheres and injecting these preparations in the intrathecal space of rabbits. The aims of the present study were to improve the encapsulation process for industrial application (scale-up), and to set up an animal model to assess the duration of effect of the new formulations. Modifications included the replacement of methylene chloride by a less toxic solvent, ethyl acetate, and the use of high molecular weight polymers to extend the release rate of the drug. The temperature and organic solvent extraction rate were fully controlled during the whole manufacturing process. All these modifications resulted in high quality microsphere batches with a CV inferior to 5% for encapsulation efficiency and drug loading. Encapsulation efficiency and release patterns were dependent on the drug payload and the polymer used. A formulation displaying a sustained release of baclofen over 174 days and a moderate burst effect of 16% in the first day in vitro was evaluated in a new reliable model of baclofen activity based on electrophysiological measurement of H-reflex in the rabbit. The activity of a very low dose of baclofen microspheres in vivo was sustained over 35 days. Furthermore, the preparation was well tolerated. These newly developed preparations are a very promising approach for enhancing the efficacy and comfort of patients undergoing spasticity treatment.

Animals↗
PubMed2005

Repair of avulsed ventral nerve roots by direct ventral intraspinal implantation after brachial plexus injury.

Currently, the authors' research confirms that,in humans, communication between the cord and effector muscles can be re-established after multi-ple nerve root avulsion by the implantation of peripheral nerve grafts. Outcomes are still modest,but the possibility of improvement exists. The technique of reimplantation makes it possible to envisage global repair with the possibility of repair of all avulsed regions. The most important factor that could maximize the extent of functional recovery is reducing the time between the injury and corrective surgery: the diagnosis of avulsion within 10 days and reparative surgery within 3 weeks is the objective. This goal will involve a global re-evaluation of how these patients are managed. The problem of the recovery of sensory function (tactile and fine perception and proprioception) warrants further work. It seems likely that methods combining medullary reimplantation with neurotization will be the best way of correcting these lesions of the brachial plexus. In this context, cross-disciplinary collaboration is probably more important than ever. The place that methods based on reimplantation will have in the final picture remains to be seen. The key question is in which patients should medullary reimplantation be attempted and which method should be used. Moreover, medullary reimplantation should be considered as an adjunct to all other surgical options and should not compromise the chance of the latter modalities to be effective.An important point remains: are physicians going to be able to map out all the boundaries of this question in the future?

Brachial Plexus↗
PubMed2005

Local and sustained delivery of 5-fluorouracil from biodegradable microspheres for the radiosensitization of malignant glioma: a randomized phase II trial.

OBJECTIVE: This study was a randomized, multicenter Phase II trial comparing the effect of perioperative implantation of 5-fluorouracil-releasing microspheres followed by early radiotherapy (Arm A) and early radiotherapy alone (Arm B) in patients with gross total resection of high-grade glioma. METHODS: Patients were randomized on clinical and radiological assumption of supratentorial high-grade glioma. All patients underwent surgery, and after resection and histological confirmation, patients randomized to Arm A received multiple injections of microsphere suspension (130 mg of 5-fluorouracil). Conventional fractionated radiotherapy (59.4 Gy) was initiated between the second and the seventh day after surgery for both arms. RESULTS: A total of 95 patients were randomized. Seventy-seven patients were treated and analyzed in intention to treat for efficacy and safety. Overall survival was 15.2 months in Arm A and 13.5 months in Arm B. In the subpopulation of patients with complete resection, overall survival was 15.2 months in Arm A versus 12.3 months in Arm B. However, these differences were not significant. Safety was acceptable with prophylactic high doses of corticosteroids. CONCLUSION: It may be hypothesized that the implantation of 5-fluorouracil-loaded microspheres in the wall of the cavity resection did increase the overall survival, but the present study was not designed and sufficiently powered to demonstrate this.

Antimetabolites, Antineoplastic↗
PubMed2005

Drug delivery into the brain using poly(lactide-co-glycolide) microspheres.

Among the strategies developed for drug delivery into the CNS, locally controlled drug release by the way of an implantable polymeric device has been developed in recent years. The first polymeric devices developed were macroscopic implants needing open surgery for implantation. Over the last few years, poly(lactide-co-glycolide) microspheres have been shown to be safe and promising for drug delivery into the brain. Poly(lactide-co-glycolide) is biodegradable and biocompatible with brain tissue. Due to their size, these microspheres can be easily implanted by stereotaxy in discrete, precise and functional areas of the brain without causing damage to the surrounding -tissue. Brain tumour treatments have been developed using this approach and clinical trials have been performed. Potential applications in neurodegenerative diseases have also been explored, particularly neurotrophic factor delivery and cell therapy.

Animals↗
PubMed2004

Marrow-isolated adult multilineage inducible (MIAMI) cells, a unique population of postnatal young and old human cells with extensive expansion and differentiation potential.

We report here the isolation of a population of non-transformed pluripotent human cells from bone marrow after a unique expansion/selection procedure. This procedure was designed to provide conditions resembling the in vivo microenvironment that is home for the most-primitive stem cells. Marrow-adherent and -nonadherent cells were co-cultured on fibronectin, at low oxygen tension, for 14 days. Colonies of small adherent cells were isolated and further expanded on fibronectin at low density, low oxygen tension with 2% fetal bovine serum. They expressed high levels of CD29, CD63, CD81, CD122, CD164, hepatocyte growth factor receptor (cMet), bone morphogenetic protein receptor 1B (BMPR1B), and neurotrophic tyrosine kinase receptor 3 (NTRK3) and were negative for CD34, CD36, CD45, CD117 (cKit) and HLADR. The embryonic stem cell markers Oct-4 and Rex-1, and telomerase were expressed in all cultures examined. Cell-doubling time was 36 to 72 hours, and cells have been expanded in culture for more than 50 population doublings. This population of cells was consistently isolated from men and women of ages ranging from 3- to 72-years old. Colonies of cells expressed numerous markers found among embryonic stem cells as well as mesodermal-, endodermal- and ectodermal-derived lineages. They have been differentiated to bone-forming osteoblasts, cartilage-forming chondrocytes, fat-forming adipocytes and neural cells and to attachment-independent spherical clusters expressing genes associated with pancreatic islets. Based on their unique characteristics and properties, we refer to them as human marrow-isolated adult multilineage inducible cells, or MIAMI cells. MIAMI cells proliferate extensively without evidence of senescence or loss of differentiation potential and thus may represent an ideal candidate for cellular therapies of inherited or degenerative diseases.

Adipocytes↗
PubMed2004

Striatal tyrosine hydroxylase immunoreactive neurons are induced by L-dihydroxyphenylalanine and nerve growth factor treatment in 6-hydroxydopamine lesioned rats.

Only a few studies mention the existence of tyrosine hydroxylase immunoreactive neurons in the striatum. These neurons are known to be increased following lesion of the dopaminergic nigrostriatal pathway. Recently it has been shown that glial cell line-derived neurotrophic factor treatment was able to increase the number of these neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intoxicated primate. Here we report that, in the rat, these neurons are responsive to intrastriatal injection of 6-hydroxydopamine and that following the lesion their number tends to increase with time. Moreover, we have shown that L-DOPA treatment for 2 weeks or nerve growth factor treatment for 8 weeks are able to dramatically augment their number.

Animals↗
PubMed2004

In vitro study of GDNF release from biodegradable PLGA microspheres.

Glial cell line-derived neurotrophic factor (GDNF) is a protein with potent trophic actions on dopaminergic neurons, which is under investigation as a therapeutic agent for the treatment of neurodegenerative disorders, including Parkinson's disease. The aim of this work was to develop GDNF-loaded microspheres, which could be implanted by stereotaxy in the brain and could offer an alternative strategy in the treatment of Parkinson's disease. A w/o/w extraction-evaporation technique was chosen to prepare protein-loaded microspheres. An in vitro release study of the protein was required to assess the retention of integrity and the performance of the microsphere formulation with regard to sustained release. In order to assess the in vitro release profile of the GDNF-loaded microspheres, a preliminary study was performed to select an appropriate buffer for GDNF stabilization, using experimental designs. GDNF was measured by both enzyme-linked immunosorbant assay (ELISA) and radioactivity using (125)I-GDNF. The GDNF-loaded microsphere release profile was assessed in a low continuous flow system, and showed a sustained release over 56 days of biologically active GDNF at clinically relevant doses.

Alzheimer Disease↗
PubMed2004

Long-term effect of intra-striatal glial cell line-derived neurotrophic factor-releasing microspheres in a partial rat model of Parkinson's disease.

Glial cell line-derived neurotrophic factor (GDNF) offers the possibility to stimulate axonal regeneration of mesencephalic dopaminergic neurons, which are affected in Parkinson's disease. Nevertheless, a safe and efficient GDNF delivery system that may be used in clinical trials is still lacking. In a previous study, we showed that GDNF-releasing microspheres can deliver the neurotrophic factor for 2 months, allowing in a partial rat model of Parkinson's disease a sprouting of the preserved dopaminergic fibers and functional improvement 8 weeks after the treatment. The present study confirms these previous observations and shows that the amphetamine-induced rotation score is still decreased 24 weeks after the end of GDNF delivery. Nevertheless, the improvement was not statistically significant at the latest time point due to the spontaneous reinnervation observed in the model used.

Amphetamine↗
PubMed2004

Stereotaxic implantation of 5-fluorouracil-releasing microspheres in malignant glioma.

BACKGROUND: The authors developed a new method of drug delivery into the brain using implantable, biodegradable microspheres. The strategy was evaluated initially to provide localized and sustained delivery of the radiosensitizer 5-fluorouracil (5-FU) after patients underwent surgical resection of malignant glioma. In this study, the microspheres were implanted by stereotaxy into deeply situated and inoperable brain tumors. METHODS: Ten patients with newly diagnosed, inoperable, malignant gliomas were included in the study, and 1 dose of 5-FU was studied (132 mg). After histologic confirmation, a suspension of poly(D-L lactide-co-glycolide) 5-FU-loaded microspheres was implanted by stereotaxy into the tumor in one or several trajectories with one to seven deposits per trajectory. External beam radiation (59.4 grays) was started before postoperative Day 7. Patients were followed by clinical examination, computed tomography scanning, magnetic resonance imaging, and 5-FU assays in blood and cerebrospinal fluid (CSF). RESULTS: The number of trajectories was adapted to the size and shape of the tumor. Microsphere implantation was tolerated well, except in four patients who received a single trajectory and experienced a transitory worsening of preexisting neurologic symptoms. There were no episodes of edema or hematologic complications. 5-FU was detected in CSF and blood in some patients at very low concentrations. The median overall survival was 40 weeks, with 2 patients who had longer survival (71 weeks and 89 weeks, respectively). CONCLUSIONS: In this study, the authors demonstrated that biodegradable microspheres could be implanted by stereotaxy and were efficient systems for drug delivery into brain tumors. This method may have future applications in the treatment of patients other malignancies.

Adolescent↗