Biocompatible poly(methylidene malonate)-made materials for pharmaceutical and biomedical applications.

In the past 20 years, mainly with the sponsorship of Laboratoires UPSA (France) and, afterwards, its spin-off company Virsol (France), several authors have studied methylidene malonate-based polymers used in drug delivery approaches and in the development of novel biomaterials. The present paper aims at summing up the preparation of methylidene malonate monomers, and essentially a novel asymmetric diester structure: 1-ethoxycarbonyl-1-ethoxycarbonylmethylenoxycarbonyl ethene named methylidene malonate 2.1.2. Their polymeric and copolymeric derivatives and a few of their applications which were reported in the literature are also presented. It encompasses the manufacturing of particulate systems such as nano- and macroparticles designed for the delivery of hydrophilic or hydrophobic drugs and biomolecules. This review article also describes their use as biomaterials of interest in the fields of tissue repair, as drug reservoirs or ophthalmology, as implants. Copolymers based on these monomers offer a large range of properties and could be used as new surfactants, micellar vectors, or particulate systems for gene delivery. Therefore, this review, certainly the first dedicated exclusively to methylidene malonate-based materials, highlights the great biomedical and pharmaceutical technology potential of these new materials.

Epidemiology of Transfusion Related Acute Lung Injury in France: Preliminary Results.

SUMMARY: The French Hemovigilance Network has been established in 1994 and records all adverse events associated with the transfusion of a labile blood products (LBP) regardless of their severity. From 1994 to 2006 35,423,172 LBP were issued, 85,812 adverse transfusion reactions notified, and 139 cases of transfusion related acute lung injury (TRALI) observed. The LBP most at risk is fresh frozen plasma (FFP), followed by platelets concentrates (PC) and packed red cells (PRC). However, because the use of FFP is not frequent in France, it only accounts for about 10% of TRALI, whereas PRC and PC are involved in the remaining cases. In no case, pooled FFP treated with solvent-detergent were involved. Patients' profiles are peculiar with a high disease burden. Therefore, targeting a prevention policy only on FFP would result in a marginal reduction of TRALI in France.

Sustained delivery of growth factors from methylidene malonate 2.1.2-based polymers.

The incorporation of growth factors into new methylidene malonate 2.1.2-based biocompatible polymeric blends of oligomers and polymers to improve their stability and controlled release was investigated. Five growth factors were used in this study: FGF2, PDGF, TGF-beta, NGF and GM-CSF. Formulation in poly(methylidene malonate 2.1.2) blends was achieved by a four-step optimized process, using different oligomers/polymers ratios. Once dried, formulations could be subsequently stored at 4 or 20 degrees C or immediately subjected to degradation in conditioned cell culture medium. Toxicity of blends and their degradation products were evaluated in several cell lines with MTT. Bioactivity and biospecificity of the formulated growth factors were investigated using MTT and immunohistochemical staining. Combined ELISA and crystal violet colorimetric assays were performed to analyze growth factors release. Limited toxicities were observed for unloaded poly(methylidene malonate 2.1.2) blends. Once optimized, growth factors formulations did not reveal lower bioactivities or loss of biospecificity. Moreover, a sustained release over a 21-day period with more than 90% of preserved bioactivity was reached. To conclude, dual growth factor delivery was made possible by the mean of poly(methylidene malonate 2.1.2) blends. These studies demonstrate the ability of methylidene malonate 2.1.2-based polymeric blends for the delivery of growth factors.

Trans-scleral diffusion of triamcinolone acetonide.

PURPOSE: To assess ex vivo human scleral permeability to triamcinolone acetonide (TA). METHODS: The experiments were carried out using scleral samples and a Franz-type vertical diffusion cell. A suspension containing TA was prepared and placed in the donor chamber. The concentration of TA in the receptor chamber was measured by high-performance liquid chromatography (HPLC) assay and expressed as a percentage relative to TA concentration dissolved in the donor chamber. Control experiments using a commercial TA suspension were performed. RESULTS: TA (+/-SEM) dissolved in the donor suspension was 10.69 +/- 1.28 microg/ml. The diffusion rate of TA varied from 30% after 1 day to 72% after 4 days, after which equilibrium was reached. The human scleral permeability coefficient (P(s) +/- SEM) was 1.47+/- 0.17 x 10(- 5) cm/s. CONCLUSIONS: TA crossed human sclera. The mean amount of drug retained in the sclera increased with time, 4 days being necessary to equilibrate the unidirectional flux. The TA permeability coefficient was comparable to that of other corticosteroids.

Development of novel 5-FU-loaded poly(methylidene malonate 2.1.2)-based microspheres for the treatment of brain cancers.

In order to treat malignant brain tumors by local delivery of antineoplastic agents, the feasibility of 5-fluorouracil (5-FU)-sustained release biodegradable microspheres with a novel material, poly(methylidene malonate 2.1.2), was investigated using an emulsion/extraction method. This polymer was expected to present a slow degradation rate, thus leading to a long term local delivery system. Microparticles were successfully obtained and characterized in terms of drug loading, size, morphology and release profile. The size of the particles was between 40 and 50 microm, which was compatible with a stereotactic injection through a needle. Sufficient drug loadings were obtained (i.e. compatible with the preparation of therapeutic 5-FU doses in a minimal volume of injection), and perfectly spherical microspheres were observed. The respective influences of the polymer molecular weight, the polymer concentration, and the emulsion time on the release profiles were studied using a 2(3) factorial design. In the same objective, the solvent extraction time was extended while keeping all the previous parameters fixed at their optimal values. The in vitro study of these different parameters allowed a reduction of the initial burst release, with a percentage of 5-FU released after 24 h that was lowered from 90 to 65%, and the achievement of a long term drug delivery system, since the release was still ongoing after 43 days. Moreover, the microparticles could be gamma-sterilized (25 kGy) without modification of the release kinetics. Thus, the requested specifications to perform animal experiments were attained.

Synthesis and characterization of poly(ethylene oxide)-block-poly(methylidene malonate 2.1.2) block copolymers bearing a mannose group at the PEO chain end.

A poly(ethylene oxide)-block-poly(methylidene malonate 2.1.2) block copolymer (PEO-b-PMM 2.1.2) bearing a mannose moiety at the poly(ethylene oxide) chain end was synthesized by sequential anionic polymerization of ethylene oxide (EO) and methylidene malonate 2.1.2 (MM 2.1.2), followed by a coupling reaction between its poly(ethylene oxide) amino- or aldehyde-end group and a sugar derivative. Different coupling procedures, either in organic media or in aqueous micellar solutions, were examined in order to optimize the poly(ethylene oxide) end-glycosylation yield. The micellar size of the functionalized block copolymers was determined by dynamic light scattering.

A novel CD4-CD8alpha+CD205+CD11b- murine spleen dendritic cell line: establishment, characterization and functional analysis in a model of vaccination to toxoplasmosis.

Dendritic cells (DCs) play an essential role in the induction of immune responses to pathogen infections. Native DCs are difficult to obtain in large numbers and consequently the vast majority of DCs employed in all experiments are derived from bone marrow progenitors. In an attempt to solve this problem, we have established a novel CD8alpha(+) DC line (H-2(k)) from spleen, which we have named SRDC line, and which is easy to culture in vitro. These cells display similar morphology, phenotype and activity to CD4(-)CD8alpha(+)CD205(+)CD11b(-) DCs purified ex vivo. Toxoplasma gondii antigen was shown to be taken up by these cells and to increase class I and class II major histocompatibility complex (MHC), CD40, CD80 and CD86 surface expression. We report that vaccination with T. gondii antigen-pulsed SRDCs, which synthesize large amounts of interleukin-12, induced protective immune responses against this intracellular pathogen in syngeneic CBA/J mice. This protection was associated with strong cellular and humoral immune responses at systemic and intestinal levels. Spleen and mesenteric lymph node cell proliferations were correlated with a Th1/Th2-type response and a specific SRDC homing to spleen and intestine was observed. The SRDC or CD4(-)CD8alpha(+)CD205(+)CD11b(-) DC line can be expected to be a very useful tool for immunobiology studies of DC.

Efficacy of paclitaxel released from bio-adhesive polymer microspheres on model superficial bladder cancer.

PURPOSE: We aimed to promote the efficacy of paclitaxel in intracavitary treatment of superficial transitional cell carcinoma of the bladder by designing bio-adhesive microspheres capable of achieving controlled release of the drug at the urothelium/urine interface. MATERIALS AND METHODS: Poly(methylidene malonate 2.1.2) microspheres encapsulating paclitaxel were prepared by a single emulsion method. Bioactivity of the released paclitaxel was confirmed by assessing cytotoxicity on MBT-2, a bladder cancer cell line. Biodistribution of particles after bladder instillation was assessed by confocal microscopy and scanning electron microscopy. In vivo studies were performed in Balb/c mice after bladder cancer was induced by BBN (N-n-Butyl-N-butan-4-ol-nitrosamine) in drinking water. The efficacy of intravesical injections of conventional and microsphere paclitaxel was assessed by histology and survival rates. RESULTS: Spherical 5 microm microspheres with 5% weight per weight paclitaxel loading ensured sustained release of bioactive paclitaxel. After bladder instillation the microspheres adhered to the mucosa and remained in the bladder lumen for at least 48 hours. In the BBN induced bladder cancer model compared with controls the 9-week survival rate was significantly improved by 2 injections of paclitaxel bio-adhesive microparticles. Microscopic evaluation confirmed the lower incidence of carcinoma in situ and high grade transitional cell carcinoma after injections of paclitaxel bio-adhesive microparticles compared with controls and with injections of similar doses of the conventional paclitaxel formulation. CONCLUSIONS: Intravesical administration of poly(methylidene malonate 2.1.2) paclitaxel microspheres is a promising approach for intracavitary chemotherapy of superficial bladder cancer.

Therapeutic effectiveness of novel 5-fluorouracil-loaded poly(methylidene malonate 2.1.2)-based microspheres on F98 glioma-bearing rats.

BACKGROUND: Drug delivery to the central nervous system (CNS) remains a real challenge for neurosurgeons and neurologists, because many molecules cannot cross the blood-brain barrier (BBB). In recent years, solid polymeric materials have been implanted into animal and human brains either by surgery or using stereotactic methods to assure the controlled release of a drug over a determined period, thus circumventing the difficulties posed by the BBB. Poly(methylidene malonate 2.1.2) (PMM 2.1.2) is a new polymer that was described a few years ago and that allows the fabrication of novel, 5-fluorouracil (5-FU)-loaded PMM 2.1.2 microspheres. The objective of the current study was to assess the therapeutic effectiveness of those particles in a rat brain tumor model, the F98 glioma. METHODS: Forty-three rats were used in this study. First, a histologic evaluation of the F98 tumor model was performed on Fischer female rats. Thereafter, different groups of rats were injected and were treated with 5-FU microspheres in 2 different suspension media: carboxymethylcellulose (CMC) aqueous solution with or without 5-FU. RESULTS: The tumor was confirmed as extremely aggressive and invasive, even in early development. The 5-FU-loaded microspheres improved rat median survival significantly compared with untreated animals, CMC-treated animals, and 5-FU solution-treated animals when injected in CMC without 5-FU, demonstrating the interest of a sustained release and the efficacy of intratumoral chemotherapy against an established tumor. CONCLUSIONS: PMM 2.1.2 microspheres appeared to be a promising system, because their degradation rate in vivo was longer compared with many polymers, and they may be capable of long-term delivery.